MAF Problems?
08-22-2010, 11:00 AM
#1
Instructor
Thread Starter
MAF Problems?
Car was running fine, then I changed the battery. First time out I got a 'Reduced Power" message and the car barely will move. Dropped the Battery and cleared the codes. Still not drive able. Car idled rough, so I swapped out the MAF Sensor with a spare I had. Car seems to idle better, but still drivability issues. When I unplug the MAF problems seems to run fine, idles fine. Hard to believe that I have two bad MAFs. What else could cause these problems?
08-22-2010, 03:39 PM
#2
Drifting
Member Since: Feb 2006
Location: Boston MA
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Removing the MAFs will put the car into speed density mode.
You should try cleaning both MAFs with brake cleaner. Do not touch or touch the sensors with any objects.
You should try cleaning both MAFs with brake cleaner. Do not touch or touch the sensors with any objects.
08-25-2010, 02:13 PM
#5
Drifting
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OK, So I'm guessing you've been driving the car around with no problems before the battery change. Or, was the car sitting for a long period of time?
The MAFs may be fine. Another thing is that removing the battery does a refresh the car, so it will have to relearn. Do you have any mods? Also, you mentioned drivibility issues? Is it rough there too? Backfire or misfire?
Just curious here, what battery did you get?
The MAFs may be fine. Another thing is that removing the battery does a refresh the car, so it will have to relearn. Do you have any mods? Also, you mentioned drivibility issues? Is it rough there too? Backfire or misfire?
Just curious here, what battery did you get?
07-12-2012, 03:56 PM
#6
Instructor
I have the same issue. Sorry about stealing the thread. However battery died over the winter and it was really dead. Then I bought a new Optima Red Top battery and gradually I got very bad idle and eventually I lost him totally. It took about 3 months to get to this point where he won't start at all. Now he cranks but won't start. Only if I disconnect MAF sensor he idles with 2100 rpm. If I connect the MAF he cranks, starts and dies within one second. He has a moderate tune 456 RWHP incl VARA RAM and FAST 90mm intake + other goodies from LS7. And yes I have checked for vacuum leaks approx 8 times already
07-13-2012, 02:08 PM
#8
Instructor
Uhhuhh AutoWiz, you wrote a lot of stuff that get straight over my head. Anyhow TB is working fine, Voltage to MAF is 12V and 4,98V for MAF and 5.0V for the MAP (two small connectors on MAF plug).
However I ended up ordering a new MAF sensor. We'll see if that will help.
I appreciate your help, thanks guys!
However I ended up ordering a new MAF sensor. We'll see if that will help.
I appreciate your help, thanks guys!
07-13-2012, 06:40 PM
#9
Pro
certain models of c5's??? no. c5's all use 5 wire maf's. you got power, gnd, sig. return, then 2 wire are iat. c5's and c6's are the same in that reguard, even the card style maf's in the z06's. and by the way, that is a veri important step to adding a sc, the RIGHT way. when boosting, the 2 wires to the maf for iat need to be cut, and an iat snsr needs to be mounted after boost device, so iat snsr is reading acurate. otherwise the vcm won't know it should be pulling time away cuz that sc is packing on the heat. this can create deadly knock/detonation. the maf will still function properly as a 3 wire maf, so long as pwr, gnd, and sig. return are connected properly.
But on a positive displacement blower i would leave the iat in the MAF and only relocate it if you plan on spraying meth accross the IAT to combat the heat you speak of. You can tune the stock heat soak table to match your combo, no need to hack as the stock knock sensor are pretty sensitive.
07-14-2012, 12:12 AM
#10
Pro
You simply tune the car to not KNOCK, you pull timing out of the High octane/Low octane spark table SIR.
Most of us who tune have seen KR, we simply back out of the throttle instead of press through with the run... IT really is pretty easy. I have even seen your precious Knock Sensor that indicate Detonation pick up "False KR".
I dont care what school you have been through. Ive seen tuning done this way multiple times by very very respectable shops!
I too have been through both The tuning school and Calibrated success. Have talked with many sought after tuners about the methods I use and all have been given the thumbs up!!
You do understand if you take time to adjust the Heat soak table properly I will still remove timing in a good fashion.... There are lots of different ways to cut a cookie here.
The method you suggest would need the same amount of tuning in the stock vette PCM to adjust for the IAT sensor under the blower. Your reasoning is a prime example of the reason Magnachargers get such a bad name for heat soak.... The stock VCM was not meant to see boost, nor was the sensor meant to be placed in the valley of the intake!
