Another stalling/rough idle/hesistation issue
08-18-2012, 10:32 PM
#1
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Join Date: Jun 2012
Posts: 45
Another stalling/rough idle/hesistation issue
Ive been battling this issue for a month and a half now and I've done a lot in attempt to solve it. So far the problem has cleared up a bunch it no longer idles roughly. Also when i came to a stop the RPM's used to dip down and stall frequently, thats been fixed. The hesitation for the most part is GONE except for once in a while it still does it after a warm start.
Here are the current symptoms of the issue: It cold starts PERFECT, idle lowers to base idle perfectly, runs like a champ. I park it, shut if off, let it sit for more than like 20 min or so and when i go to start it it starts right up then stalls IMMEDIATELY. I then have to start it up again and hold the rpms with the gas pedal at like 2-3 until i feel like its safe to kick into gear (auto tranny). It drives a little strange at first (slight hesitation) then clears up and after a little bit of driving it runs great. I don't understand what it could be I've done a lot (which have helped clear up a lot of the issue):
Cleaned TB and replaced gasket between TB and Plenum
Cleaned MAF
Changed MAF to a new one (fixed stalling i believe)
Changed spark plugs
Replaced Coil pack 3 boot because of oil being in the tube from a loose spark plug (fixed misfire in cylinder 3) (fixed rough idle)
Ran fuel injector cleaner
Changed the fuel filter
Started running 93 octane (made no difference)
Changed both o2 sensors that were drawing a code
Changed knock sensor
cleaned up grounds
Edited the throttle position screw
Today i cleaned the IACV which was nasty and this made the car much more powerful! hesitation was almost non-existent after that.
At first i had codes for o2 sensors, knock sensor and then i was getting a cylinder 3 misfire. as of today i have NO FAULT CODES. Again my symptoms are stalling immediately upon a WARM start.
My grandfather and I believe the culprit now could be a coolant temp sensor (I'm hopefully replacing this tomorrow) and another mechanic believes it could be either that or the throttle position sensor. Im posting this to see what anyone else has to say, appreciate the responses in advance. Stalling issues are very frustrating and there is a lot of "could be this" involved.
Here are the current symptoms of the issue: It cold starts PERFECT, idle lowers to base idle perfectly, runs like a champ. I park it, shut if off, let it sit for more than like 20 min or so and when i go to start it it starts right up then stalls IMMEDIATELY. I then have to start it up again and hold the rpms with the gas pedal at like 2-3 until i feel like its safe to kick into gear (auto tranny). It drives a little strange at first (slight hesitation) then clears up and after a little bit of driving it runs great. I don't understand what it could be I've done a lot (which have helped clear up a lot of the issue):
Cleaned TB and replaced gasket between TB and Plenum
Cleaned MAF
Changed MAF to a new one (fixed stalling i believe)
Changed spark plugs
Replaced Coil pack 3 boot because of oil being in the tube from a loose spark plug (fixed misfire in cylinder 3) (fixed rough idle)
Ran fuel injector cleaner
Changed the fuel filter
Started running 93 octane (made no difference)
Changed both o2 sensors that were drawing a code
Changed knock sensor
cleaned up grounds
Edited the throttle position screw
Today i cleaned the IACV which was nasty and this made the car much more powerful! hesitation was almost non-existent after that.
At first i had codes for o2 sensors, knock sensor and then i was getting a cylinder 3 misfire. as of today i have NO FAULT CODES. Again my symptoms are stalling immediately upon a WARM start.
My grandfather and I believe the culprit now could be a coolant temp sensor (I'm hopefully replacing this tomorrow) and another mechanic believes it could be either that or the throttle position sensor. Im posting this to see what anyone else has to say, appreciate the responses in advance. Stalling issues are very frustrating and there is a lot of "could be this" involved.
08-19-2012, 08:16 PM
#2
How many miles an when was the last time you serviced your transmission
a coolant temp sensor usually has more issues like a high idle and continually cycling fan.
a coolant temp sensor usually has more issues like a high idle and continually cycling fan.
Last edited by maxed_out_99; 08-19-2012 at 11:07 PM.
08-19-2012, 11:14 PM
#3
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Join Date: Jun 2012
Posts: 45
I got the car at abut 129k miles and it currently has about 159k on it.. i personally haven't had the transmission serviced but I'm not sure if the previous owner has. Those symptoms can have to do with the transmission?
08-20-2012, 07:35 AM
#5
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Join Date: Jun 2012
Posts: 45
Im not worried about the transmission, but the clogged cat is a concern, my rear cat is gone it was replaced with a high flow cat but one of my pre cats have a dent in it which bothered me even though a few people said don't worry about it. Could it possibly be the fuel pressure regulator (FPR)? If so how would i confirm that? the issue is intermittent remember and as the days go on it grows even more intermittent and less occurring. I am starting to think maybe the ECU is still re learning everything from last time i reset it
08-20-2012, 12:06 PM
#6
It might be worth it to service your trans just so you know you have clean fluid.
To check the FPR just unplug the vacuum line and see if fuel comes out then with it unplugged start the car and see if you still have the same issue.
The ecu relearn takes less time than you think and it shouldn't cause a bad start
The cat is my best guess without looking at the car. Since you said oh had all the starting issues and misfires I'm sure it was dumping fuel causing the cat to become clogged
To check the FPR just unplug the vacuum line and see if fuel comes out then with it unplugged start the car and see if you still have the same issue.
The ecu relearn takes less time than you think and it shouldn't cause a bad start
The cat is my best guess without looking at the car. Since you said oh had all the starting issues and misfires I'm sure it was dumping fuel causing the cat to become clogged
08-20-2012, 12:29 PM
#7
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A failing cat would show itself as a loss of power under moderate load after the engine is up to operating temperature. Check the fuel pressure, use a gauge!
Check the TPS, make sure it's within spec and the sweep is linear with no dropouts.
Check the EGR valve, make sure it's not opening or leaking exhaust gases when it's not supposed to. Have you tried cleaning both crank sensors? Is the default throttle stop set correctly? Does the IACV actually work?
Check the TPS, make sure it's within spec and the sweep is linear with no dropouts.
Check the EGR valve, make sure it's not opening or leaking exhaust gases when it's not supposed to. Have you tried cleaning both crank sensors? Is the default throttle stop set correctly? Does the IACV actually work?
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