The problem is that we won't be able to load the engine on the lift.
I just hope it is something we can actually see, some physical fault.

 

Yeah, I forgot to mention in my first post, I DID watch the A/F (with my Brockway) when I was out driving and it's good, 11.4-11.8 right where it was tuned with the Meth. I does sort of sound like the popping we get at cold idle. Maybe just a little too rich at that rpm and fuel is burning in the exhaust, even though A/F says differently? It seems to drive right through it and keep pulling? Would O2 sensors cause this? Only correcting (or not correcting) between 4-5k? Thanks guys keep' em coming...

 

You could log it and check to see what the 02 sensors are reading at when it seems to be happening.

If it sounds like popcorn I would say it is probably not detonation and you would think if it was you would get the opposite effect of it happening with the meth off and not happening with the meth on.

Strange for sure. You dont think it could just be an exhaust leak do you?

Mitch

 

I may try to log it/dyno it next week. Unfortunately my tuner is my logger and both of our schedules conflict right now. I have had a few people (with better hearing than I) tell me they don't think it is pinging (detonation). It is actually my intention to get the exhaust off tomorrow and look for cracks and stuff and shake the exhaust and see if something came loose? I'm wondering if (because of the cooler weather) I am experiencing a quick rich condition only at that peak TQ for 1000rpms, but not enough to do anything except **** me off? Would a bad O2 (or O2's) cause something as silly as this? Maybe they are correcting until 4k, stop then continue to correct at 5k?

 

Check if your heads are not lifting.. worse case scenario... look for some dry coolant around the gaskets...
hope it worlk out.
mark

 

You won't have to worry about it being too cold in Texas.

 

Come on now Todd. You have to admit it fells good today at that 85* weather!

 

Thanks Mark. Check it tomorrow when we get it up in the air...

 

LUCKY Bastards!!! its half that here today and raining!

 

We should have some free time Tuesday afternoon if you want to get it on the dyno in a control environment.


Can you explain the coloration between "popping" and lifted heads. I think you lost me on this one. Ive never seen blown head gaskets or lifted heads cause popping.

 

I second that, it just stopped raining here and the sun came out for about an hour, the first time in 4 days...

 

Maybe Colorinc can describe what his sounded like when his heads were lifting. Also, what gas/octane are you using? Some stations start switching over to their "winter blend" which can lead to some detonation.

 

Mike, if that popping sound is coming in at WOT it could be that you are leaning out on the top end and the O2's are lying to you. I just changed mine out, because I am trying to tune and they were giving me problems. Mine is minor but the wide bands are so important that it is worth getting new ones.

 

Dennis, did you have this exact problem or something similar? I am tending to agree a little more with the O2 theory, as I have replaced everything else!!! From what I have seen and heard, it only happens at WOT in 3rd or 4th gear at full boost. My car is tuned for 93 pump gas and meth. In the warmer weather I was seeing 1.2-1.3 on the gauge and sometimes 1.4 when cooler. The other night I saw 1.5 briefly (it was 55deg out) with the noise and immediately came home and took 1-1/2 turns out of the wastegate. Went back out, saw a steady 1.4 (which I am tuned for with the meth) and still heard the noise, came home took ANOTHER turn out (2-1/2 turns total now), which is netting me a steady 1.3 on the factory gauge, still with the noise. I find it impossible that it is detonation with ONLY 1.3 on pump WITH 100% meth injection. (I trust my tuner 100% and know he wouldn't send me out into the world with this potential problem, knowing how I drive.) The meth system is working, as none of the fail safes have told me otherwise, in fact turning the system off gets me 100% wastegate, 100% off the time, kind of like "Valet". I did this to test the high and low boost. What's confusing is I am confident that it is NOT tuning, yet it does it at 1.3 and higher and not at .8, and it's not pinging?

Thanks Tony. Lets see what Brian and I find tomorrow. Car is at his house on the lift now. We're gonna spend a rainy day scoping it out. I figure my last race is gonna be a washout anyway, if not...oh well...


PS... I also grabbed a pair of DV's today from my trusty parts guy and that will also be one test for tomorrow...I know they are supposed to honk when bad, but it would be MY luck that mine POP!!!!

 

Tony , i have heard first hand popping when heads lift.... like a poping flutter sound..