# Misfiring issues suddenly? 16v/itb's/ms1



## mk2dubbin (Mar 16, 2002)

3 weeks ago i took the trans out of my car for a rebuild - the car was running fine. flash forward to friday when i put the trans in along with a new 14# eurospec lightweight flywheel and i fire the car up for the first time and its misfiring and backfiring. i changed NOTHING on the engine except some o-rings for the side water neck.
i will run down everything i have checked during diagnosis thus far:
i have determined based on the plugs and the backfiring out of the itb's that the issue is on cyls 2/3 only. cyls 1/4 are firing normal. (cyls 2/3 plugs are wet and 1/4 are black but dry - normal for warmup...)
i have changed to a cleaned set of used plugs, new cap, new rotor, and even tried a spare distributor with no change. ive swapped the cleaned plugs to other cyls and the misfire stays on cyls 2/3.
i have rotated plug wires to other cyls thinking the misfire would jump cyls if the wires were bad - no change. misfire stays on cyls 2/3.
i have swapped the injectors to other cyls thinking the misfire would jump cyls if the injectors were stuck wide open - no change. misfire stays on cyls 2/3.
i swapped the injector connectors on 3/4 thinking the misfire would jump cyls if the ecu/wiring was bad - no change. misfire stays on cyls 2/3.
motherboard on ms1 v2.2 ecu is clean and dry with no signs of anything fried out. i have continuity on the injector harness to ground as well as to the ecu connector.
compression is pretty even across the board with #4 being lowest.
i had balanced the throttles recently with no issue, but the only thing really left is air. i.e. - 2/3 are not getting enough air at idle indicating the the throttle need adjusted. however - the misfire should go away while revving if that were the issue...
i am really stumped at this point havuing ruled pretty much everything out by process of elimination, so anything you guys can come up with would be great at this point. ive worked on it all weekend with no success and i know my car thru and thru having done all of the work myself.


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## 86Franklin (Apr 5, 2008)

*Re: Misfiring issues suddenly? 16v/itb's/ms1 (mk2dubbin)*

have you checked the cap?


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## mk2dubbin (Mar 16, 2002)

*Re: Misfiring issues suddenly? 16v/itb's/ms1 (86Franklin)*

i put a new cap and rotor on it and it didnt change anything.


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## 86Franklin (Apr 5, 2008)

*Re: Misfiring issues suddenly? 16v/itb's/ms1 (mk2dubbin)*

sorry i must have missed that line. i have no idea though..


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## need_a_VR6 (May 19, 1999)

*FV-QR*

Grounds?


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (need_a_VR6)*

all of the grounds are good and tight. the only one i moved was the main one to the trans but it is on tight and is clean. all sensors are acting normally in megatune. 
noid light indicated tonight that the injectors are pulsing correctly on all four cylinders. i re-synched the mechanical timing to the ecu as well and no change. i also messed with the throttles and took them all back to zero so they all get the same air thru the plates (unbalanced) and no change. 
at this point i think i am almost going to have to pull the cams and see if i broke a spring or something even though there is no obvious noises indicating damage...


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## need_a_VR6 (May 19, 1999)

*FV-QR*

I'd do a compression test before you pull things too far apart.


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (need_a_VR6)*

already did. compression is fairly even though #4 was lowest but that cyl is firing fine.


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (mk2dubbin)*

i am beginning to wonder if the mallory ignition is to blame. it just doesnt make sense that i cannot make it change cylinders by moving wires, plugs, injectors, or injector wiring. 
perhaps the ignition isnt telling the coil to fire correctly?


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## need_a_VR6 (May 19, 1999)

*FV-QR*

Possible, can you wire in a 7pin module on the quick? Also you might want to double check the hall and make sure you get all 4 pulses in a rev.


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (need_a_VR6)*

i came to the conclusion that i need to rewire it without the ignition as well. its going to be a big pain but its really the only way to know i guess...


