weird rpm bouncing revisited (fixed)
#1
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weird rpm bouncing revisited (fixed)
mentioned in my evap thread but I'm not so sure they are related anymore so starting a separate thread.
ok my weird symptoms are continuing and I am searching for other things to check.
to start the symptom is that when lightly accelerating the rpm'* will bounce UP and make the car surge, the car will continue to speed up like normal, in fact i often wind up doing 70mph while watching the car do this since it'* still speeding up the entire time. If I make the car downshift or let off the gas it stops and it doesn't do it under WOT or even under mid-high throttle just under normal light acceleration.
what I have checked:
most of my ignition is new (within 1-2 years) including plugs, wires and coils. i am planning a tune up and the plugs will be again
I swapped my tps out with a spare junkyard unit I had and bench tested the one that was in there, I found that it'* resistance was all crazy when holding the sensor steady at any point and thought I had found the problem, after installing the other one the car ran very weird, holding the gears til redline while driving normal and such. I came back removed the negative terminal on the battery and re-hooked it and the car ran normal. however the bouncing problem persisted.
I have inspected the vacuum lines in the engine bay and found nothing out of the ordinary
I had my cousin ride along with his obd computer scanner and we watched all the sensors and saw nothing odd, the new TPS was also reporting correctly we also took the opportunity to watch my fuel trims and they stayed mostly +5-10 and spiked at +14 under WOT
what I have not checked/replaced
my evap system is in trouble i have several codes in the computer setting the SES light all related to the evap
the o2 sensor, maf, iac, and pretty much anything else you could think of are all original
I noticed yesterday that my fuel pump (replaced before I joined the club with an airtex ) seems noisy I.E I could hear it over the motor on a cold startup outside the car
please any ideas or suggestions do not hesitate to post my goal is to get this thing completely tuned up so that I can install my zzp mps guilt free and this is problem #1 right now
ok my weird symptoms are continuing and I am searching for other things to check.
to start the symptom is that when lightly accelerating the rpm'* will bounce UP and make the car surge, the car will continue to speed up like normal, in fact i often wind up doing 70mph while watching the car do this since it'* still speeding up the entire time. If I make the car downshift or let off the gas it stops and it doesn't do it under WOT or even under mid-high throttle just under normal light acceleration.
what I have checked:
most of my ignition is new (within 1-2 years) including plugs, wires and coils. i am planning a tune up and the plugs will be again
I swapped my tps out with a spare junkyard unit I had and bench tested the one that was in there, I found that it'* resistance was all crazy when holding the sensor steady at any point and thought I had found the problem, after installing the other one the car ran very weird, holding the gears til redline while driving normal and such. I came back removed the negative terminal on the battery and re-hooked it and the car ran normal. however the bouncing problem persisted.
I have inspected the vacuum lines in the engine bay and found nothing out of the ordinary
I had my cousin ride along with his obd computer scanner and we watched all the sensors and saw nothing odd, the new TPS was also reporting correctly we also took the opportunity to watch my fuel trims and they stayed mostly +5-10 and spiked at +14 under WOT
what I have not checked/replaced
my evap system is in trouble i have several codes in the computer setting the SES light all related to the evap
the o2 sensor, maf, iac, and pretty much anything else you could think of are all original
I noticed yesterday that my fuel pump (replaced before I joined the club with an airtex ) seems noisy I.E I could hear it over the motor on a cold startup outside the car
please any ideas or suggestions do not hesitate to post my goal is to get this thing completely tuned up so that I can install my zzp mps guilt free and this is problem #1 right now
#5
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after researching the 5 (yes 5!) evap codes in the DTC thread I have maybe it is related after all I have the following codes
P0440
P0446
P0452
P0453
P1441
P0440
P0446
P0452
P0453
P1441
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My car (08 cobalt) is doing this same thing... the guy at the shop said it could be my purge valve in the tank... not sure tho... I'll need to find time to have it really checked out. The car is bad to idle weird & then just shut off too...
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If the purge valve is bad it would be like a vacuum leak. Do you have any codes? Have the car scanned. Locate where the EVAP connects to the throttle body and pull the vacuum line off, then cap that off on both sides. This shuts off the EVAP system. If things calm down then you have a issue with the EVAP.
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If the purge valve is bad it would be like a vacuum leak. Do you have any codes? Have the car scanned. Locate where the EVAP connects to the throttle body and pull the vacuum line off, then cap that off on both sides. This shuts off the EVAP system. If things calm down then you have a issue with the EVAP.
#10
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well between the new o2 and evap purge solenoid I think my symptoms are cured. I haven't gotten to drive it much in that past few days so if it flairs up again I will update and continue investigating in case some other poor soul has to deal with this. also the solenoid seems to have cured all evap codes, P0452 popped up once since changing it but then went back off with the next crank so that might have just been a fluke
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