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computer reaction to engine mechanical problems #2678304
07/17/19 01:34 PM
07/17/19 01:34 PM
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volaredon Offline OP
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I have a thread about a new set of EQ heads that I have problems with out of the gate
Not getting answers on this part of the problems so it was suggested that I change the thread title to maybe get some answers on that part of the problem.
01 Durango, 360, 258k miles

I fought an issue for a few months with a #6 misfire that wound up being internal to the computer. Thought I had that solved but not sure.i overhauled the engine for other reasons, and put a brand new set of heads on it in the process. Upon the initial test drive when the engine was reinstalled it crapped out on me. Among other things I found out that my heads were set up with too little valve clearance, 1 exhaust valve stuck open and got bent. While out on that test drive which was all of about 4 miles (was more, but I'm not counting the distance I had it on the back end of a tow strap to drag it back home)

While waiting for my son to bring his truck to get me. I tried to restart it and it wouldn't. I got out and saw my whole exhaust glowing cherry red. Ended up melting down a brand new cat converter.
Once it cooled down (it never did overheat) I hooked up a scanner and don't remember everything but I do remember that my injectors on time was almost 6 times what it should have been at idle.
I'm sure the extra fuel was what killed the cat. What I need to know is how the computer would be expected to react to such engine problems.
In other words if I put this other engine back in there that doesn't have the problems that the 1st overhauled engine did, and put the so same computer back in there with all of the same (brand new) sensors that were on the engine that had the valve problems, can I expect a repeat? Or should I send the computer back to the place that repaired it the 1st time?

In case it matters at this point, nothing has been modified. All is stock or "stock replacement"/oem equivalent
I have a couple of things that I would like to change up on it but none of that will happen until I am completely certain that it is running like it was designed to be, first. No sense adding "possible causes" of any problems to the mix.

Last edited by volaredon; 07/17/19 01:35 PM.
Re: computer reaction to engine mechanical problems [Re: volaredon] #2678372
07/17/19 05:39 PM
07/17/19 05:39 PM
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I would like more specific information. Like exactly what happened, specific symptoms please, not crapped out. That tells me nothing. Also what were the other reasons for the overhaul? And what does injectors on time mean?

As a side note new converters need to be lit off so seeing them glowing red is not necessarily bad.

I'm also assuming that your description of too little valve clearance is stem to guide clearance and not valve to piston clearance correct?

Last edited by Guitar Jones; 07/17/19 05:42 PM.

"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: computer reaction to engine mechanical problems [Re: volaredon] #2678387
07/17/19 06:06 PM
07/17/19 06:06 PM
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The computer will remember nothing of the 1st engine if its been disconnected from power for any significant amount time.....assuming its a factory puter we're talking about

Last edited by HemiRick; 07/17/19 06:07 PM.

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Re: computer reaction to engine mechanical problems [Re: HemiRick] #2678392
07/17/19 06:25 PM
07/17/19 06:25 PM
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For an engine that is stock..something there is wrong for sure...need more info or readings from your scanner

Re: computer reaction to engine mechanical problems [Re: HemiRick] #2678431
07/17/19 08:02 PM
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volaredon Offline OP
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Originally Posted by HemiRick
The computer will remember nothing of the 1st engine if its been disconnected from power for any significant amount time.....assuming its a factory puter we're talking about
yes I know that.... that is not what I am asking. I had fuel injection issues with this thing that I thought I had resolved, shortly before I swapped a completely stock rebuilt engine in there, and am wondering for one thing if the failed, fresh engine had anything to do with the prior issue. or if the issue I discovered with the heads, caused the computer and fuel system to react how it did.

OK get your popcorn or beer or Raisinets or whatever your favorite "movie food" is, here's the story.

