dave70

iTrader: (2)

I just installed a 5 psi kit on a 02 firehawk .The car is all stock other than the turbo, injectors (42#) and 3200 vig converter. He went to get it tuned and the car pulls good to 4500 RPM then it just stops making power. They swapped plugs and still the same result. I'll try to post up the dyno sheet A.S.A.P oh and the plugs are TR6's. The car is still making 5.5LBS at 4500 but the car just falls on it's face as far as power. Any ideas ? Valve springs? Help guys anyone had this problem before?

Schantin

iTrader: (6)

If the car has a stock fuel system (ie stock pump) and stock springs.....either could cause the problem described. I'd address the valvespring issue first, as float will definetly cause the problem using stock springs. Running out of fuel is also possible on the stock pump. Not a good thing either and the symptoms for that are similiar too.

Good luck

ZL1Killa

iTrader: (17)

fuel, valve float, ...just check around and make sure everything is sound

gametech

iTrader: (1)

Stock valve springs are undoubtedly your culprit, but the pushrods will also go soon. Both are an absolute MUST upgrade with FI.

dave70

iTrader: (2)

the Afr is good but the springs is what i was thinking once the fresh plugs were in and it was still doing the same thing. And if springs are upgraded so will the push rods. Do you think 918's will be sufficient?

Schantin

iTrader: (6)

Should be. I ran 918's for the first ear after installing the STS. Did fine...w a TR224 cam on it too Forgot about the pushods. Change the springs....and the rods so they don't bend under the higher spring pressure.

cracker

iTrader: (1)

Make sure your tuner knows what he is doing. Datalogging is essential to any good tune and will probably answer your question.

Fuel Pump issue...

Injector Duty Cycle...

Valve float....

etc.

-Wade

dave70

iTrader: (2)

It's being tuned at Thunder racing. One of the best in the area.But after two days it still has them scratching their heads lol I'm sure they will figure it out though.I just thought someone on here might have encountered the same problem before. I haven't seen the dyno sheet yet but from what they are telling me it's not getting ragged and falling off at 4500 its just leveling out like a plateau. They seem to think it might be bad cats. And the owner is thinking of letting them fab up a ORY for it but from what I'm told that will be extremely loud.I've heard some guys are putting bullet mufflers in the tailpipe after the turbo. How well does that work?

MonochromeSS

iTrader: (1)

I definitely wouldn't run cats on a STS. If one of those comes apart, it all goes into your turbo. Its happened before. And it wont be THAT loud w/o mufflers.

quik01ss

iTrader: (24)

i maxed out at 4700 rpm with 524 hp and 557tq and then it dropped on the dyno but when your on the street it doesnt stop pulling??

dave70

iTrader: (2)

haven't run it on the street yet. It's still at Thunder Racing.

quik01ss

iTrader: (24)

hmm try it on the street if it doesnt let up after 4500 i htink itll be ok, people said having a turbo on a dyno sucks but i dont know...also i have no cats and it still drops off after 4700

BFEGTO

take off the cats! i would rather hear a little more exhuast than having to replace the turbo.

dave70

iTrader: (2)

Well chris at sts also said the cats (stock ) could cost as much as 30-40 hp But high flows work well. I'll give the owner of the car a call he is going pick it up today

smoke20

iTrader: (2)

get rid of the cats , i run a bassani offroad y-pipe and i have a straight thru bullet in the tailpipe. car runs like a raped ape.

Zombie

iTrader: (2)

i'd say there is a 95% chance the problem is the springs. Everyone trys to cheap out on the valve springs for some reason. Stock springs are not strong enough. I floated the valves and customized my pistons on 918's but they should be ok if you keep the boost below 12psi.

Blackbird

I agree with springs. Kinda suprised a shop like Thunder would even be scratching their head on that one.

I only have 915's and they are 6 years old now and the car now stops pulling right about the same place as yours circa 5000 rpm on just 5.5psi. Pulls great til then and then just falls over and I know it's not my tune.

Dual valve springs are in my future one of these days.

Get those springs upgraded and let us know how it turns out.

dave70

iTrader: (2)

I'll do that i just wanted to check on here to see if anyone had any ideas other than the valve springs. Thunder thinks it may be bad cats. I'll post up results.

geeteego

iTrader: (1)

Cats, def. Valvesprings, def.

I would never run FI without at least an aftermarket fuel pump, valvesprings, and hardened pushrods.

02 hawk

iTrader: (11)

Yup that's my firehawk having the problems.....so i upgraded the valvesprings and pushrods....AND IT'S STILL DOING THE SAME THING....i guess the fuel pump next?????