There are a lot of people posting and helping in this thread that I trust far more than some mechanic that asks a Pontiac what? When you tell him what kind of car it is
This is TRUE! These guys are "The Experts" for sure!!
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Originally posted by JohnWPB:
I just need to read up and figure out how to test the injectors, if it is even possible when the car is running as good as it is at this particular point in time.
I took my plenum off, I had Injector pulse then took out the fuel injectors to test them 1 by one. I energized the injectors while blowing cleaner fluid through them. Only 3 came back to life so I sent them all out to get professionally cleaned. I should have them back soon. Hopefully I'll be up & running next week!
When an injector fails, it shuts down the injector drivers in the ECM so the car dies.
how does it shut down? is there a circuit beaker or thermal switch in there? Im just trying to understand what the ECM is doing when it gets a shorted or open injector.
Also remember the ECM grounds the injector wire - it does not supply power to it.
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Originally posted by Alex.07.86GT:
how does it shut down? is there a circuit beaker or thermal switch in there? Im just trying to understand what the ECM is doing when it gets a shorted or open injector.
No circuit breaker or thermal switch.
[This message has been edited by phonedawgz (edited 10-04-2014).]
Originally posted by phonedawgz: Also remember the ECM grounds the injector wire - it does not supply power to it. No circuit breaker or thermal switch.
if an injector shorts out, how does the ECM circuits deal with it?
If the injector is shorted out and too much power runs through shorted injector and grounds through the ECM injector driver transistor the transistor burns out.
80s technology.
[This message has been edited by phonedawgz (edited 10-04-2014).]
Fascinating, so that's why both injector banks are fused, the ECM grounds the injectors. Theoretically then, the fuses should be sufficient to protect the driver's from in the ECM from higher than normal current draw?
The power wires running to the injector are fused so the car doesn't burn up if you get a short. The fuse is sized (5A) to be just large enough to be dependable and not blow over the life of the car. Hopefully this would also protect the injector driver transistor but they do also go bad at times. The same amount of current would go through the drivers if they were on the power side of the ground side of the injector wiring.
[This message has been edited by phonedawgz (edited 10-04-2014).]
From the last messages, and reading how the injectors work..... thinking it all through, It would seem to me that this could not be the problem.... I mean if the resistor does overload and burn out, the car would be dead in the water till that was fixed. However the car will randomly start and run perfectly. If anything it would try to run on 3 cylinders with one bank burned out.... right?
Again, not based temperature or run time. At times it will not start after sitting for a couple days, other times it dies when running for a while.
Start your engine and let it warm up. Then pull one of the INJ fuses. The engine will continue to run on the remaining 3 cylinders. So yes if one of the injector driver transistors were to go, the engine would still run. It will run rough. It might have problems idling. It might start hard, but it would not die while driving.
Not much chance of both driver transistors failing at the same time.
Even less chance of them failing and then somehow healing themselves.
Also to note - If the injectors were to fail, the tach would still show a response while cranking.
Replace your fuel filter. when the car sits the dirt and old filter parts settle ton the bottom. As you drive these part block the filter and starve the engine of fuel until they settle to the bottom again . You'll have this problem until you replace the gas filter.
From the last messages, and reading how the injectors work..... thinking it all through, It would seem to me that this could not be the problem.... I mean if the resistor does overload and burn out, the car would be dead in the water till that was fixed. However the car will randomly start and run perfectly. If anything it would try to run on 3 cylinders with one bank burned out.... right?
Again, not based temperature or run time. At times it will not start after sitting for a couple days, other times it dies when running for a while.
you wrote you had spark & fuel pressure. the next thing IMO is either fuel injector issues or timing. Did you check spark at the coil or the cylinders?
I will try to start the car with starting fluid when this happens again. I started the car a few times yesterday, and twice today. I just tap the key, and it fires right up, idles smoothly at around 1200 RMP, no missing..... just as it should......
The fuel filter was replaced once while working on the car, and then again a couple months back the last time the tank was dropped to check everything. I also cleaned the tank, and replaced all the rubber lines with new fuel rated ones, as mentioned in a previous post in this thread.
Not much I can do I guess till it decides not to start again.
PM me your address and I'll send you a new Pink & White coil to ICM cable. I know yours looked like it checked out OK but something, well make that two things have to have troubles in them, and replacing the cable is worth a try. If you want I'll also send you a new solder on 4 pin pigtail for the other ICM connector. Solder it on with a soldering iron and heatshrink the splices. New like this one - but with the correct color wires.
