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.

Will rich cause stumbling?

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???

TPS volts is between 0.54 and 4.27 from idle to WOT.

Please note that this problem is only at full pedal WOT. Just before full pedal is great. Then blah, blah, blah,...

I can furnish scan data to anyone interested in looking at it.

Thanks.

 

if the problem appeared after changing injectors id say it has something to do with it. could be that or worn ignition parts (wires, rotor, cap, coil, etc..) but its more likely that it would occur at part throttle too with ignition.

 

No. The ignition system is completely new including a Jacob's Pro Street set.

Seems like it is too much fuel or not enough, but my scan data looks like everything is within specs.

As I said in the first posting, the problem only occurs at mashed to the floor WOT. Just before that point everything is fine. What factors come into play at absolute 100 throttle angle?

Anyone else?

 

at 100% throttle the computer is in what's called Power Enrichment mode. This is an open loop mode with no adjustments from O2 reading or anything else. Is the tuning for PE mode is way off in the chip then this would cause a problem only at WOT

Hodge

 

So if it a sensor or ignition problem then I will try altering the fuel pressure.

If that doesn't help then I need to get into some chip burning.

Anyone else with this experience???

 

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?

 

thats a dead sign of a failing pump. it cant feed enough to keep pressure when the injectors are firing alot of fuel when you floor it. looks like youve found a good culprit.

 

Your FP is waaay too high. You should be dropping it not raising it. You wouldn't hurt with another chip but try dropping it to the low 40s to see if it makes a difference. Do you smell fuel at all?
Your car is a stock or nearly stock 305 right? I still have the 22#ers @ 52 psi on my 383 with head and cam. I am waiting on a set of 26# injectors now though cuz I'm getting the rest of the super ram.

P.S. When was the Jacobs installed?

 

This problem began with the fuel pressure set at 45 psi. So bringing it into the lower 40's is not the solution.

Actually, the engine is modified. I am following the modifications of list member Willie as I am adding a supercharger now.

I have:

Jacob's Pro Street w/ 0.035 gap plugs for SC
TPIS big mouth intake
SLP intake runners
SLP 3" exhaust
SLP headers
SLP air foil
Cold air induction
crane cam set up for SC
crane roller rockers
Accel 23# injectors
SLP performance chip

Willie is running 50 + psi fuel pressure. However, he has different heads than I do.

I talked to Willie and he thinks that the STOCK ORIGINAL fuel pump in my car can't keep up with the fuel demand at full WOT.

The car does run rich at the 54 psi setting, but the BLM is modifying the injectors. The car is VERY powerful and responsive up to about 95% WOT. At 99% WOT it totally stops accellerating and vibrates vilently. I watched the fuel pressure drop from 54 to 38 psi !!!!!

This does not seem like a rich running problem since the car runs awsome except at 99% WOT. Looks like a fuel pump failure problem resulting in no enough fuel at full WOT. Just wanted to know why this is happening before just changing out the pump.