dark scorpion

iTrader: (2)

Ok.

I had another thread labelled "hesitation at acceleration" and went through
a bunch of steps to try to remedy the problem.
Here's what's been done:
New plugs, wires, cap, rotor, icm, coil
new o2 sensor
new egr valve
new map sensor
new iac sensor
new pcv valve
new fuel pump, new fuel filter (second one in 2 months)
Tried to locate and replace as many vacuum lines as possible
Today I got the chance to test the fuel pressure and with key on, ignition off
the pressure was at 40 psi.
With the car started the pressure dropped to 34 psi.
As far as I know this is within specs so what next????
I had another 3rd owner look at it and he instructed me to inspect the injectors. He checked them with his hand and I checked them with my and
the driver's side pulses strong but the passenger's side pulses weaker.
He suspected it might be the fpr but as I found out today, the pressure is
within specs.
So what next? Do I go ahead and replace the fpr, fuel lines, injectors what????????????

I am asking the experts (so to speak).
HELP!!! ( I gotta get this thing running good some time

And thanks guys!!!!!!!!!!!!!!!!!

customblackbird

iTrader: (15)

umm wow u wasted a good bit of money already. good news is u got alot of new stuff. i would think the only things to cause hesitation would be your timing and other things i posted. wats ur base timing? did u put rotor on correctly and not off the original position u could have muffed that up with the igniton stuff. (hope u went with aftermarket ignition on everything) base timing was all over from 0 to 6 degrees. i would set yours to about 8 and see if it helps. remember to disconnect the plug connector for the EST on the pass side firewall when setting base timing. again in HAYNES manual.

your fuel pressure is alil low. stock is or should be around 43.5psi. i would get a adjustable one just so u can tune it. i would also raise fuel pressure to 46-48psi. the vacume will drop the pressure, important is to set fuel pressure with vacume off.

also when u replaced the IAC did u set it right? if not u need to get a HAYNES manual FAST! it will explain how to.

next thing to check would be your TPS voltage. it should be at .46-.56 without pressing the pedal. i would set it to about .5-.52V. also when u press the pedal make sure the voltage doesnt jump around when u hold the pedal still... if it does jump and u keep the pedal steady then ur TPS is bad. should go from your base TPS voltage of .5 to 5V.

it could be injectors but lets just weed out the simple stuff and see if it helps. so check and set BASe timing, check IAC setting, check TPS setting. i would also give it a vacum check and see what vacum its pulling. are u throwing any codes? make sure there are no vacum leaks, spray brake cleaner around intake etc and see if motor changes. etc.

dark scorpion

iTrader: (2)

I was in the process of setting the timing. I plan on doing that within the next week or so.
I thought on the l98 you're not supposed to mess with the iac adjustments.
On mine, the little cover for the adjusting screw is missing. I kind of figured the guy I bought the car from messed with it. I was apprehensive about touching it myself but I might have to.
I was going to check the tps setting as well.
So first I will ck and set the timing. Then I will ck and set the iac, then tps.
I will see if the tps needs replacing.
After these steps I will post the results.
Oh yeah I will get the adjustable fpr somewhere in there also.
No codes other than the "handshake" code.

BlueIroc-Z

iTrader: (6)

Here's the Tech Article on adjusting the IAC and TPS. Might come in handy... Don't know if you've been referred to them before, but if you haven't definitely take a look. Good luck

dark scorpion

iTrader: (2)

Yes I have printed out the tech article.
Does the manual specify how to shut the vacuum off when setting the timing?
Also, how do I check the vacuum? At what point do I connect the vacuum
gauge?

BlueIroc-Z

iTrader: (6)

The distributor is not vacuum controlled. The advance is electronically controlled via the ECM. There is a little connector that breaks out of the main harness near the A/C box and the pass. fender (single wire inline weatherpack connector). You disconnect that to set the base timing. Here's a Tech Article on setting the timing.

I would think that you would check the vacuum at idle after it has reached full operating temperature. Probably just unplug the vac line that goes to your cruise and HVAC, and plug your gauge into that one (there should be two ports on the pass side rear of the plenum, one goes to cruise/HVAC and the other goes to the FPR).

customblackbird

iTrader: (15)

doesnt matter where u connect the vacume. i would prob do the cruise control since its convienent. ive done the fuel pressure regulator tho.

doesnt matter the engine. if u bought a new IAC they are usually not calibrated correctly. the correct way to adjust is in the article prob. its not just pushing it but u gotta roll it while u push it with your thumb. and has to be a certain distance. when u do the timeing/vacum. TPs, and IAC... if still it isnt correct... have u messed with the idle air screw at all? the small screw in the upper right hand side of the TB?.... this adjusts the idle with the TB blades on how far they are open without pressing the throttle.