Since the search function doesn't give me anything, I thought I'd post here.
My wife's 01 LS 2.4 sedan is having more trouble in the mornings when its cold. the car will fire up and idle fine, but as soon as you apply gas it wants to die. You have to feather the throttle and then there's a delay in response...then the car begins to run normally.
This hesitation goes away after a few blocks (once it's warmed up) and the car behaves normally. 79K on the car, new plugs, fuel & air filters, etc. Always maintained as scheduled. This problem was always there since the car was a year old or so, but its getting worse. Vacuum leak maybe?
I can't find any TSB's, but I remember seeing a similar post a while back on here. Anyone know WTF this is, and how I can stop it?
Thanks,
-Daryl Scott
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the only things i can think of would be either the air intake temp sensor or maybe the throttle positon sensor. if your ait sensor is messed up and is telling your comp that its
90 degrees out but its only 50 then yes this will cause the problem you described.
and your tps sensor has a little metal finger indide it that moves back and forth across a piece of carbon covered plastic the amount of resistance the comp measures lets it
know where the throttle blade is. once the little finger wheres a spot in the plastic then
the comp doesnt know where the throttle blade is, so it doesnt know how much fuel to give it. this problem usually happens low in the rpm band cause this is where the little finger spends most of the time on the carboned plastic and where most of the where occurs. this useully causes a surge like feeling, or stumble when trying to accelerate. the ait is cheeper so id say try it first. and buy one from g.m. not aftermarket i've had more then one person tell me the aftermarkets didn't work and then i sell them one from g.m. and the prob goes away. hope this helps and good luck.
Semper Fi SAINT. May you rest in peace.
well when its cold the computer dumps in extra fuel.....how cold are we talking here??? i get poor response in the winter too
"Official Jewish J-Body"
Thanks for the suggestions guys.
Machzel- it happens worse in the winter time, but its doing it now and its only like 65 or so in the mornings here. So its time to get this damn thing fixed
Thanks again, I'll stop by the parts house on Monday.
I think there is a reflash for this problem available from the GM dealers, look into that.
15.3 @ 89.97mph, 14's on the way?
For Sale:
Getrag '00-'02 2.4 8000kms $800
I've had the same problem with my '02 since I bought it new. I took it to the dealer once or twice back then and they were pretty useless. I keep forgetting about it until it happens. It doesn't always happen to me when its cold out, but it always happens when the car has been turned off for a few hours at least.
I usually figured it was a small leak in the fuel system stopping the fuel pressure from staying up. It usually goes away after its been running for 10 or 15 minutes.
The AIT sounds a lot more likely though. I never tried to investigate it myself because I keep forgetting until it happens, and I'm usually going somewhere.
It's really annoying (and dangerous) if you need to accelerate quickly just as it cuts out.
- Darryl
'02 Z24
I had the same condition you are describing execpt the CEL come on. Scanned it and found it to be TPS
hey i have the same problem but i let off the gas and hit it then it boggs done then it fien after liek 4 or 5 blokcs
Disconnect your primary O2 sensor before starting the car for the first time of the day. Then run it and see if it acts up. Come back and let us know.
FU Tuning
where is the primary o2 sensor locatred the one on the manifold
alright i will try it tomorrow becasue it is raining really bad today
well you got lucky....i had the same problem ....except mine ended up being a head gasket...and you know how expensive that would be.
Drive Hard or Die Trying
sounds like the 02 sensor to me...it will give you that EXACT problem if the 02 is bad OR if you have the wrong brand installed..make SURE you 02 sensors are AC DELCO ONLY! ..there is also a reflash for cold hesitation from the dealer if it persists..ive done a couple myself..but 02 is the problem 95% the time
i have a 98 2.4 cavalier and am having the same problem with hesitation on take off where i have to feather the throttle to get it to rev up and then its fine till the next time i let it sit. A friend of mine owns a shop so i hooked the car to his scan tool and it shows no codes at all. Thre car has 123k on it and the girl i bought it from said it has done this since she got it with 22k miles on it. I'm scared to pull out into traffic when i leave a parking lot casue the car dosent want to move at first. I was thinking it seemed like the fuel pressure bleeding off while sitting but from what i read it seems to be the TPS or the o2 sensor. BUt wouldnt those throw a code of some kind?
How nasty is the throttle body, I would also look into cleaning up the TB and checking the IAC "Idle air control" sensor and make sure it's not all carboned up either. Go ahead and check the front o2 though that could be the problem.
