3" GM MAF Question
Jan 26, 2011, 02:03 PM
#16
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how's your afr when the temps change from hot/cold outside with the gm maf/maf-t? I imagine you have a fixed iat signal going to the ecu so it's not going to compensate as it should. also you'll be missing the baro signal so it's not going to compensate for altitude changes either.
Jan 26, 2011, 03:55 PM
#17
Gibberish, lol.... I have no idea what you really said there. I don't know too much about the GM MAF and I know jack about tuning.
I just got the car about 3 weeks ago and it had the gm maf on it. The temps are still pretty cold right now so I wouldn't have noticed any real changes. AFR's are pretty rich while cruising at 10.2 and fluctuating and they are about 13ish at WOT. I really need a new tune so you can take those with a grain of salt.
I just got the car about 3 weeks ago and it had the gm maf on it. The temps are still pretty cold right now so I wouldn't have noticed any real changes. AFR's are pretty rich while cruising at 10.2 and fluctuating and they are about 13ish at WOT. I really need a new tune so you can take those with a grain of salt.
Jan 26, 2011, 04:27 PM
#18
how's your afr when the temps change from hot/cold outside with the gm maf/maf-t? I imagine you have a fixed iat signal going to the ecu so it's not going to compensate as it should. also you'll be missing the baro signal so it's not going to compensate for altitude changes either.
I drove from Northern California to Central Texas on a MAFT+GM3.5 MAF, didn't log anything, but nothing was out of whack as far as cruise/wot/idle/etc on an innovate LC1/Innovate Gauge combo. WOT stayed pegged at 11.1:1 wherever I was at---and I did a lot of 'merging.'
The car was even dyno tuned with the stock Mitsu MAF, but idled at 12:1 no matter what. Nothing short of rigging a stock MAF pipe to the GT35R inlet cured that issue. I didn't want to put the kind of stress on the oil/rings/etc at idle for the long trip. If scaling were pulled back, the ECU would not be fast enough to compensate for tip in and the car would stutter until out of the adjusted MAF scaling range. OT, sorry.
Actually it was the most pleasant drive I have had in a while because the idle NEVER dipped (another big pipe mitsu MAF issue) and always stayed pegged at stoich lol. 14.7-15ish cruise all the way. almost 290 miles per tank.
I'd say it's pretty safe and when using an exotic setup like that, there must be more done to the motor to warrant that modification and a wideband is highly recommended. Even with ECU SD, no WB is a death sentence.
MAFT setups are not cheap, but they still are useful for some peoples' setups. I still say stick with it lol. Have fun modding. Don't forget to get dyno tuned again!
Jan 26, 2011, 04:30 PM
#19
Gibberish, lol.... I have no idea what you really said there. I don't know too much about the GM MAF and I know jack about tuning.
I just got the car about 3 weeks ago and it had the gm maf on it. The temps are still pretty cold right now so I wouldn't have noticed any real changes. AFR's are pretty rich while cruising at 10.2 and fluctuating and they are about 13ish at WOT. I really need a new tune so you can take those with a grain of salt.
I just got the car about 3 weeks ago and it had the gm maf on it. The temps are still pretty cold right now so I wouldn't have noticed any real changes. AFR's are pretty rich while cruising at 10.2 and fluctuating and they are about 13ish at WOT. I really need a new tune so you can take those with a grain of salt.
Those numbers are way off!
EDIT: The MAFT also has to be adjusted. Take that into account when getting tuned.
Jan 27, 2011, 01:09 PM
#21
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I tried the maf-t on my TT Stealth (550awhp on pump) and had wild AFR shifts depending on the ambient temps which can swing from 60* in the morning to 95* in the afternoon some days. This caused the car to run inconsistently. It uses the same factory karman vortex maf system for what it's worth. I haven't tried a MAF-T on my own EVO but a few customers did and it made for a pretty crazy looking fuel map but it did work well enough for their needs. One other customer ditched it and went back to stock MAF.
Jan 27, 2011, 04:01 PM
#22
Ok, I logged some AFRs today on the way to work. I have about a 30 minute drive and I only mention it because just in that 30 minutes, I had some wierd changes. Car was warmed up before I left the house...
In the beginning....
Idle: 10.2 and fluctuating to 10.4
Cruise: 13.4 and fluctuating to 13.8
WOT: (3rd) 11.4 and fluctuating
About 15 minutes up the road,
Idle: 10.9 fluctuating to 11.2
Cruise: 14.4 fluctuating to 14.6
WOT: (3rd) 12.4 fluctuating to 12.8
I think maybe I just need a new tune, what do you guys think?
In the beginning....
Idle: 10.2 and fluctuating to 10.4
Cruise: 13.4 and fluctuating to 13.8
WOT: (3rd) 11.4 and fluctuating
About 15 minutes up the road,
Idle: 10.9 fluctuating to 11.2
Cruise: 14.4 fluctuating to 14.6
WOT: (3rd) 12.4 fluctuating to 12.8
I think maybe I just need a new tune, what do you guys think?
Jan 28, 2011, 03:46 PM
#25
Ok, I logged some AFRs today on the way to work. I have about a 30 minute drive and I only mention it because just in that 30 minutes, I had some wierd changes. Car was warmed up before I left the house...
In the beginning....
