Hey guys,
First off, I am fairly new to a lot of this so please - go easy on me. I did do some searching on the forum first but could not find a thread that matched the issues I'm having. If I did miss it, please point me in the correct direction - I will take my lashings.
I purchased an already modified '04 Cobra in May 2012 which has been a blast and has given me no real issues (other than not having a build sheet of everything that was done to the car...we are figuring all that out slowly), until last yesterday when we were doing some dyno runs on a friend's mobile dyno. We did three pulls (all in fourth gear).
-1st pull it all seemed happy until 5000rpm, and the engine suddenly cut out - Like a fuel cutoff/rev-limiter (which is set to 6800rpm currently), etc. Engine returned to idle, like nothing happened.
-2nd pull went just like the first, except it cut out around 4700rpm this time. Straight back to idle again.
-3rd pull was just like the first two, except this time it cut around 4400rpm. This time, I had my DiabloSport Predator logging data off of the FRPS and I see 36-39psi steadily until the car cuts, which at that point I see 0psi for only a second or two (and it is a sudden drop to 0psi, not gradual) then to 52psi which at that point the engine is returning to idle - then back to 38-39psi at idle. No codes popped up.
Driving the car, I can turn up 6k+ rpm in first and second gears, no problem. And I have turned up 5/5.5k rpm in third and fourth gears - once again, never had a problem. I repeated this on the way home from my friend's house, just to be sure - again, no issues.
Here are some of the mods and a little info (and if you feel you need to know more to aid in solving my conundrum, please ask and I'll do my best to provide that info...I'm sure I'll miss something):
-Unmolested 4.6 engine
-Kenne Bell 2.2 blower - 3.25" pulley
-Ford GT twin fuel pumps w/ Zone 5 Performance dual fuel pump driver
-Kenne Bell Boost-a-Spark
-60lb injectors
-Factory fuel rails
-JLT cold air intake
-American Racing LT headers with O/R X-pipe
-Fuel filter was replaced less than 50 miles ago.
-Fairly new (<1k miles) NGK TR6 plugs gapped at .035".
-Car currently has 77k miles. It is claimed to have only 7k miles on the build, but I'm thinking it has been together a fair bit longer than that. The best I can tell from limited documentation is that the last tune was by Pro-Dyno in Fort Mill, SC in 2010. 635hp/535tq were the numbers back then (and nothing has changed since then, as far as I know).
Any ideas or things to look for? And as always , questions, comments or snide remarks are welcome.
Josh
First off, I am fairly new to a lot of this so please - go easy on me. I did do some searching on the forum first but could not find a thread that matched the issues I'm having. If I did miss it, please point me in the correct direction - I will take my lashings.
I purchased an already modified '04 Cobra in May 2012 which has been a blast and has given me no real issues (other than not having a build sheet of everything that was done to the car...we are figuring all that out slowly), until last yesterday when we were doing some dyno runs on a friend's mobile dyno. We did three pulls (all in fourth gear).
-1st pull it all seemed happy until 5000rpm, and the engine suddenly cut out - Like a fuel cutoff/rev-limiter (which is set to 6800rpm currently), etc. Engine returned to idle, like nothing happened.
-2nd pull went just like the first, except it cut out around 4700rpm this time. Straight back to idle again.
-3rd pull was just like the first two, except this time it cut around 4400rpm. This time, I had my DiabloSport Predator logging data off of the FRPS and I see 36-39psi steadily until the car cuts, which at that point I see 0psi for only a second or two (and it is a sudden drop to 0psi, not gradual) then to 52psi which at that point the engine is returning to idle - then back to 38-39psi at idle. No codes popped up.
Driving the car, I can turn up 6k+ rpm in first and second gears, no problem. And I have turned up 5/5.5k rpm in third and fourth gears - once again, never had a problem. I repeated this on the way home from my friend's house, just to be sure - again, no issues.
Here are some of the mods and a little info (and if you feel you need to know more to aid in solving my conundrum, please ask and I'll do my best to provide that info...I'm sure I'll miss something):
-Unmolested 4.6 engine
-Kenne Bell 2.2 blower - 3.25" pulley
-Ford GT twin fuel pumps w/ Zone 5 Performance dual fuel pump driver
-Kenne Bell Boost-a-Spark
-60lb injectors
-Factory fuel rails
-JLT cold air intake
-American Racing LT headers with O/R X-pipe
-Fuel filter was replaced less than 50 miles ago.
-Fairly new (<1k miles) NGK TR6 plugs gapped at .035".
-Car currently has 77k miles. It is claimed to have only 7k miles on the build, but I'm thinking it has been together a fair bit longer than that. The best I can tell from limited documentation is that the last tune was by Pro-Dyno in Fort Mill, SC in 2010. 635hp/535tq were the numbers back then (and nothing has changed since then, as far as I know).
Any ideas or things to look for? And as always , questions, comments or snide remarks are welcome.
Josh