Plz dont bring credentials into this.... Ive tuned my share of high perf LSx's in my time.
Most of us who tune have seen KR, we simply back out of the throttle instead of press through with the run... IT really is pretty easy. I have even seen your precious Knock Sensor that indicate Detonation pick up "False KR".
I dont care what school you have been through. Ive seen tuning done this way multiple times by very very respectable shops!
I too have been through both The tuning school and Calibrated success. Have talked with many sought after tuners about the methods I use and all have been given the thumbs up!!
You do understand if you take time to adjust the Heat soak table properly I will still remove timing in a good fashion.... There are lots of different ways to cut a cookie here.
The method you suggest would need the same amount of tuning in the stock vette PCM to adjust for the IAT sensor under the blower. Your reasoning is a prime example of the reason Magnachargers get such a bad name for heat soak.... The stock VCM was not meant to see boost, nor was the sensor meant to be placed in the valley of the intake!
Plz dont bring credentials into this.... Ive tuned my share of high perf LSx's in my time.
Last edited by 06x6spdGTO; 07-14-2012 at 09:54 AM.
07-14-2012, 04:37 PM
#11
Pro
Ive had plenty of projects "SIR"
My personal Maggie LS2 uses the MAF in the stock location with IAT sensor just infront of the throttle blade. I relocated it out of the MAF as Im spraying water/meth (50/50) across the sensor and being very aggressive with the Heat Soak table if the Meth kit was to fail for some reason..
http://www.youtube.com/watch?v=qIaVX63dFPM
http://www.youtube.com/watch?v=T0GCh...9&feature=plcp
http://www.youtube.com/watch?v=LHIqZ...feature=relmfu
http://www.youtube.com/watch?v=YO1ht...4&feature=plcp
Correct me if Im wrong but the ZR1 uses a MAF, Last time I check as CUSTOM OS from HPTuners in 2 bar SD made you ditch the MAF when uploaded to the ECU.......
The ZR1 also uses a 100mm Card MAF, which IIRC uses the IAT located in the MAF Card.
Guess GM screwed up there too huh.......
Tune however you would like
LPE leaves the MAF/IAT in the stock location, your Eforce kits leave the MAF/IAT in stock location...... Relocate if you wish but how will you know what you are tuning is correct for the heat soak table or entirely too aggressive when you dont know how hot the air is in the stock Intake NOW!
Tune as you like too, but the boosted stuff Ive played with has worked GREAT without issues for along time....
My personal Maggie LS2 uses the MAF in the stock location with IAT sensor just infront of the throttle blade. I relocated it out of the MAF as Im spraying water/meth (50/50) across the sensor and being very aggressive with the Heat Soak table if the Meth kit was to fail for some reason..
http://www.youtube.com/watch?v=qIaVX63dFPM
http://www.youtube.com/watch?v=T0GCh...9&feature=plcp
http://www.youtube.com/watch?v=LHIqZ...feature=relmfu
http://www.youtube.com/watch?v=YO1ht...4&feature=plcp
Correct me if Im wrong but the ZR1 uses a MAF, Last time I check as CUSTOM OS from HPTuners in 2 bar SD made you ditch the MAF when uploaded to the ECU.......
The ZR1 also uses a 100mm Card MAF, which IIRC uses the IAT located in the MAF Card.
Guess GM screwed up there too huh.......
Tune however you would like
LPE leaves the MAF/IAT in the stock location, your Eforce kits leave the MAF/IAT in stock location...... Relocate if you wish but how will you know what you are tuning is correct for the heat soak table or entirely too aggressive when you dont know how hot the air is in the stock Intake NOW!
Tune as you like too, but the boosted stuff Ive played with has worked GREAT without issues for along time....
Last edited by 06x6spdGTO; 07-14-2012 at 04:41 PM.