I bought this 01 Durango about 6-7 years ago, with 214k miles on it. It had the highest of miles of any vehicle that I have ever bought. Yeah, I know a lot of miles but it was all "road miles" and it was a southern vehicle, very clean and rust free. It had only been in the Chicago area for a month when I got it. It is the 360, version but not an R/T. Upon buying it, I immediately did a full tuneup, replaced all belts and hoses and more preventive maintenance type repairs.
It did us great, including trip to Houston and back, serving as my wife's daily driver, and pulling my camper a couple of times in between, until it got to about 250-252ish K miles, when I started getting a chronic Cyl 6 misfire. At first it would only show up as a code, but it never "felt" like it was running bad at first. I did a complete tuneup at that point, using premium grade parts, (cap rotor wires, plugs, PCV and air filter) and it persisted. again, it didn't run like it had a miss at this time. I took the injectors into a Bosch certified fuel injection place that deals with both gas and diesel injectors, to test, flush, and rebuild them. Was told they "needed a good cleaning" but were all otherwise fine. and flowing equally.
STILL had the misfire code.

We just drove it a bit more, because it ran fine. Then it started running bad, as I remember. Its been 3 years ago now since then. I did a compression test and all cylinders on that bank were still around 150-155 PSI. Pretty good for an old engine. I tried swapping spark plugs, injectors and plug wires to see if the misfire would "follow" any of those parts to a different cylinder. It remained on cylinder #6. so I sent the computer into a place that reconditions automotive computers that was recommended to me, for diagnosis. and I went thru the whole wiring harness looking for trouble there. None found. The computer came back "repaired" as they had apparently found reason for my misfire in some loose solder joints.

By now the oil pressure was getting low ( 258K (HIGH) MILES!) and the engine was starting to get some bottom end noise. THAT'S the reason that I went and found another engine/ which I treated as a "core," and tore it down, sent the block and crank into the machine shop for all of the necessary machine work, bought all new pistons, bearings and rings to match the machine work that was done, bought the new heads, took them out of the box, and bolted them on the fresh engine. all while still driving it as needed, got 2nd engine to minimize downtime... or so I thought.
The engine that I bought and rebuilt, was out of another 2001 Durango. Identical replacement.

I also replaced the cat converter, the fuel pump, the muffler, both O2 sensors, and ALL tuneup parts (again) along with the rebuild, AND rebuilt the transmission at the same time with a reman tq converter installed, at the same time. I was setting this rig up for the "long haul" and I must say now, if I hadn't yet/ that all work done, all parts replaced were "stock replacement" (though most were bought aftermarket) and that I didn't "cheap out" on anything, and bought the best grade available of those parts on which there was a choice. Nothing was "modified".

I also went to the junkyard during this, and found another 2001 Durango 5.9 computer and when plugged into mine, it would only start/quit/ start/quit start/quit. the damn SKIM system. I hate computers. So I sent the original computer and this one back to the rebuilder, and asked them to recheck the original, or else to ONLY program my VIN into this replacement computer. "Please get me ONE good, functional computer" They did both, saying that the original computer repair needed a redo, that they were sorry about any problem, that the original tech that worked on the original computer from the Durango "no longer worked there" as they made it sound like they had had "issues" with that person and the work they had been doing.
They returned both, having done as I had requested, "no charge" saying that they "ran them on a test vehicle on site" and they were "working as designed" they sent these computers back both with a "lifetime warranty" and recently I called them and asked, they said they'd recheck their work "no problem" if I send them in/ IDK if I can trust the original one anyways, having been into "for the same issue" twice now. Initial computer rebuild, was shortly before the engine rebuild. both original and junkyard computers stacked on workbench currently collecting dust.

