Can not figure this out?
09-23-2018, 08:57 AM
#1
Drifting
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Can not figure this out?
I will try to explain whats happening the best i can..04z headers,cai,tune. as fas as i can remember this has been happen for awhile..not my dd..if i drive normal around town.. the rpms where i notice this is idle to 3000rpm this is when i get on it. Then when i hit the gas i have to push gas pedal down more and it feels sluggish no get up and go..now if i drive around in 3rd gear almost trying to raise engine temp or oil temp. If i hit the gas agian i can feel it in the gas pedal.. the car as soon as i hit the gas it takes off launches feels great. I checked to make sure my o2's are working all is gd. stumped! No codes..i have a tech2.. feels like its going in and out of closed loop is the best way to describe it..but scanner shows closed and switching normal..
Last edited by 04zjimc; 09-23-2018 at 09:00 AM.
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vettpapaw (09-23-2018)
09-23-2018, 10:53 AM
#2
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So you’re saying anywhere between 0-3000 rpm if you “get on it” its bogging down ??...if in 3rd and you do it it’s fine ??...where are your long term fuel trims sitting right now...just want to know if it’s been lean ??...does your Tech 2 show show MAF grams/second or voltage...look at that at idle and under load !!...my 01 is around 7 grams/sec at idle...should go up to around 190 grams/sec at WOT !!...both upstream O2’s should go RICH under acceleration !!
Rob
One Test Is Worth 1,000 “Expert” Opinions”
Rob
One Test Is Worth 1,000 “Expert” Opinions”
Last edited by C5 Diag; 09-23-2018 at 11:10 AM.
09-23-2018, 07:03 PM
#3
Drifting
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So you’re saying anywhere between 0-3000 rpm if you “get on it” its bogging down ??...if in 3rd and you do it it’s fine ??...where are your long term fuel trims sitting right now...just want to know if it’s been lean ??...does your Tech 2 show show MAF grams/second or voltage...look at that at idle and under load !!...my 01 is around 7 grams/sec at idle...should go up to around 190 grams/sec at WOT !!...both upstream O2’s should go RICH under acceleration !!
Rob
One Test Is Worth 1,000 “Expert” Opinions”
Rob
One Test Is Worth 1,000 “Expert” Opinions”
Last edited by 04zjimc; 09-23-2018 at 07:05 PM.
09-23-2018, 07:35 PM
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Last edited by C5 Diag; 09-23-2018 at 09:39 PM.
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FreeC5inAZ (09-24-2018)
09-23-2018, 08:35 PM
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They are hot enough !!!...You'll have issues if the O2 heater circuit is inoperative after startup...you'll be in open loop then and stay there and a DTC will set...when the O2 sensors are warmed up you'll start to see the fuel trim numbers starting to move either positive or negative...your are now in closed loop...check that with your Tech 2...during idle operation the upstream O2 sensors will be switching between 200-800 millivolts or so...the down streams will be kind of steady somewhere around 450 millivolts....just remember....LEAN IS LOW (below 450 mv) and RICH IS HIGH (above 450mv)....if O2 around 200 it's lean...if 800 it's reporting rich !!
Last edited by C5 Diag; 09-24-2018 at 12:38 AM.
09-23-2018, 09:05 PM
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09-24-2018, 07:56 AM
#8
Drifting
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09-24-2018, 08:17 AM
#9
Team Owner
Manual transmission or automatic?
09-24-2018, 08:24 AM
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Hi !!...yes, the O2 signal has a "bias voltage" of 450 mv it puts out and when the sensor is cold you can see this bias voltage if you look at O2 millivolts...all the GM's I've seen have it !!...the bias voltage lets the PCM detect either shorts or opens in the circuit...if it sees one it sets a DTC !!….if it was flat lined at 450mv you most likely have an open in the signal wire on the O2 harness side...say the O2 voltage was stuck high or low...if you unplug the O2 and it went back to 450Mv you have an issue on the O2 end !!
Last edited by C5 Diag; 09-24-2018 at 09:16 AM.
09-24-2018, 09:39 AM
#11
Drifting
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Hi !!...yes, the O2 signal has a "bias voltage" of 450 mv it puts out and when the sensor is cold you can see this bias voltage if you look at O2 millivolts...all the GM's I've seen have it !!...the bias voltage lets the PCM detect either shorts or opens in the circuit...if it sees one it sets a DTC !!….if it was flat lined at 450mv you most likely have an open in the signal wire on the O2 harness side...say the O2 voltage was stuck high or low...if you unplug the O2 and it went back to 450Mv you have an issue on the O2 end !!
Last edited by 04zjimc; 09-24-2018 at 09:47 AM.
09-24-2018, 09:48 AM
#12
Drifting
Thread Starter
They are hot enough !!!...You'll have issues if the O2 heater circuit is inoperative after startup...you'll be in open loop then and stay there and a DTC will set...when the O2 sensors are warmed up you'll start to see the fuel trim numbers starting to move either positive or negative...your are now in closed loop...check that with your Tech 2...during idle operation the upstream O2 sensors will be switching between 200-800 millivolts or so...the down streams will be kind of steady somewhere around 450 millivolts....just remember....LEAN IS LOW (below 450 mv) and RICH IS HIGH (above 450mv)....if O2 around 200 it's lean...if 800 it's reporting rich !!
09-24-2018, 10:08 AM
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Last edited by C5 Diag; 09-24-2018 at 10:10 AM.
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Irish31 (09-28-2018)
09-24-2018, 10:28 AM
#14
Drifting
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Yes, the drive by wire can be a cause but without testing you are just GUESSING !!...you have to look at TPS and APP sensor voltages...you can show the voltages TPS 1 and TPS 2 voltages in a "graph form" on your Tech 2... I don't use one but that's how you would check...now what you see on the Tech 2 or any scan tool is "processed data"...not truly LIVE as some might say...using an oscilloscope is true live data !!...this is a video of my "01 doing a TPS sweep with my scope...if you see an irregularity in the signal as you push the throttle down or back up you have a wonky sensor or possibly a wiring issue !!...did you try disconnecting the MAF and see if it hesitates ??...if you don't know how to interpret data on the Tech 2 it's basically just an expensive code reader !!
https://www.youtube.com/watch?v=a00TKvi9cWY
https://www.youtube.com/watch?v=a00TKvi9cWY
09-24-2018, 11:16 AM
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I will check this out..i do feel this in my gas pedal..when it runs strong the gas pedal is sensitive and very responsive and it takes off..when its lagging i push down on the gas and the car is flat almost like the blade is not opening.. i had this same exact problem on my 04 cobra and the gas pedal was alittle bent not pushing down anymore..
09-24-2018, 11:38 AM
#16
Drifting
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thanks i hope i find the problem! I am going to purchase hp tuners also.
09-24-2018, 11:59 AM
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09-24-2018, 06:04 PM
#18
Drifting
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09-24-2018, 06:40 PM
#19
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Just looked at my Autel...it doesn’t read MAF voltage..just airflow...ask a forum member who might have one...I think my man Froggy just bought one...I can tell you how to check it...with MAF unplugged you should have your 5 volt ref. on the yellow wire, 12 volt on the pink and ground on the black/white which is a body ground...G106 !!
09-24-2018, 06:46 PM
#20
Drifting
Thread Starter
Just looked at my Autel...it doesn’t read MAF voltage..just airflow...ask a forum member who might have one...I think my man Froggy just bought one...I can tell you how to check it...with MAF unplugged you should have your 5 volt ref. on the yellow wire, 12 volt on the pink and ground on the black/white which is a body ground...G106 !!