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Mysterious Engine Trouble...knocking and power loss.

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Old Aug 14, 2009 | 07:34 AM
  #61  
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Originally Posted by blk-majik
Did you try replacing the MAF yet? You said you found another local X who would let you borrow some parts to test... seems worth the hassle if you didn't try it yet. How is your EGT reading (err...nvm unless you installed an EGT sensor)? I was thinking LTFTs as well... might be worth double checking, especially if its outside +- 5%
Well, the AFRs are solid so we really didn't think there was any issue with the MAF. However, at this point I'm trying everything. I did find a couple of people locally willing to loan me a MAF sensor, so that's next when I get a chance to get back to the shop.
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Old Aug 14, 2009 | 08:37 AM
  #62  
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^^ try looking for someone to lend you the stock coils to...i mean it's worth a try...
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Old Aug 14, 2009 | 10:17 AM
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In no way did your cam timing get messed up right?
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Old Aug 14, 2009 | 10:52 AM
  #64  
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Originally Posted by spdracerut
In no way did your cam timing get messed up right?
Nope, haven't cracked open any part of the stock longblock.
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Old Aug 14, 2009 | 11:04 AM
  #65  
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Originally Posted by Noize
Its probably fueled that way for a margin of safety against the unexplainable knock.

His tuner is Bryan at GST (formerly Razorlab), who is easily one of the best ECUflash tuners in the Evo community. He knows exactly what he's doing, there is not an issue with the shop's equipment either, I'm sure of it.

It is simply an issue with this specific car that needs to be discovered and sorted out.
I agree that Bryan at GST has likely looked at all the angles from the tune itself, but I had to cover all the bases.

The theory of the car being in some sort of limp mode seems very plausible up until there is usually a SES light activated when that happens. It's quite amazing how much the ECU can restrict you though, when I triggered an airflow too low code the other day after making too many changes to my tables and I was flooring it and could barely get any boost. Mind you this is with a MBC so it managed to restrict boost through throttle reduction and/or timing retard. I'm almost curious enough to trigger it on purpose so I can see exactly how it's doing that so effectively.
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Old Aug 14, 2009 | 11:34 AM
  #66  
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^Is that the P1235 code, if so I triggered it on some of my runs down the 1/4 and my traps dropped from 116 -117 to about 113. So the reduction of timing is quite possible.
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Old Aug 14, 2009 | 01:39 PM
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Originally Posted by Hiboost
I agree that Bryan at GST has likely looked at all the angles from the tune itself, but I had to cover all the bases.

The theory of the car being in some sort of limp mode seems very plausible up until there is usually a SES light activated when that happens. It's quite amazing how much the ECU can restrict you though, when I triggered an airflow too low code the other day after making too many changes to my tables and I was flooring it and could barely get any boost. Mind you this is with a MBC so it managed to restrict boost through throttle reduction and/or timing retard. I'm almost curious enough to trigger it on purpose so I can see exactly how it's doing that so effectively.
Yes...Bryan cringes when he sees my car roll into the parking lot.

I agree about the SES light not coming on...but it may be one of those passive safeguards that doesn't necessarily throw a code...it just does what it's supposed to do...limit power.
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Old Aug 17, 2009 | 11:59 AM
  #68  
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Still no luck...hoping to pop into the shop this week to try the next battery of tests.
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Old Aug 19, 2009 | 11:09 AM
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So over the past couple of days I've gotten a couple of PMs from people who have found that they are having this knocking issue...interesting.

Trying out the race gas next week, no time to make it to GST this week.
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Old Aug 19, 2009 | 11:31 AM
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Did you swap the MAF yet?
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Old Aug 19, 2009 | 11:35 AM
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Originally Posted by BigT
Did you swap the MAF yet?
Doing that the same day as the race gas test...as well as the coils.
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Old Aug 27, 2009 | 11:02 AM
  #72  
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Just keeping the thread alive...100 octane this weekend.
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Old Aug 27, 2009 | 11:46 AM
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Mike I wish you the best of luck this weekend. If you need to swap out parts my car is finally running again so I can swing by GST as a parts donor if needed.
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Old Aug 27, 2009 | 01:00 PM
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Originally Posted by t12ung
Mike I wish you the best of luck this weekend. If you need to swap out parts my car is finally running again so I can swing by GST as a parts donor if needed.
Thanks man, I'll definitely let you know.

At this point, we're really just trying to isolate what the problem is. After 3 months we still don't know what to fix.
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Old Aug 27, 2009 | 01:45 PM
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Maybe just switch to E85 and add a meth injection setup to mask the stupid issue until it fails enough to finally expose what the real problem is.

Hopefully the 100 octane test will let you verify what it isn't and help you focus your efforts on what the possible reasons really are. You may want to try using the airflow and torque disable mods to just take those flow limit tables out of the picture all together.
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