Could really use some help/ideas

[nolyaw]

Went to have my car tuned yesterday and had some problems.

2.3 Whipple, 80# injectors, BAP with wiring upgrade. EGR is completely deleted.

Problem #1: When starting the car hot, it quits immediately, after about 2 or 3 tries it stumbles to life and idles perfect. No issues when motor is cold. Rail pressure is 39 psi, according to the FRPS, which is new.

Problem #2: When at WOT on the dyno the boost hits hard at 17 psi and holds, then right at 4500-4700 the A/F ratio goes crazy, looks like a roller coaster, so the tuner lets off right away.

My FP duty cycle never goes above .420, tuner says .500 is max.

He has zero suggestions, and I don't want to start throwing parts at the car, I want to be able to prove a fault. Any prior experience or knowledge would be EXTREMELY helpful.

 

[nolyaw]

No ideas?

 

[unforgiven]

What type of MAF?

 

[nolyaw]

SCT ba 3000, Accufab SB, no cats, no egr, 2.75 pulley on Whipple 2.3, 80's, Bassani LT's and exhaust, 17 PSI of boost.

Drove the car today,a nd when it hits around 45-4700 rpm, it cuts out, any gear.

Tuner says he does'nt like BAP's and thinks it messes with the FPDM, and just generally causes problems. Mechanical pressure at the rail reads 32 psi when idling. When the car is started, pressure jumps way up, then falls to 10 psi, then settles out IF the car stays running.

When the car hits 45-4700 WOT, the fuel pressure goes apeshit. We measured boost at the FPRS, so I am hoping there is not a boost actuator problem, as this vaccuum line is connected right off of the actuator valve. So the FPRS is seeing 17 PSI.

The car made 540 whp at 4700 rpm's, but that is when he had to bail.

 

[racebronco2]

Have you datalogged your voltage?

 

[nolyaw]

At no time did the voltage drop below 13.5 volts, up to 4700 rpm's.

Tonight I turned the BAP all the way down to zero (off), and the horrible running and 'cut out' at 45-4700 seemed to be gone, but I was afraid to push it any further for fear of running out of fuel. Seemed to work though. It does have the wiring uprade on the BAP.

The hot start issue remains.

 

[SVT GI]

Problem #1: When starting the car hot, it quits immediately, after about 2 or 3 tries it stumbles to life and idles perfect. No issues when motor is cold. Rail pressure is 39 psi, according to the FRPS, which is new.

Your tuner needs to play with values in the ISC_DUTY_CYCLE under FUEL_STARTUP. There are also more values under IDLE STARTUP as well. They are based on ECT (Engine Coolant Temp), so that explains why you have no issues on cold start up and under warm start up you do. Thats speaking from SCT Tuning software, not sure if you are using Diablo or other....

 

[nolyaw]

Yes, SCT. He dicked with it for a total of 4 hours. Only got 2 WOT runs that whole time. The rest was set up, and idle/ drivability. I only paid for 3 @ $100 per hour, thankfully.

Basically paid for nothing, I guess.

 

[CobraBob]

Definitely talk to your tuner about what Jason brought up. Excellent points. Maybe work with a new tuner?

 

[04sleeper]

Is your BAP wired up Pre-FPDM?

Are you sure your hoses in the tank are connected secure?

If your tuner is telling you a BAP messes up the FPDM, FIND ANOTHER TUNER!

 

[nolyaw]

I ordered an MDM Jr, GT pumps, Fore fuel hat, etc. I think at least another $1500 will solve the problem.

 

[fiveoh2go]

FIND ANOTHER TUNER!

This ^

 

[nolyaw]

This ^

Gee, guess I never thought of that :idea:

 

[Tom's_03SVT]

Check your throttle postion sensor. Has a lot of the same issues on a friends car turned out to be the TPS.

 

[greengt88]

Pprv. Not a prob. With the fore hat