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Discussion Starter · #1 ·
I ran Buttonwillow hard on Friday for 5 25 minute sessions. I spun 4 times (that is another story) and got the car pretty messed up with that fine Buttonwillow off-track dust. Yesterday I took off the race tires and put the stock seat back in, etc. Today I took the car in to my usual venue for a good detailing.

After picking the car up I ran a few errands and the first time I pulled out into traffic and revved the engine up over 4k the car sputtered. It felt different than the timing retard you get with active handling, but I turned it off anyway. I can reliably get it to sputter just as it passes over 4K RPM.

I am not getting any engine codes. This has me baffled. Any ideas?
:-? :-? :-?

Thanks
 

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Discussion Starter · #2 ·
Let me add that the entire engine, intake through exhaust is bone stock. The only deviation from stock is the 7.5 quarts of oil I run for the track.
 

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Sounds like a bad plug wire or coil. My bet is plug wire. They sometimes get fried on the manifold/header. Pull them and take a looksee.

Like DJ said, fuel filter could be another real possibilty. Your air filter would tell you, if you were blowing oil into the intake. Drips back on to your MAF. Not good and very messy.
 

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Oli,
Hope you had fun. How did you spin? Consistent error or just surface conditions? I'm with reaper. Specific rpm misses are often times plug wires. Somtimes water gets in the wrong place too with a detail. Pull spark boots and make sure everything drys over night. My trackday was a blowout. Bad tire=no fun. I am never going to the track again with only 4 tires! Twice now I have had tire issues and a very short day. Don't let it happen to you. Find a way to carry extra tires to the track especially at dirty tracks like WSIR!
 

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fatbillybob said:
Oh, Also, if you can't figure it out the GM dealer with the tech unit can run the car up to 4lk get the miss and tell you where it is. Sometimes it is worth the $85 bucks.


Make sure that they run the diagnostic with the A/C running. For some reason, that was the only way the Tech II could find my bad plug wire.
 

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A bad wire or plug will not show a code. You need to scan for missfires with a scan program. I use EFILive (works good)
If it is a fuel problem then a scan will not show a "misfire" as ALL cylinders could be misfiring and it will not pick that up as it is all uniform misfires. Scan programs look at time between cylinder firing and it has to have some that are firing good to compare.
You can also look at the lifts and duty injector duty cycles to see if you have fuel issues
 

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Sounds to me like your fuel pump is dying. My 97 camaro had pretty much the same symptoms when it's fuel pump went out. Either that, or the detail shop got something important wet.
 

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Discussion Starter · #11 ·
Hi FatBillyBob and others:

Thanks for your replies.

I drove my Z06 today after is sat in the garage last night with a warm engine. Today I let it warm up and then revved to 4k. The problem is gone. This leads me to believe something did get wet. Now I need to figure out what and how.

I will get back to you later tonight on why I spun 4 times. I am at work now and I don't have time to make the post.
 

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Discussion Starter · #13 · (Edited)
Why did I spin 4 times on Friday?

Some of you have asked why I spun 4 times on Friday. The simple answer is I overdrove my car for my driving abilities. If you are familiar with Buttonwillow, we were running configuration #13 counter clockwise. I was running on my CCW's with Hoosiers. My first off-track was not actually a spin, but more of a sprint car slide across the infield coming into the Sunrise turn. I started braking just before the slight drop away on the little knoll coming into the turn. I let the car get just a little sideways and I drifted inside and onto the dirt infield and layed a rooster tail of dirt onto the inside of the turn. Shame on me and apologies to the other drivers. I ended up back on the asphalt and cranked a hard left and just made the exit of the turn.

My next two spins were on the slowest part of the track through Cotton Corners. Both times I was following faster drivers and learning what I could. But while I was keeping up, I was obviously driving just beyond my means. Through these corners the back-end of the car tends to get pitched back and forth a bit from the quick direction changes. Twice I just let the momentum on the rear get away from me while simultaneously not keeping the rubber interface hooked up to the asphalt. The 2nd time I did it I was following John Wurth of Speedventures. He set the fast lap of the day at 2:01. I was running mostly 2:05s and 2:06s, so you get the idea why I pitched it away there.