Not to hijack, but I have the same kit and have yet to hook it up. What did you use to attach to the schrader valve as I don't believe that fitting comes in the kit..
PM me your address and I'll send you a new Pink & White coil to ICM cable. I know yours looked like it checked out OK but something, well make that two things have to have troubles in them, and replacing the cable is worth a try.
Will do, just let me know how much for it + shipping
The Harbor Freight kit worked as is. I did not have to add anything to it. There is one hose in the kit of the 2, that has the correct end to fit the Fiero. The other end of the hose attaches to the gauge. You do not need any of the fittings / adapters that are in the kit for the Fiero.
The fuel filter was replaced once while working on the car, and then again a couple months back the last time the tank was dropped to check everything. I also cleaned the tank, and replaced all the rubber lines with new fuel rated ones, as mentioned in a previous post in this thread.
Not much I can do I guess till it decides not to start again.
Just checking, did you replace a pice of rubber hose in the tank at the fuel pump at all? Just want to make sure that if you did the hose was rated as submersible in gasoline.
I used an inline spark checker today, and I am getting spark, but it would still not start.
So, It all came down to the fuel pressure, and I was SOOooo hoping that the pressure was non existent or really low. At least I would then know it was just a matter of dropping the tank to fix it. The car does not want to cooperate however, and the fuel pressure is perfect.
So, I have air, fuel, and spark..... THE three things needed for an engine to run, however mine is not running.
John, you have fuel pressure, spark and air.
Question is, is fuel getting through to the cylinders?
5 pages and no fix? Forget prior posts and Let fix your car
ok when the pump doesnt run, turn the key to on but don't crank it, does the check engine light come on in bulb test? this shows if the ECM is getting power AND ground. leave the key in the on postion and shake/wiggle all the wiring harness, mainly the grounds on the head, if there is a short you will here the pump kick on as you break and reconnect the short.
I had this happen once, ground barly came out of the terminal, when it would cool it would start up, get hot or hit a bump and it would die.
in the fuel pressure test does it hold pressure after the pump stops?
if you replaced the distrib, the after market ones have long wires on the pick up coil and they tend to get pintched by the distrib cap, check that the wires are tucked inside of the cap.
Since some times you have no fuel pressure, we can rule out everything else but fuel and fuel control. Forget ign stuff. Yes the ICM fires the injectors, but you would still have fuel presure.
I would say check for exhaust leaks as that will add heat to the engine bay and can cuase vapor lock, not like old school vapor lock but the fuel boils in the lines. IE long drive, quick stop, won't start, wait starts. I don't know if it get hot like here in Vegas, but that happens every summer here. but it you go out and the car has sat overnight and won't start, prob not the case.
I agree. Ive had 45 year old cars that had perfectly fine ignition coils. To me thats an item you replace when its broke.
I agree with a points type distributor however since with an electronically controlled coil the secondary voltage can jump back to the primary coil and kill the ICM. We have all seen on here people who have had repeat ICM failures. I think the majority of repeat ICM failures are either from deteriorated insulation in the coil and high resistance in the spark plug wires or bad pick up coils with intermittent troubles. I think the heat related failures are not nearly as prevalent as generally assumed on here. This link does talk about DIS but the same problem with secondary voltage reaching the primary that happens with DIS happens on Fiero ignition systems - http://www.wellsve.com/vide...gnitiontraining.html
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if you replaced the distrib, the after market ones have long wires on the pick up coil and they tend to get pintched by the distrib cap, check that the wires are tucked inside of the cap.
Yes and it can show up as an intermittent. Also you can have this if you only replaced the ICM. They put wires on them that are longer to make sure they are long enough but they don't realize what happens.
The one on the right has the problem.
This is what I did on mine to make sure the wires didn't make it to the edge. I untanged one of the wires and removed it from the connector, then twisted the wires, and then reinserted it into the connector.
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Since some times you have no fuel pressure, we can rule out everything else but fuel and fuel control. Forget ign stuff. Yes the ICM fires the injectors, but you would still have fuel presure.
You will get the first key on 2 sec of fuel pump running but you won't get the additional running during cranking without ignition pulses.
With a bypass fuel pressure regulator like the Fiero has and a properly operating fuel pump, if the fuel in the lines did boil and become vapor the vapor would be pushed back into the tank once the key is turned on.
