03 Cobra hit 6500, it falls flat on its face

[Termi Mo]

I have an 03 Cobra and I can drive it as hard as I want going straight ahead, however, if I were to try and do a donut it dies down almost as if the traction button is on. I have had the scanner on the car and there were two stored codes, P0148 for fuel delivery error and a p0234 for engine overboost.

Does the boost bypass mod trigger a p0234?

I have installed a fuel pressure tester on the car while at idle to make a comparison with the reading on the scan tool and they are very close. I drove the car with the scan tool and graphed the frps and it would spike to approx 70psi and then work its way back down. I have also recently changed the fuel filter as well as dropped my fuel tank to see if there may have been contamination of any sort in it. Any ideas or suggestions?

Thanks in advance

 

[cobracide]

Doughnuts? What is your 1/4 of a revolution time? lol. Anyways.. How full is your gas tank?

 

[Termi Mo]

Since I initially noticed it I have been following other threads and I know to keep the car above 1/4 tank, if that is what you are referring to.

 

[cobracide]

Yeah

 

[Black Cobra]

PPRV delete? Maybe fuel pump hoses are kinking under that particular g loading.

 

[Termi Mo]

I haven't done the PPRV delete, is that the type of reaction you would see from one that is malfunctioning?

 

[04DeadShort]

When exactly is your FP spiking to 70psi? If it keeps that up, your gonna be replacing a fuel rail pressure sensor soon.

 

[Termi Mo]

My mistake guys, the frps shows that there is a spike to 60psi and it only does it temporarily during gear shifts. On a straight run while accelerating the fuel pressure is around 38 - 41 and at 5900 it dropped to 34 psi. When i sink the clutch it temporarily spiked 60psi and then after releasing and accelerating in second it dipped back to 30psi and remained at around 35 through second. What I also noticed is that it seems like im hitting the limiter at 5800-5900 rpm's, aren't the cars suppose to spin more rpm's than that?

 

[BTRStang]

pprv delete? Maybe fuel pump hoses are kinking under that particular g loading.

+1

 

[Jimmysidecarr]

Quite odd for a Terminator with ZERO MODS.:dw:

 

[Termi Mo]

It has been a few weeks since the original post but I have thrown quite a few solutions at the car and none is resolving the problem. I have done the pprv delete, I have also replaced the frps and even the fpdm. If I line up and do a 1st to 4th gear pull i get the p0148, I did a snapshot and fuel pressure is constant throught the rpm range at around 40 psi. I have noticed that if i shift late and hit 6500, it falls flat on its face and if I pull another gear it remains bogged down, is this normal? Also, are there any pids in particular that I should view to assist in diagnosing the problem.

The car has the following mods
JLT ram intake
Flowmaster catback
The car was purchased with both of the above

Recently installed
4:10's
Suspension mods (ftbr, h & R sports steeda bumpsteer and x2 ball joints)
pprv delete

Could it be possible that the car has had a tune installed by a previous owner, and if so how can I find out?

 

[TRBO VNM]

LOL, donuts. Really man? Is this some new kind of racing or something?

First I would say it is how much fuel you have in the tank and really, 1/4 may not be enough considering what you are doing to that car. All the 1/4 level reports are in regards to launching at the track and the initial hit. Going around in circles you are forcing the fuel to one side and it will remain there, where the drag strip it is an initial thing and then comes back.

Second, it looks like your fuel pressure is low. Your base pressure stock should be 39psi and then for every pound of boost, you get a pound of fuel, so you should see about 47-48 psi at WOT with a stock boost setup.

you mention PPRV and you dropped the tank, I assume you checked the hoses? Have you logged FPDC?

