Do to limited space in the engine bay, time, and the fact that he is using this as a daily driver. I didn't want to get to far into it.

I offered up any available spare parts and tools for testing. I wanted to scope the Ignition system and look at the sensors but we ran out of time. I will admit that turbo systems are not my strong point but I did speak with other members regarding this type of set up and though it is possible that there may be wiring issues there are other mechanical things that could also be affecting this.

Visually we did not see anything that was bent, broken or other wise out of place. That doesn't mean that the valve springs are not week or that there is not other issues like a stretched timing chain...

According to Henry, a Cylinder contribution test was inconclusive as well. You could preform the test and it would appear like 2 cylinders had issues. Perform the same test again and almost every other cylinder would have issues.

We tried swapping coil packs an ECU's using different tuning software with no luck. They also put in new plugs as well as some point.

 

I'm wondering if the springs or lifters are going soft.

 

Entirely possible... I would like to yank at least 1 valve spring out and check it my self. Especially since its when you go into boost.

 

From my understanding the problem comes and goes it seems as thou it is more temperature related than boost related.

 

Sounds like the symptoms that Holty's truck displayed only to find out his valve springs were getting weak ( 918's ) Once warm it would miss fire bad as soon as you put it under a load, fully heat soaked it would miss even at idle.

 

Same springs, same basic problem...

Like I said I would like to get one out and check it.

 

how many miles do your current springs have on them?

 

First off there needs to be a compression test done with all the plugs out, tb set @ wot and injectors disconected. If that pans out shift points need to be lowered to 5200 or so and slowly raised up to a max of 6k. That engine has pac springs in it and a mild cam profile should not be a problem unless maybe the engine got over reved during the mile when trans wouldn't shift. A hard enough valve float could indeede kill the springs the short shift will tell the tail.

As many misshaps that have happend to this thing with running lean under boost, meth probs etc while running 91 oct I would be surprised if pistons are still in good shape.

 

After talking with Jarrett some today, I ordered some new springs and they should be getting shipped to me in the next few days and will have them swapped out as soon as they arrive. I think Jarrett and Joseph are right and I'm pretty sure I over-revved the engine at the mile. The symptoms sound very much like what Holty had so I'm crossing my fingers that this is the issue. As far as running lean, if there's any saving grace in that regard, the truck was run on 50/50 mix of 91 octane and 110 race gas at the mile and at the Throwdown. Meth worked in two of the mile passes when I was holding down the 'test' button so it didn't run lean on the passes that I did run it hard.

Henry played with the tune while we were on the freeway and found some interesting combinations where the motor would run better. If he overrode the PCM and commanded 11.0 AFR and 30 degrees of timing the engine would run alot better. It still had very little power comparatively but at least the misfires would stop and it cleaned up the idle too. Same thing at 12.0 and 30 degrees. However when he would drop the timing to 25 degrees it all turned to crap again regardless of the command AFR. Also when left up to the PCM, when cruising or idling the timing would go from 25 to -5 every rotation on all cylinders all trying to compensate for each other and trim the AFR's. It got so confused it couldn't keep up with itself and I'd have to lightly stab the throttle to get it to chill out.
Regardless, the more I talk to others about it the more convinced it's weak springs, could be a few of them or it could be all of them but there are definitely more than one. I'll ask Richard at WCCH to test them when I get them out.

 

Jarrett, I did a quick delivery for Richard and dropped some heads off at Dutweillers and he thought we might of mushroomed a valve. He let me use his stuff and Henry and I did a quick compression test on two of the cylinders we thought were bad and found them to be @ 170. We also scoped half the cylinders and found nothing to indicate any broken ring lands. I think the motor is relatively healthy with the exception of the springs.
Keep ya posted.


PS Jarrett I'm posting some video's of you in action pretty soon!!