Engine Bogging Down, Misfiring

[LeSabre in Buffalo]

Remember, 2 bottles of the Gumout Regane (NOT the cheap stuff, you want the $4.50 bottles at Wal-Mart) on half a tank. That will be strong enough to clean out most of whatever dirt is in the injector.

If you can leave it in the tank over the course of a week or so, that's more effective than doing it on a long trip all at once. Some gas with the cleaner will be remaining in the injectors, able to work while it's sitting.

[The_Maniac]

To my knowledge, most (not all) of the time, a GM fuel pump just DIES, no warning.

Now, the symptoms given are reminding my of a problem I had with the 3100 in my Grand Am. During a 20 mile drive, it would surprise you with a moment of lack of power (not responding to more gas). Shortly, this got worse and worse. To the point a bulk of my 20 mile commute with "under powered" and mis-firing.
In efforts of trying to learn more and figure this out, I had access to a OCT Scanner. I got home one day and the car was running for crap, hooked it up and the ONLY number who's value changed based on running like crap or running good (and I compared to the wife's Grand Am with the same 3100) was the Injector Pulse Width. While it ran like crap, the computer opened the injectors more, when it was fine, the IPW matched the wife's car.

About 4-5 months prior, I did plugs and wires (I was reluctant to check those since the car ran fine for a while).
I had a spare ignition module, had it tested at the parts store, swapped it, tested my original one and tested it. Both tested good and no change.
I was poking around, wiggling wires while the car was running. I placed my hand on a coil pack and suddenly found, dependant on the pressure I applied, the car would work/not work. I had a spare coil pack, swapped it and the problem has been GONE (and that possible faulty pack garbaged).

Since then, I found on this forum a tech how-to for testing the coils. I am suspecting that might be the next logical point for you. My problem was intermittant, yours sounds like it's now constant. You also found reversing two wires sharing the same coil resolve the problem. Perhaps there is an internal fault on the coil messing things up. I would start with that.

Another thing you could do (and I know it's NOT recommended).... Take a wire off that suspect coil, start the car. Should be tons of arcing if the tower is good. Turn off the car, put that wire on and pull the other one. If you find one tower not arcing, you have the problem figured out. Again, I know it's not advised (seek the tech info on testing the coils, probably a LOT easier).

[thunderpanda]

To my knowledge, most (not all) of the time, a GM fuel pump just DIES, no warning.

Now, the symptoms given are reminding my of a problem I had with the 3100 in my Grand Am. During a 20 mile drive, it would surprise you with a moment of lack of power (not responding to more gas). Shortly, this got worse and worse. To the point a bulk of my 20 mile commute with "under powered" and mis-firing.
In efforts of trying to learn more and figure this out, I had access to a OCT Scanner. I got home one day and the car was running for crap, hooked it up and the ONLY number who's value changed based on running like crap or running good (and I compared to the wife's Grand Am with the same 3100) was the Injector Pulse Width. While it ran like crap, the computer opened the injectors more, when it was fine, the IPW matched the wife's car.

About 4-5 months prior, I did plugs and wires (I was reluctant to check those since the car ran fine for a while).
I had a spare ignition module, had it tested at the parts store, swapped it, tested my original one and tested it. Both tested good and no change.
I was poking around, wiggling wires while the car was running. I placed my hand on a coil pack and suddenly found, dependant on the pressure I applied, the car would work/not work. I had a spare coil pack, swapped it and the problem has been GONE (and that possible faulty pack garbaged).

Since then, I found on this forum a tech how-to for testing the coils. I am suspecting that might be the next logical point for you. My problem was intermittant, yours sounds like it's now constant. You also found reversing two wires sharing the same coil resolve the problem. Perhaps there is an internal fault on the coil messing things up. I would start with that.

Another thing you could do (and I know it's NOT recommended).... Take a wire off that suspect coil, start the car. Should be tons of arcing if the tower is good. Turn off the car, put that wire on and pull the other one. If you find one tower not arcing, you have the problem figured out. Again, I know it's not advised (seek the tech info on testing the coils, probably a LOT easier).

Ya I plan on doing that same basic test later today, but i have extra spark plugs and i will just plug a loose one into each post on each coil and find out which ones work. Hopefully I will have time to do that tonight

[1oldman]

I have had the same problem, but it was the Ignition Control Module both times. It also destroyed the O2 sensor, coil packs, and spark plugs. The O2 and plugs had the strangest odor I have ever come across. The car runs great after also replacing the manifold gaskets and having the valves ground. The biggest improvement was finally getting a good Ignition Control Module. Good Luck! - BC

[thunderpanda]

Hey can you guys help me identify some of these parts? First, what is this guy with the green tab:

And then what are these three things going in there. Specifically i am looking for the MAF

[thunderpanda]

Okay guys, I have made a major breakthrough. I am not completely out of the woods yet but I think I have the majority of the problem narrowed down to one component: The Mass Airflow sensor. I did some research and found that a bad one can lead to the majority of the symptoms i am experiencing. The hesitation, trouble idling, random dying when cool, trouble in the mid range of rpms especially, and smell of gas when car is in use (that was one that I didn't realize my car was doing, I thought it just smelled like that all the time because the gas tank leaked sometimes).

