kp

iTrader: (34)

Recently at the track i was having some weird air/fuel issues. Almost like a rev limiter kicking in. Looking through the logs it seems to have cleared up when a P0103 code set. My MAF is maxed ot about 4500rpm so it really isnt in the picture at all making a pass at the track.

My first question will the MAF freaking out change my fueling at WOT when in PE? Also does setting the P0103 code keep the car in SD until the code is cleared or only while its a current code and not history? I dont log the MAF s I dont know whats going on with it but I didnt notice the car running every different while that code was set so I'm not sure what was going on..

jimmyblue

iTrader: (11)

When the MAF is "maxed" it is still in the picture,
but it's providing corrupted data (presumably
you have a cobbled tune that "deals with it").

On the other hand a 1-bar MAP sensor might
also be pegging out, and around the same
point. The '98s and '99-'00 have other oddities
about the fault mode, like using secondary VE
table (another possible airflow-value point of
divergence) etc.

Logging the Dynamic Airflow and the MAF airflow
across this event-boundary would be interesting,
see if your air (hence fuel and spark) is changing
significantly. But the setup may be double-gimp
(both MAF and MAP are pegged) and the different
behavior is like cane vs crutch.

kp

iTrader: (34)

LOL, my 'cobbled' tune has been running well in the 9s and street driving like a stock car for nearly two years so thats not the point here I woudl assume @14psi the 1bar MAP is pretty well pegged also.

My main question is if the MAF starts throwing out some weird numbers (its maxed by 4500rpm) will it affect the WOT fueling. Its been working fine without that code for a long time so something happened.

Also does it stay in SD mode until the DTC clears or only when the P0103 is current?

LostCauseZ06

iTrader: (4)

with my Z06 i have my maf corruption set at zero, it throws the p0103 code and throws it into speed density, as long as the code in a current and not a history the car will continue to run in speed density, speed density will pull directly off your VE tables and use the multiplier for PE mode... at least thats the way i understand it, im still pretty new at this stuff though but its worked pretty well for me so far

kp

iTrader: (34)

Thats what I would assume as well, but when the MIL cam on the car idled and drove around no different and with a stock VE table it will pretty much die at low throttle if I disconnect the MAF so i cant see it being in SD.

After that the code was in history and it still ran fine. Figured with all the SD guys they would know for sure what happens when the p0103 sets, the service manual says it goes to SD also but doesnt say if it stays there or not. Just trying to track down why the car ran like crap 1/2 the night then cleared up..

SMOKINV8

iTrader: (6)

I'm fairly confident that just throwing the P0103 code doesn't throw you into SD. When we set the MAF Fail Hz to 0, the P0103 is a direct side effect of when the car does enter SD, but that doesn't mean P0103 by itself means you're in SD.

If thats right, then that would explain why your car still idles fine while your SES light is set.

LostCauseZ06

iTrader: (4)

which MAF are you running KP??

LostCauseZ06

iTrader: (4)

the only way to throw a p0103 code is if the frequency on the MAF is exceeding the max allowed frequency that you set in the PCM, that code is not in there just to enable speed density, on a stock car it is in there to detect a problem with the maf and to get rid of the possibility of it reading insane amounts of air and flooding the motor with fuel. therefore if the limit is ever reached (throws the code) it throws the car directly into speed density to base calculations off the VE tables because its assuming your MAF is malfunctioning..

if the P0103 code is a CURRENT code, not a history code, then the car should be running in speed density...

for the record... sometimes the MIL light will stay on for codes like that.. even if its not a current code... if i throw that code it keeps my light on even if its stored in the history and not a current trouble code.

SMOKINV8

iTrader: (6)

So if his car is throwing a current P0103 code, he is without a doubt in speed density at all times while its current?

kp

iTrader: (34)

The only time it was current was on one pass when the MIL light came on half way down. Car was still missfiring oddly so I let off, it still drove down the return road fine and idled OK so I dont think it was in SD. After that the light was on but it was just a history code and I didnt clear it for the rest of the night. After I swapped plugs the missfire went away but I wasnt 100% sure if the P0103 had something to do with the missfire or it was the plugs.

Pro Stock John

iTrader: (34)

PO103 in your context is the 'high frequency maf code.'

Back in the day LT1'ers would use a MAF Massager.

kp

iTrader: (34)

I know that But having problems and seeing that code for the first time together in a couple years makes you go 'hmmmmmmmmm' lol.

