Fuel problem or Ignition problem
Thread Starter
Teching In
Joined: Dec 2005
Posts: 28
Likes: 0
From: Omaha, NE
Fuel problem or Ignition problem I have a 99 z28 and I have been experiencing some stuttering problems. It seems that when i am driving along at about 2000 to 2500 rpms the car kind of cuts out for a second then goes at full power, it is really quick sort of stutter. It also will do it sometimes at 3000 to 3500. I have replaced my fuel filter, and I have used fuel injector cleaner, and tried some HEET because the car tends to sit outside for periods of time. I have also checked the fuel pressure and it was reading 60 at idle, which I hear is ideal or normal. None of the things I have done above has helped the problem. I am now beginning to think that it is not a fuel problem, but something with ignition? Any help is greatly appreciated.
Thank You....
Joe
Thank You....
Joe
Fuel pressure appears normal. Does this happen at level
cruise, or when you are opening the throttle? The latter
would indicate a discrepancy between the speed-density
and the MAF airflow, stumble while you are in unsteady MAP
and come back when the MAF is back online. If it's at cruise
then you have to look at the misfire angle, borrow soneone's
scan tool and see if a single cylinder has a problem. The
other thing it could be is that when you cross fuel trim cell
boundaries, if the trim is grossly different you could have a
momentary stumble until the short term trims come around
to take up any slack. All of this wants more than guessing,
need to hook it up and read the tea leaves.
cruise, or when you are opening the throttle? The latter
would indicate a discrepancy between the speed-density
and the MAF airflow, stumble while you are in unsteady MAP
and come back when the MAF is back online. If it's at cruise
then you have to look at the misfire angle, borrow soneone's
scan tool and see if a single cylinder has a problem. The
other thing it could be is that when you cross fuel trim cell
boundaries, if the trim is grossly different you could have a
momentary stumble until the short term trims come around
to take up any slack. All of this wants more than guessing,
need to hook it up and read the tea leaves.
Thread Starter
Teching In
Joined: Dec 2005
Posts: 28
Likes: 0
From: Omaha, NE
Wouldn't it throw a code if there was a misfire? To answer your question, it seems to be doing it when I am accelerating or opening up the throttle, say when comming out of a turn and shifting through the gears when it reaches those rpms, it stutters. In other words you are saying that I should find someone whith a scanner and have them check the the ignition? Should I clean my MAF sensor? What would be the best and most safe product, I have seen some intake cleaner at the parts store, should I use that stuff? I think it is made by CRC or something like that.
Thanks again
Thanks again
Last edited by CamaroJoe99; Jan 24, 2006 at 06:11 PM.
Thread Starter
Teching In
Joined: Dec 2005
Posts: 28
Likes: 0
From: Omaha, NE
Anyone else got suggestions...I only have about 66,000 miles on it, I don't know whether I should check the plugs or if it would be a bad coil somewhere. I am out of ideas, anyone that may have some other input, feel free to say something.
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Thread Starter
Teching In
Joined: Dec 2005
Posts: 28
Likes: 0
From: Omaha, NE
Is it ok to take out your egr system, if so what all does that include the removal of? also do you get any HP gain from doing so? Does it make you show check engine all the time if you do want to take it out?
I have the same problem and alot of us do. i only started having it once i installed long tubes and true duals. I only seem to notice it on cooler days. My theory is that with the coating on my headers the o2's cool to fast and when I get into the car and drive they are not warm enough to read properly. i mostly notice the problem if i go out to the store about 5-10 mins away then go to leave and give it some gas it will bogg. I have had it happen one time as well after my car sat for a few days and it was colder out. I have read of people with a similar problem try and swap to vette O2's but that did not fix it. So i as well am still lookin for a solution. But It does seem odd the the egr to my understanding only works during start up for a short while and that is when i have my issues. So i may try to remove it and see if there is any change.
Originally Posted by the_beast
i took the car to computer checking,,and the guy there told me these things
-2 coils
-oxygen sensors
-egr valve
i changed only the two coils and i still have the problem , !!
-2 coils
-oxygen sensors
-egr valve
i changed only the two coils and i still have the problem , !!
TECH Regular
Joined: Mar 2005
Posts: 426
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From: saudi arabia
what would be the problem if this happens right after I took the car to the car washing !!! does the water leak to the computer and cause this !!! or, is there some cut wire !! I'm sure it is something FAULTY when the water touch it ,,but what is it !!! I DONT KNOW ,,
any ideas !
i think it's better not to wash the car again !! lol
any ideas !
i think it's better not to wash the car again !! lol
Thread Starter
Teching In
Joined: Dec 2005
Posts: 28
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From: Omaha, NE
I think I found the fix....I did some more thread searching and I found out that we are not the only ones with this problem...it is more common than not. Anyway, I saw that someone had said to change the Throttle Position Sensor (TPS)...I work at Advance Auto Parts and we sell them for like 35 bucks or something like that, and I bought one up and installed it earlier this week and it seems to be working right again. I havn't driven it much yet except for a couple of minutes that night to test it out. All seems to be ok, plus the car does seem to have a little quicker throttle response! that could just be me though, I havn't driven the car much before this night because it has been under its cover for the winter. Now I get to dig into the speaker problem...I have my two front door speakers not working and my two rear seat big speakers seem out...Anyone know why?
Thread Starter
Teching In
Joined: Dec 2005
Posts: 28
Likes: 0
From: Omaha, NE
OK, so i thought that this solved the problem, but it didn't...now I am clueless as to what to go with next...dont have a ton of money to throw parts at it trying to figure it out...if anyone else has Ideas, Im listening....Do shops have a diagnostics machine that you can run while you are driving the car to see whats happening while the car is in motion? and is it expensive?
I have the same problem but when I mash it hard it backfires and shuts off. My friend has a scaner and I drove while he watched the scanner and no codes or missfires nothing. Simple thing to do check your plugs and wires first. I would disconnect the MAF to see if that is your prob. I am thinking I need to change cam and or crank sensors as my next step.
Originally Posted by CamaroJoe99
It seems that when i am driving along at about 2000 to 2500 rpms the car kind of cuts out for a second then goes at full power, it is really quick sort of stutter. It also will do it sometimes at 3000 to 3500.
* What codes (if any) are showing?
* You need to datalog the car when this happening. This will greatly help to pinpoint the problem.
* What mods are done to the car (especially recently)?
There could be countless causes, but don't rule out an electrical problem like a short.
Anybody find a fix for this issue? Have a 00 t/a with the a hesitation & backfire out of the exhaust around 3000-3500 @ wot. No codes found, car doesnt have any misfire codes did a CKP relearn it stopped for 1 wot run and returned for the next 3.. Cannot figure this out!