My last spin was entering the big Riverside turn. I usually come in at around 115mph or so, I brake very lightly while entering to get the front wheels hooking up and then drive through to the apex and exit. On my last session of the day I over braked, got the a$$-end hanging out again and drifted in a slide from the outside entrance of the turn towards the inside of the turn. First my left front hit the dirt, then my front right. At this point I knew it was over so I stabbed both pedals. She spun around completely and I ended up with my two right wheels on the asphalt. The dust cleared quickly and I checked for traffic. A yellow GT3 that I had passed on the front straight had still not cleared the dogleg from the Lost Hills turn so I took off and stayed ahead of him.

The guy in the GT3 was telling me how he is a BMW driving instructor and that he owns two other race cars. He was a little arrogant considering I passed him every session. He did get much faster as the day progressed, but not fast enough. My friend Kevin kick my a$$ in his GT3 when we go out together. So I know his car could do it.

I ended up with the 4th fastest lap time of the day and a 3rd session averaging 2:06. I am pretty happy with that being the novice that I am. While I am progressing quickly, I do have a faster car than most other drivers, so I still have a lot of work to do to consider myself a good driver. I plan to keep working on it. Therefore I will be back out there May 6th.

Come on out and join me, Kraff, Americanmusl, RCorr, Jairl, and several others here on the Z06 forum.

:ity: :ity:
 

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Oli,

Who is may 6th? SV again or???? Do you think these "off" issues are 100% your mistakes or do you think there are car set-up issues that could eliminate or reduce? I once went from an undriveable car thinking I was a complete idiot to a chassis rake change making my car run like a completely new car.
 

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Discussion Starter · #15 ·
I may have rake issues. I am too novice to know at this point. I know my alignment and corner weighting is spot on, but rake I don't even know how to check or adjust.

If anyone can help me understand rake and set-up, I would be appreciative. Getting the rake right, assuming it is off, will only make my car faster, but I don't diminish for a moment that I did simply make driving errors.
 

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Discussion Starter · #17 ·
Why is rake important?

Thanks IT L GO:

That is the first explanantion I have seen on how to measure and set for rake.

I am still left with the question of "what are the implications of rake?" What happens if it is not set right? There is a 1/2" to 3/4" range. How does the car behave at the lower end of this range vs. the higher?

Does anyone know these answers?
 

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Well Oli,
Coming in 4th fastest time 3 seconds off the leader and you a newbie sounds to me like you can drive. I wish I could do that. Granted the Z hp and torque help but it is not always a slam dunk to drive a high HP car well. Unfortunately the only way to check your rake is to try changing it. Maybe DJ/subdriver or others can post here how sensitive a Z is to chassis rake. My non-Z I can feel 1/2" changes. So if you really are new maybe you can try dropping the rear 1" and go back to the track and see what happens. Personally I adjust from one end or the other only so as to not confuse myself. In my case with a rear heavy car 40/60% weight bias I notice that if I lower the back more than stock I get better 100mph+ braking stability and my rear sticks better and I get less terminal oversteer ala 911 porsche. I would think that this would be especially benefiical with a hi torque Z. However, while I own a Z I have no track experience with one. DJ others who race you guys have comments?
 

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CCW at Buttonwillow is a hoot, but also the most prone to various off track adventures. Most clubs only run CW because of these issues.

Depending on the miles on the car and the year I would check the obvious first.

Air filter - Lots of off track the fine dirt gets by the filter and can really plug it up bad. If you have oil in the MAF area the dirt can stick to the wire and do all kinds of crazy stuff.

Good points on the detailing if the engine was washed. But most of the water related issues should have dried out by now.

Being bone stock - I would not think it's a plug wire but other here most likley have more track miles than I do with these cars and may know better.

AROSC is out there on memorial weekend. I saw the date for the 6th, but have to pass. Come out on the 22nd, we normally have 4-6 Z's. BTW 2:06 CCW is pretty darn good.
 
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