Surging idle with video
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
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From: Franklin Square NY
Surging idle with video
I am getting a surging idle after replacing a oil pressure switch/sensor. I did reuse the gasket, gasket does have 0 miles on it.
I did just install these heads 243 heads that i rebuilt (i doubt this is an issue)
The MAF sensor is still really new (less than 50 miles new)
I made 2 videos so you can see what i am talking about
Tell me what you think.
I did just install these heads 243 heads that i rebuilt (i doubt this is an issue)
The MAF sensor is still really new (less than 50 miles new)
I made 2 videos so you can see what i am talking about
Tell me what you think.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,604
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From: Cape Coral, Florida
25 ???...your long terms ??...WOW !!...you’re running super lean...I’m surprised for don’t have a lean DTC...P0171/0174....run the RPM’s up to 2500-3000 as see if they decrease...if they do you have a vacuum leak big time !!!...my short terms are 3-4...the long terms job is to keep the short terms at 0 !!...watched the video just now...sorry...and saw your bank 1 O2 are around .100...SUPER LEAN !!...I’d spray some brakekleen around your intake manifold and all vacuum lines and see if engine RPM changes !!
Last edited by C5 Diag; Jul 28, 2018 at 12:52 PM.
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
25 ???...your long terms ??...WOW !!...you’re running super lean...I’m surprised for don’t have a lean DTC...P0171/0174....run the RPM’s up to 2500-3000 as see if they decrease...if they do you have a vacuum leak big time !!!...my short terms are 3-4...the long terms job is to keep the short terms at 0 !!...watched the video just now...sorry...and saw your bank 1 O2 are around .100...SUPER LEAN !!...I’d spray some brakekleen around your intake manifold and all vacuum lines and see if engine RPM changes !!
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
25 ???...your long terms ??...WOW !!...you’re running super lean...I’m surprised for don’t have a lean DTC...P0171/0174....run the RPM’s up to 2500-3000 as see if they decrease...if they do you have a vacuum leak big time !!!...my short terms are 3-4...the long terms job is to keep the short terms at 0 !!...watched the video just now...sorry...and saw your bank 1 O2 are around .100...SUPER LEAN !!...I’d spray some brakekleen around your intake manifold and all vacuum lines and see if engine RPM changes !!
Also get the p0507 code in pending.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,604
Likes: 4,060
From: Cape Coral, Florida
Ok !!...let me know how your fuel trims look after you replace the intake manifold gasket... also your MAF sensor issues. I bought a smoke machine last week and I also found my PCV elbow leaking...it was leaking where the metal conductor goes into the elbow...what a crappy design...and the GM Engineers were worried about condensation on the PCV valve...LOL !!...0507 should clear when you get the leak taken care of !!...I was thinking...disconnect the MAF sensor and see if those fuel trims decrease at higher RPM’s...a “under reporting “ MAF can cause a lean condition. Another thing...spray propane into your brake booster line and watch your Pre Cat O2’s...let me know if they report “rich”...around 900 mV’s !!...just want to cover all the bases...we call it an “O2 response test” !!!
Last edited by C5 Diag; Jul 28, 2018 at 07:57 PM.
Le Mans Master
Joined: Jul 2010
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I believe if you disconnect the maf sensor it will default to the ve table and should run rich. If that stabilizes the idle then you know it has to do something with the fuel. Doesn't hurt to try. It rule out vacuum leak
Last edited by helga203; Jul 29, 2018 at 08:50 AM.
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Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Yes !!...if the MAF sensor is disconnected it will revert to “speed density”...the MAP sensor !!
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
Yea so replacing that gasket pretty much got rid of that surging idle. It idles now at 750 +/- 50 rpms without a tuned pcm i will switch the pcm and give yall an update tomorrow.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,604
Likes: 4,060
From: Cape Coral, Florida
i guess wait till everything is buttoned up....takes awhile for those fuel trims to come back down...don’t know if your scanner has a fuel trim reset function.
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Hey !!...so these snapshots are with the tuned PCM and MAF all hooked up and driving the car for a bit ??...Bank 1 looks a little lean at idle and Bank 2 has a total fuel trim of +11 but lets look at these numbers after a day or 2 of driving if you haven't done so yet !!...a nice drive to Jones Beach a few times would be in order...LOL !!
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
Hey !!...so these snapshots are with the tuned PCM and MAF all hooked up and driving the car for a bit ??...Bank 1 looks a little lean at idle and Bank 2 has a total fuel trim of +11 but lets look at these numbers after a day or 2 of driving if you haven't done so yet !!...a nice drive to Jones Beach a few times would be in order...LOL !!
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Great !!...headed down to the Outer Banks in a few weeks....let me know how the car is running....if you want I can leave the beach stuff home and just bring all the diagnostic equipment down there...LOL !!