Turbo'd 8 won't rev above 6k
 

Ok... holster those flamethrowers.

I'm looking at an 8 that has a Garrett turbo, Cobb AP, new cat, and some other work done to it. The seller has no details on the history of the car other than what we can see with our own eyes.

Car starts and runs fine but throws CEL's and won't rev above 6k. Anyone know what might cause a cutoff at 6k?

I wish I had more details, but am really trying to find out if this might be a relatively inexpensive fix or if I'm signing up for a bag of financial hurt.

Any thoughts you can provide are greatly appreciated.

lack of fuel and/or air? :-P

An aftermarket turbo? Check

Seller doesn't know anything about it? Check

Doesn't run very well? Check


Sounds like that is something that you shouldn't even consider purchasing... You should be assuming that it is a "bag of financial hurt", even if the problem can be pinpointed, which I doubt.

Some possibilities:
- ECU flash has problems / bad tune
- Sensor malfunction
- Improper installation of turbo hardware
- vacuum leaks causing intake valve problems
- ignition is being overwhelmed
- etc...


If you are seriously considering buying it, get a compression test, get the CEL codes and come back. Probably should get full pics of the entire installation, a copy of the tune, etc... as well to even have a reasonable chance of diagnosing.

It could be many things. Is this a custom turbo kit? It is hard for us to say, it would need to be properly diagnosed in person. Stock coil failure will cause an abrupt hesitation in the rev range when they are failing but like I said, any input would be guessing without knowing much more.

Compression test and tuning details are a no go. The car is out of state and was bought at auction.

So what you're basically saying is that this could be as simple as a tune or it could be as bad as a new engine.

boosted with a "new" CAT ... that is another warning sign you should consider. Why have a CAT at all? Why just recently replaced? It takes me down a path where I start to question the health of other things upstream.

Yes it could be something simple or it could be a total clusterfuck. The latter is more likely. Got any pics of the turbo setup? That would help us identify the kit.

Engine bay pics attached!

My guess? It has to pass emissions to be street legal in whatever state it came from. No?

If it was auctioned what would it matter? Even a low compression motor can run for quite some time boosted. If you've got experience, or are willing to learn, go for the leap of faith... just set aside about $5,000 beyond what you initially pay to cover all the unknowns.

It looks like the Turblown (c#$ks#$kers) kit or a custom setup based on that shitty kit. Either way, the OMP has been relocated to the firewall so stay away. It would need substantial work to get that car where it needs to be. It is likely in limp mode due to the OMP relocation.

The car is $9k as is. Would I be better off getting a high mileage chassis for ~$7k and having someone do it correctly from the start?

I'm curious -- what's the major issue with relocation of the OMP?

Relocating the OMP is bad because no lubrication or cooling of the seal is happening inside the engine. Premixing the fuel does not make up for the absence of a functioning oil metering system. And if the OMP got damaged or out of whack in any way the ECU will put the car into limp mode. That kit was designed by a really lazy person. Done properly, the piping should clear the OMP and allow it to remain. I would also venture to guess that the APV motor is gone and the APV's are locked open as well.


Fixing that car properly would cost a few grand as is and there is still a lot you don't know. Buying a used turbo RX8 with little knowledge on the subject is just a very bad idea man.

Awesome. I appreciate all the feedback. I'm guessing someone cut their losses after realizing their mistake. I'll play it safe and wait until the right one comes along.

Thanks,
Mike

can you elaborate? I thought pre-mixing with 2 stroke oil completely makes up for the omp-delete.

Early on some of the race teams running the Renesis tried the premix only route and had failures. On the Renesis, the oil metering system is critical to engine longevity. Hence why it was totally redesigned for the series II Renesis. I know RX-7 guys do it, but that has nothing to do with the Renesis. The oil injectors are there to lubricate and cool and both are important, more so on a turbo Renesis. You want to be able to increase the rate the OMP delivers oil VIA the Cobb or other EM solutions and premix if you wish. Personally I run a SOHN injecting Idemitsu and have increased OMP rates.

Premix doesn't get injected when off throttle on decel while in gear, omp injects oil at all times when it's needed. It can't make up for what the omp does.

And without omp injection, the side seals run way hotter, leading to early failure.

does this apply only to renesis engines or rx7 engines as well?

Good thinking...thats what i'm doing, full time rx8 searching...I know the perfect blue,white or yellow are hidding somewhere waiting to be found...lol...

Only the Renesis. Our side seals sweep right past the exhaust ports, so the exhaust is helping to superheat the seals. The prior RX-7s have peripheral ports, so the side seals are comparatively very far from the exhaust port. Side seals were not a problem for RX-7s.

Both good points as well.

The seller said it has been driven 1500 miles in it's current state. That can't be good.

But doesn't some of the premix survive the combustion cycle, thus continuing to provide lubricity?

It will be burned off due to heat...