Lean Misfires at 2700-2800 rpm - Page 4 - 3000GT/Stealth International Message Center

badass3000 · 10-11-2006, 07:49 PM

I unpluged my ABS, and ECS moduals = no change
swaped in a known good ecu = no change
trying a different fuel controller in the morning...

DoctorDex · 10-11-2006, 08:59 PM

I'm interested to see if the different fuel controller will fix the problem.

As far as my other issue, with the spark blow out on the rear bank, I'm going to try swapping my fuel lines tomorrow, so the front bank will receive fuel after the rear bank. I'm hoping this way I can rule out a lack of fuel being the reason for my very lean rear bank O2's @ WOT.

Declan

AudioPmp23 · 10-11-2006, 11:05 PM

Hey I know this prob wont fix that specific issue but I just found out that having the stock wastegate solenoid electrically connected can still cause a vac leak even with the cap on the lower nipple. I tested it out with a hand pump vac/gauge tonight.

LeMoN1438 · 10-12-2006, 12:16 PM

Quote:

Originally Posted by DoctorDex

Correct me if I'm wrong, but it seems odd that coils would cause problems solely on the front bank because each coil supplies spark to both a front and rear bank cylinder. If it was a bad coil, you'd think that you'd have problems on both the front and rear. Maybe your coils were just weak in general??

It did seem odd, but thats the readings that were displayed on my datalogger. The rear bank would read .92 while the front would read ~.62, during the misfire/stutter/power loss above 4000rpms. Perhaps a faulty coil wire was the culprit, since I swapped out the entire assembly.

badass3000 · 10-12-2006, 10:07 PM

DoctorDex I am 100% sure your MASS is toast!!!
My LT1 was faulty also.
seems it is a common fault for GM cars too!
moral of story=GM parts suck!

DoctorDex · 10-12-2006, 11:30 PM

Thanks for the heads up. How did you determine your LT1 was bad? What tests can I run on mine to determine if it is the cause?

Declan

badass3000 · 10-13-2006, 12:02 AM

the guys at 3SX told me that it was a known fact that there can be problems with GM mass's and it is always around 3000rpm.

DoctorDex · 10-13-2006, 03:03 PM

I believe you, but it kind've strange because its not like the the GM MAS knows what the RPM is. Even if I add enough fuel to get it ~ stoich, I still get misfires. I've also noticed that it'll misfire (backfire) during decel when it hits 2700 rpm.

keithmac · 10-13-2006, 03:30 PM

Could it be resonance in the inlet manifold causing the MAS to miss-read (seems one of the only factors that`s rpm dependant?) but after saying that if you`ve increased the fueling to compensate it shouldn`t be an issue.

10-11-2006, 07:49 PM	#31 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: one "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm I unpluged my ABS, and ECS moduals = no change swaped in a known good ecu = no change trying a different fuel controller in the morning...

10-11-2006, 08:59 PM	#32 (permalink)
DoctorDex Forum Member Join Date: Jul 2005 Location: Saskatoon, SK Drives: '91 VR4 Trader Rating: (13)	Re: Lean Misfires at 2700-2800 rpm I'm interested to see if the different fuel controller will fix the problem. As far as my other issue, with the spark blow out on the rear bank, I'm going to try swapping my fuel lines tomorrow, so the front bank will receive fuel after the rear bank. I'm hoping this way I can rule out a lack of fuel being the reason for my very lean rear bank O2's @ WOT. Declan __________________ '91 VR4 - Modlist: DR650R Turbos, Snow Stage 2D Alky Kit, DSM SMICs, blowthrough ported LT1 MAS, Dejon Tool intakes & y-pipe, Blitz DSBC Spec R, HKS SSQV BOV, PTE 580cc injectors, Aeromotive FPR & Filter, Hotwired Supra Pump, ek2mfg fuel loop & spacer, HKS DLI, MSD Wires, Apex'i S-AFC II, MAFTranslator, Turbobob ECU, Scanmaster III, LC-1 WBO2, ESP Downpipe, Vac/EGR delete, Gutted Precats and Test pipe, Maximal Solid F/R motor mounts, 300m 18 spline output shaft, Centerforce Dual Friction Clutch, RPS Flywheel, Powerslot slotted rotors, Goodridge SS Brake lines, Hawk Pads (front), Stillen Metal Matrix Pads (rear)

10-11-2006, 11:05 PM	#33 (permalink)
AudioPmp23 Getrag Wrestler Join Date: Aug 2003 Location: Lakewood CO Drives: Pearl White 93 VR-4 Trader Rating: (3)	Re: Lean Misfires at 2700-2800 rpm Hey I know this prob wont fix that specific issue but I just found out that having the stock wastegate solenoid electrically connected can still cause a vac leak even with the cap on the lower nipple. I tested it out with a hand pump vac/gauge tonight. __________________ Hi my name's Nate and I've been addicted to boost for four years now...

10-12-2006, 10:07 PM	#36 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: one "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm DoctorDex I am 100% sure your MASS is toast!!! My LT1 was faulty also. seems it is a common fault for GM cars too! moral of story=GM parts suck! __________________ ++++++++++JUNE 2007 RIDE OF THE MONTH+++++++++++ Slideshow1..........Slideshow2..........My Photobucket..........My ImageStation.........MOD LIST Questions about the silver car?.....Rear message board info.....Turbo oil cap info.....nicest ass

10-12-2006, 11:30 PM	#37 (permalink)
DoctorDex Forum Member Join Date: Jul 2005 Location: Saskatoon, SK Drives: '91 VR4 Trader Rating: (13)	Re: Lean Misfires at 2700-2800 rpm Thanks for the heads up. How did you determine your LT1 was bad? What tests can I run on mine to determine if it is the cause? Declan

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10-13-2006, 12:02 AM	#38 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: one "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm the guys at 3SX told me that it was a known fact that there can be problems with GM mass's and it is always around 3000rpm.

10-13-2006, 03:03 PM	#39 (permalink)
DoctorDex Forum Member Join Date: Jul 2005 Location: Saskatoon, SK Drives: '91 VR4 Trader Rating: (13)	Re: Lean Misfires at 2700-2800 rpm I believe you, but it kind've strange because its not like the the GM MAS knows what the RPM is. Even if I add enough fuel to get it ~ stoich, I still get misfires. I've also noticed that it'll misfire (backfire) during decel when it hits 2700 rpm.

10-13-2006, 03:30 PM	#40 (permalink)
keithmac Forum Member Join Date: Sep 2006 Location: YORK / UK Trader Rating: (1)	Re: Lean Misfires at 2700-2800 rpm Could it be resonance in the inlet manifold causing the MAS to miss-read (seems one of the only factors that`s rpm dependant?) but after saying that if you`ve increased the fueling to compensate it shouldn`t be an issue. __________________ JDM GTO TT, Emanage Blue - 450`s Hotwired Walbro - Gutted MAS - K&N Blitz SSBC - Aquamist Water Injection