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Re: Coughing/popping when revved
[Re: bonefish]
#1585405
02/28/14 02:36 PM
02/28/14 02:36 PM
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Joined: Sep 2006
Posts: 3,009
Sac, CA
mopowers
OP
master
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OP
master
Joined: Sep 2006
Posts: 3,009
Sac, CA
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Quote:
sounds like it could be 180 out.have you had the dist out?
I have. Other than the popping, it runs and idles fine. Would it run well if the distributor was 180 out? Either way, I'll verify it tonight though. Thanks
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Re: Coughing/popping when revved
[Re: mopowers]
#1585408
02/28/14 03:14 PM
02/28/14 03:14 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Bad plug or plug wire. Accel pump (insufficient stream amount/duration). Possible vac leak as you noted. rotor phasing/reluctor gap issues
live every 24 hour block of time like it's your last day on earth
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Re: Coughing/popping when revved
[Re: buildanother]
#1585409
02/28/14 03:55 PM
02/28/14 03:55 PM
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Joined: Sep 2006
Posts: 3,009
Sac, CA
mopowers
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Quote:
Agreed it can't be 180 out, and have you verified no round cam lobes. Isn't this an ongoing problem from an earlier post? 
I've been trouble shooting this for a little while. Unfortunately, my time's been taken up by other things. Go figure... I have not verified round cam lobes. What's the easiest way to do this? Pop the intake?
Quote:
Bad plug or plug wire. Accel pump (insufficient stream amount/duration). Possible vac leak as you noted. rotor phasing/reluctor gap issues
I don't think it's an accel pump problem since it happen when the rpms are brought up slowly. It usually happens around 1800-2000 rpm.
I actually had the distributor apart to limit the mech advance and noticed the reluctor wheel was off by about 1/4". The roll pin was gouged into the branze shaft collar. I've since corrected it and and the gap and it didn't make a difference. I haven't checked rotor phashing though. It's gotta be better than when the wheel was way off. Or maybe that's why whomever did it, did it???
All the plugs look fine. Should I go ahead and replace them? Maybe one at a time?
Other than replacing the plug wires, is there an easy way to test plug wires to find a bad one??
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Re: Coughing/popping when revved
[Re: 71yelladustr]
#1585411
02/28/14 05:36 PM
02/28/14 05:36 PM
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Joined: Sep 2006
Posts: 3,009
Sac, CA
mopowers
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Quote:
 about checking for a flat cam. Pull the valve covers and crank it over with the coil wire off. If one is flat you will see a noticable difference in movement of the rocker arm on the one that is flat. 
I guess that'll be first on the agenda to test then. Man, I sure hope that's not the issue. If it is, there's definitely gonna be a few beers tossed back.
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Re: Coughing/popping when revved
[Re: mopowers]
#1585412
02/28/14 06:24 PM
02/28/14 06:24 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Posts: 36,040
Lincoln Nebraska
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Sounds like the plugs are OK & likely the wires are also & I'm assuming 5/7 ain't crossed. I would ohm them & wiggle the ends as you watch the meter & power brake the eng at midnight with the hood open & see if there's a light show (grab a helper). You really need a vac pump (they're pretty reasonable) to check phasing/gap as the vac adv (only) alters phasing and gap so the pump lets you check em anywhere from no vac (what you have if on ported at idle) all the way to full vac. Holler how it turns out & what it ends up being
live every 24 hour block of time like it's your last day on earth
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Re: Coughing/popping when revved
[Re: RapidRobert]
#1585414
02/28/14 07:07 PM
02/28/14 07:07 PM
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Joined: Sep 2006
Posts: 3,009
Sac, CA
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Quote:
Sounds like the plugs are OK & likely the wires are also & I'm assuming 5/7 ain't crossed. I would ohm them & wiggle the ends as you watch the meter & power brake the eng at midnight with the hood open & see if there's a light show (grab a helper). You really need a vac pump (they're pretty reasonable) to check phasing/gap as the vac adv (only) alters phasing and gap so the pump lets you check em anywhere from no vac (what you have if on ported at idle) all the way to full vac. Holler how it turns out & what it ends up being
I've double and triple checked. firing order is all good. Engine fires up fine and ides clean and smooth at 850rpm.
I will definitely check for a light show in the dark.
What do you mean by 'ohming' them. I'm assuming you mean checking the resistance? Can I use a regular multimeter? How exactly is this done?
I do have a vacuum pump. When I had the distributor out, I noticed the reluctor gap closes a bit when vacuum is introduced. However, since trying to diagnose this issue, I've had the vac adv disconnected and the port on the carb plugged.
So, after checking the plugs and wires for resistance and shorting and checking for a rounded cam lobe, what next? Should I replace the orange box with a parts store replacement temporarily to see if that changes anything?
Thanks so much for the help. This is starting to get really frustrating.
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Re: Coughing/popping when revved
[Re: mopowers]
#1585415
02/28/14 07:12 PM
02/28/14 07:12 PM
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Joined: Jun 2006
Posts: 5,159
CT
GTX MATT
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master
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Did you reinstall the reluctor wheel in the correct position? I believe they're are two.