When I initially got the rebuilt engine into the Durango, it seemed to run fine, while idling in my garage, while I ran it at "break in" RPMs/ I put new lifters in during the rebuild, but the original cam that this engine had come from the factory with. I ran it to temp that night, set SYNC, then let it cool, repeated that the 2nd night, the 3rd night I started it up and let it warm up, then decided to take it for its maiden voyage.
It went poorly, to say the least. I live in the country so I can drive "however," as conditions warrant. so I tried to build up to 60MPH. Accelerated normally, no "holeshots" or anything like that. I never made 60MPH. I think I got to 50 or so during the whole 4 miles it ran. at this time I put it to the floor to see if that would help, it didn't. it topped out at 50, and was losing that.... It ran like I would expect one with a weak fuel pump to run. but the fuel pump was replaced upon the engine rebuild, and once I got it home and started evaluating things (the next night) I tested fuel pressure and it was dead nuts on spec.

On the test drive... pulled out of my subdivision, went ~300 yards, made left turn. for the 1st 1/2 mile, speed limit was 35, so I didn't get crazy. at 1 mile is a STOP sign. After leaving STOP sign I tried to get up to 60, never got there. at 2nd mile I made a left turn. died. started right back up. went 1 mile. went to turn left again. Died again. Wouldn't restart. Called my son for his truck and a tow strap. Was looking around under the hood while I waited for him. Was dark out, was easy to see the whole underside of the Durango ahead of the muffler glowing cherry red. and yes I melted the cat. I looked thru it before I installed it, and again after I removed it, in prep to pull the engine again, and it was a melted blob. not just "lit off"...

I got it to start the next night, I plugged in my scanner and I don't remember all of the parameters, but one that I do remember, was having an injector "on" time of 17.some milliseconds at idle, when I was expecting to see around 3-4 milliseconds. At this point because I had been "everywhere else" on this engine, I went to a junkyard and found an intact looking wiring harness from another 2001 Durango with the same engine as mine has, bought it and installed it. tried running engine, no change. "grasping at straws" at that point, would the long "on" time be a result of the stuck valve, or because of the clogged exhaust, not being able to breathe at that point?

and the reason that I decided the engine had to come out again was that at this point I drained the oil to do the "break in" oil change, engine had 2-1/2-3 hours on it at this point. and it came out as a silver slurry like I have never seen, fresh rebuilt engine or not. This was NOT my 1st engine rebuild, probably (at least) my 10th. and I have done my son's 360 since, with no issue.

at this point I was pissed, put it on the other side of the garage (inside), and told my wife to take my 2nd Dakota.... and let the Durango sit. I had to cool off. I had never experienced any of these issues, let alone all of them on one overhaul.

fast forward almost 3 years... I parted out and junked a 92 318 Dakota, which has been my faithful daily driver for the previous 3 years and over 60K miles. Trans issue, something major ate itself, and it wasn't as nice as this Durango is, body showing its age, so my wife and kid talked me out of fixing the trans. so even with 226K miles "I know where this engine has been" and it still ran fantastic with minimal oil consumption, so my initial thought was to just stab this longblock into the Durango. The wife has been on me, she absolutely loves driving it for some reason. and all I see around for sale like it, are rotted out. This one that I have, isn't.

In the meantime I found a 136k mile 360 magnum on CL, out of a 2000 Durango RT (yes I know the RT means nothing about "hi perf" with that engine, vs the one in my SLT, I have seen that come up over the years, the Durango that this engine came from being an "R/T," is nothing but a coincidence)

I bought this engine, and decided to re gasket it while it was out, as a preventive maintenance precaution before I stab it in, and decided that as long as I pulled the heads "anyway" to replace the head gaskets "while I had it out," I wanted those new heads on this engine that had cost me $700 a few years ago. $700 is a lot of money to me. To some it may not be.

It wasn't until I went to pull that new set of EQ heads/ with the intention of putting them on this short block, that I did anything with the Durango, or the engine that I rebuilt for it, since the initial job went to $#!t. and while pulling that set of heads, first I discovered a badly bent #4 exhaust pushrod. Then I found the #4 exhaust valve "hung open" when I pulled the valve covers.
I got the heads off and discovered a witness mark on the #4 piston and aforementioned exhaust valve bent. I also discovered, upon pulling these heads back off, that the valve chambers in cylinders 1,2,3 look like a set of heads that had been bolted on and pulled right back off, without having been run. Valve chambers on cyls 4-8 were blacker than coal// and obviously had been fed way too much fuel.

