Not your average misfire...Help!

I am having a nightmare of a time trying to troubleshoot a rather unusual issue before getting tuned. Most of the back story can be found here:

 

http://legacygt.com/forums/showthread.php/curtiss-05-lgt-build-journal-223213.html?t=223213

 

But in a nut shell Ill give you more of the back story. After swapping in my newly refinished motor I got a base tune from lets say a very reputable tuner here in the CT area that tunes at two shops. It was set up to break in the motor before hitting the rollers. The car pretty much ran uneasy since day one but overall drove pretty decent. Had issues stabilizing idle but never threw any DTCs so I just assumed it was a tuning issue while running on the base tune. I go to hit the rollers and they send me home saying Im misfiring on cyl 3 and 4. I couldn't believe it. Sure enough my accessport was showing dead misfires on cyl 3 and 4. After talking with my tuner he insisted it was something mechanical and likely failed injectors.

 

Okay well heres the thing, I am a mechanic by trade so of course I took it home and did my usual diaging same as I would for customer cars.

 

Here is the weird part, I found that the misfires only happened while sitting still, foot on clutch, put it in gear. Then while driving up until 2k then they would stop.

 

At this point I checked the obvious stuff:

Swapped fuel injectors

Swapped coils

Swapped plugs

Checked plug gap

Swapped MAF with one from a Forester XT we have for sale

Checked compression 120 across the board which I think is acceptable for a new motor which at the time had 600 miles on it

Did a boost/vac leak test. Smoke tested the intake under pressure and found zero leaks.

 

Nothing moved or changed. After getting so fed up I emailed Brentuning and got a base map from him just for diag purposes. By the way I must say Bren has been very helpful during this whole nightmare and really wanted to work with me on this but hes now stumped as well.

 

Anyways I flashed his tune on and guess what, codes for misfires finally came up and also Crankshaft Performance A which I know from experience is almost always a timing issue. So go to check my timing marks and of course everything is perfect, except I found a broken tooth on the exciter ring of my crank gear. I thought eureka that's it! Swapped it out with one from my old motor and now oddly enough it gets weirder. The car now runs sooo much better obviously however the same misfires have now moved from cyl 3 and 4 to cyl 1 and 2 and illustrate the same symptoms! For some reason my original tune has many factors and DTCs turned off which is making diag a nightmare.

 

So here is where I am at I am all out of options. I know that this factor changed when I replaced the broken crank gear so of course I verified timing again, took the timing belt back off to verify tension in the belt and retimed the motor which did nothing.

 

So here is the short version:

 

Symptom: Misfires on cyl 1 and 2 ONLY when the car is at a complete stop, foot on clutch and put it in any gear. Logging my accesport it shows dead misfires which I barely feel on cyl 1 and 2 the second the car is put in gear. Take it out of gear, the count goes to zero, put it back in gear, count goes infinitely up. Take it out of gear it goes back to zero.

 

While driving it has no misfires at all. Non.

 

As soon as you through it in neutral it has no misfires. As I approach a stop it begins to misfire. If Im coasting and press on the breaks hard, it begins to misfire and then as soon as you touch gas it stops.

 

Things I have checked:

 

Swapped plugs

Swapped coils

Swapped fuel injectors several times

Smoke tested the intake system under pressure with no leaks

Checked grounds

Checked battery voltage

Checked oil pressure

Checked operation of AVCS, swapped solenoids and verified oil level

Compression test

Verified valve lash was set correctly

Checked mechanical timing three times

Swapped crank sensors

Unplugged neutral position switch

 

I plugged in our dealer scanner and looked at many data pids including MAF voltage, O2 sensor operation which may be my next target and various other things

 

Mods:

Brand new oem 257 shortblock

Heads completely refinished, decked, hot tanked, new guides and seals and valve lash set basically a complete valve job done by a reputable machine shop

BNR 18g turbo

DW 850 side feeds

DW fuel pump

AVO TMIC

Turboback

TGV Deletes

Up pipe

Grimspeed 3 port EBCS

Turbo Inlet

JDM 6 speed swap

 

Stock STI flywheel so no its not a lightend flywheel issue

Southbend clutch kit

Stock intake

Stock MAF

 

What other factor am I missing? What would cause a dead miss ONLY the second the car is put in gear clutch in? Driving wise it feels great! At idle in neutral it doesn't miss. As soon as it has a slight load from putting it in gear, it begins to miss.

 

What would mess up ignition timing at this stage? What should I log? This is embarrassing as a mechanic that I cant figure out a simple misfire on my own damn car when I work on Audis and Mercedes all day.

