When the car is cold...and only when the car is cold, it likes to run absolutely horrid. You all know I've replaced all the sensors under the hood exept the knock sensor and the oil pressure sender.

Anyway heres what it does... When it starts up in the morning, it takes many cranks. Less cranks now since I tuned it up with a new distributor, 8mm plug wires, new AC delco spark plugs, cap& rotor is only about a year old.

If I tryo to say, bring the RPMs up to 3,000, it'll rev up to 3000, then dip down to 2700 and 2500 like it's not getting adequete fuel pressure or something. I don't know. When its warm the engine and fuel pressure seem fine. The car bogs waaaay down when its cold, slows down to a crawl, then putter...putter..putter VARROOOOOM it goes and speeds up and gets better... When its running crummy, and I floor the gas, the car will throw fits and go into what can be described as nothing other than "convulsions" and will violently shake back and forth, what causes it seems to be the engine is sputtering, full power one second, nothing the next. Needless to say I try not to make it do that a whole lot for fear of busting engine/ tranny mounts.

I don't know if this is related, but the "upshift" light comes on even at really really low RPMs. Could my ECM be messed up?

I'm really stumped. I'm going to go to discount auto tonight and replace my EGR valve. The one thats on there looks really old.

I've replaced all the vacuum lines I could find, and I've hunted around with a spraybottle to see if I could find a vacuum leak...none.

Any other ideas? Have I neglected something?

My timing is fine too, I've checked that.

Whats going on with my car?

I can't wait till I get rid of TBI for my carb...maybe that will solve some problems!

 

ttft,ymf'ers!

 

CC,

Hang in there, we'll get to all of them sooner or later...

First, you presumably replaced the TPS. Even though your's is non-adjustable, the voltage at teh closed-throttle position must be under around 0.85VDC so the ECM can "learn" the closed position when the ECM powers up. If it isn't below the spec, you'll have all kinds of issues, like the SHIFT light, SES, stalling, etc.

Also, it would be very helpful to know the fuel pressure.

It's possible that the ECM is "flaked-out", but the ECM can only act on what the sensors are telling it. And it presumes that fuel pressure is adequate, since it doesn't monitor pressure. Before you slide in a new ECM, you need to make sure the rest of the controls are correct.

Your EGR can also cause lots of problems, especially if it is leaking through. That would be a good item to check.

 

Thanks... This problem has once again shredded another tranny mount. I'm going urathane this time.

The TPS is brand new.... any way to adjust it if its out of whack?

 

maybe fuel filter... i had the exact issues with my old TBI, and changing the filter cured it. got lucky it was an easy fix.

just a thought...

 

About all you can do is check the voltage at closed throttle position and make sure the voltage change is linear through the range of operation.