 

[Termi Mo]

Sorry guys but the title is a bit off at this stage. Initially this is when I noticed the problem but since it is now noticeable driving under "normal" conditions. I replaced the hoses while doing the pprv delete. Here are some numbers that I recorded on a custom data log:

TPS RPM FRpsi FPDC FP monitor DC MAF Advance STFT B1 B2
.98v 922 40.32 24.4% 3.1 % 9.19 22 -.7 -.7
3.58 2108 41.19 36.5 3.1 92.69 11 10.8 11.2
4.66 5058 40.32 50.0 3.1 255.98 20 21.9 21.9

2nd gear
TPS RPM FRpsi FPDC FP monitor DC MAF Advance STFT B1 B2
4.66 5422 41.48 50.0 3.1 280.45 20 21.9 21.9
4.66 6450 49.75 47.0 3.1 332.06 24 24.2 20.5
4.66 6132 34.88 48.9 4.2 335.16 30 42.9 42.9

3rd gear
TPS RPM FRpsi FPDC FP monitor DC MAF Advance STFT B1 B2
4.66 5240 39.82 50.0 3.1 300.49 20 42.9 42.9
4.66 5514 38.58 50.0 3.1 310.68 20 42.9 42.9
4.66 5992 34.52 50.0 3.6 347.56 22 42.9 42.9

If there are any other pids I should log please let me know.

Thanks for the help

 

[TRBO VNM]

what are you logging with? Wondering if those 50% with the FPDC is really 100% so then you are maxing the pumps out. Did you drop the tank recently to confirm the hoses are still on the pumps and everything in the tank and still tight? And no kinks?

 

[Termi Mo]

Yes, I am certain that the fuel hoses have no kinks and also the y are on tight. I have been logging with an OTC Genisys. As per your previous post, I am not quite getting the fuel rail psi, however, the duty cycle should have compensated shouldn't it?

 

[Jimmysidecarr]

I fixed your title and cleaned up some posts.

I also wonder if your logger is giving actual FPDC instead of the 1/2 value percentage we see on the SCT and a few other units?? If so you may have one of the pumps gone or going out.

 

[mach1033]

what are you logging with? Wondering if those 50% with the FPDC is really 100% so then you are maxing the pumps out. Did you drop the tank recently to confirm the hoses are still on the pumps and everything in the tank and still tight? And no kinks?

I believe you are right about the pumps being maxed out. If I remember correctly you would need to double that fpdc number. So its one of two things going on here. He has more mods than he knows but he seems like he could figure it out considering that he is datalogging himself or he needs new pumps. I think its the pumps getting ready to crap out.

 

[encasedmetal]

OP- word of advice, when you're in the upper RPMs as you are in the posted datalogs, you are in Open loop (this is usually transistioned to after 0.5 load and beyond from closed loop obviously). when you are in Open loop, STFT (short term fuel trims) don't need to be logged since they are not active when in OL. and yes I believe as well that you need new fuel pumps given the fuel pressure you are recieving per your duty cycle

 

[TRBO VNM]

I fixed your title and cleaned up some posts.

I also wonder if your logger is giving actual FPDC instead of the 1/2 value percentage we see on the SCT and a few other units?? If so you may have one of the pumps gone or going out.

kinda what I am thinking. If the hose is not off, then a pump could be going or is about gone.

I believe you are right about the pumps being maxed out. If I remember correctly you would need to double that fpdc number. So its one of two things going on here. He has more mods than he knows but he seems like he could figure it out considering that he is datalogging himself or he needs new pumps. I think its the pumps getting ready to crap out.

yup, another option. mods he doesn't know about.

OP, take a pic of your engine bay and post it up

OP- word of advice, when you're in the upper RPMs as you are in the posted datalogs, you are in Open loop (this is usually transistioned to after 0.5 load and beyond from closed loop obviously). when you are in Open loop, STFT (short term fuel trims) don't need to be logged since they are not active when in OL. and yes I believe as well that you need new fuel pumps given the fuel pressure you are recieving per your duty cycle

yup. STFT is for your idle and cruising.

 

[hotcobra03]

have you put the boost bypass mod back to stock and see if this still happens?