LifesHarlequin

I've got a 95 z28 (4L60E) with the following modifications:

Kooks 1-5/8" Long Tubes
Magnaflow Dual High Flow Cats (not a California car, so stock car had single Cat)
Corsa Cat-back
K&N CAI
1.6 Roller Rockers
Dual Coil Valve Springs
Ported and Polished LT1 Cylinder Heads (2.0 / 1.6)
NGK Iridium Plugs
MSD Plug Wires

Currently she makes enough power to do burnouts with traction control off, but I've never had her officially dyno'd, nor has she ever been tuned. With A/C on, she never gets past 180-190 deg coolant temp. However, if I turn A/C off, the car will get hot (not over-temp) but hot at idle. As soon as I start moving, it will begin to cool down to 190-210, but as soon as I come to a stop again, the temp will immediately begin to increase. Also, after a good 20min running, the car will begin to back fire slightly given any moderate throttle, but will catch itself after a few seconds. Never the less, after the 20min running she will also feel as though she has a little less power.

My question is whether never having the car tuned could have this effect, and if this sounds symptomatic of a car running lean after the initial warm-up of the engine? The only other things I can think of is stock O2 sensors not enjoying the Kooks Headers, the NGK plugs just not agreeing with the electrics, Optispark is new, but fuel injectors aren't (bought used because strapped for cash and a bad shop somehow damaged my originals during my heads install)...

With the wife having lost her job, its very hard for me to afford taking the car around for diagnostic fees, so if you have any ideas, I'd truly appreciate them.

ss.slp.ls1

iTrader: (36)

How hot does it get? With stock tune, normal LT1 operating temp is ~210-225 degrees. What size injectors did you get? If the are a different size than stock, you need a tune, but with the other mods, you already need a tune anyways.

trippinholyman

yeah what he said, fix your tune. lt1 engines run hot in these cars with the way they were designed, as long as you dont get past 235-240 you're fine. you could just have unburnt fuel in your headers causing the backfire.

with all those mods def get a tune if you dont have one, youre wasting fuel, not running at the best mix you're losing power that you should have

Cross

iTrader: (10)

Kinda out there but you said with the AC on its fine and while I am not 100% sure on the LT1 fan setup I know most have a fan that comes on with the AC and one that comes on with the Coolant temp sensor... Possibly one fan is dead?

As they said though with different heads you should be tuned no questions asked.

But as for me on temps all my LT1 F-Bodys have never gone over 190-200 while crusing/stopped and I live in the desert. *Shrugs*

LifesHarlequin

Thanks guys.

The fuel injectors are stock, but used stock. The car won't over temp (230-245) but it will skirt it in idle, and you're right about the LT1 fan setup, which is why I keep my AC constantly running. The other fans do work, but I suppose I never noticed how hot the stock setup gets until after I got my mods.

I also just got an email from Jeff Creech from Carolina Auto Masters, and he agrees with what you guys are saying about the tune, so hopefully, since he's very well versed in LT1 tuning especially, he can sort it out.. just need to work up the money for the full dyno tune and catch him next time he's tuning in VA, and I'll let you guys know the results.

Jeff also mentioned something about how ported heads don't seem to enjoy stock cams, but told me he could fix it with the tune.