[FORZDA 1]

Well, codemaster883 came over on Sat for a look-see on his random missfire problem after the timing chain replacement. He had already replaced the plugs AND the coils, so they're assumed good. Car is all stock, except Injen CAI, TS BPV, and AP w/OTS tune. No CEL upon arrival, so no freeze-frame data to look at, but saw timing at idle was jumping around from +8 to +11 deg when it should have been +10 steady.... Went to inspect the likely culprits and:

1) Pulled the fender liners and found the crank sensor and wiring all looked good.

2) Disassembled, inspected and cleaned the Turbosmart BPV. It was a bit sticky, but didn't find any leak paths, so all looked good.

3) Found the MAF sensor was a mess with some kind of sealant goop that attacked and destroyed the O-ring(!), the screw tabs were bent and the seal lip cracked so the MAF wasn't seating fully into the Injen CAI hole. Looked like a total loss at first, but was able to clean it up and install it with a new O-ring so all good! (Possible Missfire Cause!)

4) Found the TMIC inlet hose (hot pipe) a bit loose and pulled away from the seat by ~1/4", so installed it fully and tightened up the clamp.(Possible Missfire Cause!)

5) Found the TMIC cold pipe flange bolt (1 of only 3) missing and oily goop leaking out! Installed a bolt and tightened it down.(Possible Missfire Cause!)

Ok, time for a test drive, so codemaster took it out while I picked up tools, etc. Came back with a hesitation/missfire/noise in 3rd at WOT. Hmmm, ok let me drive....

Took it out to my local test track (a safe, straight country road) and made two 2nd - 4th gear WOT runs and got the hard missfire(?) both runs. Not fuel-cut type events, but certainly something wrong with ignition. Codemaster sees a KR of 5.8 on the AP. "Normal" driving has no obvious problems. He has no boost gauge or DH for multiple PID watching, so pulled over to set up AP for data log. While I'm checking the data log set (new version AP with no dongle and it is a bit flakey, so had to disconnect/reconnect and while I'm dicking with that, codemaster notices a noise up front.... Oh crap!

Yep, the dreaded deep-sound of rod (IMO) knock and I also could feel the clutch pedal pulsing with light foot application....

No more time to continue any checks as codemaster must head home to prep for an appointment with a (current)significant other. NO hard running allowed! Hope it doesn't pop on the way home! Oh well, he's taking it to the dealer today for further diagnosis, but it doesn't sound good. I'm sure he'll chime in soon with an update.....

 

[smoker6]

:O Oh no. Another one, and so close to home.

 

[IHeartGroceries]

Life sucks. I can't wait for my big day.

 

[Road Rage]

sorry dude, i hope its not as bad as it sounds

 

[sp33dy6]

LTFT? STFT? A/F at idle?

 

[smoker6]

Life sucks. I can't wait for my big day.

I almost groaned you for your pessimism.

 

[FORZDA 1]

LTFT? STFT? A/F at idle?

Good question, but I didn't see them myself. Codemaster said they were all good, so I went about looking for the timing problem that the recent CELs indicated. REALLY needed that AP data log, but was SOL...

Let me take this opportunity to STRONGLY recommend a DH for Speed3/6 drivers AND a separate boost gauge. Preferably analog, but digital is better than nothing.....!

 

[sp33dy6]

hmmm this is very interesting.. im deff gonna stay on top of this one.

 

[codemaster883]

Ok LTFT - was -2+4 and short WOT was about the same. and 14.9ish at idle. seemed ight to me. when people say+-8. on long(cobb said). but iv been talkin to alot of people who race and it could be lifter noice,off timing bc i did just get the chain replaced. and could b bearing or somthin . dono ima have to wait til friday to get it in there bc of work exc..

 

[MPSdriver]

A dashhawk should have been installed on the speeds from the factory... was my first mod and I can't leave home without it

What are your hopes from the dealer, this doesn't sound good? Sure hope they can help. How many miles you got?

Btw props for you Forzda 1 for helping another member out like that, I wish somebody with a speed6 and your XP's lived anywere close to me.

 

[FORZDA 1]

hmmm this is very interesting.. im deff gonna stay on top of this one.

Yeah, he was obviously pretty bummed out (and me too because I was driving!), especially considering he had just forked over some serious $$$ to have the timing chain/tensioner replaced, plus the plugs and coils. This car is a 2006 w/~55k miles. He has been in contact with Cobb about the OTS map and KR issues.

The car sure had several issues that were quite easy to find, but I don't think we found the root cause of the Random Missfire. It still has a problem OTHER than the knocking.... I'm wondering if the camshaft VVT actuator was working properly...? I posted in another thread the way the ECU determines Random Missfire and there is a whole list of possible causes, yet most would have additional problems as well.

I hope he will chime in here soon.

 

[sp33dy6]

The reason i ask is my Ltft are 20 and my A/f is on point from 14.6-14.8, boost leak was done engine bay was examined by about 4 mechanics and nothing.. and when at idle my rpm seem to bounce from 700-8xx..

This car is really something, i have an 06 with 48k on it. BT and all.

 

[codemaster883]

ya def need to up on ur Ltft bc they should b +-8 and u gota tune? and mine was bouncin until i replaced coils. then like everyother day if get a missfire cel . but i mean it ran totally fine .

 

[FORZDA 1]

ya def need to up on ur Ltft bc they should b +-8 and u gota tune? and mine was bouncin until i replaced coils. then like everyother day if get a missfire cel . but i mean it ran totally fine .

There you are! Hey, did you take the car to Hall today?

 

[codemaster883]

na not yet. friday or sat might just get it took in on a flat bed lol. so i dont risk it blowin up if it is a bent rod or somthin of that bad. and its free so dont waste gas lol

 

[FORZDA 1]

na not yet. friday or sat might just get it took in on a flat bed lol. so i dont risk it blowin up if it is a bent rod or somthin of that bad. and its free so dont waste gas lol

Good idea!

 

[sp33dy6]

sorry to thread-jack, but what you guys think is wrong with my car? lol. something? or nuthing?

 

[FORZDA 1]

sorry to thread-jack, but what you guys think is wrong with my car? lol. something? or nuthing?

Sure sounds like a vacuum leak post MAF or a flakey MAF sensor..... What are your mods?

 

[FORZDA 1]

Ok LTFT - was -2+4 and short WOT was about the same. and 14.9ish at idle. seemed ight to me. when people say+-8. on long(cobb said). but iv been talkin to alot of people who race and it could be lifter noice,off timing bc i did just get the chain replaced. and could b bearing or somthin . dono ima have to wait til friday to get it in there bc of work exc..

It is definitely possible that timing chain/tensioner issues may be causing the base timing to jump around as the root cause of the Random Missfire CEL, AND it could be the reason the rod(s) bent(!) as well. If the timing wandered off and went advanced during the WOT it could result in severe detonation at high rpms which could indeed result in the hard miss we felt and could take out a rod(s) in a single event. In the DISI the rods are forged and will bend first rather than snap like a pretzel.

Actually it might be best if it is timing related as Hall could be held liable for the resulting damage after their work on the car. Bad news for the tech if true, but it may help you pay $$$ for the current repairs...?

 

[codemaster883]

if it was timing related. how could i tell them they have to fix it?