scarybowtie

iTrader: (9)

My bolt on, cam, 243 head 01 z started cutting out really bad under a heavy load, or in upper rpms wot. Its been throwing a tps code (dont remember which one) so i changed it but it didnt fix it. Put a fuel pressure guage on it and even at wot fuel pressure never dropped below 58psi. I had a bunch of spare parts laying around so we swapped mafs, cam sensors, and injectors to no change. Cam and 243s were on the motor when i got it so i pulled the valve covers and it looks like maybe 918 springs with aftermarket seats and keepers. Also trick flow 7.5 push rods. The cam is .580 .590 lift. I dont know how many miles are on the springs so could they be weak and floating bad? Or maybe a lifter failing?
Thanks for any input -Josh

Whiteaw57

iTrader: (2)

First thing id do and do it asap is have those springs checked. I had 918s on mine and a full history of the car. Still swapped em for peace of mind. Thats a tale-tell sign of worn out springs. They'll be breaking soon if thats the case

scarybowtie

iTrader: (9)

Definately the next thing I'm checking. Wasnt sure if there were any other ideas. I'll keep this updated

Whiteaw57

iTrader: (2)

well there are definitely a lot of things it could be but youre describing valve float symptoms on a setup youre unsure of the mileage on a somewhat failure prone spring. Id say thats cause to check them first if you catch my drift. Best of luck with it.

P.S. if it were me I would just put a new set of duals in it and be done. Know what you have in front of you. The new Brian Tooley set seems to be the new hot ticket at $219

Old Geezer

iTrader: (3)

"been throwing a tps code (dont remember which one) so i changed it but it didnt fix it."

This begs the question: Why throw all kinds of parts at it, when there's already an unresolved issue w/ the TPS code??
Sounds like time for a data log session.

scarybowtie

iTrader: (9)

I know that sounds like an ignorant statement. It was late and I'm on my phone. I had searched the code here on tech and it seemed to be a common problem. It might have been fairly common for cammed cars or maybe it was commin in ported tb cars? Also when i got it to my tuner he also said it was common and didnt affect anything and he turned the mil light off for that code. I'll pull the code again and report back.

scarybowtie

iTrader: (9)

UPDATE: i pulled the springs off and had them checked and ALL were bad. In fact one only had 70lbs. Seat pressure. So i ordered pac 1219s and installed and it still cut out. I performed a compression test and 2 cylinders were very low, so i pulled the heads and 2the valves were bent. (I assumed from the dead springs) so off to the machine shop they went for a rebuild. Got them back and they were like bramd new, installed them and the car did great! Till the first time i went WOT to redline. It started doing the same thing it was befpre... another compression test determined another cylinder had only 20psi compression. Pulled that head back off and sure enough another bent valve. Had the head fixed and began searching for the problem. The piston came out of the hole same as all the others and the lifters looked good. I got a flashlight and looked at the cam and it actually had grooves and pits wore into the cam from where the lifters rode???
So... not sure if that caused my valve to contact the piston but im starting fresh with a new cam and lifters and will need shorter pushrods.

99Bluz28

iTrader: (35)

The damage to the cam is most likely from the bad /worn out valve springs.

scarybowtie

iTrader: (9)

True. But i still dont see what caused the second bent valve with new springs and everything