07-15-2012, 01:08 AM
#12
Pro
the 2 bar os does not ditch the maf. you have to command the maf to fail a 0 hz to force it into speed density. and it is an easy swap to switch to a card maf. just get maf for ls7, then goto hptuners tune repository, find a stock tune for a ls7, and copy and paste your maf tables to get your starting point, then use vcm scanner to plot hystograms, and tune the maf. i just got done installing a 6.1L hemi and magna sc. the sc took a plastic iat in its base with an extension harness. yes there would be some tuning involved as temp readings from iat will be noticeably hotter than from outside throtle body, but in the end, it is still the more accurate way to go. when i add the wideband o2 into the mpvi pro interface, i drill a 7/8in hole in the exhaust as close to, or in the manifolds, or right at the collector, then weld in a bung, and after tuning, it gets a plug, wheras a lot of ppl would just use a wideband mounted into a piece of pipe and stick it in the tailpipe. the difference there is how fast the mpvi interface sees the changes in afr. i am real big on all around driveability in my tuning. and when i am done, my tune is verified by logging a healthy road test, both in traffic, and on highway, and afterwards, making sure that no where in the log was there any ks noise, and that ltft's stay with in +/-2%
As the expert you claim to be I wouldve figured you would have know not to have your LTFT on the + side.... (Care to explain why, or do you need to read your Advanced Edition of Tuning School.com first)
Secondly, why would you even run the restricted MAF tube when you have to fail out the sensor on a 2 bar SD anyways, Why even spend money on the damn sensor to fail it out?????
Do you even know why you need to run a 2bar SD??? Youve MAXED the MAF out in most cases and can no long accurately fuel the beast without hacking the PE table and 11,500hz+ side of the MAF to get your desired AFR.... The stock PCM on the E40/E67 and 99+ LS1 PCM stops at 105 KPA, (You can use the boost reference guide in your precious tuning school manual and figure out for the rest of the class where 105KPA is). The upgraded 2 Bar sensor will give an extended boost section on the stock PCM when the custom OS is uploaded so you can correctly fuel when higher boost ranges.
Third, I have tuned Card Maf's No lessons needed here.... I have street logged plenty on the cars Ive tuned as thats how I start with most of them...
To verify your MAF starting point with the LS7 card you would first want to start with some damn good Injector Format before you start plugging away..... Otherwise leave the stock MAF to verify you have good injector data. ^ Heres a brain buster for ya on the MAF topic, what happens if I load the LS7 MAF data using the LS3/7 Card MAF but install the car in a 130mm Tube????
Either way, Preach all you want but looks too me that following your format is a not the way I would choose... I prefer safety with CONSISTENCY in performance.
since your not supposed to tune with ANY KR, Blip your throttle a couple times and watch your scanner...... (Have fun with the TIP IN)
Taking a couple online classes has given you a slight EGO... your theroy of not ditching the MAF but having to FAIL it out proves it..
Last edited by 06x6spdGTO; 07-15-2012 at 01:23 AM.
07-15-2012, 01:20 AM
#13
Pro
Only reason I'm still in this debate with you, is the advice you give could come at the cost of others.... thats the main problem with these forums...... Alot of sexual intellectuals lurking with shady advice...
Alot of work/time/money could be lost for no particular reason, unfortunately I have had to learn this the hard.. so when I see the chance to save others sometime and a little $$ I dont hesitate to offer a hand.
I've clearly stated my method and reasons behind it... Tune as you wish, there are reason ppl say to go to a reputable shop/tuner
Alot of work/time/money could be lost for no particular reason, unfortunately I have had to learn this the hard.. so when I see the chance to save others sometime and a little $$ I dont hesitate to offer a hand.
I've clearly stated my method and reasons behind it... Tune as you wish, there are reason ppl say to go to a reputable shop/tuner
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CorvetteCam91ZO7 (01-23-2021)
07-15-2012, 02:26 AM
#14
Pro
2 bar os is just what it says, man, 2 bar. it adds a boost ve table. i'm sorry your maf fails at 11,5k tho. but if you put maf inside a larger orifice, the same volume of air will travel slower and bring down them hz. then you tune your maf. thats whats good about card style. they can be put in any size orifice you choose. so if your maf maxes out, get a bigger bore maf, or get a bigger intake. no need to take technology out of the car, right?
Still care to enlighten the group about positive fuel trims??
Didnt know how blip the throttle was that funny but you will most definetly get KR while cruising....
Tune a ZR1 tell me where the MAF fails if not adjusted properly (table says 15000hz tho), E40 + PCM have a low and high value for MAf as well fyi.... correct me if Im wrong but the table says 13300hz there
Ever seen the wideband sensor for a chassis dyno?? Its a tailpipe sniffer......
Im starting to wonder if you have ever "tuned" a car on the dyno on your own, or if your another shade tree, anus plumb bob feel street tooner?
Last edited by 06x6spdGTO; 07-15-2012 at 02:35 AM.
