Went for a drive to warm up the car to perform WOT tests. While driving around I had the cut out open. During the warmup period, the SES light went on. I scanned it and it was 32 EGR diagnostic SW signaling incorrect EGR valve operation, and 48 MAF circuit problem. The MAF was plugged in at this time. I cleared them and drove for 10 more min and they never came back. Performed two tests at WOT with cut out open, the first test both O2's went to 987 and stayed there steadily. The second time one side went to 972 and the other 982 and stayed there. What does this lead you guys to believe?

 

Lack of back pressure will set the DTC 32 code for low EGR flow. Supposedly, there is a timing reduction made in the PCM when that code is set.... but I don't know that for a fact. I haven't used the stock PCM for 8 years now. Keep in mind that EGR is not used above 3500rpm or at WOT, so it shouldn't be a big problem at the track.

As a rough inidicator, which is all the stock O2's are, you are running on the rich side. That could account for the car not performing like it was before. I'd guess that there might be 15-20HP difference between running very rich and running with the A/F ratio where it is supposed to be, but that is just a rough estimate.

I suspect if you look at the long term fuel corrections, its adding a lot of fuel in closed loop, and that carries over to the fueling calcualtions at WOT. First you need to identify if there is anything causing the PCM to add extra fuel, if that's what it is doing. You have to figure out if you have a "true" lean condition or a "false" lean condition that is adding the extra fuel. And, I think its time for a tune. You definitely have enough mods to justify a tune, and you may be compounding the problem with the Granatelli. Ask your tuner if he feels he can achieve a better tune with a stock MAF or with the Granatelli.

 

And I agree... "Drag Racing....." isn't really the best forum, so lets move it to "LT1/LT4 Engine Tech".

 

I had the same thing happen to me when I installed my Heads & LT4 hot cam on my Vette a few years back. I ran WORSE times in November air than I did in July when I was stock at Commerce. Two things Fixed it: This was on a More Performance tune

1. PCM for Less tune
2. New Accel 30 lb/hr injectors.

My trap speed increased 12 mph and my ET droped 1.5 seconds in the same November air a few weeks later.

 

the pcm tune is going to be the biggest thing to correct your problems. The aftermarket maf also needs to go. Sell it and never look back, its only causing you problems. The best thing to do would be getting it on a dyno for tuning. But no matter what you do ditch the maf and tune it. Better times will come after that. good luck

 

You should also ditch the stock lt1 valve springs and rockers imo. The stock springs are the more urgent of them, they're maxed out on a stock cam, even the springs that come witht he hotcam kit are marginal. Get the thing tuned as well, you cant get the revs out of it that a cammed lt1 needs with the factory tune, its probably shutting you down where your peak power is. If you really want the most out of it, get a cable and tunercats and learn to do it on your own.

 

I agree, get those springs out of there and the maf and get a tune and you will be very happy.

 

feenix88 - You didn't bring this up when we were playing with your car last night, I have tunercat, some other fun software to change tunes to uses your Vin and the cables needed for the 95, so after you get the valvetrain in we can play with the tune a little if your interested. I think I have a hotcam tune laying around somewhere...

 

That would be AWESOME! I planned to order a tune after the valvetrain upgrades. You are quickly becoming one of my favorite buddies. Im going to owe you big time!

 

Make sure the bellows is seated correctly on the TB. There have been countless posts where members have actually ripped the bellows installing it onto the TB in thinking it was on correctly.

 

I like how you have your times in your sig and say completely stock... an LT4 Hot Cam is not stock in ANY car. Not even a LT4 car.

 

Perhaps that was the ET ran before the mods were done?

 

He said that his previous times were with the hot cam, also stated the the car had the hot cam in it when he bought it, so he has never had the car completely stock.

 

See... says except here but bone stock in sig times, lol.

 

You are right. I will change the sig immediately since it bothers people. Thanks for contributing to the thread.