Okay i can really feel this happening from third gear on up because what happens is that when vtec engages on my gs-r (5200rpm) the car just falls flat on its face and when the car finally goes past 5600rpm then it starts pulling like in normally does.
First and second i can t really notice the difference because the rpm's go by substantionally faster.

The car is not stock. its a built gs-r with s2s2 cams, CTR pistons 81.50mm, 3 angle valve job, milled etc.

I know someone will say that the cams need a higher vtec crossover but i disagree with that because i got it tuned 4 weeks back and have not changed a single thing since then, and the car pulled and felt crisp.

This loss in power problem just started happning 1 1/2 ago.I had started noticing it when my car started to run really rich and would keep stalling out and dying at idle. Well it turned out that my intake valves were showing a 60% leakdown so what had happened was that the air was just getting past the valves and the fuel was just stuck over there drowning the motor.

I got the a new valve job on the head since then with over sized valves, new guides and everything and the car seemed to run a whole lot better but it would still stall out randomely. Well this time we saw that the TPS was reading at 27%, so basically the car is dumping fuel when it shouldn't at idle.(still runs rich)

Now my question for you guys is that given this TPS problem could it have something to do with the car loosing power right when vtec engages and then400 rpms later it goes to the way it should be?

Also what other factors could be considered to this mystery stalling problem?

I know its a long read but i've been going everywhere and a lot of people, including myself are stumped about this damncar!! I would really appreciate the help guys.


the car is tuned with a hondata s200 system and i did take it back to the tuner to see if it was the tune but it wasn't nothing had been changed on it. this is also where we found out that the tps was reading higher.
Among other thing the oil level and everything is fine as well

 

thanks again guys

 

check your catalytic converter for cloggage.

 

I have no cat all i have is a test pipe in there.

 

how good of a tune did you do on it?

 

very reputable tuner John from LHt performance down here by tampa. I already took it to him and nothing has changed on the tune. The car felt crisp when i got it back after it was tuned. Now it just does this, along with the idle problem.

 

your AFR at VTEC looked good then?

 

yup the airfuel and everything was fine. Could the Tps be throwing it off?

 

A bad TPS could give symptoms like you've described. Swap throttle bodies with someone and see if it runs smoother.

It sounds similar to an experience I had and it was the TPS.

 

I just got a new tps ill put it on in a day or two and let you guys know what happened.

 

Skunk2 website says you cannot runs S2 cams with oversized valves. Check your clearance on the VTEC lobe because the valves might be hitting each other