Car is breaking up when I stab the throttle

Boostedsvt3660

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SOS. I finally got my 04 cobra back together and I am having an issue that has myself and some reputable people stumped.

Whenever I stab the throttle it jumps into boost and falls on its face almost to the point where it stalls. Sometimes even backfires. This does not occur when I slowly climb rpms. Fuel pressure looks good inside the car even climbs with rpms. I fell it goes lean when I stab it.

The car was recently remote tuned. The tuner has not been able to find an issue. I have a video but it is to large to attach, but can supply per request. As well as logs. I am in need of help as I have checked next to everything. I will offer a case of beer for whoever helps with the solution as I am now an alcoholic after this.

Setup on the car as followed.
2.9l Whipple crusher. 3.0 upper 4lb lower
Fore return dual pump on a Hobbs. Has fore rails also.
Id1050x injectors
Custom cams, springs, seats etc..
Head studs
Arh long tubes.
Full stock ignition.
Trunk mount tank.
Wot box. Everything disabled during these tests.

Things I have checked and/or brand new. Even the new stuff I tested.
Tps new set KAM 3 times now.
Iac checked it's good.
Map new.
Maf new.
Cam position sensor. Tested.
kmj alternator. Tested.
Coil packs. Tested.
New br7ix gapped at .22 as tuner stated.
All new vac and fittings. Checked with spray method and applied air with soap and water.
Same test done for exhaust leaks.
Check electrical connects and cleaner them all.
Frps new.
compression test.
battery is older but maintains good voltage when car is running.14.x
Head gaskets new as well as intake manifold.
 

SVTdreamin04

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Can you post some of your data logs? That would be helpful.


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SVTdreamin04

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I will add, my car done the same thing. Ran fine when getting into the throttle slowly, but when you would stab it, it would cut out and go lean. Battery voltage at idle was over 14 but dropping very low when stabbing it. My alternator eventually checked out and was the culprit.


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01yellercobra

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Have you tried disconnecting the Hobbs switch and running the second pump full time just to see what happens? Is the FRPS still hooked up?
 

Boostedsvt3660

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Can you post some of your data logs? That would be helpful.


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This is what I currently have. I am going to get some better logs today and will post results.
 

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  • newest datalog on base.csv
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  • voltage.csv
    211.3 KB · Views: 48
  • datalog 9-4-21.csv
    453.8 KB · Views: 50

Boostedsvt3660

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Have you tried disconnecting the Hobbs switch and running the second pump full time just to see what happens? Is the FRPS still hooked up?
Yes I have tried both pumps full time. Frps is still there. Only thing I have not done which I am going to try today is switch pumps around period but I doubt that will do much.
 

Boostedsvt3660

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I will add, my car done the same thing. Ran fine when getting into the throttle slowly, but when you would stab it, it would cut out and go lean. Battery voltage at idle was over 14 but dropping very low when stabbing it. My alternator eventually checked out and was the culprit.


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I do have my stock alt I could try. It still worked when I removed it but would flash once and awhile. I would hate to buy new just to check being the kmj has a lifetime warranty
 

SVTdreamin04

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Pull a data log with battery voltage to see what it is doing. I assume you tuned the car with a wideband?


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Boostedsvt3660

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Pull a data log with battery voltage to see what it is doing. I assume you tuned the car with a wideband?


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I have a wideband but not to sure if it's reading correct from what the tuner said. I have a log built for today with a bunch of stuff. I will add once I get it.
 

SVTdreamin04

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I have a wideband but not to sure if it's reading correct from what the tuner said. I have a log built for today with a bunch of stuff. I will add once I get it.

Without knowing if this is correct, you’re kinda taking a stab in the dark with what is really going on when data logging.


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me32

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How many miles on the coils? Have you pulled the plugs after the test runs?
 

Boostedsvt3660

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Pull a data log with battery voltage to see what it is doing. I assume you tuned the car with a wideband?


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Here the newest log. I put a bunch of stuff in it. This is both pumps running. No Hobbs.

Car idles like shit until warm still even after setting kam. Only have about 12 in of vac slight shake to the car. Leads me to think vac leak but still have not been able to find with air pressure and soap. May pull the manifold to check and make sure it's good.
 

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03' White Snake

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Did your tuner set the computer to return style in the tune?

Check the MAF is plugged in? Are you running a JLT intake tube? sometimes the wires are bent too tight and break internally. Try wiggling the wires with it running.
 

MG0h3

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A. Stop stabbing the throttle or otherwise causing your failure

B. Did I miss who tuned it? While a catalog may not be what diagnoses the problem, the symptom should be visible; being lean or rich. The not sure if WB reading correctly statement is very concerning.


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Boostedsvt3660

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How many miles on the coils? Have you pulled the plugs after the test run

Did your tuner set the computer to return style in the tune?

Check the MAF is plugged in? Are you running a JLT intake tube? sometimes the wires are bent too tight and break internally. Try wiggling the wires with it running.
No jlt. The 2.9 crusher tube with a slot style so it has the converter and wired to the oat wires
 

Boostedsvt3660

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A. Stop stabbing the throttle or otherwise causing your failure

B. Did I miss who tuned it? While a catalog may not be what diagnoses the problem, the symptom should be visible; being lean or rich. The not sure if WB reading correctly statement is very concerning.


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Dunn tuned. The wide band has always read good but he says not to trust autometer. It bounces around.
 

03cobra#694

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What do you recommend? I have heard some good stuff
Just plane old TR 7. I run the TR 6, but I have no where near the boost you have. I had the TR6ix for a while. Nothing but issues with breaking up and crap. Switched the normal plugs, night and day difference. Gap seems tight. What kind of boost are you seeing?
 

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