So I read on these forums that a quick test to see if the MAF sensor was bad was to just unhook it and see how the car performs. So I tried it. And it drove TONS better. It had a little trouble at lower rpms (probably because the mix was too air rich) but once I got to higher rpms it took off like it hadn't done in a long time. I haven't been able to clean off the MAF yet and see if i can still use the same one yet because I don't have the special torx wrench needed to take it off, i will get it tomorrow. But Ya I will keep you posted on how it turns out.

[myfirstbonnie]

First picture I am not seeing a green tab.

Second picture: IAC (idle air control), MAF (mass air flow), and TPS (throttle position sensor)

[thunderpanda]

First picture I am not seeing a green tab.

Second picture: IAC (idle air control), MAF (mass air flow), and TPS (throttle position sensor)

Hey thanks for that, it will help me out. And in the first picture I guess its more blue than it is green... It is the thing with the blueish piece of plastic where the wire connects to it

[harofreak00]

Thats the Boost Control Solenoid (BCS)

[enslow]

If your OBDII scanner can read real time data, look up the MAF data. According to the FSM, it should read 4-7 g/s, and increase to 100 g/m or more at WOT just before the 1-2 shift. Obviously, the WOT measurement must be taken by a passenger in the car.

[1oldman]

There is a possibility it could be the ICM. It is amazing that they can be marginal, cause the missfire you describe and just not fail. Once I had to go through 3 of them before I found a good one. One failed and took out the coil packs, spark plugs, and O2 sensor. I was not a happy camper

[renchjeep]

Have you checked fuel pressure at the fuel rail yet? Maybe a fuel pump going bad, or a clogged strainer.

ALWAYS run the spark plug wires to the proper cylinder. NO MATTER WHAT!

Updates?

[renchjeep]

Did you do both plugs and wires? Also, are you certain you seated the wires properly on the plugs? I find it tough to get the rear 3 wires on the plugs properly. Also, the use of dielectric grease inside the boots can help keep moisture out and prevent arcing.

Ya I had just replaced all the spark plug wires like a month ago because a squirrel had chewed on them... so they are all still new. And I am pretty sure I have them all plugged in properly, i may double check tomorrow though. I haven't had too much trouble getting them on though, given that they are new and the dielectric grease is a good lubricant so they slide right on.

I think the two most likely REMAINING problems are possible bad fuel pump and possibly some bad fuel injectors still. I had replaced all of them, but i replaced them with junkyard ones which I guess may not have worked. Unfortunately since multiple cylinders are misfiring according to my OBD, i can't pinpoint it to a specific cylinder that needs help.

I wonder what else the squirrel found tasty? Maybe some injector wiring?

[thunderpanda]

Have you checked fuel pressure at the fuel rail yet? Maybe a fuel pump going bad, or a clogged strainer.

ALWAYS run the spark plug wires to the proper cylinder. NO MATTER WHAT!

Updates?

Ya I have kind of migrated the thread to a new one, just to keep everything focused and current. This one was getting hard to follow I think.

Unfortunately I cannot head your warning for putting the spark plugs to the proper cylinders. If I did, I could not drive my car and I have to work. I have them configured in a way that should TECHNICALLY be exactly the same since each coil fires at the same time on both posts. I just swapped the two on each coil. If you can figure out WHY this could possibly make a difference, that would go a long way in solving this mystery I bet. I tested each coil and post, and had one bad coil and replaced it but everything else was fine. It still drives like crap if I have them plugged in the standard way. And by crap I mean 0-45 (top speed) in like two minutes. Its still crap with it the current way, but at least I can get to freeway speed in maybe 45 seconds. If its downhill...

I have not been able to check the fuel pressure at the fuel rail, though from the smell of my car and its symptoms, I think the engine is getting way too much gas or at least not igniting the gas it is getting properly. It could still conceivably be a problem with the injectors or fuel rail somehow.. I though of just taking the whole fuel rail out and running the car and seeing if gas squirts out of each one... I don't know if that is a legitimate test or not.

And as for your comment about the squirrel and the injector wires... that is actually a good idea to check... I never saw anything super obvious but looking closer might be a good idea.

[thunderpanda]

SOLUTION FOUND (to 90% of the problem anyway): It was the ignition control module. Replaced with one from the junkyard and BOOM. Good as new! Still misfires a bit in the midrange, I think an injector or two is still bad, But it is literally TEN TIMES better. It is probably 85% of its new self. Thanks for your help!

[RunningBonneville1]

Try Disconnecting the MAF Sensor and then trying starting your car. It should start now. My brothers car had trouble starting, bogging down and then dying. I disconnected his MAF Sensor and BOOM it started right up! It took a min to idle out correctly, but it did. If you do this and it works then it means you have a Bad MAF Sensor, thats all. Good luck and let us know if it works!

[Jrs3800]

Thread was figured out 2 years ago... Don't dig up old posts...