Just picked up a 92 Dodge Colt for fuel economy reasons, but it needs a fair amount of work. Biggest problem: Injectors for cyls. 1 & 2 aren't firing.

How I'm testing: I pulled the fuel rail w/ injectors out of the intake enough to place a drinking glass beneath the injector under test, with only the electrical connector for that injector connected. With key in run position, I used a remote starter button to crank the engine.

The injectors in question are OK, as I jumped them to the connector for cyl. 3 and they sprayed just fine (as well as a resistance check; all 4 @ around 14.5 ohms). Also tested resistance to ground of each pin of each connector. The 2 bad ones measure roughly the same as the 2 good ones. This tells me that I may have a marginal connection (somewhere between the connector and the computer) that is opening under load, but I don't know much about these cars or their common problems. Anyone very familiar with these guys? HELP!

Don`t take this wrong....I really can`t believe one of those is still on the road.....that said....It`s been a while since I delt with those but here goes,
First check that you have battery voltage to the 2 dead Injectors while cranking..I don`t remember exactly which years but alot of the Mitsu`s had what to you should look like a slightly large ballast resistor on the firewall or core support, It is porcelain with 5 wires and is a dropping resistor pack for the injectors 12 volt feed and are prone to failure.
When you check for voltage at the injectors, use a test light as you need to load the circuit, a DVOM won`t do it.
If you have voltage at the injector feeds then start tracing the injector grounds back to the ECU.
Verify spark to those 2 holes even though you know the injectors are not firing, this will confirm that the Cam angle sensor is ok.
If that is all ok then it is possible the ECU has succumbed to the all to common 5 volt line capacitor failure internally or it lost a couple of injector drivers.

Hope that helps
Rick

Check a wiring diagram. I had a Toyota that had 2 dead. It was a shared injector ground at the ECU (batch fired). Cleaned the connector and it lived.
See if the 2 share ANY wiring to narrow down the issue.

To Rick,

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Don`t take this wrong....I really can`t believe one of those is still on the road.....

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LOL - no offense taken! 185,000 mi. for $350! Hope I didn't pay too much! (Timing belt scenario scares me next, as I have no maintenance records, and it's an interference motor.)

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...alot of the Mitsu`s had what to you should look like a slightly large ballast resistor on the firewall or core support, It is porcelain with 5 wires and is a dropping resistor pack for the injectors 12 volt feed and are prone to failure.

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Sounds familiar. I'll have to check it tomorrow, but that makes a lot of sense (something opening under load, as a power resistor might). Thanks for the reminder about the test light for a load, too.

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If you have voltage at the injector feeds then start tracing the injector grounds back to the ECU.

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I'm trying to track down some service lit at the moment to get the connector pinout at the ECU to aid in tracing. Would there be only one ECU? Looks like one below the dash, in the center, behind the console.

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Verify spark to those 2 holes even though you know the injectors are not firing, this will confirm that the Cam angle sensor is ok.

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All wires have spark. I figured this car has a simple ECU & sensor system, so I didn't think a cam or crank sensor problem would cause a failure to half the injectors consistently, but I may be wrong.

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If that is all ok then it is possible the ECU has succumbed to the all to common 5 volt line capacitor failure internally

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Sounds like a high ESR (dried up electrolytic cap) problem? And I hope it hasn't lost any injector drivers. I've been able to find some Mitsu Mirages in the junkyard so far, but my chances of finding a Colt for an ECU will probably be slim to none.

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To RodStRace,

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It was a shared injector ground at the ECU (batch fired). Cleaned the connector and it lived. See if the 2 share ANY wiring to narrow down the issue.

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Thanks for the tip from your experience. That's exactly why I'm trying to get a hold of some service lit., to help with the tracing.

I'll post back with what I find tomorrow.
-Allan

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I'm trying to track down some service lit at the moment to get the connector pinout at the ECU to aid in tracing. Would there be only one ECU? Looks like one below the dash, in the center, behind the console.

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I have said diagrams ...I can`t scan them until tonite though.
I went and looked this morning, 92`s do not have the resistor pack on the injectors...common splice for feeds from the relay and individual ground returns to the ECU (dedicated driver for each)..very basic

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Sounds like a high ESR (dried up electrolytic cap) problem? And I hope it hasn't lost any injector drivers. I've been able to find some Mitsu Mirages in the junkyard so far, but my chances of finding a Colt for an ECU will probably be slim to none.

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Actually it isn`t a dryed up problem, Some genius is his infinate wisdom decided to spec a 6 volt rated cap on a 5 volt line, While in theory this should be ok, toss in heat vibration and age and it isn`t.
It starts leaking and corrodes the board, This Cap is on the 5 volt line to the Microprocesor and in it`s early stages of failure can be seen with a scan tool (noise on sensor voltages and just general wierd stuff happening) once the trace opens, you are walking..I have repaired over a 100 of these thru the years as there are times you just could not justify a 1200 dollar ECU for a 1000 dollar or less valued car....The fun part of it all, once the cap fails and prior to the trace opening...toss a battery charger on it on "boost" for whatever reason and the Micro WILL cry foul and thats it...you`ll need a box.

Rick

I've also read these cars suffer from the typical mitsubishi ecu cap issue. My bro's got a 93 colt and he has lucked out so far. Only issue he had was a dead distributor(all-in-one unit, nothing individually serviceable). From what I've read, grounds also seem to be an issue on these cars, they need to be checked and redone if needed.

Thanks for the tip on the ECU problem, guys. I just now got back from my 3.5 hour Google research mission! See, this is why I quit posting on Moparts years ago - I get carried away and spend too much time reading tech stuff! Seriously though, I found out enough to confirm that the injector problem may indeed be caused by the failing cap(s). It's now after 10:00, I haven't eaten dinner, and I have to get up early, so I'll have to get back to the vehicle in the coming days, rainy weather permitting. I'll let you know what I find.

To Rick: Yes, I'd be very interested in the diagrams. PM me, please. As for the cap issue, by "drying out" I'm including losing electrolyte due to leakage. (There's less in there.) I'm sure you're aware that high temp hastens their demise, leading to swelling, venting, leakage and/or drying out. Any of these are usually accompanied by a significant increase in ESR. The ones that are just drying up but not showing the other symptoms are the hardest ones to catch. That's why I really miss the ESR meter I used at a former employer's. Also, I believe it can be a self-feeding problem, as I've seen some where the cap itself was running hot with the increased ripple. (This is where an under-spec'd voltage rating like you mentioned can really come into play.) An under-engineered component value (like cap rated voltage or temp) is something that the manufacturers can often get away with, given the fact that the warranty can expire before the problem rears its ugly head. I've replaced tons of electrolytics in computer, audio and video equipment, the latest being my bro's failed Mitsubishi (surprise!) big screen TV which was less than 5 years old. I replaced the original 25V, 85-deg. caps with 35V, 105-deg. ones, and fresh Panasonic ones from Digi-Key at that, not the cheap crap that they put in it.

Thanks again.
-Allan

UPDATE:
Well, I pulled the ECU, and sure enough, it has the capacitor leakage problem. The electrolyte from the 47uF cap has done significant damage to the traces and through holes, and it just so happens that the injector driver transistors are right in the same area, with two of them having corrosion at their leads. I'll be working on the board and ordering new caps this week, and I'm keeping my fingers crossed that that's the problem and that the PCB isn't too badly damaged. Thanks again guys for the tip that led me in that direction. Also, thanks for the ECU pinout, Rick. It may still come in handy.

-Allan

p.s.- I'll post some pics of the damage later.

Started new thread with pics of damage:
https://board.moparts.org/ubbthreads/show...e=0#Post5132647