Idle: 10.2 and fluctuating to 10.4
Cruise: 13.4 and fluctuating to 13.8
WOT: (3rd) 11.4 and fluctuating
About 15 minutes up the road,
Idle: 10.9 fluctuating to 11.2
Cruise: 14.4 fluctuating to 14.6
WOT: (3rd) 12.4 fluctuating to 12.8
I think maybe I just need a new tune, what do you guys think?
In the beginning....
Idle: 10.2 and fluctuating to 10.4
Cruise: 13.4 and fluctuating to 13.8
WOT: (3rd) 11.4 and fluctuating
About 15 minutes up the road,
Idle: 10.9 fluctuating to 11.2
Cruise: 14.4 fluctuating to 14.6
WOT: (3rd) 12.4 fluctuating to 12.8
I think maybe I just need a new tune, what do you guys think?
Unless you have a pre-callibrated WBO2, try re-doing a free-air callibration and see if the numbers sway. Have a reputable tuner here fix those numbers...seems like nothing that can't be handled over e-mail for these guys. They may have you "zero out" the MAFT and retune your ECU from that point on. I would.
Cruise looks good lol.
Good luck man.
Jan 28, 2011, 04:04 PM
#26
I'm heading up to Force-Fed in Fayetteville by next weekend so I'm not too worried. Things were a little crazy today though.
This morning the car jumped to 3k rpms upon start up and eventually when it warmed up it dropped back to normal idle (1100k) Then the **** hit the fan. I was cruising and barely made it out of the neighborhood before the revs started dropping and killed the car. Every time I had to stop, I had to keep my foot on the gas to keep the car running. Then later in the afternoon the problem was gone but it would hesitate really bad and backfire until I got into boost. Boost would be normal then it would spike to around 34 psi and I had some compressor surge. It has done that the rest of the day. So I had to drive back home shifting around 2 - 3k so it wouldn't go into boost.
I'm gonna do a leak down test and boost leak test tomorrow and see what the hell is going on. I thought IAC but I dunno.
This morning the car jumped to 3k rpms upon start up and eventually when it warmed up it dropped back to normal idle (1100k) Then the **** hit the fan. I was cruising and barely made it out of the neighborhood before the revs started dropping and killed the car. Every time I had to stop, I had to keep my foot on the gas to keep the car running. Then later in the afternoon the problem was gone but it would hesitate really bad and backfire until I got into boost. Boost would be normal then it would spike to around 34 psi and I had some compressor surge. It has done that the rest of the day. So I had to drive back home shifting around 2 - 3k so it wouldn't go into boost.
I'm gonna do a leak down test and boost leak test tomorrow and see what the hell is going on. I thought IAC but I dunno.
Jan 28, 2011, 05:34 PM
#27
I'm heading up to Force-Fed in Fayetteville by next weekend so I'm not too worried. Things were a little crazy today though.
This morning the car jumped to 3k rpms upon start up and eventually when it warmed up it dropped back to normal idle (1100k) Then the **** hit the fan. I was cruising and barely made it out of the neighborhood before the revs started dropping and killed the car. Every time I had to stop, I had to keep my foot on the gas to keep the car running. Then later in the afternoon the problem was gone but it would hesitate really bad and backfire until I got into boost. Boost would be normal then it would spike to around 34 psi and I had some compressor surge. It has done that the rest of the day. So I had to drive back home shifting around 2 - 3k so it wouldn't go into boost.
I'm gonna do a leak down test and boost leak test tomorrow and see what the hell is going on. I thought IAC but I dunno.
This morning the car jumped to 3k rpms upon start up and eventually when it warmed up it dropped back to normal idle (1100k) Then the **** hit the fan. I was cruising and barely made it out of the neighborhood before the revs started dropping and killed the car. Every time I had to stop, I had to keep my foot on the gas to keep the car running. Then later in the afternoon the problem was gone but it would hesitate really bad and backfire until I got into boost. Boost would be normal then it would spike to around 34 psi and I had some compressor surge. It has done that the rest of the day. So I had to drive back home shifting around 2 - 3k so it wouldn't go into boost.
I'm gonna do a leak down test and boost leak test tomorrow and see what the hell is going on. I thought IAC but I dunno.
+1 on the boost leak test. It will save time if you tell the tuner that you have done this and corrected any issues.
Do not let your car overboost/drive easy and post some numbers after the tune heh.
Jan 28, 2011, 05:51 PM
#28
I'm driving easy as I can without stalling right now, lol. I'm gonna do the boost leak test tomorrow and fix anything I can. I'm also thinking part of my issue could be an old IAC, the car does have over 80k miles but the motor only has about 13k. I ordered new plugs (bpr7es) and I'm gonna do an oil change and any "tune up" maintenence that I can before I go. I PM'd Jason today to see what it would cost to just go SD so I may just say f--- the GM MAF
Jan 28, 2011, 06:04 PM
#29
I'm driving easy as I can without stalling right now, lol. I'm gonna do the boost leak test tomorrow and fix anything I can. I'm also thinking part of my issue could be an old IAC, the car does have over 80k miles but the motor only has about 13k. I ordered new plugs (bpr7es) and I'm gonna do an oil change and any "tune up" maintenence that I can before I go. I PM'd Jason today to see what it would cost to just go SD so I may just say f--- the GM MAF
I knew I stayed up countless hours back in 2008 disassembling and re-assembling and adding and taking away from the MAF fueling routine for a good cause lol.
I'm still trying to defend the MAF lol/but I really don't care. Let us know what Force-Fed thinks.