1987 GN intermitently cuts out/stumbles

[realspartan]

Hi guys,

Took out for the second time since winter storage and it intermitently cuts out and stumbles. Quite weird actually since it could be running perfectly but as soon as you try to accelerate or rev it cuts out like there is no fuel being supplied to the engine. On the highway, you can reach 60-65mph but cannot really accelerate any faster without it stumbling/misfiring. I also does the same thing in park or neutral when trying to rev steadily; you can rev to 3-4K and then it just stumbles but not all the time, Any ideas? Could it be bad gas since almost no one uses 94 octane anymore? I did fill up my others cars with 94 and did have some rough idle issues but nothing like the GN. It was at 3/4 tank when I took it out, filled it up and still the same problem. I did add stabil before storage. Plugs and fuel filter where changed last year and have less than 500 miles on them; the wires have about 5000 miles. The car has about 37000 original miles.

What could be the problem and where do I start?

Regards,
Realspartan

 

[pdooley]

hi, i'm no expert but these cars cut out under load sometimes b/c of the coilpack.
this problem usually only shows up under boost though.
you can ohm out the coil to check. should be around 11-12k ohms.

 

[3-5.0]

Is your engine light on?. Mine came on and had a miss when revved at idle,I found one post-yeah one post! on the coil pack that was rusted over,all the others looked new. I did an ohms test and from what I can gather is there are 3 banks and you test the resistance between the two posts opposite each other?. Anyway I got 9-10k on two of them and one was nothing.

Also from what I found is one of the leads under the coil pack lid can short out from being bent down and contacting something under that factory sealant.

 

[realspartan]

No service engine soon light is on...

 

[WH1_T-Type]

Try testing your MAF as well. When my OEM one started to go the symptoms were very similar. Get the car to idle and using the handle of a screw driver give the MAF a firm tap. If you hear a note change in the engine than it is going out. Honestly, mine DID NOT change sound at all, but I had access to a known good one so I swapped it out and it completely fixed my issue.

Good luck.

 

[Red C5]

I would start ignition or fuel. Maybe maf too.

 

[turbov6man]

Try unplugging the Maf after it's running. Computer will code and if it revs good and runs ok. Then you can look further into bad mass air. Not a perfect test but a cheap way to see if it's a bad mass air.

 

[TurboBuRick]

If it does it in park too, my guess is ignition. Check your crank sensor. Make sure the wheel is not making contact with the sensor. Check your balancer bolt. Make sure it did not come loose. If all that checks out run it in batch fire and see how she acts. Do that by starting the car and unplugging the cam sensor.

RL

 

[QWIKSIX]

Mine did the same thing. After checking and/or replacing all the suspected fuel and electronic parts I was getting frustrated. I finally found that the insulation had melted on the hot wire from the battery to the starter. Under acceleration the motor torqued over just enough to touch the exposed copper causing a short and the miss.

 

[realspartan]

Mine did the same thing. After checking and/or replacing all the suspected fuel and electronic parts I was getting frustrated. I finally found that the insulation had melted on the hot wire from the battery to the starter. Under acceleration the motor torqued over just enough to touch the exposed copper causing a short and the miss.

 

[realspartan]

I want to thank all of you for your feedback. The problem was my MAF. I tapped it with my hand while the car was idling and the engine would stumble and then smooth out. Replaced it with a spare that I had and no more issues. Actually runs better than ever.

You guys saved me headaches and money. I was ready to change my coil and ignition module and if that wouldn't work the fuel pump.

Once anagin thanks.

Best regards,
Realspartan

 

[WH1_T-Type]

Cool. Glad you found the issue.