Ok.. so i let the car warm up to 130 degrees before driving anywhere. I back out of the drive way and the first shift is ok.. but then it seems like the gas pedal isn't doing much. I get to the end of the street to turn (about 50yards) and i give it a little more gas than usual .. and it almost stalls as the rpm's go up! It did NOT like the higher rpms (around 2000). I got to the light about 100-150 yards further down the street and stopped and turned like usual and gave it some good throttle and it was fine... WTF?!??

So, just imagine yourself driving away from a stop ... the more gas you give it, the faster you go ... but I would give it more gas and it wouldn't go any faster.. and when the rpm's get up there it still wouldn't be going anywhere and would attempt to stall.

I was logging with Datamaster while all of this happened, and I'm going to post it in just a second.


WTF is going on ???? TC problem or tranny?!?!?!? And why is it only doing this when cold??? I works PERFECTLY after driving a few hundred yards.

EDIT ok.. i just got done looking at my tranny temps.. and it's not actually being caused by cold fluid, because the fluid is less than 10 degrees hotter than when I started the car when it works right. That's not enough difference to be causing this problem. It didn't get above 100 until 5 minutes after my car started (and the drive at the end of the street only took a minute or so.)

Ok, here are two graphs from datamaster.



You can tell exactly where it was messing up. The blue line is the throttle position %. the red is RPM's, purple is slip rpm, and black is speed. When i gave it throttle, the rpm's didn't go up nor did the speed. In fact the rpm's went down on the second and third times i gave it throttle.. which is exactly when it was trying to stall on me. That is exactly what happens when it's cold.





[Modified by Glock'94, 12:29 PM 5/7/2002]

 

ttt!

 

Add the Injector Pulse Width to the graph and post it.
I suspect you are not getting fuel.

 

I think that's BPW right? Base Pulse Width??


[Modified by Glock'94, 12:20 PM 5/7/2002]

 

Ok, here is a graph at point 422 and a graph at point 423. Notice the rpm's in the first graph are higher than in the second graph.. HOWEVER the % throttle in the first is lower than in the second... by nearly 3x's! This is puzzling to me. I'm getting much lower spark advance in the second one too. Notice the time of each of those points. Both of them happened within 1 second.

And actually.. i'm running kinda rich (110-114 BLM range lately because of the humidity I think).






[Modified by Glock'94, 12:35 PM 5/7/2002]


[Modified by Glock'94, 12:41 PM 5/7/2002]

 

Mine used to do that a little bit when the exhaust was cold and the cats were not on the car. Mine had to do with exhaust flow and back pressure not working properly until the pipes get all heated well. It does not do it at all with cats on. Usually only hessitated on the first turn in the morning. It may or may not be the same thing happening to you.

Could the plugs be fouling from sitting at idle?

 

Hmm... very well could be something like that. I have gutted cats and no mufflers. (putting high flow cats on sometime soon).

I doubt it could be fouling plugs because it will do the same thing if I just start her up and drive off.

I'm going to go start the car and try and rev it a tad without even moving it (park). Think that will eliminate cold pipes if that's the case?


[Modified by Glock'94, 12:48 PM 5/7/2002]

 

Like I said, it looks like it is not getting fuel.
O2 sensor say's so. RPM's say so.

The next Q is it because the ECM is not providing fuel or is there not enough fuel (pressure)? The Inj PulseWidth will tell you this. I am not sure what the data logger is calling "base". Sorry not familiar w/ that software.
If you can map the Inj PulseWidth w/ RPM & TPS, it should be obvious.

 

Can it be that it is running so rich that it is stalling the engine when you get on it when it is cold.

Jay

 

Ok, i'll post an excel of the inject pulse width.. it won't let me graph it.

 

It's running the same richness after a couple blocks though.. and it's fine. I still think this has something to do with the transmission or TC.... lets eliminate the engine first though.

 

Chris, i just went in the garage and reved it up to around 3k while cold (not something i really like to do), but it was fine. I think something with the TC or tranny is holding back the engine from spinning at the higher revs when the TC stalls out. But I may be wrong.

 

Here is an excel of it
http://www.gulicks.com/vette/programming/5-6problem.csv

 

It only did it under load.

 

wow.. i hope it's something as simple as that! No way to really know until I can order my direct replacement cats. (and until I can actually work on my car again when my torn muscle FINALLY heals ... it's already been 2 months :( ).

 

Did the engine get a little hotter after couple blocks or is the temp the same.
I dont see that the RPM will trop because of the trany it will just make it work harder.

Jay


[Modified by MrJay, 1:02 PM 5/7/2002]

 

The engine was only about 15 degrees hotter and the tranny was maybe 5-10 degrees hotter (after a couple of blocks). So I don't know that it has anything to do with temp now. I just revved it in the garage at 74degrees and the engine was fine ...


[Modified by Glock'94, 1:04 PM 5/7/2002]

 

I dont know much about programing so I dont know what number you sute have but IAC number is high and it goes up when that happend.

Jay

 

That's because I gave it gas :).

 

Ok I see
But I thought IAC was for the Idel.

Jay