as listed i have a 93 vtec with 261xxx miles. I am getting a rough almost violent shake when i start the engine cold, i.e when i wake up in the morning to go to work or when i start car after work and its been sitting for a while. The shake is like it is struggling to start then when it turns over it gets a couple of rough shakes. If i just drive to the store, or somewhere for a short time period and come back to start the car, it turns over smooth. It seems to only be doing this when the engine is cold. I got the car not running at 255xxx and have done the following work, as this may help someone diagnose the problem:
1. replaced the tranny with a 99, used the existing starter from the 93
2. new battery and battery cables
3. cleaned the FITV, IACV, TB, and replaced the seals.
4. flushed the coolant

The issue has been consistent for several months but just recently started to get worse. Initially when i got the car running the idle fluctuated on a cold start which was fixed when i cleaned the FITV valve. I aslo adjusted the idle speed a little down. Help will be much appreciated. thanks.

 

slightly loose/bad motor mount, maybe. when your car is cold, it's going to have the most vibration, and it's going to be the hardest to crank which means more vibration. for it to be a "violent" shake, i would assume the motor is moving more than it should.

 

Thanks for the input, I'll go back and check the mounts. I was thinking it was lacking one of the three components for the start, fuel, air, spark. Any chance one of those systems fault or go bad over time that would cause the issue during a cold start?

 

violent shaking? no. you can have issues from that, but i don't see it do that. maybe a shudder...

maybe an issue between the flywheel and starter, but i don't know why it wouldn't do that all the time.

you may have a combination of issues. you don't have engine dope for motor oil do you? i could see that causing issues until the motor got warmed up good.

 

Hmm, lean condition can cause some violent bucking of the engine, maybe a vacuum leak someplace? Anybody else have a suggestion?

 

I've got the same issue. when I start the car in the morning it turns for a few seconds longer than it should before catching and starting up. When it finally does catch, it misses/starts rough for another 1 or 2 seconds and then will idle normally. After that it starts normally. It only rough-starts in the morning... has to be a spark, timing or fuel problem...