2009 Ford Mustang V6
97 Sunfire, 2.4 5-spd, same thing... starts fine but within a minute starts surging 500-1200 rpm, does this for about 20-30 seconds, then all is fine. If you hit the throttle, it'll stall out. No CEL or codes stored. I've replaced both oxygen sensors, cleaned the throttle body, EGR ports, IAC.
TPS reads correctly so I doubt that's the problem.
While it happens mostly at idle on cold start (any ambient temp), it's worse when hitting the throttle, so I doubt the IAT really has anything to do with it.
EGR ports had no carbon blockages, and the shop I had it at recently said there was no problem with pintle position performance.
I've replaced the fuel pump/sender assembly because the gas guage wasn't working properly, the rear oxygen sensor due to pre-heater CEL code, front oxygen sensor because it was cheap enough, NGK Iridium IX spark plugs about 5k ago, fuel and air filters recently also. There was a vacuum leak at the MAP, replaced the hose but this stumbling on cold start still exists. I've done all sorts of searches here while lurking for several months and this is the only thread I've seen about it but no real cure. Any ideas or suggestions would be greatly appreciated.
TJ
did you replace the sensors with AC DELCO? if you didnt then you didnt help it...other than that you might want to go to the dealer and try the cold start hesitation reflash..if you know someone at a gm dealer they can do it for free..if you were around texas id do it for ya
scott (section8cav) wrote:did you replace the sensors with AC DELCO? if you didnt then you didnt help it...other than that you might want to go to the dealer and try the cold start hesitation reflash..if you know someone at a gm dealer they can do it for free..if you were around texas id do it for ya
i called my local dealer about the reflash and they said there was nothing available for the cavaliers as far as what i described. Is there a service bulletin that they coudl look up that would have the info they need? or could i buy anthore ecu from a junkyard and send it to you to reflash or does it have to be in the car to be flashed? PM me any info you can give me, i've checked all the sensors and scanned the car for codes and nothing is wrong with it but it still stalls out and hesitates at first take off.
im gonna tell ya straight up.. this sounds just like an 02 sensor..but the reflash is there weather they know it or not..i did it to my 2000z when i bought..i noticed it when i did the update reflash..one of the things listed was an update softwear for "cold hesitation"..even though i didnt have that issue i did it anyway..personally i wouldnt want you to buy an extra pcm and pay all the money in parts and shipping at that not the real problem
wouldnt the o2 sensor set a code or at least store a code in the ecu that i could pull out with a scan tool? i'll look into the o2 sensor and replace it to see if that cures the problem. which one should i try first?
no..it wont always throw a code..mine didnt ..and it took me a YEAR to figure out the problem..mainly cus i kept replacing it but the problem never changed..then someone asked me what brand i was replacing it with..i said "which ever brand auto zone sells" which happens to be bosch..i was told to replace it with ONLY AC delco..i did, and the problem never returned and for the whole year i never got a CEL ..it was the first sensor in the down pipe..it controls the a/f more were as the one in the cat just reads how well the cat is burning the unused fuel..
i would start my car..it would idle and rev fine..but after less than a minute it would seem to try to die..the rpm would jump up then fall again..and it would do this for a bout a minute after each start up..more so when it was cold..and if you tried to drive it right after start up it wouldnot accelerate..it seemed the more you pushed the pedal the more it would die..until it got it out of its system anyway...if this sounds like your problem i highly suggest an AC DELCO 02 replacment.....this has worked for many before with this problem...i hope it helps you as well
thanks for the advice Scott, i will pick up the AC delco o2 sensor today and get it in this week.
I really think the issue is O2 sensor related. I also think it is more because the 2.4's do not have a heated O2 sensor. When the car is ready to go into closed loop the primary O2 sensor is not up to temp, so the computer does not get a good reading and flips out. I have had this on my old 97 Z24 and on my current 01 Z24. I could disconnect the O2 sensor and the car would run fine, but would throw a code (because the sensor is not connected). I would try this. If it does not act up it is related to the O2 sensor, and more than likely more to do with it not being up to temp. I installed a non AC delco heated O2 sensor on my 01. This has pretty much solved my issues.
FU Tuning
Sorry for not posting back so soon, but yes, I replaced the upstream OČ sensor with one from the dealership and the problem is now gone. It starts up and runs fine when it goes into closed loop. Don't bother with the Bosch sensor, go right for the GM part.
