Hi Nick.

First as others have said, start off with a colder plug and check to make sure it is the proper heat range. I doubt it's spark related but anything is possible.

I feel like I'm saying this alot lately but I generally see the problem you are having when the valvesprings are too weak. Raising the boost equals more backpressure which makes it increasingly difficult to have solid valve control on the exhaust side.

I may have missed it but what are you running for seat pressure? Fwiw I would personally run 185-200 on the seat, 425 over the nose, and good pushrods with your combination though some would tend to disagree with me.

BTW, nice #'s! There's definitely more in it once you get it straightened out.

 

got tricks from tooley, not sure on the spring
i hear ya on springs but why @ 7.5 psi???
i gotta set of coils and stock wires...ill pull the coil harness and lay the rack of coils on the gm valve covers and go for it.

what plugs do u recommend that wont give casual street drivin issues?

 

Usually when a motor fails to rev higher, 9 times out of 10 it's a bad cam/crank sensor, from what I've seen. I've had a couple friends with this issue and everytime it was the crank sensor.

But as others have said....

Check to make sure you aren't floating the valves, check cam and crank sensor, make sure you don't have a pinched wire possibly contacting a header, and/or try a colder plug.


Best of luck to you with that badass setup.

 

this set up is a little more complicated with the dam ETC!!!
u guys dont have to deal w/it ...its open a huge can of worms that could be causin issues....

guys at hp tuners have been sending me some betas so...........


to hell with 1514 dtc...not gettin it but never the less!

 

Damn nice setup i like that, good numbers to

 

as i turn up the boost the car cuts out at a lower rpm...ect....
7.5psi = 6100
12psi = 5800
19psi = 5500
21psi =5250

That's very telling. You could change the cam/crank sensor since it's so easy to do, but I'd be surprised if that's the problem since you have a rpm delta.

First thing I'd do is check the spring pressure and see what you have...sounds like that's the problem.

BP7EFS NGK stock number 3526 is a great street/strip plug. Ran them last year in the low 9's (best 9.2) and they idle great on the street. This is for the non gasketed LS style head.



Good luck.

 

appreciate it!

ill throw a spare set of STOCK coils and wires in the origanal location and install new crank sensor(cheap) and see what happens.if still there off to buy nd install springs.....hate throw parts at it but....................

 

Sweet ride man, hope you find the problem out soon. Very intellegent guys here will get you back on the road

 

First off, congrats on the setup and numbers thus far! Looks to be a bad *** car.

I tried looking around on CorvetteForums to see if there was any other information there that may not have been discussed here, but was unable to find the thread.

I think the suggestions here have been very good, and would definitely look into the plug gap, and a colder set of plugs. I would try a bit tighter gap, say around a .030, possibly as low as .028

Not trying to toot my own horn, or anything, but I'm running a .029 gap in my neon @ 30psi, 600+ HP. No issues with spark blowout, whatsoever. But I was getting spark blowout at .035 gap at around 26 psi. Definitely worth a shot checking that out.

Also, I noticed you were running 2 different widebands, looks to be one installed on the car, and one from the dyno. I noticed they didn't correlate very well, and one of the two has a much slower feedback rate than the other (green line has allot more spikes and dips, which leads me to believe it has a faster feedback rate, also thinking it is the one installed in the car?).

The thing I'm really wondering, is if you are monitoring both banks of exhaust, or just one. Also, do both banks merge together in the exhaust stream somewhere? If so, and the wideband that is reading leaner is monitoring the AFR from the exhaust exit, I have to wonder if the combination of one lean bank, and one rich bank is causing the tailpipe afr's to seem good(or in the middle of the two banks), but in all reality, one bank is just much leaner than the other. Something to think about.

Other than that, the only other thing that I would agree with that has been mentioned here, is the possibility of valve float. It would make sense, that the greater the boost, the sooner they float. But that also goes without saying for spark blowout or leaning out...the higher the boost, the sooner and more obvious the problem.

Props on the setup, though! Very sweet.

 

How much boost? Whats the plug gap? Did you bump up the spark dwell any? After it does what it does, does it set any codes at all? Do you have to clear them for it to run normally again?
The ETC cars do have airflow issues on higher boost applications. The IFR and VE need to be scaled down to cure them. Dont know if yours falls into this category. If its going into Reduced Power, this is probably your problem. If its not, then its something else.
Edit: Sorry, didnt read enough of the thread. My questions were answered.
Edit 2: Agree with boostjunky. Gap em at .030

 

I have seen spark issues do this many times, most people don't realize that as the pressure increases the ability for the spark to jump the gap decreases.

I have also seen too hot of a spark plug cause misfires by a certain RPM.

I would concentrate on getting the best spark that you can to the plugs, and like was recommended above, a colder plug, like a 7 or 8 and a .028" gap. Try to change one thing at a time.

The springs are 150-160 lbs on the seat, we have a larger set of K-Motion springs that set up at 200 lbs on the seat and are a direct swap, you can also simpley shim the springs you have to 180 lbs if you want to try it. What cam are you running? Is it XE-R lobes? What lift also? Thanks.

BTW, Killer setup and killer power you are making.

 

thanks brian.....Killer Heads..hehehehehehe

lobe sep 116

intake 233
lift 598

exhaust 228
lift 587

 

I'd try:
TR8's gapped at .025, (.025 to check)
Stock coils with stock wires (just to check),
And then mess with springs

Your custom spark plug wires and the coil wires might be crappy so if you can easily swap them to check I would.

 

picked up a set of TR7....take em back and get 8's?...car driven on the street...
will gap .25

ill run on the dyno with new plugs and gap, if still there then ill run custom O/S that HP just sent me.
still there ill relo coils...
if still there then ill scream..hehehehe

man i find it hard to believe that my tr6 cannot handle 7.5psi? now combine that with long azz wires......maybe

dyno date this saturday

 

Hey Nick, your car obviously has some very serious time spent on it. It is beautiful man. If you come to wanting the coils at some point, you will want the MITSUBISHI coils not the Delphi ones, they are inferior compared. Coils part # is GM 12558693 then you will need bracket part # 12569188 and Speed Inc has the truck wires for this 10.5" I think Unless you want to run the wire setup that you previously had. I dont think you can buy the coils new any more you will have to find them used, but the bracket you can get at the dealership or maybe SDPC has it. I am leaning towards your springs, with your problem changing as the boost and rpm increases. I wanted to get this info to ya on the coils as you seemed to want it, and they do have better performance. Hope to see you get it worked out soon bud.

 

well i appreciate the complimants!

stopped by dale cherry's place and they actually have those coils in stock!.
dale is a one of the best BS3 tuners/installers in the country. john meannie recommends these coils too! i actually have one of those sitting right in front of me...same part #

the spring cannot handle 7psi of boost?

 

What springs are you running?

 

the spring cannot handle 7psi of boost?

If they are 150/160 on the seat as posted they "should" be ok at 7psi with your cam. I'd still pull a valve cover and test the spring pressure to insure it is 150....easy insurance.

I ran the BP7EFS plugs at 0.32 at 18psi at 6700rpm without any problems. Time to spin some wrenches.

 

Isnt .025 a little tight on the plugs? I thought these things made better power with a wider gap like .035-.040? I could be wrong but i thought its better.

 

I don't think the plugs are the problem since you have the problem even at lower boost. I made 1090 rw on TR6s with stock coils....valve springs or crank sensor would be where I would be looking.