I have never had to deal with sticky valves on a car or truck I have had a couple of tractors that came to me with stuck valves from years of sitting outside before I got them which I had to free up in order to get them going, (mostly Kohler, single cylinder cast iron) but that is different from this situation.
I will add at this point, that I am a fleet mechanic for the State of Illinois, have been for 6+ years, and was an alignment/brake guy for ~20 years before I got this job, I deal with cars daily. Not my 1st rodeo.

I still have the original engine that was in this Durango, sitting on a dolly in my garage too. All that has been done to it was to pull the right side head for a quick look to see if I had a sunk valve or something. so I have the original engine, the one that I rebuilt, and this one that I just bought off of CL that I am getting ready to drop in there, so that we can drive this thing for the 1st time in nearly 3 years. I have plans for that original engine, and the failed rebuild too, depending on what I find when I get it back onto the stand. My son wants to build a "stroker" out of one of them.

so after all of that, (which was asked for, so I answered) this is partially a "chicken or egg" kind of inquiry, am wondering if the sticky valves/ and the resultant delayed closing/ bleedoff of compression, had anything to do with the computer dumping so much fuel, because of what the computer might have "seen," or if there might be "something else" going on.
I DO NOT WANT and CANNOT AFFORD a repeat. Those damaged heads are at the machine shop, I was told by the machine shop, upon their teardown, that they were "set up from the factory" with all of the stem to guide clearances, too tight. They had to pound out all of the exhausts once they had the springs off. I'm finding more and more reports of the same problems with EQ heads, mostly from right around the same time frame that I bought that particular set of heads and put them onto my engine. which would have been Oct of 2016.
the hope is that I get this other engine prepped and installed and wired up, that this was the extent of all the problems, that they were "all" caused by the too tight valve clearances, and NOT some other underlying issue.

This Durango will be with us until it rusts itself into the ground. I almost bought a 2018, Hemi, 1500 reg cab with an 8' bed recently..... but walked away when I found out that I would be on the hook for 7 long years. I had always said I would never again do a 5 year loan/ as I had done in the year Y2K on my Wrangler..... so if I wont do 5 years, I sure in the He11 don't want 7 years of payments! This Durango did us well and can/will do so again. My monthly payments are exactly $0.00 and will be as long as I own it. as is the monthly payment on all of my vehicles (this happens to be the newest by "model year" only... next closest, and it happens to be my most recent purchase is a 99 Dakota) I want a rust free square body D/W series truck again.

Even if they were "free", I do not like newer vehicles. Too costly, too much plastic and too much "offshore" content, not enough steel for me. Working on newer vehicles makes me appreciate my 78 Sport Fury that much more. seeing 2010-13 F150s at work, with so much rust already, sure doesn't inspire me to go buy anything that new.

I would appreciate some "general" talk about "how a computer might react" and what the sensors might be seeing, to cause the computer to react such a way, with various mechanical engine issues.

Re: computer reaction to engine mechanical problems [Re: AARCONV] #2678432
07/17/19 08:03 PM
07/17/19 08:03 PM
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volaredon Offline OP
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Originally Posted by AARCONV
For an engine that is stock..something there is wrong for sure...need more info or readings from your scanner

It has been 3 years I only remember a couple of things about it from back then.

Re: computer reaction to engine mechanical problems [Re: volaredon] #2678472
07/17/19 10:17 PM
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ok posting to get this thread next to original thread about the EQ head problem for reference.... (for the moment anyway)

Re: computer reaction to engine mechanical problems [Re: volaredon] #2678646
07/18/19 12:19 PM
07/18/19 12:19 PM
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I believe you may have had a very small head gasket problem with the first engine. If the wiring is bad or an injector shorted, open or otherwise inoperative you should get an injector code. It only takes a very little amount of coolant leaking into a cylinder to set a misfire code.

