banditz28

iTrader: (8)

I just finished installing a comp cams 224 cam in my z28 along with pushrods, stock rockers, springs, oil pump, timing chain. I finally got it back together and cant get her to idle. i tried the post about not drilling your TB just adjusting the screw and reseting your tps.

https://ls1tech.com/forums/pcm-diagn...er-tuning.html

I got it to the point where it will fire right up but as soon as you try to let if idle it backfires like hell then dies. I've heard of many people running this cam and some bigger on stock tune without problems. I dont know why mine is having so many issues.

Also i am using hptuners the early serial edition, but the newer edition will be here on saturday. I just need her to run enough to get her to the tuners. any advice/tips would help.

Doc

iTrader: (9)

Did you try a TPS reset? Anytime you move the TB set screw you will need to perform this function. With the key on engine off, disconnect the TPS pigtail from the sensor. Shut off the vehicle. Reconnect the pigtail to the sensor. Key on, engine off, connect the scantool. Verify you have a TPS DTC. Clear the DTC. You are now reset. You have to have the failure and reset in order for the system to re-learn the new physical zero / closed throttle blade position.

banditz28

iTrader: (8)

I tried reseting the tps and it worked but that still doesn't solve my extreme backfiring issue. im gonna try to upload a video of it.

banditz28

iTrader: (8)

nothing?? should i return the screw back to stock position and try drilling the TB to see if that helps. im guessing the backfiring is due to me running stupid rich because of no tune but there has to be a way for me to get her to run just down the street,

5.7 ute

Not necessarily. Have you confirmed the cam is installed correctly? Rocker geometry & lifter preload is correct?
A small cam like that shouldnt have too many issues with a near to stock or stock tune IMO.

Doc

iTrader: (9)

Really no need for drilling the TB as the thread you pulled up stated. You did not mention what type of exhaust you are running? An exhaust leak on an untuned car can cause the pcm to indiscriminately dump fuel like you are describing.

banditz28

iTrader: (8)

I'm running loudmouth pipes with a cherrybomb muffler with no cats. I know before the cam i did have a few backfiring issues but mostly only when it was coming down from high rpms. There is a little leak on the drivers side pipe just after the o2 sensor where its not fitting right after I had to take it off for the install of the motor mounts. also i dont know if I mentioned it before but when i first fired it up it idled fine but that was just open headers.

01Z28M6

Like 5.7 ute wrote about checking the install. I would be wondering if I was off a tooth on the timing chain.

banditz28

iTrader: (8)

That seems to be my only option right now so i'm gonna tear it down to the timing chain and double, triple check it to make sure its dead on. but the car runs fine at a higher rpm would it do that if it were 1 or 2 teeth off? again thanks for the replies i'll keep ya updated.

Texas_WS6

iTrader: (9)

Pull a plug and do a compression check before you take it apart. You might get lucky and find the compression is good, if the cam was out of time enough to cause backfire, I would expect the compression gauge would read low. just a thought to hopefully rule out cam timing. Or if you have a degree wheel you can check the valve events, this will tell you if the cam is installed correctly or not.