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## ValveCoverGasket (Mar 20, 2002)

*Re: FV-QR (mk2dubbin)*


_Quote, originally posted by *mk2dubbin* »_i came to the conclusion that i need to rewire it without the ignition as well. its going to be a big pain but its really the only way to know i guess...

maybe toss a scope on the hall output like paul said... before you go through and rewire everything


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (ValveCoverGasket)*

i dont have access to a scope unfortunately and its one of those things i really have no need for 99% of the time so i cant justify buying one. ill look in the bentley and see if theres another way to test it. the odds of two distributors doing the exact same thing would be pretty low though...


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## ValveCoverGasket (Mar 20, 2002)

*Re: FV-QR (mk2dubbin)*

ah, missed the part where you swapped the dist already... sorry








can you maybe post a datalog of the misfiring for us? maybe something jumps out after having a few sets of eyes on the logs


_Modified by ValveCoverGasket at 9:16 AM 4-7-2010_


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (ValveCoverGasket)*

yea i will try to do that tonight for you guys. i think i have a short one of maybe a mile of driving like that. i looked at it briefly and aside from the erratic a/f from misfiring i think it seemed relatively normal on quick glance.


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## need_a_VR6 (May 19, 1999)

*FV-QR*

You can check the hall output with an LED I think the test is in the bentley.
If rpm looks good on the input side, I'd be thinking the ignition box.


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (need_a_VR6)*

bypassed the ignition tonight and wired in the bosch icm and stock coil. seemed a tad better at idle and revving, so i took it out for a spin and datalogged for you guys. needless to say it ws still misfiring and i got a few hundred yards from my house and it shut off. coasted into my driveway and saw that the connector came off the hall sender.
plugged the hall sender back in and cranked it over and i have no tach signal in megatune. put the ignition back in and i have the same problem - no tach signal. no tach signal on the cluster either. i tested the voltage at the hall and have no voltage on pin 3 and 3.86 on pin 2. pin 1 is ground.
it was 9:00 then and i try not to piss the neighbors off with my loud car after 9 unless i really need to so that was it for tonight. i am attaching the datalog and wiring diagrams for you guys to reference. its been over 3 years since i installed it and i have honestly forgotten a lot of the intricacies of how it all works...








http://www.ryanrupp.com/album/...4.xls 
wiring diagram for non-ignition setup:








wiring diagram for ignition setup:


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## ps2375 (Aug 13, 2003)

*Re: FV-QR (mk2dubbin)*

At this point I'd put the other dizzy back in. Almost sounds like the hall sender right now. Or the voltage from the MS to pin2 is low, I'd have to look at my MS stuff. I thought that was fed with 5vdc or is it 12vdc? I suppose if I looked at your diagram a little better, I'd see the "5V" on pin3.
With the hall sender connector disconnected, do you have 5V? If not, go to the MS unit and check that part of the board.




_Modified by ps2375 at 11:09 PM 4-7-2010_


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## need_a_VR6 (May 19, 1999)

*FV-QR*

You can feed it with 5v or 12v, your board mods just have to match. 
The 3.whatever volts on the center pin of the hall is just coming through the pullup.
Make sure you're getting 5v on pin 24 (tps vref) it looks like you might have lost either connection or 5v power totally.


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## ValveCoverGasket (Mar 20, 2002)

*Re: FV-QR (need_a_VR6)*

id suspect your 5v supply, and do like paul said for pinning out the tps - do you have the tps power spliced into the hall 5v line? thats usually how i wire them up...


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## mk2dubbin (Mar 16, 2002)

*Re: FV-QR (ValveCoverGasket)*

right now it is wired just like it shows with two separate power wires. unless youre talking about on the board, at which point i have no idea. this is an early patatron ecu (pre fall-out). i guess if i killed the output to the hall i could just tap into the tps 5v then correct?


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## ValveCoverGasket (Mar 20, 2002)

*Re: FV-QR (mk2dubbin)*


_Quote, originally posted by *mk2dubbin* »_ i guess if i killed the output to the hall i could just tap into the tps 5v then correct?

yeah assuming the board is set up for 5v, which it sounds like it was


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## need_a_VR6 (May 19, 1999)

*FV-QR*

If it's a Pat board you have 5v coming out of pin 24 as well as pin 26. See if you get the same (5v) at both those spots.


