is it missing or something else?

[BlackVert]

i just replaced my fuel pressure regulator with a stocker and replaced my stock mass air meter. the swap out went fine and there are no leaks or anything. it starts up fine and idles fine. but ...

when i am crusing at about 1700 rpms and i go to about 1/2 throttle, it jerks and feels like it misses a few times until it gets up to about 2200 rpms. after that it accelerates smoothly again.

any thoughts?

- chris

 

[hawaiian]

i just replaced my fuel pressure regulator with a stocker and replaced my stock mass air meter. the swap out went fine and there are no leaks or anything. it starts up fine and idles fine. but ...

when i am crusing at about 1700 rpms and i go to about 1/2 throttle, it jerks and feels like it misses a few times until it gets up to about 2200 rpms. after that it accelerates smoothly again.

any thoughts?

- chris

Funny you should mention this mine is doing something similiar i have a hesitation off idle. hoping this is air in the regulator trying to get out. let me know if you fix it. and what the cause was or seemed to be.

 

[BlackVert]

11/02 update: i replaced the fuel filter this morning. still the same.

when i re-installed the stock mass air, the screen was broken around the edges, so i did not install it. thinking that its absence may cause the meter to return incorrect info, i bought some 1/4" mesh at home depot and cut a piece to fit the meter. it is now in place. hopefully it will help. it did seem to drive ok, but the car had not warmed up yet and it always runs better before it is warmed up, so the jury is still out ...

 

[BlackVert]

11/03 update: the screen did not help. it is still behaving the same. the wierd thing is that when it is cold, it runs fine. it only starts this behavior after it is warmed up.

i am checking the fuel pressure next.

ps - i realize it looks like i am talking to myself ... but this is just as good a place as any to record notes and the notes may be helpful to someone else seeing the same behavior.

 

[mackey]

So why did you take it out?

 

[Scott_95GT]

I'm no technician, but it could be your harmnonic balancer starting to act up. Happened to my last 95gt. Good luck.

 

[BlackVert]

I'm no technician, but it could be your harmnonic balancer starting to act up. Happened to my last 95gt. Good luck.

was yours acting like that? ok when cold, hesitating and jerking during acceleration when warm?

So why did you take it out?

take what out? the adjustable fuel pressure regulator? it was bad. you could see where gas was slowly seeping out and you could smell gas from it under the hood when the key was in the on position.

 

[Scott_95GT]

It started to go bad when the motor was warm, but it got worse over the next two days, and was acting up from a cold start right away. I dunno

 

[BlackVert]

11/08 update: checked fuel pressure

line on: 33
line off: 42

looks like the pump is ok.

i put in some fuel injector cleaner today. i don't expect it to help.

next: buy a gauge and check the vacuum. also buy a timing light and check the timing.

i am starting to suspect the O2 sensors, even though they were installed new in may 2004 when the heads and intake were installed ...

 

[Chythar]

I'm not so sure about the O2 sensors, I thought they were mostly to tell the computer if you were rich or lean? I'd personally check the distributor and see if you're getting proper spark.

I'd suggest searching the forum on how to check and see if your distributor is the issue. Any one else have ideas?

 

[BlackVert]

11/10 update: i popped the distributor off this morning and the contacts and rotor looked corroded.

i also noticed that the spark plug wires are 8.5 mm ones from MSD.

lunchtime today will find me getting and replacing those ...

 

[Chythar]

11/10 update: i popped the distributor off this morning and the contacts and rotor looked corroded.

i also noticed that the spark plug wires are 8.5 mm ones from MSD.

lunchtime today will find me getting and replacing those ...

*takes off his blindfold and looks where he threw the dart....bullseye!*

 

[BlackVert]

11/10 update (#2): unfortunately, a new distributor cap and rotor did not help. i guess i'll try going back to the other fpr.

 

[Chythar]

11/10 update (#2): unfortunately, a new distributor cap and rotor did not help. i guess i'll try going back to the other fpr.

*watches in disbelief as the dart falls out of the dartboard*

Well, at least you've avoided a future issue - your contacts & rotor are now fresh.

 

[gcomfx.com]

That's a half throttle... how does it run through the gears at WOT? The reason I ask is that some sensors are ignored at WOT... so it could be one of those?

My car kinda stumbles at half throttle, but runs fine at WOT... which is what I care about the most. Or should I say is what it runs at the most?

 

[BlackVert]

That's a half throttle... how does it run through the gears at WOT? The reason I ask is that some sensors are ignored at WOT... so it could be one of those?

My car kinda stumbles at half throttle, but runs fine at WOT... which is what I care about the most. Or should I say is what it runs at the most?

WOT: runs like crap. once it pinged so bad it scared me. i have been driving really gently since.

the more i read about it, the more it sounds like the stator or the tfi module to me.

 

[BlackVert]

11/11 update: hall effect sensor replaced today ... it did not fix it.

I am going to log the ECT to rule out the ECT sensor. i suspect the FPR again ... i am going to replace the FPR with an AFPR.

it should read 39psi with the vacuum off and plugged, right? i don't think i plugged the vacuum tube the last time i read it ...

 

[mytight95]

plugging it won't matter...........o2's are ignored at wot............maybe a bad coil.....engine ground.......have you checked all your plugs.....you might have a bad injector or something..........anything i can help with or might have that you need man......let me know and i will get it out to you.....


jason

 

[BlackVert]

plugging it won't matter...........o2's are ignored at wot............maybe a bad coil.....engine ground.......have you checked all your plugs.....you might have a bad injector or something..........anything i can help with or might have that you need man......let me know and i will get it out to you.....

jason

ok thanks ... so the 42/33 still hold then.

thanks for the offer of stuff. if you happen to have a coil, that would help rule out (or prove) if it is the coil.

i increased the maf_transfer function to make it give more fuel. that helped, but it still feels like it is missing. i have another afpr on the way, should get here monday. i might put the other (leaky) afpr back on just to see what happens.

i suppose i should also pull some plugs and see what they look like, even though they were just replaced in may when the heads and intake were done.

- chris

 

[1105]

I'm going to say its a spark problem and not fuel. My car has done that for awhile now and one day on my way home just cruising down the road the tach just started jumping all over the place and the car was bucking really bad. Anyone know if there is a way to check to make sure the TFI module is still good?