Mechanical overrev, 9k
 

Got 3rd instead of 5th at the track, saw 9k before clutching. Seemed to run ok after that for a few laps but then lost a ton of power. But only temporarily. Power cam back but dropped a lot again, as if ECU going into a limp mode. Sounds like some lifter noise at hot idle in pits.

Pondering:
Do I run 3lap TT? Just drive home 150 miles away, or have it flat towed to shop?

Just listened to friend's same year 86 sounds same lifter noise so mildly encouraged...

Lost power on extended hard left and power loss felt similar to fuel starvation I've had before, but have just under 3/4 tank so...

I've zinged mine about that hard before and it was okay. If it kissed a valve you'd know it, I don't see a lifter being an issue, they move almost nil.

I loose power after long hard left! The car gets a massive pop tune sound. I`m not sure if it`s a traction control shutdown or fueling issue

This helps a LOT.

https://www.verus-engineering.com/sh...e=2&category=1

If everything sounds normal I wouldn't worry about it. If you broke something you'd know.

Thank you

Rocker retainer may have come off which is typical on an over rev.

Some companies sell a revised rocker/retainer this not susceptible to this.
https://denstoj.com.au/products/fa20...r-retainer-kit

I did a small money shift in the car this weekend in the AM. Car shrugged it off and I even managed to match my best AM time at 2:30 in the afternoon in 85-90f weather. Safe to say power seemed fine [emoji106]

If your going to do the fuel door flapper mod might as well replace the fuel pump while your in there.

As others said of she sounds fine then I would not worry.

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I don't think it's fuel starvation. I went ahead and fuelled up and ran my 3-lap time trial, no prob. I did slower times than 1st practice this AM by 1 second but mainly because I was too tentative and worried, my fastest lap I actually didn't do the 4-5 shift on the front straight, which cost me 0.3 sec. Car seemed to behave normally during TT. I got 2nd in TT to a Hoosier-shod Miata (dedicated track car) by less than a tenth, DOH!

In open-track after TT, the power-loss coming out of turn 6 (NHMS, long heavily cambered left hander) happened again, with a nearly full tank. Hmmm...

Was able to capture it in log files via ECUtek (which I'm a total newb to), gonna send .csv log files to tuner to get an idea what's happenin. Seems like VVT might not be VVTing, doesn't sound like anything BAD is happening, it just goes limp.

TL/DR, it's still happenin and it aint' fuel starvation (I don't think)

So it throws a code and goes into limp? If you were in limp you would be stuck below 4000 rpm

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No codes thrown, just loses power, then kinda recovers after a bit. *Almost* as if it were fuel starvation.

Weird. Is it easy to replicate? I would think if it was a VVT issue it would give you a code P00XX code for camshaft position correlation or response.

Just cause you have a full tank you can still get fuel starvation
@CSG Mike

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How's the dipstick reading? What's the oil temp?

Plenty of oil, if anything too much, it was reading low so I added some but I think I misread so now maybe it's 1/2-quart HIGH.

Oil and coolant temps same as always, nothing untoward there.

Get the log to the tuner. They would be able to tell you. No sense us guessing

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I money shifted mine and it ran fine. But two years later engine started knocking. Did track days in between never over revved it again. Not sure if related but probably was, car had 56k miles with a few dozen track events.

You can't starve a full tank but you can starve at 7/8 tank under the right conditions

Hmm, the only stints when this happened were ones where I didn't start with a full tank...
New Hampshire Motor Speedway turn 6 is a banked left-hander which blends into turn7, combined turn is >180 degrees. But I've never had fuel starvation here before, even on Hoosier A7s last year. I was running Nankang CR-1s yesterday.

Interesting. How's steering angle different with the two cars? Are you steering more on the Hoosiers?

Best practice may be to run a full tank or a secondary pickup.

Same car, same setup, I'd guess I may be cranking in more steering angle for max grip with the Nankangs.

Full tank works as I need a full tank for my min. weight for time trial anyway.

Hopeful that it is indeed fuel starvation, I sent data files to Zach, looking forward to see what he thinks.

I don't think it's fuel starvation if it correlated with an over rev. I wonder if there's any trouble codes that have not resulted in a CEL that can be seen via techstream.

ecutek would should show these as well which he has access too.

I'm aware - it was more focused on seeing if there's anything he can get insight to prior to waiting for a tuner to review things.

Tuner sez "100% typical fuel starvation". Whew... Honestly I've never felt like I had more grip railing around NHMS turn 6 than on the CR-1s, I'm liking these tires a lot so far. Still, fuel starvation at 7/8 tank?! I might hafta do something about that before Palmer if only to avoid paying for at-the-track fuel for every session!

The issue also correlates with not starting session with a full tank. But yeah, the 1st time it happened was only a few laps after the overrev. Engine sounded extremely valve-noisy to me but then I listened to my bud's same-year 86 and it makes the same noises (mostly injector noises I think). We have similar setups, and our acceleration plots fell right on top of each other so my engine is performing normally otherwise.

Still, I was thinking that maybe VVT mechanism(s) might have been damaged and might quit "VVTing" after a few laps, but why would it reliably fail at exactly the same spot on the track every time? @CSG Mike's post about starvation "under the right conditions" is hugely encouraging. Heavily banked 180-degree left-hand NHMS Turn 6, with a little flat table top I use at track-out, while continuing left into Turn 7, on tires that honestly feel faster and more confidence-inspiring here than even 8-cycle Hoosiers I was on last fall, might all add up to "the right conditions".

Your post made feel better about my money shift lolz

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Bingo.

Fuel pickup is on the driver side.

I also get the the loss of power ,with exhaust backfiring, after a double left hander that links(Fish Hook). 6k rpm in 3rd on semis with less than a 1/2 tank or 3/4+ RHD. Must be fuel as I have not revved past 7.6k and it only happens when you nail the section.

Can someone school me, isn't our rev limiter set well below 9k?

One Scenario.. 4th gear 7.5k rpm and shift into 5th, but you hit 3rd gear by accident. Mechanical over rev! 9k rpm give or take

Not an issue with auto, but with a manual, you have full control over the gears and revs. An extreme example, but the ECU can't stop you from shifting into 1st gear going 60 mph. The rev limiter is only controlled under acceleration, not through gear changes, as this is purely mechanical.

Would this be able to check our ECU for evidence of an overrev event? And if so, how can we find it? Thanks.

Only if it created a code but not over rev

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Speaking of fuel starvation - whats the fix here? Aftermarket fuel pump?

Race car? Surge tank.

No not race car, more dual purpose track/street car. I guess there's not really a solution for that scenario?

Just run a full tank.

Is this adequate with F/I + R-comps though? Sounds like F/I for a street car basically means no racing slicks/high Gs otherwise.

EDIT: Sorry to hijack thread lol