I recent had my maf, wb, and fuel trims go crazy. I am getting the maf circuit code, and the wb and maf are showing super lean but the fuel trims are not that bad. Is this a sign my maf sensor is shot? I tried increasing the ve and maf tables but its still going lean. Also I know noticed sometimes after the engine has reached operating temps its not going into closed loop all the time. Any help on what this could be would be appreciated.
I can't open your log with my scanner(are you using mpvi3?) Trust the wideband if it was installed correctly and in a good location. You could be in Fault-open loop. I would start with checking fuel pressure, because that would cause all sorts of fueling issues. When you say the trims aren't that bad, what are they? click the details tab under the channels list, does it have any other codes? Is it lean all the time? just at idle? or what rpm range is it lean?
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
Wb installed correctly. Was working fine. I was wrapping up part throttle of a blended tune and this started. The maf code for the low circuit is showing now and the maf and wb are lean when in closed loop but before the maf code came up I had the wb close to zero and wrapping up the map. Mpv2 is what I’m using. Ltft showing -5 to -6 lean on maf and wb. No other code other than a ac clutch switch. Fuel pressure is normal. I was wondering if a vacuum leak could throw that code?
Last edited by 2000Phoenix; 10-15-2022 at 10:15 PM.
ok, so I had to do some digging on how to run vcm suite version 5 to view your log and keep version 4 for everyday use and the ability to edit things they took away. I now have both versions working. First problem I see is that your MAF g/s is absurdly high, it's like 55g/s at idle. It should match your dynamic airflow which is around 7g/s at your idle speed. Something is wrong. Also the O2 mv just drops to dead lean or short to ground. Post your tune file, you might have accidentally jacked up a setting. I need to see the tune to help any further.
Last edited by Matt Vardaman; 10-16-2022 at 12:36 AM.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
I raised the map and ve table to see if it would go richer but it did not I will post the tune up when I get up in the morning so you can give me your opinion.
Last edited by 2000Phoenix; 10-16-2022 at 09:06 AM.
Here is the tune. Again I tried raising the map and the ve to see if the maf and the wb would go positive but they didn't im thinking it the mass air flow sensor. Let me know your thoughts. Thank you again. car was giving the symptoms. Bucking and struggling to idle all of a sudden.
I looked through the tune, nothing stands out. I used a couple different compare files. The main thing I wanted to see was that at 3500hz MAF the tune says it should be 11.38 g/s and the log shows 57 g/s at the same hz. The maf could be completely bad, but I haven't come across that symptom ever before. I would try logging again and moving the harness around that goes to the maf. It could be bad, but it seems like a wiring problem. I say that because none of the data makes much sense. You could also just unplug the maf and log idle again and post it. See if the fueling is ok with the maf unplugged.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
All the symptoms fit for a bad maf it looks like. Harness on the maf was changed yo a newer 5pin when I upgraded to an 01-02 operating system. It’s jerking and and keeps throwing the maf code. I have a 03 z06 5pin maf coming in tomorrow to see if it fixes the issue. I will follow up after i test it. Thanks again for looking.
Last edited by 2000Phoenix; 10-17-2022 at 07:43 AM.
Maf f/u. New adapter harness, and maf. Scanner still throwing code. Car is still stumbling and showing lean on wb. Narrow band Ltft are good and maf did come down but the car is still stumbling bad. Car has No cats. I redid the plumbing on the. Maf and everything looks tight and snug. Weird this happen out of know where. I saw people mentioning raising the delta air. I have never touch that but reading what it does I see it does effect that p0101 maf code. I guess it’s worth a shot. If anyone has any other ideas it would be appreciated.
How far did it come down? Does it read what it's supposed to according to the maf curve in the tune?Originally Posted by 2000Phoenix
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
I raised it by 1.15 across the table some areas were at 3 and others -7 but then there were still high lean spikes at +10. It’s really speratic and all over the place. Question, where is the fuse for the maf sensor? I was thinking if there is one maybe it’s bad? Code comes back after I clear it. Something change or went bad but I can’t seem to pinpoint it.
