After warm up car just hesitates
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After warm up car just hesitates
hello I have a 02 6 speed c5 and after I start the car and let it warm up it misfires and hesitates while driving for like the first 2-3 minutes then goes away or if I go somewhere and I let my car turned on just parked it will start doing the same thing it has 102k miles new starter,alternator,spark plugs,spark plug wires,coil packs,fuel pump,fuel filter and the check engine light won’t come on only when I’m coming to a stop the check gadge well pop up then because when I’m coming to a complete stop the RPMS drop pretty low
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From: Cape Coral, Florida
Any current or history codes you can pull up through the DIC ??...might give some direction for a diagnosis. Could be MAF sensor issue, clogged fuel injector...hard to diagnose just based on symptoms !!
Former Vendor
Joined: Dec 2009
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From: 19804
Check intake couplers to make sure everything is seated. Also check for vacuum leaks around the intake. If you see nothing then have someone with HPtuners or a better scanner than autozone log the car and watch fuel trims and all data. Someone who know what there looking at logging will be the quickest way to pinpoint the issue.
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The codes that came up are P0131,P0151 I’m not sure if it’s the o2 sensors or not because I have a feeling it’s something els because for both to go out is kind of weird
Last edited by Temps_c5; Dec 22, 2018 at 06:05 PM.
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From: Cape Coral, Florida
Both DTC’s are “low voltage” on both banks and sensor 1 (upstreams)...just because you have O2 DTC’s always doesn’t mean it’s an O2 issue...the DTC sets if the PCM sees less than 200 Mv’s (LEAN) for about 30 seconds on the signal circuit...now getting some scan data concentrating on fuel trims and O2 sensor data (graphed waveforms) would help immensely in the diagnosis...I doubt both O2 sensors circuits (would be an open or short to ground) went bad at the same time...since it’s both banks it could be a vacuum leak...not high enough to set a P0171/0174 DTC but high enough to keep your O2 Mv below that 200 Mv threshold !!...with a vacuum leak the car runs crappy at idle but OK at higher RPM (when you have less vacuum) !!
Zen Vet Master Level VII
Joined: Mar 2016
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From: Southlake, TX
Well, you need to fix what the sensors tell you is wrong before you can go on to something else. Since both 02 sensors failed, your computer is sending all sorts of crazy signals for rich/lean condition and making your car run funny.
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Okay well I’ll change the o2 sensors for some new ones and I have a air filter on the way but just Incase it’s a vacuum leak what would be the best way to find a leake and where would I look at .....sorry never had to look for a vacuum leak I’m new to this
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From: Cape Coral, Florida
To be honest with you if you’ve never did this kind of work as you say I’d take it to a reputable shop to save yourself some time and money and FRUSTRATION !!...to properly check the O2’s a graphing scan tool is best or a DVOM if you’re a DIY’er...changing the O2 sensor without checking the wiring is just a crap shoot...a smoke machine is best and FASTEST way to find a vacuum leak but again for the DIY’er you can use Brake Kleen or even a spray bottle of water ( you can hear the water getting sucked into the leak) and spray it around the intake bellows downstream of the MAF sensor, intake manifold, PCV lines, brake booster. Now where in the country are you located ??...didn’t see that in your profile... really helps if you add this info...you can live in the next town over from someone with some diagnostic equipment that can lend a hand. Here’s a video on finding a vacuum leak and checking GM O2 wiring !!
Last edited by C5 Diag; Dec 23, 2018 at 11:47 AM.
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To be honest with you if you’ve never did this kind of work as you say I’d take it to a reputable shop to save yourself some time and money and FRUSTRATION !!...to properly check the O2’s a graphing scan tool is best or a DVOM if you’re a DIY’er...changing the O2 sensor without checking the wiring is just a crap shoot...a smoke machine is best and FASTEST way to find a vacuum leak but again for the DIY’er you can use Brake Kleen or even a spray bottle of water ( you can hear the water getting sucked into the leak) and spray it around the intake bellows downstream of the MAF sensor, intake manifold, PCV lines, brake booster. Now where in the country are you located ??...didn’t see that in your profile... really helps if you add this info...you can live in the next town over from someone with some diagnostic equipment that can lend a hand. Here’s a video on finding a vacuum leak and checking GM O2 wiring !!
https://youtu.be/adkFTSoxM6Q
https://youtu.be/9CPqbaSgcok
https://youtu.be/adkFTSoxM6Q
https://youtu.be/9CPqbaSgcok
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From: Cape Coral, Florida
Smart decision !!...say you changed those O2 sensors and that didn’t fix it..,well some would change them again and that’s not the fix so now you’re chasing your tail.,,.please let us know what the fix is !!...a competent shop shouldn’t have to replace 3 parts to fix those DTC’s !!