All your subsequent problems are from the new heads with the tight valve guides.


"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: computer reaction to engine mechanical problems [Re: Guitar Jones] #2678661
07/18/19 12:54 PM
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Originally Posted by Guitar Jones
I believe you may have had a very small head gasket problem with the first engine. If the wiring is bad or an injector shorted, open or otherwise inoperative you should get an injector code. It only takes a very little amount of coolant leaking into a cylinder to set a misfire code.

All your subsequent problems are from the new heads with the tight valve guides.


That (original) engine never used a drop of coolant, I've seen what a combustion chamber that has taken on antifreeze looks like, usually very clean vs the rest. The original engine was pulled when the oil pressure started to tank, and it started to rattle at idle from the bottom end.
I was wondering how many of the other issues since I replaced the engine were from the tight valves, I'm really hoping that to be the case.
But being as how the place that I sent the computer to, as much as said that they found issues within that could cause a misfire code, and when it last ran it was dumping fuel, I can't help but wonder if there's still an issue there.

What would the computer have "seen" on account of the tight and slowly closing valves that would make it react like that??? Just for future knowledge more than anything

Re: computer reaction to engine mechanical problems [Re: volaredon] #2678681
07/18/19 01:23 PM
07/18/19 01:23 PM
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Originally Posted by volaredon
Originally Posted by Guitar Jones
I believe you may have had a very small head gasket problem with the first engine. If the wiring is bad or an injector shorted, open or otherwise inoperative you should get an injector code. It only takes a very little amount of coolant leaking into a cylinder to set a misfire code.

All your subsequent problems are from the new heads with the tight valve guides.


That (original) engine never used a drop of coolant, I've seen what a combustion chamber that has taken on antifreeze looks like, usually very clean vs the rest. The original engine was pulled when the oil pressure started to tank, and it started to rattle at idle from the bottom end.
I was wondering how many of the other issues since I replaced the engine were from the tight valves, I'm really hoping that to be the case.
But being as how the place that I sent the computer to, as much as said that they found issues within that could cause a misfire code, and when it last ran it was dumping fuel, I can't help but wonder if there's still an issue there.

What would the computer have "seen" on account of the tight and slowly closing valves that would make it react like that??? Just for future knowledge more than anything


Without having access to the sensor readings it's hard to say. There certainly would have been a diluted fuel air mixture, missfires and who knows what else. If there was a code(s) set then a look at the freeze frame data would give some insight. I'm sure the O2 sensor readings were off.


"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: computer reaction to engine mechanical problems [Re: Guitar Jones] #2678733
07/18/19 03:55 PM
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Long darn post, but I hope the troublesome lower plenum gasket was addressed during all this mayhem.

Re: computer reaction to engine mechanical problems [Re: buildanother] #2678740
07/18/19 04:28 PM
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At this point, the only thing that makes any sense to me is to have the EQ heads repaired, put them back on...... put the motor back in.

Should be able to read what’s going on with the sensors, etc, in real time with a scan tool..... right?

If things look amiss, try the other computer.

I really don’t ever work on computerized engines at all, but I seem to remember having a conversation with someone once about breaking in a new motor in a car with cats, and they were saying how running at a high idle without the car moving and having air running around the cat that they can overheat and fail.
I don’t know if this is true or not....... but perhaps there’s some truth in it, and your two night garage run in sessions compromised the cat from the start.


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Re: computer reaction to engine mechanical problems [Re: buildanother] #2678869
07/18/19 09:33 PM
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Originally Posted by buildanother
Long darn post, but I hope the troublesome lower plenum gasket was addressed during all this mayhem.


yup it was, originally with all stock plate and screws (did not bottom out as some claim) but now that engine is back apart I bought an aluminum plate for it.