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## mk2dubbin (Mar 16, 2002)

i have finally finished rewiring the car and doing a wire tuck etc while i was at it. i found that the 5V signal wire to the hall sensor was broken and that is what cause the car to stop running. however, the car is still misfiring and i am slowly retesting things to no avail. timing light confirms consistent spark on all plug wires with new plugs and rebalanced throttles. 

i am getting sensor reading noise to the ecu now. the tps, clt, and iat sensor signals are jumpy. the tps and iat are on one ground wire and the clt sensor is on another - with both wires grounded inside the cabin on the ground block by the fuse block. another issue i am having is that as soon as the fans kick on, the car dies immediately and it makes little to no difference what battery correction i use. this is potentially an issue due to the poor running so i am not particularly concerned about that at the moment.


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## need_a_VR6 (May 19, 1999)

What does the battery voltage graph look like in the logs both with and without the alt exciter wire plugged in.


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## mk2dubbin (Mar 16, 2002)

i currently don't have the exciter wire hooked up now that i think about it... would it matter for anything other than the idiot light in the mk2 cluster?


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## need_a_VR6 (May 19, 1999)

The battery won't charge at all without it.


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## mk2dubbin (Mar 16, 2002)

i didnt even think about the wire when i re-wired the motor. i will add that to my to-do list. i was too focused on my other issues at the time i guess. thanks for the reminder! 

when i put the trans back in with the lwfw, i lined up the timing marks and put a line on the fw. (eurospec lwfw didnt have a timing mark on it.) pulled the trans last night and checked timing mark on flywheel vs. stock flywheel. looks like i sheared the crank key again. the mark i put on the flywheel thru the bellhousing is roughly 15-20 degrees advanced from TDC on the stock flywheel. i am assuming this is my issue. 

i will pin the crank gear when i put this one on and will hopefully never have another issue with it. i had it happen about 3 years ago on this motor as well and just put a new gear and bolt on it.


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## ValveCoverGasket (Mar 20, 2002)

mk2dubbin said:


> i currently don't have the exciter wire hooked up now that i think about it... would it matter for anything other than the idiot light in the mk2 cluster?


 
what was the ms saying your battery voltage was at?...


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## mk2dubbin (Mar 16, 2002)

i have no idea honestly. i dont have a gauge set for that and i wasnt logging at the time. i have wired that in now so hopefully when i can run it long enough to kick the fans on - i will run a log then. the unstable sensor readings havent gone away yet and i have checked the grounds. since i am alpha-n, the unstable tps signal is messing with my fueling at idle on top of the backfiring issue i have been fighting. 

i have verified all timing now, put on a new timing belt, checked cam timing and re-synched the timing to the ecu. still cyls 2/3 only and i have ruled out everything now and it is still doing it. half tempted to pull the head and take it apart but there shouldnt be anything wrong in there that wouldnt have manifested itself by now thru all my testing and diagnoses....


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## ps2375 (Aug 13, 2003)

Are your sensors grounded where the MS is? Is it near the ground for the O2 heater ground or the wide-band ground? If the wide-band ground is too near the MS ground, I have read that can create noise, the mounting instructions for mine state to have the heater ground away from other "sensitive" grounds. The noise you are seeing really sounds like it could be a grounding issue.


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## mk2dubbin (Mar 16, 2002)

as soon as i read your post i remembered that from the initial wideband install a few years ago. i moved the heater ground to the fuseblock and it is much improved but i think i will have to go even further for it to completely go away.

i got the engine up to temp with batt voltage at 13.8, fans kicked on and the batt voltage dropped to 12 and stalled the motor out. did it two or three times as i was testing it.

engine is still misfiring on cyls 2/3. i am going to pull the head and disassemble it to see if it is a mechanical failure like springs or something even though it is highly unlikely i would drop springs on two cyls at the same time... i just dont know what to do with it anymore because i cannot explain the problem. 

thanks guys for your help and input thus far, i really appreciate it!


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## ps2375 (Aug 13, 2003)

W/o going back and reading, have you done a compression test? And are you using batch fire, if so are 2 & 3 on the same channel? Have you swapped the channels to see if it is MS related?

Never mind, I just reread the first page of thread.....


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