 

Also sorry for the long thread but there are a lot of factors here. Please, anyone with any insight or anyone who has had this problem let me know.

Did you do leak down or compression test ever?

Did you do leak down or compression test ever?

 

Compression but no leakdown yet.

sounds like its some sorta sensor very possibly an 02. i feel like it would knock while driving if it was something mechanical.

I mean it drives pretty much perfect without a hiccup. Just those idle misfires are keeping me from a tune.

Real stumper I know

this is far fetched but... thinking about any driveline changes when clutch is in vs out..

possible knock sensor/ loose something thinking its knocking? causing it to pull timing??

Im by no means a tuning guy, but Ive read a few times how loose things can cause it to show/cause knock..

 

you may want to search the forums- theres a few threads about misfires- you may want to PM one of the guys in those threads that "talk a lot of tuning" there is some pretty detailed long term diag getting done in other threads

Ill check for that in the forums. I was kinda thinking the same that its possibly driveline related since its only im gear at idle. Ran the same setup with my stock motor and had no issues but its always possible something got loose this time around.

So again after getting my "diagnostic" base tune from Bren I immediately had codes for crankshaft performance. From my experience that's almost always a timing issue or correlation issue with the crank and cams. Well it led me to one problem but caused another...

 

http://i8.photobucket.com/albums/a46/Killerguitars/20140916_1941302_zps23e5c937.jpg

 

Yep a broken tooth on the exciter ring of the crank gear. I drove around with this for two weeks. My previous tune didn't throw any DTCs or anything. This is why this is a nightmare to track down, the ecu is not picking up on problems!

 

So back to replacing it and checking the timing marks again and again and again, everything is dead nuts. Iv never had a problem timing a motor.

 

http://i8.photobucket.com/albums/a46/Killerguitars/20140916_2007102_zps8a1f4be5.jpg

 

This however did NOT solve the issue. Now the new problem is that the misfires moved from cyl 3 and 4 to cyl 1 and 2.

 

Same symptoms exactly. Everytime I put it in gear it does it. Now I trouble shot it further. Unplugged the front O2 sensor to see what happens. No misfire! But that did not condemn the O2 sensor. It does the same thing if I unplug the MAF or MAP or anything really that throws an active check engine light. As long as the light is on and the car is in sort of a "limp" mode it will not miss at all.

 

With everything plugged in it still misfires on cyl 1 and 2. I think the mixed crank signals threw off the misfire counter and it really wasn't misfiring on cyl 3 and 4 although it thought it was. In reality it was missing on 1 and 2 the whole time.

 

This leads me to believe despite it being sorta obvious, that it is something drivetrain related because seriously looked at and ruled out all the obvious stuff.

 

Usually you only see something like this when lightened flywheels are installed. I don't have that just a Southbend clutch kit and a machined stock STI flywheel. Same setup I ran before I swapped the motor and no misfires then.

 

On Brens tune if I let it sit in gear it will throw a flashing check engine light and throw DTCs for misfire 1 and 2. On my other tune it will not. There is no rough idle. There is no sign of a misfire. The only real evidence that it is misfiring is on the accesport and nothing more.

 

Something is causing the computer to recognize a misfire only when the car is put in gear something is causing mixed signals for ignition timing because nothing else mechanical is causing the problem.

I would go 02. I have an Autel that can map O2 stream . I am guessing the dealer tool can as well. See what it does. Maybe the knock as well? The Autel is pretty good at sniffing bad sensors. I imagine the dealer tool is better.

 

Still in person I'd be scratching my head a bit. Also any independent wideband on the car?

I would go 02. I have an Autel that can map O2 stream . I am guessing the dealer tool can as well. See what it does. Maybe the knock as well? The Autel is pretty good at sniffing bad sensors. I imagine the dealer tool is better.

 

Still in person I'd be scratching my head a bit. Also any independent wideband on the car?

 

We use an Autel as well! The Maxidas unit. I was able to graph the O2 data but its non conclusive. It showed its slightly lazy but nothing too crazy. I may end up replacing it just for that reason but even with a lazy O2 its odd that the misfires come on the second its in gear and go away when its pulled out.

 

The Autel shows the same evidence under the cylinder roughness monitor.

 

As far as knock when its misfiring it shows nothing for knock correction. AVCS is operating as it should within 2 degrees of each other so I see no fault in the notorious OCVs

 

I test the knock sensor with the old school stand by of putting a striker bar right on the engine block and tapping it with a hammer and saw the knock spikes and correction so its operating as it should. Forgot to mention the above.

