mypontiac

I have a 1991 TA 305 w/ 5 speed. I just replaced the stock injectors with Accel 23# injectors.

Now the car runs great with the exception of full WOT. Almost all of the way to the floor is fine, but a full stomp get you a lot of vibration and hesitation. Basically no power and stumble.

Do I need to change the injector constant on the chip??? Or does this sound like something else.

I will be running a scan on it shortly to see if I am running rich at WOT. Will rich cause stumbling?

Thanks.

Vader

You might actally be lean. The rumor is that GM rates their injectors at a lower pressure, so that any replacement injector must have a higher flow rating in order to even be equal to the OEM units. I've heard that Accel 24# injectors are the functional equivalent of 22# OEMs.

mypontiac

Maybe, but my nose scanner tells me that I am definitely running rich at idle.

Guess I just need to take some readings.

Was hoping to get some suggestions in advance though.

Thanks.

jocww

i have the same problem cept i have a 84 l69 5 spd carb wats my problem

mypontiac

I ran a scan today. At WOT my BLM's were at 128 and O2's were between 850 and 900. So this looks OK to me, but the car still stumbles and loses power???

What else can I look for ???

Vader

The BLM is "perfect", but if the O² numbers are millivolts and not crosscounts, you might be a little rich - but just a little.

It is possible that the ignition system can't handle the compression pressures at WOT. If the spark is blowing out under compression, you would get incomplete combustion, lack of power, and maybe the higher mV readings. I'm just speculating....

mypontiac

Hope this isn't the problem. I have a new Jacob's ignition since I will be adding a supercharger in the next 4 weeks.

But please note that the problem only occurs when the pedal is completely mashed down. Almost all of the way down is great. That is what does not make sence.

I can send you a file of the scanned data if you are up to looking at it.

One thing that I noticed is that my Throttle sensor volts are always at 0???

Thanks.

mypontiac

I rotated the throttle position sensor and got it to read 0.54 v at idle and 4.27 v at WOT.

The car still runs like cr#p at WOT mashed to the floor???

Runs great just before full pedal.

First is like being shot from a cannon, but you can't go WOT since the RPM's jump up so fast.

This is more like cruising in third (manual tranny here) and then pushing it straight to the floor. Then bog, bog, bog,............till you let up a little. Then off you go!

I wonder if it has something to do with the fact that at WOT there is no vacuum. My vacuum gage goes to 0 at WOT.

Any suggestions here???

I can provide scan data. No trouble codes.

Thanks.

Sitting Bull

You probably need to be running richer secondary rods and also need to adjust you Air Valve tension. Try a set of DR rods and a B hanger. They're pretty cheap, $15 should get them both with change back.

Go to this site's Tech Articles and look up the one on tuning the QJet. It tells you how to fix what's ailing you

mypontiac

Hey guys!?!

Any help for a TPI car???

Losing sleep here.

Looked through so many posts. None specific for just losing power at WOT.

Thanks in advance.

Sitting Bull

I hate to say it, man, but that's the reason a LOT of people just finally toss their fuel injection and put on a carb. It is SO much easier to diagnose

Be sure to post your question on the TPI board, though.

mypontiac

At WOT the car loses power. I brought the fuel pressure (no vacuum) up to 50 psi from 44 psi. No difference at WOT.

I then raised the pressure to 54 psi (no vacuum). Still no difference. I watched the Fuel pressure gauge more closely on this run however. I noticed that as I was excellerating the fuel pressure climed to 54 psi w/ zero on the vacuum gauge just before WOT. At WOT the vacuum still registered zero, but the fuel pressure dropped from 54 psi to 36 psi !!! What's up with that???

So accellerating at about 95% WOT I am getting 54 psi of fuel pressure, but at 99% the pressure drops to 36 psi and the car stops accellerating and stumbles.

I also noticed that on the data that I was experienced some knock retard??? Maybe a result of the stumbling as opposed to vice versa??

Looks like I have a fuel problem as I checked an initial run with my stock coil instead of my Jacob's and had the same problem.

Suggestions???

Do you think the fuel pump is going bad?