Your Ve table has some really really low numbers in the table. That doesn't look right. The base running airflow is way jacked up. If this car is still a manual trans car, it should be all zeros in the park/neutral row. The first screenshot is a manual vette, and the second is yours. The IAC park position airflow table is high at normal operating temps. Do you still have your stock file? Any one of these problems could really affect idle quality.
braf.pngidle settings2.jpgidle settings1.jpg
What are the details of this car? Engine mods, cam size, etc. The details aren't there in you original post.
Last edited by Matt Vardaman; 10-17-2022 at 11:53 PM.
When I upgraded to a 01 pcm I missed changing that area. Weird it just started having this issue. I will up date to see if it helps with the stumbling. Car specs: ls1 with mild cam ported stock intake and heads. 1 7/8 headers no cats, moser 9inch with 390 gears and a borla exhaust/6speed. I have the stock file which is why I was able to upgrade the ecu.
Last edited by 2000Phoenix; 10-18-2022 at 12:06 PM.
Update. I up the fuel trims by 10% and zero out the idle air coolant lower table and its still stumbling. Maf code came on again and one point on the scan one of the narrow bands bottom out to zero and hung there. Could this be a bad 0xgen sensor as they are brand new with the maf? Could there be a fuse for just the maf thats going bad or maybe something mechanical has gone bad on the motor thats causing the maf to act up? Any thoughts on this is appreciated.
Follow up. Finally got a solid sign from the scanner. Went to get gas and after cranking the car back up. Maf code was thrown but this time the maf and the wide band went lean together. Could the 3pin to 5pin adapter maybe have gone bad. Any thoughts are appreciated. posted pic of the adapter I have been using and scan.
Did the car fireup and run right on the newer pcm? looked at the warmup log on 101822.hpl and the oxygen sensors are switching but your short term fuel trims aren't moving like they should in relation to the 02 mv. In closed loop stft should switch fast and that's not happening. I'll look at your newest tune file and see if I can find out why stft aren't switching, but it could be a wiring/pinout issue. I have never used the maf harness adapter before, what brand is it? All of the maf code issues and the maf reading like 50g/s high on your early log could definitely the harness adapter. It could be losing connection intermittently.
Last edited by Matt Vardaman; 10-23-2022 at 12:37 AM.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
Apologies, its a stock pcm and I upgraded to 01-02 operating system. I’m betting their not moving right due to the maf going in and out. Harness is by vortec. I have one coming from ws6store made by casper to see if it fixes the issue. Maf is brand new Delphi.
Something odd in the tune is the DFCO enable temp is 414 degrees which is way outside the range of -40 to 285. Also you fixed some of the braf but missed the 90* and 111* cells they are 4.06 and 2.42 g/s and that's way low. Highlight from 46 to 154 and interpolate. That will get you a more reasonable number in those cells.
Last edited by Matt Vardaman; 10-23-2022 at 01:01 AM.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
I wanted to eliminate the popping. It was running fine also until the maf started throwing a code.
So it could be a pinout difference between the 2000 early pcms and the later OS. I know the 2001 and later pcms/os's are much better than the 99-00 in the trucks and 97-00 in the cars with the primary and secondary VE tables. The stft not moving in closed loop at idle is strange, because the O2's are switching like normal and the stft is what drives the switching. Try turning on Open loop STFT and log the idle warmup again. I hope the casper electronics adapter will get rid of the code, and fixes that issue.
2001 Silverado 5.3 - 209/217 cam, GT45 Turbo on 7lbs, Aem x-series wideband, 50lb/hr flex fuel injectors, on E85 with content sensor
1999 Silverado 6.0/4L80E Summit Stage one camshaft, 317 heads (replaced cast iron)
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