So a background. Car is a 2003 cobra with about 95k miles. Was smoking a lot at startup and was slightly low on compression. I got back from a deployment a year ago and decided to pull the motor and refresh and rebuild it along with adding a fuel system and a whipple 2.9.
Current Mods:
Stock block .20 over
JE dished pistons
Nitride rings
Stock crank
Stock Rods
Stock heads refreshed/rebuilt, added manley springs, stock cams
Melling oil pump, new water pump etc
ARP everything
Fresh timing set
All seals, gaskets, rings etc replaced
Whipple 2.9 stock pulley
EGR delete
JLT RAI
SCT BA 3000
Afco H/e
Fore rails
Fore hat, dual gt pumps pprv delete (still returnless)
Dual fpdm/upgraded wiring
-8 feed
Seimens deka 80lb inj
RXT clutch, 28 spline i/s, MGW
Mac LT, lethal o/r x, magnaflow catback
autometer vac/boost, oil pres, water temp, wideband a/f
Anyway when we fire it up it goes straight to 2500-3000rpm and stays there for a few seconds and begins to race up past 3k sometimes close to 4k on its own where we promptly shut it off. Motor sounds mechanically fine, however we haven't ran it for more than 30 seconds. Usually only 5-10seconds at a time.
First thing I did was change the iac and tps with no change to the problem. Swapped in stock maf, same result. Double triple checked tps voltage it is always reading .96-.99 with the motor off. Double checked throttle body stop, it is positioned like it is suppose to be. Tried to isolate a vacuum leak, can not find one yet. Car pulls 15in of vacuum while its running, off of the stock gauge source. Re did the lower manifold with blower to heads install to make sure it wasn't a lower manifold leak with no change. Also made sure the lower intake vent line is secured on the under side of the manifold. Plugged all vacuum lines on back of blower accept for the lower intake manifold vent to pcv line. Same result, still goes to 2500 and begins slowly racing.
Tuner came over and messed with the start tune for the car, could not change the result at all. We even disconnected iac, tps and maf while blocked all air source from the throttle side car still wanted to run really rough at around 1000 (all vacuum lines were hooked up). Re loaded stock tune does same thing accept running ridiculously rich and smoking out my garage. Tuner is convinced it isn't in the tune, nothing he did cleaned it up at all to at least show a different problem.
This is a brand new motor, never has done a full break in. This problem has stumped multiple knowledgeable and experienced modular guys. We have endlessly searched the internet and this site with no luck to someone with a similar situation. Closet we have gotten was two old threads of people who did an EGR delete and had a 3k idle after, however they never posted a fix. Now I need your help!
-Matt
Current Mods:
Stock block .20 over
JE dished pistons
Nitride rings
Stock crank
Stock Rods
Stock heads refreshed/rebuilt, added manley springs, stock cams
Melling oil pump, new water pump etc
ARP everything
Fresh timing set
All seals, gaskets, rings etc replaced
Whipple 2.9 stock pulley
EGR delete
JLT RAI
SCT BA 3000
Afco H/e
Fore rails
Fore hat, dual gt pumps pprv delete (still returnless)
Dual fpdm/upgraded wiring
-8 feed
Seimens deka 80lb inj
RXT clutch, 28 spline i/s, MGW
Mac LT, lethal o/r x, magnaflow catback
autometer vac/boost, oil pres, water temp, wideband a/f
Anyway when we fire it up it goes straight to 2500-3000rpm and stays there for a few seconds and begins to race up past 3k sometimes close to 4k on its own where we promptly shut it off. Motor sounds mechanically fine, however we haven't ran it for more than 30 seconds. Usually only 5-10seconds at a time.
First thing I did was change the iac and tps with no change to the problem. Swapped in stock maf, same result. Double triple checked tps voltage it is always reading .96-.99 with the motor off. Double checked throttle body stop, it is positioned like it is suppose to be. Tried to isolate a vacuum leak, can not find one yet. Car pulls 15in of vacuum while its running, off of the stock gauge source. Re did the lower manifold with blower to heads install to make sure it wasn't a lower manifold leak with no change. Also made sure the lower intake vent line is secured on the under side of the manifold. Plugged all vacuum lines on back of blower accept for the lower intake manifold vent to pcv line. Same result, still goes to 2500 and begins slowly racing.
Tuner came over and messed with the start tune for the car, could not change the result at all. We even disconnected iac, tps and maf while blocked all air source from the throttle side car still wanted to run really rough at around 1000 (all vacuum lines were hooked up). Re loaded stock tune does same thing accept running ridiculously rich and smoking out my garage. Tuner is convinced it isn't in the tune, nothing he did cleaned it up at all to at least show a different problem.
This is a brand new motor, never has done a full break in. This problem has stumped multiple knowledgeable and experienced modular guys. We have endlessly searched the internet and this site with no luck to someone with a similar situation. Closet we have gotten was two old threads of people who did an EGR delete and had a 3k idle after, however they never posted a fix. Now I need your help!
-Matt
