Lean Misfires at 2700-2800 rpm - Page 11 - 3000GT/Stealth International Message Center

badass3000 · 12-04-2006, 08:33 AM

well I got my ECU back from Avpro (again) but I cant tell if its good yet because I have discovered that I have a failed coil pack, well actualy half a coil pack. I droped a cyliner because the coil wont send a spark to only one plug, thought that was impossible but aparently not. I use Accel coils if it makes a difference. So mabey just mabey the studdering was linked to a failing coil pack?

DoctorDex · 12-04-2006, 06:33 PM

Are you 100% sure its the coil pack? Was the problem solved by changing your coil pack?

Could our troubles be caused by a weak PTU?

badass3000 · 12-04-2006, 07:23 PM

the coil had good input (the +12vdc and trigger) b/c one side would fire a handheld sparkplug. But the coil would not spark with any combo of plug/plugwire on the other post.
so 99% sure.

DoctorDex · 12-18-2006, 03:06 PM

Quote:

Originally Posted by keithmac

When I did mine I noticed a track that runs directly under C04, looks like this is the first possible potential board failure from acid damage, worth checking the continuity of that track. My caps didn`t look that bad, a little leak out of C04 but it was enough to make the car hideous to drive at part thottle.

Are you sure it wasn't C104 you're referring to? On my board, C4 doesn't look like a capasitor. I'm not sure what it is exactly, but it some kind of little square thing.

Edit: On second look over, I don't believe there is a C4 on my board.

Edit 2: I take that back, there is a tiny little cap named C4. Its right beside D102.

badass3000 · 12-18-2006, 03:44 PM

C means it IS a cap

DoctorDex · 12-18-2006, 05:19 PM

Edited:

I finally got a chance to pull my ECU today and I checked the continuity of as many circuits as I had patience for. I have a 1st Gen ECU with a part number of MD159966. There is another number on the case and I'm not sure if its used for anything, but its E2T35678

I measured the polarity in two directions. Here's what I found:

DMM Diode Test (
_____|_+_to_-_|_-_to_+__ |
D102 | 490 | infinite |*
D103 | 453 | 685 |*
D104 | 531 | - |
D106 | 532 | - |
D107 | 557 | - |
D108 | 567 | - |
D111 | 553 | - |
_________________________
D105 | 438 | - |

Capacitors (@ 2000K Ohms Setting on DMM)
_____________________
C102 (22 uF) = 022 <-- @ 2000k Ohms
C104 (100 uF) = 0 (but @ 2000 Ohms = 266). **
C105 (47 uF) = 0.03 --> 0.02

* Resistance and bidirectional current flow differed between D102 & D103 versus D104, D106, D107, D108, D111 despite appearing to be the same component. I'm curious as to whether or not this is significant. Does anybody have an explanations? The only explanation I can come up with is that its not actually measuring the resistance across the diode, instead its taking a long route through the boards other circuits and it measuring the resitance in parallel to another diode or resistor.

As an experiment, I'm going to change out my caps tomorrow because I'm especially worried by C104 & C105. I think I might also switch out D102, D103.

Thanks.

Declan

DoctorDex · 12-18-2006, 08:52 PM

Quote:

Originally Posted by badass3000

C means it IS a cap

Thanks for pointing that out. So, does "D" mean its a diode?

If that's the case and since Diodes are only supposd to allow current to go in one direction, then maybe I have something wrong with D102 or D103? Either that or I'm measuring the resistance through the long route.

keithmac · 12-19-2006, 03:09 PM

Yeh, sorry it was a typo, I meant C104.

Quote:

Originally Posted by DoctorDex

Are you sure it wasn't C104 you're referring to? On my board, C4 doesn't look like a capasitor. I'm not sure what it is exactly, but it some kind of little square thing.