Brent@LPE

I was pulling a vette today "a little different with drive by wire " we installed a fuel system and boost referenced regulator, I bet I made six pulls getting the fuel dialed in with no problems, let it cool dowwn for the final pull and @ 6100 I felt it shutter and lifted... looking at the data the only only thing that was obvious was that injector duty cycle dropped like a rock from 83% to 65% for no known reason,like I said we had multiple pulls with no problems...a little more digging and i had tripped P0103
in history but had not set the light... the car was cooled down and ready to make the number I guess a little more than we anticipated
I have never seen it tripped on a F-body KP but trust me dont let it happen again

Brent

kp

iTrader: (34)

Thanks for the reply Brent,

I only have one log when it happened but the injector duty cycle and RPM didnt log. The wideband was jumping beween 11 and 17:1 but I didnt know if it was just the logger screwing up or the a/f jumping around like that because of the logger being messed up - hard to look at the wideband in 1st or second gear.

Here is a video of the car, first pass it pretty much just shut off and then was decent. Second two I didnt even bother making a full pass, I did some 6500rpm burnouts and the car never missed a beat so its very possible the MAF is on its way out. If you watch the vids it sure dont sound like an ignition missfire, almost like a rev limiter, that why I'm not so convinced it was the spark plugs even though the car cleared right up after I changed them.

http://video.ls1tech.com/video/26a53...1d015ecb01.htm

I guess its time to suck up and ditch the MAF and go SD, its had a hard life and has served well for eight years I would have never guessed the MAF freaking out would affect the WOT fueling that much. Also goes to show you how important a good logger is, The car ran well last couple passes so I dont think I hurt anything and the plugs I pulled out looked fine but with no logger I was 100% in the dark on what was going on and should have made fixing that my first priority but I was convinced the two step was screwing up since that was the last thing I did to the car..

Brent@LPE

i hear you on the last thing you did to the car! we were also like WHAT HAPPENED!! I was really rich and scalling back just a tad and I felt a flutter ' you can feel everything on a dyno' the thing shot from 11.6 to 16.1 and chip was flailing his arms around and we got all turned around like what in the world did we do now!!!
but it was easy fix just got by us
Im going to pull the plugs in the morning and read her out Ill let you know

I like the MAF myself with the centrifigul stuff it works out well for us but you got a race car ya know

What MAF do you got?

kp

iTrader: (34)

Stock 98 descreened MAF, the original that was on the car.

Honestly for my car it worked perfect, the car was like 100% stock as far as starting and driving and the only thing that needed to be touched up was the PE table for big weather changes. The plugs out of mine looked fine even after 6 aborted 1/2 track passes of it not running right, good thing is at 16:1 a/f it will pretty much just shut off like the rev limiter and thats exactly what it felt like. All the plugs I took out showed no signs of detonation at all. After I swapped the plugs it cleared up and ran the best ever at this track at like 3000' DA so I doubt its hurt. Just went out and looked at those plugs again and there is no signs of detonation.

I'm just wondering if if the MAF is going bad and causing it or something else like it hitting above 14Khz and the PCM is switching to SD table when it does it so it doesnt overfuel and it just needs the limit for fail set up higher. The stock VE will be way too lean at WOT if it switches to SD but I wonder wht the huge fluctuation, unless when it 'fails' it goes right to SD and then back to normal when it goes below 14Khz. If thats the case then just raising the fail frequency would be an easy fix.

I havent logged the MAF hz in ages, I have no idea what frequency it hits at at high rpm with boost.

Brent@LPE

I logged MAF hz today and was getting 13950 I just moved the fail to 15000
.my plugs looked fine also but I know that it did go lean
thank god it was really quick you know
everything went really well today had no other problems

move that sucker out of the way and go for glory dude!!!

good luck- Brent

kp

iTrader: (34)

I went through some older logs I had when I logged the MAF and the hz never went above 13000 but I did swap cams and bigger exhaust and moved the MAF position slightly. I found a brand new MAF so in it goes and I'll just bump the fail up to 16K and see what happens. I'll log the frequency for a few passes and see where its at. I never thought about the frequency getting high enough to make it fail

Glad yours worked out OK

kevin

SUCK MY SS

iTrader: (14)

sorry to revive an old thread, but what about if the po103 code is being set at idle, and when cleared will come back immediately...it will state history,immature,current, and pending i believe...i have tried a good working maf with no success... does the 98 camaro MAF differ from that of a 99+ car?

pdsq98gt

Sounds like your car has been tuned before in SD. If you have HPT look under engine diagnostics and airflow in the editor and see what the MAF fail frequency is. If it's set at 0, someone has changed it.