Re: computer reaction to engine mechanical problems [Re: fast68plymouth] #2678877
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Originally Posted by fast68plymouth
At this point, the only thing that makes any sense to me is to have the EQ heads repaired, put them back on...... put the motor back in.

Should be able to read what’s going on with the sensors, etc, in real time with a scan tool..... right?

If things look amiss, try the other computer.

I really don’t ever work on computerized engines at all, but I seem to remember having a conversation with someone once about breaking in a new motor in a car with cats, and they were saying how running at a high idle without the car moving and having air running around the cat that they can overheat and fail.
I don’t know if this is true or not....... but perhaps there’s some truth in it, and your two night garage run in sessions compromised the cat from the start.



I hadn't heard that about frying a cat, you could be right.... don't know. but it wasn't glowing until after that 3-1/2 miles that I attempted to drive the thing.

the EQ heads were in the machine shop with that intention, as you say to do, before I came here to post.... the EQ heads are going onto the 136K mile engine, that I recently got off of CL. and THAT engine is going in, just using the shortblock, the rest is brand new parts that I had already replaced on the original rebuild. and the intake off the CL engine had a bit more erosion around the water ports than I feel comfortable with (probably would have been fine) the best of the 6 or so stock intakes that I have here collecting dust, is going on in its place. The water pump, hoses, and tuneup parts were all brand new, so those are staying on the truck.
and yeah just like last time it will have the scanner connected before I hit the key for the 1st time when it goes back together.
and yes, I seriously thought about going with a different intake and a 4 barrel Edelbrock carb on this thing. do away with the damn computer.

I do have a couple of small mods I'd like to do on this thing, (that I'd figured on originally, after it was broken in) but not until I make sure all runs as intended in stock form, 1st.
Nothing serious, just a set of stainless shorty headers, a set of 1.7 roller rockers, and maybe a slight tune..... not sure on that last part....
I want to initially run this thing without a cat, til I make sure that it won't kill the next one... they aint cheap. I forget what I paid for the one that died, but as I remember it was a Magnaflow.

can anyone tell me what the computer was seeing, that would have caused it to dump so much fuel? (IF it wasn't because the computer is also FUBAR) and why it was only the cylinders "as the block is numbered" including and after the one that bent the pushrod and bent the valve, and not the 3 ahead of it?

Last edited by volaredon; 07/18/19 09:58 PM.
Re: computer reaction to engine mechanical problems [Re: volaredon] #2718748
11/23/19 09:18 PM
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a long overdue update

well I'm up and running again, took my sweet time between the "kid glove" treatment, and still being PO'd at this vehicle and situation, haven't been in a hurry to get it going (have 4 vehicles for 2 drivers so haven't been a huge sense of urgency)
got the heads back.... according to the machine shop, many intake valve guides were tight as well as the rest of the exhausts....fixed now. . engine's in, got ~300 miles on it.... so far so good, but there was 1 other issue with the setup that was a contributing factor...
.
The stock original injectors from the Durango (were on the original engine when I bought the rig) were BAD.... I had taken them in for flush and test and rebuild, shortly before that engine came out when I was fighting the original cyl 6 misfire.....and came up "GOOD" under flow testing at the injection place back then''' there were issues with a couple, back then/ but I had some identical spares laying around, that I took to the injection shop, were given "the treatment" and was told they were "fine".... but in the end, they weren't// and contributed to a lot of frustration and extra cost, in getting thru this issue.
they were put onto the 1st engine that was overhauled, and which gave me the silver slurry when I did the initial "break in" oil change.... something else I had never seen. I guess the excess gas had diluted the oil in the cylinders, and thinned my oil, unknown to me at the time. remember... this 1st engine had a whole 3 HOURS, of run time, on a fresh total rebuild.

