Slow to build boost in first gear.

[dyermullet]

When starting from a stop (drag strip type launch stalled some off the brakes). The car will only build 15psi of boost in first gear then when it shifts it jumps up to 18psi (which is where it is set). This is a 87 stock turbo, stock injectors, turbo tweak chip, stock stall ect.

The car has recently got new plugs and wires (last week).
There are no preturbo exhaust leaks (checked last week).

I need some direction on where to start trying to trouble shoot the car.
The blms are around 121 under cruise. The O2s are around 790 through all the gears.

I am getting a little sick of the car it runs good some days and then not on others. Does everyone else have these problems with the car being flakey? I want it to run the same everytime I get in it? Should I just not be expecting to be able to have that?

What would cause it to not build as much boost in first gear? It is still using the stock wastegate setup with the solenoid, should I try running a different setup?

edit: Also fuel pressure was checked 2 weeks ago and I have plenty 45psi hose off (237 regulator) and 1lb for pound of boost.

[phil_long]

Well, one thing I can say about these cars from experience is that they never really run the same everyday. Im not saying it'll be a huge huge difference from one day to the other, but I have noticed that my car pulls different at times than others. Are you still running the stock fuel pump?

[chrisgarrett46]

When I hear those symtoms, I always suspect the cat. Could your cat be clogged?

[dyermullet]

307 fuel pump, no cat.

I drive my roommates cars LT1 ad LS1 camaro's, they run the same always they have goot part throttle feel and responce, and they have manuals which I like better (my other 2 vehicles are manual.)

I'm not ready to give up on my car yet it is just getting real frustrating.

[Steve V]

I would get rid of the stock injectors.

[motorhead]

Look to the camshaft. Flat lobes can lead to a sluggish start. I have a similar problem to yours and this may be my next step.

HTH.

FWIW, these cars are very temperature and barometricaly sensitive.

[dyermullet]

I have 118,000 miles. I was planning on doing a compressor test soon. And this winter I'll have lots of time so I could check valve lift.

[dyermullet]

Originally Posted by Steve V

I would get rid of the stock injectors.

I had the stock injectors cleaned and flow this spring. After I grad. from college I plan on upgrading injectors and turbo, but untill then I am try to get by and have fun with what i have.

[dyermullet]

I leaned it out some. It is pulling better, but the boost is still a little slow coming up in first gear. It is up to 15psi real quick then takes a little longer to get up to 18. I am going to the track next friday so I'll try tuning it somemore then.

[Real-T]

If you have a stock MAF another thing to check is the MAF and its readings.

During a WOT check to see if it is indeed pegging at 255 or close to it at 15 psi.

Another thought is that if it swings up high even when it is well below 15psi, then the MAF may also be suspect. You mentioned you leaned out the fuel and it got better, maybe the MAF is swinging up high and the ECM is dumping fuel for the short time it's in first gear, then the car/rpm/airflow finally catch up with the MAF reading ?

It's stretch, but may be worth checking to strike it off the list ?

Do you have a recording scantool ? That would help pinpoint the probem too.

Of course if you have a LT1/LS1 MAF with a translator, these problems are less likely to happen. (IMHO)

[dyermullet]

Stock maf. I know it maxes out the maf. I'll check to see if I can find where the maf maxes out but I only have turbolink so the datalogs are almost worthless. I don't have a way to get the files from my laptop to my desktop computer to put on the internet.

[dyermullet]

Figured it out.

I cleared out the computer (disconnected power). Car went back to normal.

Scott

[jurassic five 7]

When you disconnect the battery, or orange wire for the computer. The settings (BLM's/INT) will stay 128 all the time until it the chip 'learns' again and it'll go back to what it was before.

-Adam

[dyermullet]

I understand how it works. Somehow the values in the computer got corrupted when my battery went dead. And whatever was effected caused the car to run rich and the comptuer was using the blms to try to lean it back out. After reseting my WOT values were back to where they used to be and also BLM under cruise was back to normal. Cross counts were back in the 50 range like normal. Durring the F'd up time the cross counts were only in the 40 something range. Those are still good cross counts to me and is part of the reason it took me so long to figure it out.

From now on after the car has been sitting for a long time I guess I'll clear the computer before driving so I don't have to worry about this happening again.

[jurassic five 7]

What do you mean the cross counts were in the 50's? or 40's? Cross Counts cycle from 0-255. If your CC stop or slow down that means a bad o2 sensor.

-Adam