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Extremely rough idle. Then stall.


Jon89le
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Started about 2wks ago. The first time it happened my car was on a forward incline and low on gas so i figured it was sucking in vapor bc as soon as i turned the car around it idled fine. Well that was 2wks ago. Hasnt happened since until 2nights ago. Running fine, shut it off, go to Sears, come out, nothing. Barely started and would not idle. It would idle very very rough and stall out. If i gave it steady med-heavy throttle it would idle real rough,but was just dumping fuel out the tail. My buddy followed me home and the whole time i could not get the car to rev in drive above 4k. I was at a yard yesterday so i picked up a new ECM and dropped it in but it made zero difference. None of the wires seems to have come undone and the fuel pump was replaced maybe a couple hundred miles ago. When it happened the second time at Sears the motor was hot and I just started it now before and after the ECM change with the motor cold and still same. Any ideas please let me know. Thanks

 

 

Oh yea, and no SES light. WTF does it take for OBD1 to set an SES?!?!

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"dumping fuel out the tail" :eek:

 

Are you sure it was fuel :question:

 

Check resistance on each injector....

I think that's just an analogy :rolleyes:

 

I'd check your O2 sensor if it's been a while since that was replaced, then plugs/ignition stuff, then injectors.

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I thought about the O2 (which was done less than a year ago) but iirc the ECM doesnt use the O2 until the motors warmed up to regulate fuel. Might be wrong. How bad does a motor run if a cylinder is not firing? Im also assuming its spark related since not much can change vacuum wise between shutting the car off and turning on.

 

I should also add that this past time when it happened. After trying the car for an hour it finally held a low rpm rough idle which is how I made it home.

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First I would make sure you have spark going to the plugs. If you have that, then pull the plugs.

 

As far as how bad does it run when your drop a cylinder, well not good. Youll feel the car missing and it will vibrate very badly. And it will only get worse as RPM levels increase.

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My rough idle throughout the years was caused by: Injectors, bad plug wire, line popped off MAP sensor (threw code) and now bad Fuel Pressure Regulator. Btw, what yard do you go to? The Hyde Park ones suck

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I normally hit up A&T in Hyde Park up there when im home in NY since its a pick n pull. They sometimes have w-bodies. Im down in DE for school and I went to Harrys u-pull-it in Hazleton PA. Extremely big yard but not many w-bodies.

 

On the car im pretty sure now its a coil that completely failed. I just need to now find out which one of the three. If i pop them off can i check them by checking the resistance between the leads? Any way to test the module?

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If you had a dead coil, the car would run rough, but it shouldn't run as bad as you described. Another way you can easily test to see if there is a coil that isn't firing is to pop the wires off of each coil, and then start up the car. You will easily be able to tell which one is bad, becuase the car won't run any worse when you hit the dead one.

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Autozone should be able to check the modual. I bought a new one stupidly and I still have my old one that I'm pretty sure still works. If ya make it back upstate, its all yours

 

A&T is ok.....

Molts is a bunch of assholes

 

I still think we need better jys lol

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If you had a dead coil, the car would run rough, but it shouldn't run as bad as you described.

 

Even if the car only ran on 4cyl.? The idle is so bad with hitting the throttle that any worse it woudlnt run at all, lol. Do you know what the resistance should be on the coils?

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My car lost coilpacks twice in its life with me and I was always able to drive it to my Dad's house on 2-3 cylinders. It wasn't fun, it wasn't pretty, but I managed to do it and keep up with traffic just fine. Red lights were a little sketchy though. My car did something similar to that right before I got rid of it one morning. I had to crank it for like 10 seconds, it would finally start up and vibrate the hell out of me, I give it just a little gas and it died. But then two days later I managed to drive it to my Dad's house incident free :willynilly: When I get into fixing that car I'll tell you what I find.

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I had to crank it for like 10 seconds, it would finally start up and vibrate the hell out of me, I give it just a little gas and it died. But then two days later I managed to drive it to my Dad's house incident free :willynilly: When I get into fixing that car I'll tell you what I find.

 

Yup, thats exactly my issue. I had my dad read me some of the trouble shooting diagrams for checking to see if the module or coil is bad with the correct voltage/ohm readouts. I'll be checking that as soon as i get my hands on a meter.

 

How would i check the resistance on the injectors? Would i just check the resistance between the two leads at the injectors harness?

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I had to crank it for like 10 seconds, it would finally start up and vibrate the hell out of me, I give it just a little gas and it died. But then two days later I managed to drive it to my Dad's house incident free :willynilly: When I get into fixing that car I'll tell you what I find.

 

Yup, thats exactly my issue. I had my dad read me some of the trouble shooting diagrams for checking to see if the module or coil is bad with the correct voltage/ohm readouts. I'll be checking that as soon as i get my hands on a meter.

 

How would i check the resistance on the injectors? Would i just check the resistance between the two leads at the injectors harness?

 

My problem could be different though considering I have the 2.3 Quad4 in my Cutlass... could be simlar to though.

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well.. had trouble with the vert last night. it is doing exactly what you describe :(

 

I also have a phantom coolant leak. i can smell it. I think the system is bleeding air in and leaving the temp sensor high and dry when I stop! wrong temp = wrong fuel mixture = rough running.

 

also think I have an intermittant coil. :(

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Ok, I checked the ohms at the 3pin connector on the DIS module as per my service manual. I connected the leads on my meter to terminals A and C on the connector and read about 915ohms. The book states it should be between 900-1200 so im ok there.

 

Next it says to check the voltage which should read 100mV. Does anyone know where the heck im checking this voltage at? My service manual is about 200miles away so I cant reference anything. I'll be checking to see if my coils are firing after my buddy comes over to crank the motor.

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my car had the same problem but it would idld fine and would not rev past 3k changed fuel pump and it fixed it i would lay money on the pump not flowing the right amount of fuel to maintain the engine when its running check fuel perssure when running it should be around 50 pounds iirc but i would lay money on the fuel pump being bad

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