My car is tuned to 15 psi until 5000 rpms, then tapers boost down to 13 psi till redline due to the fact that my tuner could not keep the ECU from cutting fuel after a certain point. Tuner thinks it's the Unichip, and I need a UTEC, but I'm not so sure. Here's what I have:

AAM fuel return
RC 650 injectors
TS reflash for injectors and raised rev limit (<- big red flag)
Unichip

There has to be a problem somewhere, because I've read many accounts of the Unichip handling much higher psi than what I'm seeing. Peter from APS told me in a PM that one of their shop cars is at 24 psi on the Unichip.

I'm thinking of driving down to SGP soon to have it checked. They've had the Unichip up to 17 psi with no problems.

-Chris

 

We just tuned our Z to 616HP @18 PSI on Pump fuel/GReddy kit/RC 750cc/Prototype swirl tank-return fuel system/UTEC. Works flawlessly

You should be able to do it on the Unichip, but not w/o more serious tuning. It is my understanding (keep in mind we just recently became a Unichip tuner) that by increasing the boost to such high levels, it changes all the load sites. Basically, everything needs to be rescaled and retuned. I don't even know the limitations of the Unichip X1 driver box or the amount of scaling the Dastek software has, but whenever you have to rescale it can be like starting all over again=more time involved. There are always less orthodox/back door methods to compensate for maxing out certain sensors, but I believe this is not the way to tune, especially for a street driven car. Ex. running extreme fuel pressures to compensate for inadequate sized fuel injectors.

APS has been tuning Unichip for possibly over a decade. They are masters of tuning on that platform. I'm sure they could tune up to 30+ PSI. They are even helping develop windows based software in conjunction w/ Unichip. It will be better soon.

I'd like to get more Unichip tuning under my belt, but for now I hope this helps.

 

Thanks, USED.






I guess I would have gotten more interest if I asked "which turbo kit should I buy?".....

 

Let us know what you find out... I remember Peter saying that their kits aren't tailored for the reflash at all....

Oh yeah, as far as which kit to get, I'd say go to http://www.************************/products_usa.html

I just love how that name gets bleeped.
In honor of the banned one from the bleeped site:

 

Do you have a bigger fuel pump ? Did you reset the ECU ?

Danny

 

I am no engineer or anything, but I think the flash is causing he problems. All that was done to his ECU was flash the injectors so the Unichip would have enough room to scale the fuel. As far as the rev limiter I don't see how that could be the problem. My ecu is flashed for the injectors, rev limiter, speed limiter, tb, and timing maps. I am using an EU and not the unichip, but I don't see how flashing would cause problems. If I remember correctly Peter was said reflashing the ECU would not be safe because the tune is not set up for that. Failsafe got a custom tune so the reflash should be a problem.

 

The flash shouldn't pose any problem. We tuned just yesterday the following setup:

APS Twin Turbo
Unichip
RCE 650cc
AAM Fuel System
Prototype Fuel System Stage 2 Upgrade
AAM ECU Flash
Pump Gas

16psi @ 570rwhp

The Unichip, when setup properly, will be able to control your fuel. If you don't have any luck the guys at AGP are awesome so you'll be in great hands.

Hope this helps,

 

Have you checked the fuel pressure? Did you increase the size of the fuel supply system?

 

I can only guess that Tuan took everything he could think of into consideration. He tried tuning it higher but he said the fuel and throttle kept cutting out, and he couldn't figure out any way around it. And yes, I have the AAM fuel return system. I guess I need to take it somewhere that has tuned the Unichip past 500whp on a built motor.

 

Mike, if you don't mind my asking, what all did you reflash your ECU for, besides scaling injectors? If I sent my ECU to you, could you look at it and see if there's any red flags?

 

Whats your compression ratio?

 

The problem, as you know, is not that you are running lean...its that your fuel is abruptly cutting out, and your engine dies after a WOT run. At least that is what I recall from our conversation on the phone.

Something else is at play here....its not something as simple as lack of fuel, or improperly scaled injectors. You have more than enough injector and fuel pressure to meet your needs.

Is it possible you have a defective Unichip or a wiring harness?

 

I asked about your fuel supply system not fuel return system. Do you have adequate fuel pressure and fuel flow to support high power?

 

Walbro 255

 

Before you go much further I would definitely check fuel pressure and fuel flow. I think you are out of fuel supply to support any higher horsepower, this may well prove to be one of your tuning issues though not all of the issues, hope this helps.

George

 

Surely, Tuan would have kept an eye on the fuel pressure while tuning. He also said throttle was cutting as well as fuel. The throttle wouldn't cut off if it ran out of fuel, would it?

Another shop told me that on a Dynapack dyno, if you don't have the loads set right, it will somehow cause the VDC to act up, even if it's switched off. But, if you ran it on the street, it would run just fine. My tuner insists this is not the case though. Any thoughts from the dyno experts??

Thanks for your help, George

 

I don't know if your tuner had a fuel pressure gauge connected or not, most tuners use a high speed air fuel ratio meter to check air fuel mixtures, maybe fuel pressure and flow was not checked, I simply don't know. It would be worth asking if the fuel pressure and fuel flow was checked as I genuinely suspect that your fuel system is dropping fuel pressure. I know that the guys at APS have run a number of VQ engines with bigger cams at quite high boost with large injectors and a massive fuel supply (drop in twin fuel pump assembly) tuned via the Unichip computer. Hope you get on top the problem real soon.

George

 

Again, I dont think this has anything to do with fuel pressure, becuase Tuan at GRD has tuned tons of these things, and the AAM system has a fuel pressure gauge right on the regulator. The sudden throttle and fuel cut points to something other than running insufficient fuel pressure, IMPO.

 

I'n just saying that I feel that the fuel supply system will not be large enough for the intended power level - there may well be another problem/issue though making sure that the fuel supply is large enough fo the application is both necessary and commom sense.

George

 

Absolutely correct, and since it takes about 30 seconds to verify the fuel pressure, it was likely the first thing that Tuan did.