95 grand am 3.1L: Gas in oil

[Texan4Life]

1995 Grand Am 3.1L with about 95,000 miles.

It will chug and sometimes shutter if you try and use more than 1/2 or 3/4 throttle. no power like driving a freight train if you dont want it to shutter.

no codes. Horrible gas mileage.

oil on dipstick reeks of gas a few days after oil change.

new ECM put in (and programmed) my GM dealer.

what we have done:
NEW:
Intake manifold gasket, intake plenum gasket, fuel injector orings, air filter, fuel pressure regulator, fuel filter, thermostat (just cuz it was easy to do with manifold off), spark plugs (again easy cuz off having manifold off).

and the plastic vacuum hose assembly (new from GM) from pcv valve to throttle body and then to somewhere else don't remember, but it was broken.

when we did the spark plugs 4 were clean and normal looking while 2 we black and sooty.

Changed oil after doing manifold gaskets and new oil is smelling of gas again with all the same symptoms.

Either we still have a huge vacuum leak or there is a dribbling/bad sray pattern injector(s).

Added fuel injector cleaner into the gas tank.

anyone have any other ideas?!?

[Texan4Life]

oh yeah and when doing the intake manifold we did not find any other vacuum hose/line problems

[IsaacHayes]

Several things can cause it to run rich like you are seeing.

Since you've replaced some things already, I won't mention those. Sensor also can cause it, like the engine coolant temp sensor, or a bad O2 sensor saying it's lean so it dumps a ton of fuel.

BUT since you said 2 plugs were sooty, it's a safe assumption that those 2 cylinders have leaking injectors or no spark...

So you've narrowed it down to 2 cylinders, so it's probably not a crapped out O2 sensor, or engine coolant sensor reporting wrong.

Those 2 cylinders, are they running off the same coil pack? If so replace it. Are the spark wires ok? Do you have a spare ICM to test with or take yours to get tested at the parts store?

If all that passes, then it must be leaky injectors. But I'd look at spark first on those 2 cylinders.

[Texan4Life]

thanks for the reply....

wouldn't it set a misfire trouble code if a coil pack was having a problem?

[Schmieder]

thanks for the reply....

wouldn't it set a misfire trouble code if a coil pack was having a problem?

IsaacHayes is right on track.

Some cars set SES on a slight breeze, some you can rip to pieces and still no SES light.

Try unpluging the spark cables to 1 of the 2 cylinders with sooty plugs and see if the situation changes any. If no/mild change in how it acts, then swap the coil packs but keep the same spark plug unplugged. If it gets worse, then its safe to say the coil pack in question is bad.

Are you sure the cables were wired to the coils in the right order? Since there are 2 bad plugs, having 2 cables swapped incorrectly could cause that. Like mixing up cylinders 1 and 5. I believe they should be paired as 1-4, 2-5, 3-6 since a spark is thrown twice per cycle. If you don't have such a pairing, your cables aren't wired correctly.

But I may be wrong about that. Let someone chime in to assure or not.

If it is leaky injectors, I believe the fuel rail pressure would drop quicker then normal once the car is shut down. Or two injectors are pig dirty pissing fuel instead of spraying fuel. In that case, I don't think intank fuel injector cleaners would work. They would need off vehicle cleaning or replacement. But check spark first.

If the two dirty plugs are cyl 5 and 6, I might say your car has been running hot and the heat is varnishing the injectors during heat soak. But that is just a logical guess, I'm not sure if that would be the case or not.

[Texan4Life]

Car was running fine since we got it @ 60,000 miles. Didn't touch the wires until taking off the intake manifold. So the wires were right when the problem happened.

Where is the ignition control module? I didnt know you could get them tested.

The car isn't here ATM. But I will ohm the wires and see if the two cylinder wires are next to each other on the coil pack.

[Schmieder]

Car was running fine since we got it @ 60,000 miles. Didn't touch the wires until taking off the intake manifold. So the wires were right when the problem happened.

