420A 2g GS sputtering issue 2k-4k rpms

[TheLunarEc1ipse]

Hey Y'all!
I have been having this really odd sputtering issue for quite a while now, and have tried a few things to try and fix it with no luck.

The car has a really weird sputter in between 2k-4k rpms, higher or lower it goes away. On top of that the car seems to completely shut off while stationary, and even while moving. From start up the sputtering doesn't usually happen, but after the car has shut off 2 to 3 times, it then starts to sputter. The sputtering is most evident in 4th and 5th gear, but can be observed in 2nd and 3rd, although not that as violent. At times, while being inconsistent, the idle likes to hang at around 1.5k rpms, until I add a blip of throttle, and then it falls down to the 800-1k zone.

I have replaced coils, the coil pack, fuel filter, and the fuel pump, and really have had no luck. After every part replacement the car seemed to be fine, until around 30 minutes of the test drive. I don't think it has anything to do with fuel because of the sputtering being within a certain part of the powerband rather than the whole powerband, but I could be wrong. My best guess is that it has something to do with the ECU, but I'm really not sure.

Any help would be greatly appreciated!

 

[tschuhly]

Have you checked for a vacuum leak? An easy way that I have heard to do this is turn the car on and while its running spray some brake cleaner around (don't drown the engine in it). If the RPM's increase, then you have found your vacuum leak.

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[TheLunarEc1ipse]

Have you checked for a vacuum leak? An easy way that I have heard to do this is turn the car on and while its running spray some brake cleaner around (don't drown the engine in it). If the RPM's increase, then you have found your vacuum leak.

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I'll give it a try.
One thing I really should mention, because I guess it could most definitely be a reason. One of the previous owners did some sort of EGR valve delete. For the longest time I thought nothing of it, but now that I think about it, this could easily be causing it.
What do you fellas think? I think this sputter could easily be pre detonations.
I have a video that I can upload on what these "sputters" sound like.

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It only "sputters" under throttle.

 

[99dsmer4g63]

Check the coolant sensor for the ecu and its wiring it becomes corroded easily being under the cap and vacuum leaks.

-Daniel

 

[TheLunarEc1ipse]

Check the coolant sensor for the ecu and its wiring it becomes corroded easily being under the cap and vacuum leaks.

-Daniel

Any idea where that could be?
Also the thing I don't fully understand is would a vacuum leak explain the consistent sputtering in that part of the powerband? or would that better explain the idling issue?

 

[tschuhly]

I would say your onto something with the egr delete. However, I will allow someone more knowledgeable than I to help you out with the specifics.

 

[99dsmer4g63]

I would hook an obd2 scanner to the car and watch the coolant temp. See what it reads when the car is cold. It should be around ambient air temp. See if it goes to near 200 degrees after warm. The sensor itself is one under the radiator cap with 2 wires not one. See if the plug is in good shape.

Vacuums leaks would make idling and really any other condition not ideal but idling usually the worst. It’s best to check for them first.

As far as randomly shutting off I’d suspect a faulty crank sensor plug or wiring. What year is your car?

-Daniel

 

[TheLunarEc1ipse]

I would hook an obd2 scanner to the car and watch the coolant temp. See what it reads when the car is cold. It should be around ambient air temp. See if it goes to near 200 degrees after warm. The sensor itself is one under the radiator cap with 2 wires not one. See if the plug is in good shape.

Vacuums leaks would make idling and really any other condition not ideal but idling usually the worst. It’s best to check for them first.

As far as randomly shutting off I’d suspect a faulty crank sensor plug or wiring. What year is your car?

-Daniel

I'll take a look, the car is a 1995 GS

 

[99dsmer4g63]

Yeah that would be a good place to start for a 95. Inspect the plug on the crank sensor.

-Daniel

 

[TheLunarEc1ipse]

Yeah that would be a good place to start for a 95. Inspect the plug on the crank sensor.

-Daniel

I'll take a look! Any other suggestions?

 

[BLACK'98DSM]

Pull the spark plug cables and see if the tubes are full of oil...

 

[TheLunarEc1ipse]

Found coolant on my spark plugs gentleman, I feel stupid for not checking those initially, thanks for the help anyway lads. I believe this may be the reason for all my issues.

 

[tschuhly]

Cars are complicated. Sometimes it just takes a little help.

 

[TheLunarEc1ipse]

Is there a good brand or site you guys would recommend buying a head gasket from?

 

[TheLunarEc1ipse]

Deeply apologize everyone. I miss interpreted what was on the spark plug, it was not coolant, I'm pretty sure it was left over fuel. What ever the case, I replaced the Valve cover gasket, and am still having the staling and sputtering issues.

 

[TheLunarEc1ipse]

Yeah that would be a good place to start for a 95. Inspect the plug on the crank sensor.

-Daniel

I did check the Crank position sensor plug, and it for some reason was covered in what appeared to be older oil. Do you think that could be a reason for the staling? or maybe in the sputtering also?