LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Engine has either a dead cylinder or severe misfire under load

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Old Aug 10, 2012 | 05:16 PM
  #1  
tylerwerrin's Avatar
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From: Santa Monica, CA
Engine has either a dead cylinder or severe misfire under load

Hi guys,

Ugh, this engine has fought me every step of the way. As soon as it's driving and I'm moving onto the next step, some other problem rears it's head.

Here's the new problem for today:

This morning I drove it about 20 miles to work a job off campus, and everything was OK. On my way back to the office, i noticed the car started vibrating more in the lower RPM ranges while on the freeway. It almost felt as if I had a severe tire out of round, or something along those lines. However, the tires were brand new. I revved the engine a few times in neutral and felt that the engine had a vibration that wasn't there before, like it was missing. However it wasn't intermittent -- it was constant, like nothing is firing at all.

I pulled over, inspected the tires -- everything looked ok. I revved the engine in neutral a bit and it seemed a bit better. However, as soon as I got on the road under load, the vibration would be much more noticeable. I had to get back to the office so I drove the car back -- it made it back OK. I noticed that the RPMs seemed to be smooth enough at idle -- no HUGE vibrations, nothing more than usual anyways.

I took the car home and drove it around the block with TTS datamaster running. The results I got back were wierd:

https://dl.dropbox.com/u/24984984/aug%2010-3.uni

Anyways, if anyone has any ideas of what to check for -- I pulled the injector clips and noticed that two of the cylinders seemed to have no effect when I pulled them off -- one POSSIBLY had a slight effect on idle, but it was hard to tell. The other felt like there was no change (these were Cylinder 1 & 4 respectively... cylinder 4 had the "slight" change.)

Any help would be appreciated -- i don't get why it would suddenly konk out like this!
Old Aug 10, 2012 | 05:47 PM
  #2  
Kevin Blown 95 TA's Avatar
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Joined: Oct 2001
Posts: 2,684
Re: Engine has either a dead cylinder or severe misfire under load

You could have a cracked or fouled plug or shorted/open plug wire. Or the plug wire might not be in the distributor all the way or on the plug all the way. It is possible, but less likely, the problem could be in the distributor cap. There could be a problem with your injectors, too. You can swap them around or substitute some known good ones for troubleshooting.
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