Random thought. Maybe the clutch is not fully disengaged causing slight drag on flywheel. Far fetched as well but you ruled out so much already....

sorry if i missed this but did u replace the crank pos sensor?

Random thought. Maybe the clutch is not fully disengaged causing slight drag on flywheel. Far fetched as well but you ruled out so much already....

 

Hmm very interesting thought! I suppose thats very plausible.

 

sorry if i missed this but did u replace the crank pos sensor?

 

Yep. It was brand new factory but I threw my old one in for giggles and no change.

You said it was fine on the stock engine. Is this engine different then stock ?

 

LWFW and LWCP ?

 

Did you replace the black o-rings with the new larger orange ones ?

 

Has the Tuner gone for a street tune, realtime data logging ?

 

Try my Tuner, he's in Vernon CT just off exit 65 on rt84. www.tuningalliance.com he has a thread in the Vendor Forum here.

You said it was fine on the stock engine. Is this engine different then stock ?

 

LWFW and LWCP ?

 

Did you replace the black o-rings with the new larger orange ones ?

 

Has the Tuner gone for a street tune, realtime data logging ?

 

Try my Tuner, he's in Vernon CT just off exit 65 on rt84. www.tuningalliance.com he has a thread in the Vendor Forum here.

 

Stock STi flywheel resurfaced for the 6 speed and no brand new brandddd new harmonic ballancer.

 

Got on the dunno and he noticed the misfires on his laptop. I never noticed while driving which is what pisses me off. The tune throws no DTCs and the car runs beautiful.

 

Which O rings are you talking about? I bought a complete engine reseal kit from subaru.

Intake manifold to TGV's.

Intake manifold to TGV's.

 

 

Got yah.. OEM lower TGV to heades crush gaskets with the ruberized seal in them, new oem orange upper intake to TGV gaskets and new lower ruel rail injector seals, the five sided ones.

 

Besides I already smoke tested the intake under pressure with no leaks and it holds a good solid 20inHg or so at idle.

Havent had much time in the last few weeks to look but got around to some work tonight.

 

Went back and started over with the neutral safety switch. Now before anyone says anything yes I checked it before but that was when the crank gear had a broken tooth so it was misfiring no matter what and was leading down the path of misdiagnosis.

 

I bypased it at the harness and found that in fact when the switch is activated the misfire counter goes up. Just took two leads of wire at the harness and watched the misfire count go up. On both the access port and my dealer scanner I found that when I touched the two leads together the switch goes from on to off under the neutral position monitor and the 1 and 2 misfires go up the second I do this.

 

So pretty much yes everytime its put in gear it misfires for that reason.

On my way to work this morning I tried my cruise control and found its not working as well so yes the car is getting mixed signals.

 

What I want to know is, should the switch be on in neutral and off in gear? I would assume so because the ECU is seeing it go on and off.

 

Tried using the six speed switch which I know you dont use but nothing changed.

 

So is there more to thise sensor than I think? To me its a two wire sensor normally open. Iv heard of the reverse polarity sensors but why would that make a difference?

 

I feel like there must be some sort of rom update or something thats making it get mixed signals.

Can you pull the switch out of the tranny and test it ?

Do you have the service manual ?

Can you pull the switch out of the tranny and test it ?

Do you have the service manual ?

 

I can and I do. All it says is in neutral it should be less than one ohm and in any other position should be at least 1 mohm which to means infinate resistance aka open circuit. So to me its just an on off switch. Through my accessport it says on in neutral and off in gear so its working and sees the change.

 

When I bypassed it, I just probed the harness and touched the two wires together with test leads and it goes off when touched and on when open like it should. Doing this while watching the misfire monitors it would show misfires on the two cylenders when touched and stop as soon as I disconnect it. I made myself a misfire button.

If avcs is advancing the timing then wouldnt that mean the sensor is working as well?

Has anyone heard of any rom updates for cruise control or neutral safety switch problems? I think it may be possible that the rom is wrong or not loaded right because this only started after I flashed the car. I drove with this transmission in before I even swapped the motor for over two months.

Has anyone heard of any rom updates for cruise control or neutral safety switch problems? I think it may be possible that the rom is wrong or not loaded right because this only started after I flashed the car. I drove with this transmission in before I even swapped the motor for over two months.

 

Yes. Was your original firmware id one of the ones below? Then later, was the flashed one a different one?

A2WC510N

A2WC511N

A2WC522N <-- the "newest" version, probably what you want

Yes. Was your original firmware id one of the ones below? Then later, was the flashed one a different one?

A2WC510N

A2WC511N

A2WC522N <-- the "newest" version, probably what you want

 

Wow! Um Im not really sure how to check honestly. AP manager?