Bad Miss

cosmo22nov

cosmo22nov

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Joined
Jun 11, 2007
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Alright so my 94 has a pretty bad miss. Ive read some other threads and other people that have a miss seem to be noticing them most around 1250 rpm then they go away after that. well mine is pretty noticable all the time and its the worst right around 2000rpm. When im going down the highway at 2000 rpm with my converter locked it feels like i am in a massage chair because the truck vibrates so much. im just trying to find a way to diagnose what the problem may be. All help is appreiciated.

Thanks,
Tanner
 
i can hear the miss in the exhaust note while its sitting in park. ill go free rev it in a couple mins and let you know if i notice anything.
 
alright i just checked it in neutral and it is just as noticable when you free rev it.
 
Loosen each injector line one at a time while its idling. If it's a dead miss you should run across one that doesn't affect the idle, that's the dead cyl. If there is fuel getting to the injector, then have the injector tested. You could also swap injectors to see if the miss moves with the injector. If not start looking deeper....
 
Another idea is start it when it's cold, rev it at the RPM it misses most and and let it run there a couple minutes, then shut it down. Open the hood and feel each exhaust outlet to see if any feels cooler than the rest & that would be your weak cylinder.

If it just started happening something might be up with an injector.
 
well its been this way since i bought the truck and ive put about 6,000 miles on it. and i heard about a guy who bought one of those laser thermometers were you point it at each exhaust manifold runner to determine the miss, i might try that. ill also make sure my valves are adjusted correctly. if that doesnt work ill try loosening the injector lines and checking timing and fuel pressure. thanks for the suggestions guys.
 
i also dont know if this has anything to do with it but when i got it it didnt idle correctly so i had to set it. and i got it to where i liked it but if i let it sit in park or neutral it would start to gain rpms and free rev by itself up tp around 2000 rpm. so i have to have the a/c on in park or it will start to free rev by itself......
 
cosmo22nov said:
i also dont know if this has anything to do with it but when i got it it didnt idle correctly so i had to set it. and i got it to where i liked it but if i let it sit in park or neutral it would start to gain rpms and free rev by itself up tp around 2000 rpm. so i have to have the a/c on in park or it will start to free rev by itself......
Click to expand...

Could a GSK do this if it wasn't adjusted equally? Just thinking out loud.
 
Yes, you could check them so they are even to rule that out. just count the clicks
 
My buddies truck did this when his governor was extremely tight. Any more than 500rpm idle it would rev its self up to about 2200 rpm and drop back down. It would do this about 6 times then kinda level out for a second then start the cycle again.
 
mine GSK did that as well. i had to run them really loose so as to not want to rev up. got rid of them and didnt have that problem.

Garrett
 
it has some 4k springs in the pump, but it was like that when i bought it and i have never messed with them before. what would i do to check it? anyone have a good link with pics for adjusting a gsk?
 
follow regular gsk install instructions.

then you will have to custom grind a old big flat head screw driver with a slot in the middle to clear the stud but still turn the retainer.

back the retainers off until you dont feel any resitance from the springs and the spring cap is loose.

then turn the retainer back in starting with the first "soft click" which is just to get the first bit of tension on the spring, then 4 clicks after that.

after member of the board told me to set them at 4 clicks, i have had no issues since!
 
cosmo22nov said:
it has some 4k springs in the pump, but it was like that when i bought it and i have never messed with them before. what would i do to check it? anyone have a good link with pics for adjusting a gsk?
Click to expand...

I think you also want to make sure all the shims are out from beneath the retainer. Someone more experienced will quickly correct me if that's not true (I hope).
 
I would loosen injector lines first and see if you have good fuel at the injectors.
 
Once you get beyond the basic troubleshooting that has been suggested in this thread, I would strongly suggest a leak down test. Of course that is assuming that you don't find a simple problem that takes care of the issue along the way.
 
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