Where is the ignition control module? I didnt know you could get them tested.

The car isn't here ATM. But I will ohm the wires and see if the two cylinder wires are next to each other on the coil pack.

Right, I would say bad coil, wires or leaky/dirty injectors. Pretty much what Isaac suggested.

IIRC, the ign control module is what supports the coils. And they aren't cheap.

Check the coil pack for cracks if the 2 plugs are the same coil pack. Sometimes they can crack and cause problems w/o SES in my experience. But I am just a Grand Prix owner, not a technician.

[bszopi]

Yes, the ICM sits directly below the coils.

[torq455]

more air/fuel, with more throttle, increases the density inside the cylinder, which adds resistance. that requires more energy from the coil in order to make a spark. if that's the case, then the engine should run leaner. little or no combustion means the oxygen hasn't been used. therefore, the ecm commands more fuel. i don't understand why there is so much fuel in the oil, unless you do have leaky injectors and drive short distances. another cause for a rich condition is a bad map sensor. it's possible to have more than one thing wrong at a time.

[Texan4Life]

so a parts store like autozone can test the ICM?

is there a way to test the MAP sensor?

[jawalkerjr]

As far as I know, AutoZone & O'Reilly have the capability to test modules. If I remember correctly, that year GM uses what's called "waste spark", one transistor firing positively & then firing negatively to fire two cylinders. But based on what you are reporting, gas in oil, I'd suspect dirty/stuck injectors on those two cylinders. I usually pull the injectors & clean them out of the engine, but maybe someone knows a way to do it through the fuel rail.

[Schmieder]

If you have a volt meter, you can test the MAP sensor.

Get a conductive needle and pierce the light green wire.

Turn the key to run but do not start the engine.

You should get 4-5 volts from the light green wire.

Now, start the car. You should get a much lower voltage due to the vacuum. Probably around 1-2 volts.

If that is the case, your MAP sensor is good. Unlike the TPS, there should not be voltage errors in part throttle. If the run/no start and idle voltage levels check out fine, the MAP is fine.

But as far as I know, your car won't run at all if the MAP is bad, but I can not confirm that as it is what I heard.

[Texan4Life]

THANKS GUYS

I figured it would have set a code for a bad coil.

the two dirty plugs were from cylinders 1 and 4. 1 and 4 share a coil.

I had the ICM checked and it passed. But the guy ran the test again while I watched and showed me how when it hit the 4th green light it would dim and flicker then finish the test. He says technically it should be good, but he has never seen it flicker like that before.

I agreed and got a new ICM (80 bucks), that didn't do the trick so I went and got a new coil (25 bucks) and that fixed it right up.

Or there was more than one problem. Changed the oil again and this time it should stay gas free.

thanks again.

[bszopi]

The bad coil might have started to affect the performance of the ICM. So it's probably best to have replaced both. Would hate to have just replaced the coil, then the ICM fail, which could potentially take out all of the coils. Glad to hear it seems to be fixed though!

[Schmieder]

THANKS GUYS

I figured it would have set a code for a bad coil.

the two dirty plugs were from cylinders 1 and 4. 1 and 4 share a coil.

I had the ICM checked and it passed. But the guy ran the test again while I watched and showed me how when it hit the 4th green light it would dim and flicker then finish the test. He says technically it should be good, but he has never seen it flicker like that before.

I agreed and got a new ICM (80 bucks), that didn't do the trick so I went and got a new coil (25 bucks) and that fixed it right up.

Or there was more than one problem. Changed the oil again and this time it should stay gas free.

thanks again.

Good deal! I'm happy for you. People on this forum are really, REALLY great.

Smart move getting both the coil and the ICM. btw, have any idea why the coil pack died? If it was age, might want to replace the other two if your not to low on cash flow. This way, one that may die soon won't take out your ICM as well.

If I ever have an automotive question or problem, my first place to ask is here. They have helped me out A LOT, which is why I decided to become a site supporter.

Anyways, congrats and happy driving