[This message has been edited by phonedawgz (edited 10-08-2014).]
Originally posted by phonedawgz: With a bypass fuel pressure regulator like the Fiero has and a properly operating fuel pump, if the fuel in the lines did boil and become vapor the vapor would be pushed back into the tank once the key is turned on.
LMAO, you would think so, but no. I deal with this every summer here on multiple Fieros.
Well you think you have a handle on this so, I'll just step back, good luck.
Well you think you have a handle on this so, I'll just step back, good luck.
No no no no.... there will be NO stepping back! Not till this is fixed. This is a trouble shooting thread, so please feel free to come up with ideas. Also expect that some of those ideas will be shot down. That is all part of trouble shooting, eliminating things till a solution is found (hopefully! ! !)
I will wait till the new ICM <-> coil wire arrives, (Thanks phonedawgz!) and I get everything soldered together. I will also try to change the pickup coil, and inspect the distributor to see what shape it and the bearings are in. I am flying Andrew (1984WhiteSE) down from Minneapolis the 8th of November to help me on the car, and he is far more of a mechanic than I am! It will be a working vacation for him A couple days on the car, a few at the beach and touring South Florida.
Tests from the past few posts:
- Yes, the check engine light does come on in bulb test when the key is turned on. When the car starts, the light goes out, and no trouble codes are in the computer.
- The fuel pressure peaks at about 45psi as shown above. When I let it sit for a while, it drops to around 30 psi and remains there for quite a while... greater than 10 minutes or so. If needed I can time it
- Original distributor, and the wires are in great shape, no pinches, or broken wire casing.
- I do have an exhaust leak, on the front (towards the back of the car). Though remotely possible, I doubt is it boiling fuel in the lines from that.
No, I'm good, you got someone flying in, I was going to offer that. (and I would have brought all the parts needed to damn neer rebuild the engine/Fiero) And the post whore of the forum says he's got it. He always has the most obscure answers instead of the most common answers. So yeah I am steping back.
BTW did you ever test one ICM to confirm it was bad? The whole thread says "you have a bad ICM" (not that I work on more Fieros that most people see in there lifetime) Sorry a bit jadded
No, I'm good, you got someone flying in, I was going to offer that. (and I would have brought all the parts needed to damn neer rebuild the engine/Fiero) And the post whore of the forum says he's got it. He always has the most obscure answers instead of the most common answers. So yeah I am steping back.
BTW did you ever test one ICM to confirm it was bad? The whole thread says "you have a bad ICM" (not that I work on more Fieros that most people see in there lifetime) Sorry a bit jadded
No, I have no way of testing the ICM's here, nor do the part stores that I go to have the equipment, as I have asked.
I am at the point that I am seriously doubting that it is an ICM. When the car started doing this some time ago, I agree, it screamed ICM. When I replaced it, it was a couple days before the car started again. Then again it acted up, and I put the old ICM in, and the car ran fine. This time when it quit, I purchased a brand new Made in the USA ICM, and installed it, and the car would not start. I am willing to bet that I probably have 3 working ICM's here.
Andrew was originally coming down to help me redo all the bushings and suspension on the car. Now I am hoping that he will be able to help me figure this problem out. I am just at the end of my rope here trying to find the problem. The real kick in the butt is that right now it is running great. I can walk out there and just tap the key and it will start. With it running this good, no trouble codes, and while running, wiggling EVERY wire, connector, & plug that I can find, it continues to run.... How the hell do you trace the problem down?!
It has done this 3 times in the past now, running great and I think it is fixed. It is then at some random point, the car quits and gets towed home. There were 2 instances, that after the car sat for a half hour to an hour it did restart and I did not have to get it towed. Before you think it is something to do with heating up, there have been days and days that the car would not start, and one day it just does.
the only thing we dont know is if there is FI pulse when it doesnt start.
...and how is the ERG valve. if it is stuck open the car may not start.
did you ever try to start it with starting fluid?
I have no idea the condition of the EGR Valve honestly.... as for starting with starting fluid, that is on the list of things to do the next time it will not start.
Have you check the crank position sensor. Your car would start fine but would shut off without warning. No codes. Restarts fine again. Runs great for a while then it would happens again.
Have you check the crank position sensor. Your car would start fine but would shut off without warning. No codes. Restarts fine again. Runs great for a while then it would happens again.
No I haven't checked it. Is there a way that I can check it?
