Running Rough at Idle
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Assembled the air cleaner assembly after checking MAF sensor. Then I went on to scan the LTFT and STFT values. Here is what I came up with at idle...
LTFT B1 3.1%
LTFT B2 2.3%
STFT B1 .8%
STFT B2 .8%
None of the values were exact as they were varying slightly.
I tried to get the highest value written down.
None of the values were over 10%
Moved the brake booster hose around also. No change at all in idle quality.
LTFT B1 3.1%
LTFT B2 2.3%
STFT B1 .8%
STFT B2 .8%
None of the values were exact as they were varying slightly.
I tried to get the highest value written down.
None of the values were over 10%
Moved the brake booster hose around also. No change at all in idle quality.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,562
Likes: 4,034
From: Cape Coral, Florida
Assembled the air cleaner assembly after checking MAF sensor. Then I went on to scan the LTFT and STFT values. Here is what I came up with at idle...
LTFT B1 3.1%
LTFT B2 2.3%
STFT B1 .8%
STFT B2 .8%
None of the values were exact as they were varying slightly.
I tried to get the highest value written down.
None of the values were over 10%
Moved the brake booster hose around also. No change at all in idle quality.
LTFT B1 3.1%
LTFT B2 2.3%
STFT B1 .8%
STFT B2 .8%
None of the values were exact as they were varying slightly.
I tried to get the highest value written down.
None of the values were over 10%
Moved the brake booster hose around also. No change at all in idle quality.
Pro
Joined: Mar 2018
Posts: 660
Likes: 63
From: Fresno CA
Clean the MAF sensor ONLY with MAF cleaner (source it at your local auto parts store). The bottle will have specific instructions, but essentially you'll be spraying the sensor opposite the side of the plug. Don't touch it with your fingers.
Last edited by theandrewo; Nov 27, 2018 at 03:10 PM.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Originally Posted by theandrewo
Clean the MAF sensor ONLY with MAF cleaner (source it at your local auto parts store). The bottle will have specific instructions, but essentially you'll be spraying the sensor opposite the side of the plug. Don't touch it with your fingers.
I touched it and wiped it with carb cleaner It's reinstalled and functional at this point.
Pro
Joined: Mar 2018
Posts: 660
Likes: 63
From: Fresno CA
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Ok I'm stuck again. There is a definite miss at idle that I can hear.
I see some cylinder tests on the scan tool. I have to get familiar with the tests.
What do you guys think about changing the intake gaskets?
I see some cylinder tests on the scan tool. I have to get familiar with the tests.
What do you guys think about changing the intake gaskets?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,562
Likes: 4,034
From: Cape Coral, Florida
Get familiar with your scan tool...your fuel trims are fine...YOU DON’T HAVE A VACUUM LEAK !!...what do your misfire counters show with your new scan tool if it shows that ??
Last edited by C5 Diag; Nov 28, 2018 at 10:17 PM.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
I noticed some individual cylinder tests but not a misfire counter.
It might be there if I dig deeper.
Back to work.
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Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,562
Likes: 4,034
From: Cape Coral, Florida
YES !!...get back to work and quit sluffin’ off Buddy...LOL !!...if u want take some pictures of those menu items we will probably be able to help !!!
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
I've been reading the 132 page instruction manual online.
I have found the "misfire" menu and other engine tests that I can do.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Misfire Numbers
The miss fire counter showed these as the highest values for each cylinder. The car is idling terribly while testing. Hopefully this points me to the problem. What do you make of it? I see no more menus to adjust or change anything related to misfires on the scan tool.
Cyl 1= 3
Cyl 2 = 92
Cyl 3 = 64
Cyl 4 = 27
Cyl 5 = 32
Cyl 6 = 5
Cyl 7 =13
Cyl 8 = 2
Cyl 1= 3
Cyl 2 = 92
Cyl 3 = 64
Cyl 4 = 27
Cyl 5 = 32
Cyl 6 = 5
Cyl 7 =13
Cyl 8 = 2
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,562
Likes: 4,034
From: Cape Coral, Florida
All these cylinder misfires counting up while you’re at idle or are they history ??...I’ve never seen ALL cylinders misfiring !!..unfortunately you can’t “change” or “adjust” anything to fix your idling problem with your scan tool...you need to diagnose !!... if you have a misfire it can be fuel related, ignition related, or even compression issues...what do your long and short term fuel trims (percentage) look like at idle and at higher RPM’s ????
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Let me get back in there today and recheck the counts.
Anything else that I should be eye balling while I'm there?
Last edited by Street Rat; Dec 2, 2018 at 09:32 AM.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Misfire Numbers
These are the numbers I just got for misfires on each cylinder. Live data. Don't give up on me guys. Give me some direction for a remedy even if it is a recommendation for a trip to the shop.
Cyl 1 = 0
Cyl 2 = 12
Cyl 3 = 8
Cyl 4 = 3
Cyl 5 = 4
Cyl 6 = 0
Cyl 7 = 2
Cyl 8 = 0
Cyl 1 = 0
Cyl 2 = 12
Cyl 3 = 8
Cyl 4 = 3
Cyl 5 = 4
Cyl 6 = 0
Cyl 7 = 2
Cyl 8 = 0
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,562
Likes: 4,034
From: Cape Coral, Florida
If those 5 cylinders are indeed misfiring at idle I would expect to see your LTFT elevated if it was a ignition related misfire and REALLY elevated if it were a fuel related one (injectors)...but with all that excess oxygen in the cylinders and no fuel your O2 sensors would see a lean (low Mv) signal and you would have high LTFT’s... but your 2-3% LTFT’s look great. Are the misfiring still counting up at higher RPM ??...is the Check Engine Light flashing ??...any P0300-0308 DTC’s ??...since you changed plugs and wires I would pull the 5 plugs out do a visual inspection (recheck gap and check for a cracked plug) and make sure the plug wires are FIRMLY seated on both ends !!...for any misfires I always throw my scope on the engine and check the cam and crank sensors...what you might want to do is spray a little water mixed with baking soda on the ignition system in a dark garage and see if it looks like a lightening storm under there !!
Burning Brakes
Joined: Apr 2011
Posts: 1,149
Likes: 107
I cannot diagnose your misfire but I do recommend pulling the injectors and having them flow tested and cleaned. Some places will test clean an return in two days. If the injectors are not the problem it will bring peace of mind.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
I'll be checking injectors and coil packs today with the scan tool.
Back to work.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
If those 5 cylinders are indeed misfiring at idle I would expect to see your LTFT elevated if it was a ignition related misfire and REALLY elevated if it were a fuel related one (injectors)...but with all that excess oxygen in the cylinders and no fuel your O2 sensors would see a lean (low Mv) signal and you would have high LTFT’s... but your 2-3% LTFT’s look great. Are the misfiring still counting up at higher RPM ??...is the Check Engine Light flashing ??...any P0300-0308 DTC’s ??...since you changed plugs and wires I would pull the 5 plugs out do a visual inspection (recheck gap and check for a cracked plug) and make sure the plug wires are FIRMLY seated on both ends !!...for any misfires I always throw my scope on the engine and check the cam and crank sensors...what you might want to do is spray a little water mixed with baking soda on the ignition system in a dark garage and see if it looks like a lightening storm under there !!
I'll check the plugs and wires again today. I had the same symptoms prior to changing the spark plugs and wires. I am also going to check the exhaust temperatures on the various exhaust manifold runners. I have an infared heat measuring gun to do that.