Wideband AFR Problem?
Wideband AFR Problem? Well I just installed my wideband and was trying to see the results of this and trying to diagnose my issue of my car missing every once in awhile. So here are my results.
At idle it would sit anywhere from about 12.5 - 14.3 or so. Car is a head/cam car so I expected it to vary a little. That's expected correct?
At WOT it would be around 12.6-12.9 or so. That is also good, isn't it? Car is tuned so it should be good.
But every once in awhile my car will seem to hesitate and seems like it loses all power. I got to see what the AFR was doing while it did this. So I'll just be cruising and it will seem like it loses power and cuts out a little. The wideband went straight to 24.4 when it did this? So it's running real lean when it starts missing? This seems real strange and I have no clue what it can be. But when it starts missing a little you can just punch it and go WOT and it cleans right up and goes to 12.6-12.9 or so. What is going on with this?
At idle it would sit anywhere from about 12.5 - 14.3 or so. Car is a head/cam car so I expected it to vary a little. That's expected correct?
At WOT it would be around 12.6-12.9 or so. That is also good, isn't it? Car is tuned so it should be good.
But every once in awhile my car will seem to hesitate and seems like it loses all power. I got to see what the AFR was doing while it did this. So I'll just be cruising and it will seem like it loses power and cuts out a little. The wideband went straight to 24.4 when it did this? So it's running real lean when it starts missing? This seems real strange and I have no clue what it can be. But when it starts missing a little you can just punch it and go WOT and it cleans right up and goes to 12.6-12.9 or so. What is going on with this?
I'm not sure about LTFT's how do I check this?
Can you monitor tps voltage or maf frequency? Just a thought...maybe a funky sensor? Then again, if LTFT is highly negative, that also might be an indicator of a sensor being suspect.
I just know something is still wrong and I can't locate it. I mean I even switched my passenger o2 to the driver side when it said it was bad and it didn't correct when I installed my wideband. It may be the ext. harness is bad. I probably just need to go get one of those corvette o2 sensors and install it and take it back if it doesn't fix it.
I really have no way to do this. I had a predator tuner but my friend dropped it and it doesn't work now. I may have to see if I can locate someone with EFI Scan or something like that.
I just know something is still wrong and I can't locate it. I mean I even switched my passenger o2 to the driver side when it said it was bad and it didn't correct when I installed my wideband. It may be the ext. harness is bad. I probably just need to go get one of those corvette o2 sensors and install it and take it back if it doesn't fix it.
I just know something is still wrong and I can't locate it. I mean I even switched my passenger o2 to the driver side when it said it was bad and it didn't correct when I installed my wideband. It may be the ext. harness is bad. I probably just need to go get one of those corvette o2 sensors and install it and take it back if it doesn't fix it.
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When I start the car up and only on startup it will run good for like a few minutes. Then all of a sudden all kinds of powerloss and change in the motor tone. Wideband goes to 22.4 and sits there except when you shift gears and for a split second it fixes then starts doing it again. I also heard this real loud sucking noise near the intake when it was idling and doing this today. Is the MAF doin this? It was like a real loud noise that sounded like it was sucking air in. But the strange thing is all of a sudden after driving it for like 5 minutes the car just clears out and runs perfect and doesn't do this anymore until you turn the car off no matter if it's warm or still cold. It will startup and then after a minute do the same thing and then fix and not do it again. I'm completely stumped... and want to run it into a lake.
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If you are still running a MAF, with the engine running, lightly tap the MAF with the plastic end of a screwdriver, if it misses, get a new MAF. If it does not miss, buy some MAF cleaning spray and clean the MAF per the instructions and see if that helps.
TECH Resident
Joined: Oct 2005
Posts: 781
Likes: 0
From: Taxme, Ohio
Spraying starting fluid around the intake areas, including the base of the manifold while the engines runs and the symptoms are present can tell you something. You can also unplug the MAF and see what you get.
I'm trying to understand what tapping the MAF will accomplish??
I'm trying to understand what tapping the MAF will accomplish??
Haven't tried any of this been busy but thanks for the input. Could it be a vacuum leak if it sucks really loud and you barely rev it and it goes away? I mean it only does this louding sucking every once in awhile when I start it but after driving for like 5 minutes it's perfect again. No strange noises and car runs good. Could this be a bad MAP? I'm getting my friends T/A tom and going to switch some parts and see if I can find the culprit of my problem.
it sounds like your maf transition to your ve table may be off. if you have any modifications before the maf than stock you MUST recalibrate the maf sensor. when your vehicle transitions from maf frequency to map tables they need to be a smooth transition. I have seen this identical problem with boosted vehicles that when they transition from atmospheric pressure to any boost it will hesitate or misfire. if you correctly calibrate the maf table then correctly address the map table I imagine you will see the small problems like this disappear.
11 Second Club
Joined: May 2004
Posts: 528
Likes: 0
From: Ky
502 Rules!
sounds to me like a bad MAF or miscalibrated MAF vs VE table. when the car transitions from VE to MAF the values crash together. You need a smooth transition between the two. As stated by Jrocstar.
If you have a copy of HP Tuners or EFI live use your wideband to calibrate the MAF. Follow the Greg Banish DVD step by Step!! So ppl recommend using the the LTFT's to calibrate the MAF but if you have slow sensor response (Cold Sensor's), the LTFT route is a waste of your time. WIDEBAND CALIBRATION FTW!!!
If you have a copy of HP Tuners or EFI live use your wideband to calibrate the MAF. Follow the Greg Banish DVD step by Step!! So ppl recommend using the the LTFT's to calibrate the MAF but if you have slow sensor response (Cold Sensor's), the LTFT route is a waste of your time. WIDEBAND CALIBRATION FTW!!!
Well today I took a 85mm MAF off of a truck at my buddies shop and it seemed to clear up a little but not all the way. I was messing with it and when he put his hand over the maf it like cleared right up. It's acting like it's getting too much air? I'm completely confused? Does it need a 75mm maf? lol
