AFR idel problem

zuperman 370 · 06-18-2014, 12:48 PM

Hello guys I have a gtm stage 2 sc and recently been facing problems with the AFR reading at idel, first of all the rpm Is shaky, and the afr sometimes reads between 17 and even goes up to 18 and at idel the car sometime cuts off kind like it will turn off then goes bk to normal how to explain it kinda like the belt losesns then tighten the car is hesitant and kind of laggy sometimes dont know if this is a tunning issue mechanical where should I start looking p.s dont know if this causes issues but im running a stage 2 gtm sc but the pully im using on it is the stage 1.5 pully please advise guys on where I should be looking

Nixlimited · 06-18-2014, 02:09 PM

sounds like potentially a BPV problem? Wondering if the SC spinning at idle is not bypassing the extra air and causing the lean condition. Or it could be a vacuum leak post-MAF that is throwing the readings off (i.e. not accounting for all the air entering).

theDreamer · 06-18-2014, 02:11 PM

Had a similar issue, it was a tune problem.
Tuner needs to adjust the fuel/MAF readings I believe it is for idle. I would do a check of the system for leaks, but this is what caused my issue.

zuperman 370 · 06-18-2014, 02:22 PM

Thank you for the input guys can this potentially be dangerous on the engine during driving afr is good and stable only happens during idel so recordation to get the car mechanically checked for leaks etc then look at the tune

theDreamer · 06-18-2014, 02:25 PM

By the sounds of it you are having the same issue I had, tune check should fix it.
Also, are you running GTM can tune or a custom tune?

zuperman 370 · 06-18-2014, 02:36 PM

Quote:

Originally Posted by theDreamer

By the sounds of it you are having the same issue I had, tune check should fix it.
Also, are you running GTM can tune or a custom tune?

No I am running a custom tune thing is this guy tuned many fi 370z and it's starting to act up recently but wasn't happy with the drivability of the car ever since day one how can I explain it shifts in automatic and sometimes in manual isn't sharp the rpm is slow to react and sometimes jumpy also running a gym upgraded tranny, haven't been happy with drivability it's ruining the experience

1slow370 · 06-18-2014, 03:11 PM

the way i understand it is the gtm transmissions and valvebodies need to have the transmission table in the ecu tuned for them or they don't shift right/slip, you're tuner would need to talk to gtm and make sure the transmission is being told to do what it needs to properly. If you buy a $6000 transmission but don't get the tune adjusted for it you risk burning up the new transmission.

zuperman 370 · 06-18-2014, 03:33 PM

Quote:

Originally Posted by 1slow370

the way i understand it is the gtm transmissions and valvebodies need to have the transmission table in the ecu tuned for them or they don't shift right/slip, you're tuner would need to talk to gtm and make sure the transmission is being told to do what it needs to properly. If you buy a $6000 transmission but don't get the tune adjusted for it you risk burning up the new transmission.

Come to think of it he was complaing about some slip on the dyno where can we get a hold of gtm with their messed up situation

1slow370 · 06-18-2014, 04:53 PM

If you didn't flash the tune that would cause it, another case of not following the instructions haha, I saw on myg37 there was a guy who just did the same thing, except he burned up one transmission, replaced it with another transmission, damaged that transmission, swapped in a new stock valvebody, then finally got around to tuning it after throwing out the gtm valvebody

Edit: if only he had put the gtm valve body in and then tuned it.

zuperman 370 · 06-19-2014, 01:13 AM

damm i hope that no damage has been done to the transmission but i dough it as car hasent been pushed or driven much the past year

Jordo! · 06-19-2014, 01:55 AM

Definitely make sure you have the right tune on there!

The idle issue is very possibly a bad bypass valve. Any hiss or whistle under the hood?

zuperman 370 · 06-19-2014, 02:41 AM

by bad bypass do you mean the pvc bypass is connected wrong or filter is dirty needs cleaning, there is a whistle but i assume its the sound of the sc unit also at times in idle the its as if the car stalls, stops for a sec as ifi twill turn off and then goes back to normal, at this time as well the afr goes to 17 18 and sometimes ---- comes on no reading

1slow370 · 06-19-2014, 11:29 AM

no he means the blow off valve looking thing could be open when it isn't supposed to be, on the supercharged cars i believe the norm is that it is supposed to be open under idle though to allow the excess air to recirculate. the idle is most likely an issue with the maf curve, when they tuned your car for WOT they mostlikely adjusted the k value to bring the ecu closer to the afr targets and never went back in and tweaked the maf values below 2 volts to get the idle back.

EDIT: if it was slipping already don't drive it and get the transmission tables tuned ASAP!!

Nixlimited · 06-19-2014, 12:25 PM

Quote:

Originally Posted by 1slow370

no he means the blow off valve looking thing could be open when it isn't supposed to be, on the supercharged cars i believe the norm is that it is supposed to be open under idle though to allow the excess air to recirculate. the idle is most likely an issue with the maf curve, when they tuned your car for WOT they mostlikely adjusted the k value to bring the ecu closer to the afr targets and never went back in and tweaked the maf values below 2 volts to get the idle back.

EDIT: if it was slipping already don't drive it and get the transmission tables tuned ASAP!!

I would think tuning too, but he said the problem has just recently developed. I would think a tuning problem would have been apparent from the start.

1slow370 · 06-19-2014, 05:28 PM

oh i thought he was recently retuned, assuming the tune was good check for air leaks between the maf sensors and the throttles. anything before the maf wouldn't cause it, unless it was something really wrong like the bypass valve stuck closed at idle.