I put the injectors on the 2nd engine, the CL used engine that I only regasketed, replaced the timing chain on, and bolted the now, fresh valve-jobbed EQ heads onto it.
Not a total overhaul like the 1st engine got. But put the same set of injectors on that had come off the original, and had gone onto the rebuilt, and now onto this engine. Upon initial getting going, I could tell something still wasn't right, but was having trouble diagnosing...… a lot of " that can't be the problem... that and that and THAT were "just" replaced.... cant be bad...…" was a major mental block for me in figuring this mess out...but it was now apparent that the remaining problem was going to be a part that I had just replaced, with the initial rebuild....
I put new O2s on this thing AGAIN with this replacement engine, I wish I could tell you how many O2s I have put onto this rig since I have owned...… and the upstream was blacker than coal in no time. so now what.....and I replaced the car with a pipe "for now," so I don't burn up another... while I was putting the exhaust back on this thing from the 2nd engine replacement, I had a chunk of melted cat come out of the Y pipe that I didn't know was in there.... from the 1st replacement cat, as the original cat hadn't melted down, even though it had been giving me a PO420 before I went thru all of this mess.

I was ready to scrap both computers I have for this and buy another...…

but I thought about it some more, and "let me try 1 thing 1st"..... I had an injector rail that Id gotten from a buddy, leftovers from his project.... 360 fuel rail off an 01 Ram 1500..... but he had swapped a set of 4.7 injectors onto his original rail.... new injectors, not a lot of miles but had been sitting several years. it was "something".... and I knew that his truck had run perfectly fine with these injectors. His truck was the same year ,with the same engine as mine. so "why not" can't hurt at this point, and "success," world of difference.... "replace with known good part"..... and that was the rest of the answer.... there was a problem with those original injectors as well that I wasn't recognizing, with all the rest of the mess. It was the injectors, not the computer.

I ran it as long as I could with a straight pipe in place of the cat, and after about 170 miles I got the CEL and the dreaded PO420.... so I had to put another d@mn cat on the stupid thing to keep the light off.... I was really hoping not to..... I had the same "cheat" in place that shut the CEL and code PO420 off for the duration of the original motor and cat being in place....worked with a so/so cat but not with no cat.


have since replaced the rear leafs with brand new, all 4 shocks, all bushings in front with poly, (including sway bar, bushings in all 4 control arms, and rack mount bushings) and a fresh alignment and so far so good with this thing...… now to drive it til it rusts into nothingness...…
on the initial rebuild and such, I had been SO careful not to screw anything up, and in the end it was 2 things that I paid someone else to "make sure all is right with" that bit me in the azz.... the injectors and the new, so called "ready to run" heads, that definitely weren't "ready to run"....

Re: computer reaction to engine mechanical problems [Re: volaredon] #2720450
11/30/19 02:32 PM
11/30/19 02:32 PM
Joined: Jan 2016
Posts: 45
Illinois
S
SIX225 Offline
member
SIX225  Offline
member
S

Joined: Jan 2016
Posts: 45
Illinois
You said you rebuilt the engine. Doesn't the distributor (cam sensor) need to be timed/synced to the crank position sensor. I think you need a scan tool to do this. Had a misfire condition on my '98 Durango that was intermittent. Don't remember the final fix, but I did replace the pickup in the distributor and replaced ignition wires that weren't all that old. Didn't retime it because I didn't move the distributor body. Another thing that caused some other varying intermittent problems was frayed wires in the upper steering column at the ignition switch.

Re: computer reaction to engine mechanical problems [Re: SIX225] #2720460
11/30/19 02:52 PM
11/30/19 02:52 PM
Joined: Jan 2008
Posts: 2,195
ILLINOIS
V
volaredon Offline OP
top fuel
volaredon  Offline OP
top fuel
V

Joined: Jan 2008
Posts: 2,195
ILLINOIS
I was long past setting sync when this issue came up. Wound up being a combination of the bad heads and some injectors that were stuck stuck wide open.







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