Lagging TR

[BuickTV6]

Hey guys I got a problem. my car is running kinda weird, wanna know if you guys ever heard of this. Idles rough, but when driving its fine. TPS and maf are good. both changed, and even swapped others in to see if it would make a difference. Also changed the IAC. Made none. If I floor it from a dead stop, sometimes it stalls. And if it doens't stall, it will hesitate quite bad. There also seems to be more turbo lag then used to. If i try doing a burnout, the engine sits there, at about 1,000Rpms tires slowly spinning. Then after about 3 or 4 secs, it jumps up to 5000 rpm, and the tires are smoking. Why this lag? When run in backup spark and fuel mode, she run great. If i unplug the tps, or the maf and drive it, it seems to be fine. Cept it stalls with the maf unplugged which is understandable. Can anyone think of what might be causing this problem?

 

[mycarsucks]

I think I have a very similar problem that I am currently trying to diagnose. My car idles rough, and works great most of the time. However, when under a harder acceleration my car stutters. I however have not tried to unplug my tps sensor. When you said you unplugged your sensors, do you think that you did them at the same time, or one at a time. I'm thinking that my tps sensor cuold be the root of my problem, but was not aware that I could unplug it. You also say that it runs fine in backup spark and fuel mode. What exactly is that. I will have nearly all day tommorrow to work on this problem, so hopefulyl I will be able to give you an update.

 

[BuickTV6]

Well i actually plugged out each sensor one at a time to see if I could determine anything. The car runs way better without the TPS plugged in. Pretty well whevener you loose a critical sensor like the tps,or maf, the car goes into backup spark and fuel mode. i'm sure theres many other names for this. All it does it rather then reading off that sensor, it uses presettings stored in the ECM. You guru's can correct me if im wrong too, but thats how I understand it. when it reads from the sensors, it does not run that great. only if its cold. When cold, it idles better, and is more responsive!

 

[GNeric]

Check the EGR and make sure it isn't stuck open. My T did this when I first got it and ran the same way for about 2 weeks (despite having a 2.42 geared 7.5 and a 1300 stall converter) until I found the egr open at idle. EGR stuck open is a big unmetered vacuum leak.

 

[BuickTV6]

EGR

I checked the EGR, looks a little gross. When i the push the diaphram up, it falls right back down when running pretty well all the time... Does that mean its bad? When does it usually close?

 

[mycarsucks]

What are your IAC numbers in closed loop idle? What are your tps numbers at the same time? Mine runs much better without the tps as well, and I just set it and still have the same problems. My IAC numbers are way off though, so I think that may be the problem. Ill set them tommorrow and tell you what I find out.