06-18-2014, 12:48 PM	#1 (permalink)
zuperman 370 Track Member Join Date: Dec 2009 Location: BAHRAIN Posts: 944 Drives: 370z 2010 at blue Rep Power: 17	AFR idel problem Hello guys I have a gtm stage 2 sc and recently been facing problems with the AFR reading at idel, first of all the rpm Is shaky, and the afr sometimes reads between 17 and even goes up to 18 and at idel the car sometime cuts off kind like it will turn off then goes bk to normal how to explain it kinda like the belt losesns then tighten the car is hesitant and kind of laggy sometimes dont know if this is a tunning issue mechanical where should I start looking p.s dont know if this causes issues but im running a stage 2 gtm sc but the pully im using on it is the stage 1.5 pully please advise guys on where I should be looking

06-18-2014, 02:09 PM	#2 (permalink)
Nixlimited A True Z Fanatic Join Date: Aug 2009 Location: San Diego Posts: 1,235 Drives: 15 GT-R / 11 Prius Rep Power: 26	sounds like potentially a BPV problem? Wondering if the SC spinning at idle is not bypassing the extra air and causing the lean condition. Or it could be a vacuum leak post-MAF that is throwing the readings off (i.e. not accounting for all the air entering). Jordo! likes this. __________________ Car Sold! Pleasure being a part of the Z community. New ride: 2015 GT-R - 647 WHP / 641 WTQ (e85) & 543 WHP / 519 WTQ (91)

06-18-2014, 02:11 PM	#3 (permalink)
theDreamer A True Z Fanatic Join Date: Feb 2009 Location: Texas Posts: 30,879 Drives: 370z Rep Power: 4211	Had a similar issue, it was a tune problem. Tuner needs to adjust the fuel/MAF readings I believe it is for idle. I would do a check of the system for leaks, but this is what caused my issue. __________________ theDreamer's Z // Fast Intentions // Uprev // GTM // HKS // TEIN theDreamer's Silvia // URAS // GREDDY Houston Zs // Facebook // Twitter // Instagram

06-18-2014, 02:25 PM	#5 (permalink)
theDreamer A True Z Fanatic Join Date: Feb 2009 Location: Texas Posts: 30,879 Drives: 370z Rep Power: 4211	By the sounds of it you are having the same issue I had, tune check should fix it. Also, are you running GTM can tune or a custom tune? __________________ theDreamer's Z // Fast Intentions // Uprev // GTM // HKS // TEIN theDreamer's Silvia // URAS // GREDDY Houston Zs // Facebook // Twitter // Instagram

06-18-2014, 03:11 PM	#7 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	the way i understand it is the gtm transmissions and valvebodies need to have the transmission table in the ecu tuned for them or they don't shift right/slip, you're tuner would need to talk to gtm and make sure the transmission is being told to do what it needs to properly. If you buy a $6000 transmission but don't get the tune adjusted for it you risk burning up the new transmission. Wonka2581 likes this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

06-18-2014, 02:22 PM	#4 (permalink)
zuperman 370 Track Member Join Date: Dec 2009 Location: BAHRAIN Posts: 944 Drives: 370z 2010 at blue Rep Power: 17	Thank you for the input guys can this potentially be dangerous on the engine during driving afr is good and stable only happens during idel so recordation to get the car mechanically checked for leaks etc then look at the tune

06-18-2014, 04:53 PM	#9 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	If you didn't flash the tune that would cause it, another case of not following the instructions haha, I saw on myg37 there was a guy who just did the same thing, except he burned up one transmission, replaced it with another transmission, damaged that transmission, swapped in a new stock valvebody, then finally got around to tuning it after throwing out the gtm valvebody Edit: if only he had put the gtm valve body in and then tuned it. Wonka2581 likes this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

06-19-2014, 01:13 AM	#10 (permalink)
zuperman 370 Track Member Join Date: Dec 2009 Location: BAHRAIN Posts: 944 Drives: 370z 2010 at blue Rep Power: 17	damm i hope that no damage has been done to the transmission but i dough it as car hasent been pushed or driven much the past year

06-19-2014, 01:55 AM	#11 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 419	Definitely make sure you have the right tune on there! The idle issue is very possibly a bad bypass valve. Any hiss or whistle under the hood? __________________ Enjoy it. Destroy it.

06-19-2014, 02:41 AM	#12 (permalink)
zuperman 370 Track Member Join Date: Dec 2009 Location: BAHRAIN Posts: 944 Drives: 370z 2010 at blue Rep Power: 17	by bad bypass do you mean the pvc bypass is connected wrong or filter is dirty needs cleaning, there is a whistle but i assume its the sound of the sc unit also at times in idle the its as if the car stalls, stops for a sec as ifi twill turn off and then goes back to normal, at this time as well the afr goes to 17 18 and sometimes ---- comes on no reading

06-19-2014, 11:29 AM	#13 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	no he means the blow off valve looking thing could be open when it isn't supposed to be, on the supercharged cars i believe the norm is that it is supposed to be open under idle though to allow the excess air to recirculate. the idle is most likely an issue with the maf curve, when they tuned your car for WOT they mostlikely adjusted the k value to bring the ecu closer to the afr targets and never went back in and tweaked the maf values below 2 volts to get the idle back. EDIT: if it was slipping already don't drive it and get the transmission tables tuned ASAP!! Jordo! likes this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50 Last edited by 1slow370; 06-19-2014 at 11:31 AM.

06-19-2014, 05:28 PM	#15 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	oh i thought he was recently retuned, assuming the tune was good check for air leaks between the maf sensors and the throttles. anything before the maf wouldn't cause it, unless it was something really wrong like the bypass valve stuck closed at idle. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

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