Edit: On second look over, I don't believe there is a C4 on my board.

badass3000 · 12-20-2006, 09:49 AM

i think diode is CR, ad D might be a potentiometer

badass3000 · 12-20-2006, 09:51 AM

Eiather way, unless you know what you are doing you could destroy IC chips, exspecialy if your using an active (digital) multimeter. reason being is that diodes need eiather 0.5vdc or 0.7 vdc to work and the digital meters produce that voltage and you could be putting it in the wrong spot... so stop

12-04-2006, 08:33 AM	#101 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: 18 Y.O. "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm well I got my ECU back from Avpro (again) but I cant tell if its good yet because I have discovered that I have a failed coil pack, well actualy half a coil pack. I droped a cyliner because the coil wont send a spark to only one plug, thought that was impossible but aparently not. I use Accel coils if it makes a difference. So mabey just mabey the studdering was linked to a failing coil pack?

12-04-2006, 06:33 PM	#102 (permalink)
DoctorDex Forum Member Join Date: Jul 2005 Location: Edmonton, AB Drives: '91 VR4 Trader Rating: (13)	Re: Lean Misfires at 2700-2800 rpm Are you 100% sure its the coil pack? Was the problem solved by changing your coil pack? Could our troubles be caused by a weak PTU? __________________ '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, Dual feed fuel system with Aeromotive FPR & filter, Hotwired Supra pump, ek2mfg plenum 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 mounts, 300m 18 spline output shaft, Centerforce Dual Friction clutch, RPS flywheel, GC coilover conversions with helper springs, Powerslot slotted rotors, Goodridge SS brake lines, Hawk pads (front), Stillen metal matrix pads (rear)

12-04-2006, 07:23 PM	#103 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: 18 Y.O. "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm the coil had good input (the +12vdc and trigger) b/c one side would fire a handheld sparkplug. But the coil would not spark with any combo of plug/plugwire on the other post. so 99% sure.

12-18-2006, 03:44 PM	#105 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: 18 Y.O. "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm C means it IS a cap __________________ ++++++++++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

12-18-2006, 05:19 PM	#106 (permalink)
DoctorDex Forum Member Join Date: Jul 2005 Location: Edmonton, AB Drives: '91 VR4 Trader Rating: (13)	Re: Lean Misfires at 2700-2800 rpm Edited: I finally got a chance to pull my ECU today and I checked the continuity of as many circuits as I had patience for. I have a 1st Gen ECU with a part number of MD159966. There is another number on the case and I'm not sure if its used for anything, but its E2T35678 I measured the polarity in two directions. Here's what I found: DMM Diode Test ( _____\|_+_to_-_\|_-_to_+__ \| D102 \| 490 \| infinite \|* D103 \| 453 \| 685 \|* D104 \| 531 \| - \| D106 \| 532 \| - \| D107 \| 557 \| - \| D108 \| 567 \| - \| D111 \| 553 \| - \| _________________________ D105 \| 438 \| - \| Capacitors (@ 2000K Ohms Setting on DMM) _____________________ C102 (22 uF) = 022 <-- @ 2000k Ohms C104 (100 uF) = 0 (but @ 2000 Ohms = 266). ** C105 (47 uF) = 0.03 --> 0.02 * Resistance and bidirectional current flow differed between D102 & D103 versus D104, D106, D107, D108, D111 despite appearing to be the same component. I'm curious as to whether or not this is significant. Does anybody have an explanations? The only explanation I can come up with is that its not actually measuring the resistance across the diode, instead its taking a long route through the boards other circuits and it measuring the resitance in parallel to another diode or resistor. As an experiment, I'm going to change out my caps tomorrow because I'm especially worried by C104 & C105. I think I might also switch out D102, D103. Thanks. Declan Last edited by DoctorDex : 12-19-2006 at 12:28 AM.

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12-20-2006, 09:49 AM	#109 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: 18 Y.O. "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm i think diode is CR, ad D might be a potentiometer

12-20-2006, 09:51 AM	#110 (permalink)
badass3000 Wanted: Traction Problems Join Date: Nov 2002 Location: Jacksonville, Fl Drives: 18 Y.O. "badass" VR4 Trader Rating: (18)	Re: Lean Misfires at 2700-2800 rpm Eiather way, unless you know what you are doing you could destroy IC chips, exspecialy if your using an active (digital) multimeter. reason being is that diodes need eiather 0.5vdc or 0.7 vdc to work and the digital meters produce that voltage and you could be putting it in the wrong spot... so stop