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: Coughing/popping when revved
[Re: Paul_Fancsali]
#1585418
02/28/14 07:21 PM
02/28/14 07:21 PM
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Joined: Sep 2006
Posts: 3,009
Sac, CA
mopowers
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Quote:
Engine grounded/ control box grounded ? First step would be check and be sure wires are in correct order, second check coil output. The dist here is very suspect I would pull it and replace it with known good dist. If that does not work get a advance timing light and see what timing you have when it pop's I try getting mine to 38-40 degree's total If it talks turn it back if not give it more you could have damper that is going off by ring slip{ not Likely but possible if original}Also a vacuum leak will do the same Thing valve springs can do it also{ not likely}
Engine has a good ground. Haven't checked the control box ground though. I will!
How do I check coil output?
Since I don't have a spare distributor, should I go buy a parts store replacement and try it? They probably have one in stock.
I've double checked the dampner mark with my TDC tool. It's only off 1*.
Haven't been able to find a vacuum leak.
I will pull the valve covers this weekend and give the valve train a looksee.
Thanks so much for the input guys. Keep it coming!!! Sounds like a have quite the laundry list to go over this weekend. I really appreciate it guys!
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Re: Coughing/popping when revved
[Re: mopowers]
#1585420
02/28/14 08:03 PM
02/28/14 08:03 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Posts: 36,040
Lincoln Nebraska
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Yes check the resistance with your multimeter on ohms (probably the K range). Clip the meter tips to the plug wire ends with some extra alligator clips so your hands are free so you can wiggle the plug wire ends as you watch the meter. if you disconnected the vac adv & set the gap at .008" then the reluctor gap ain't the problem. For the phasing turn the housing till a reluctor tooth is dead even with the magnet. set the rotor on the shaft. install the cap & make a mark on the top circumference of the metal housing just below where the cap sets plumb vertical from the center of the cap terminal "bulge" closest to the rotor. Take off the cap & see how far the rotor tip centerline is from your scribed mark. Then pump up the can & hold it & turn the housing till the tooth is back dead even with the magnet. See how far the rotor is now from your scribed mark & note that vac adv will shift rotor phasing CCW on a SB and CW on a BB. Not sure how much gap will suffice before the available voltage is less than the required voltage (varies with every ign setup) & also an excessive radial distance between the rotor tip and the the cap terminals aggravates this (NAPA Echlin MO3000 rotor with a .060" longer metal tip helps with this-$8 & change out the door or make your own longer one) but post what you get. You have the circumferential distance (phasing) & the radial distance & if the total distance of both is too much it will misfire (more so) under load when the required voltage is the greatest but it sounds like you ain't under alot of load at that time so.... Keep us updated
live every 24 hour block of time like it's your last day on earth
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Re: Coughing/popping when revved
[Re: RapidRobert]
#1585421
03/01/14 01:45 PM
03/01/14 01:45 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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It's not a flat camshaft. You'd notice that at idle. It's ignition.
With an inductive pickup timing light, the one where it clamps over the wire, check every wire up to the rpm range where it starts missing.
In other words, put the clamp on the #1 wire, pull the trigger and watch the flashes as you go through the rpm range where you get the miss. Do this for every cylinder.
You will probably find that one or two cylinders have gaps in the flashes as you get into the range where you notice misses.
When you have narrowed it down to two or however many cylinders, change the plugs in them and retest. If it still keeps happening, swap wires with known good and retest.
I believe that what you are seeing is the result of carbon tracking or a bad plug, and when the cylinder pressure reaches a certain amount, the resistance across the plug gap is more than the resistance through the carbon track or plug. Voila! Misfire happens.
Last year I changed the plugs and wires on my wife's 4-cylinder, using Autolite plugs and Beck-Arnley wires. After a few months the car would occasionally have a stumble at idle, just enough that you'd notice it. I couldn't figure it out.
I was out of town, so she took it to the local garage and the guy correctly diagnosed it as ignition problems. There was carbon tracking in the plug boots. I would have never expected that as I had used new brand-name parts specifically built for the engine in question. But, changing the wires and plugs solved the problem completely!
R.
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Re: Coughing/popping when revved
[Re: dogdays]
#1585422
03/03/14 02:08 PM
03/03/14 02:08 PM
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Joined: Sep 2006
Posts: 3,009
Sac, CA
mopowers
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SO, I knocked out a few things on my list this weekend. Not as much as I wanted, but here's what I did (in no particular order): I double checked the grounds under the orange box- no change. I swapped the orange box with a cheap parts store replacement- no change. I currently have it timed at 20* initial and 35* total. I tried 10*, 15*, and 25* initial- no change I put a timing light on each plug wire and brought up the rpms until it starting popping. I couldn't find the cylinder with an inconsistent flash. I even did this in the evening and couldn't find anything. I ran the car at night to check for shorts along the plug wires. I actually saw one flash one time. It looked to come from either the 1 or 3 cylinder near the plug. This only happened once and I could not duplicate it, even though the popping persisted around 1,800 rpm. I forgot I loaned out my multimeter, so I wasn't able to ohm the plug wires. I plan on borrowing one from my neighbor today or tomorrow to check those. Still need to check rotor phasing as well. Something I did notice was that sometimes when it pops, it'll start the starter spinning. And sometimes the starter will make a loud shreaking sound. Not sure what all that is about... I was able to get a video of the popping. Hopefully this shows up. The quality is bad but you can hear the popping as I bring up the rpms. 
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