KyleW707

Car is a 97 z28. When I originally bought it, as far as the engine goes, it had stock heads, lt4 hotcam, and shorty headers, ran fine. Then did a full rebuild and added le1 heads, cc503, long tubes, tune, again, it ran fine. Then did le2 heads, cc306 and now it runs rough at idle. I can hold it at 1000-1200 rpm and it smooths out, and when I rev it, it's smooth as can be, doesn't hesitate or anything. Fpr, injectors, and acdelco (denso) o2 sensors were on the previous build and were bought new (build had about 200 miles on it before I tore it down again), but I checked them anyways and they're fine. New acdelco plugs gapped at .45 with the le2 and c306. I can think of only two other things that may be causing this. One, would be the plug wires, from when I bought it until now, it had Taylor 8.5mm wires, without giving it much thought, I replaced them with new acdelco 7.5mm. Problem??? Two, it's still not tuned for the le2's and cc306, it's still on my le1 and cc503 tune, but I think that's less likely of the two. Any other ideas? Pulls no codes, and never has besides an icm code, that has been there since I've bought it, but I haven't had any problems with it.

big hammer

does it sound like this?

draggin97s10

iTrader: (2)

Needs to be tuned

KyleW707

This is it, you can hear it almost die after the 2nd rev. Idling the whole car shakes. I understand the cc306 is choppy, but I also know the difference between choppy and rough. It's more like a big or multiple misfire, but it's not pulling any misfire codes, not even po300 (random/multiple cylinder misfire)

http://youtu.be/FSNaeg6hDi4

pillarpod

I would start with ^^THIS^^ problem first.

guppymech

iTrader: (7)

Probably the lack of a tune for the 306, idle sounds too low for that cam.

KyleW707

Guess I'll start with the tune, won't be back in town until next weekend though! I'll have to get a obd2 mail order until I can get it to my tuner. Still looking for a 94-95 pcm so my guy can tune it though. If y'all hear of one let me know

guppymech

iTrader: (7)

Madtuner sells pcms, at least until Sept 1 when he ditches the LT1.

KyleW707

Old tune was through pcmforless, probably will just have them reflash it and go from there

BALLSS

if you have a scan tool, check IAC counts at idle...are they pegged at 160?

email your tuner and ask if your tune needs to be adjusted for this new cam (likely)

KyleW707

I do have one, but currently out of town for work until next weekend

KyleW707

Good thing about my tuner, he used to have a lt1 with the 306 so he shouldn't have any problem tuning mine!

Spartan7

iTrader: (7)

There's your problem right there. They suck, get a decent tune from someone else. I would also do what was said before, and check your IAC counts.

I ran a 228/236 just fine for a few miles on a tune for a 222/230 and it did not have the problem you had, just throwing that out there.

Puck

iTrader: (17)

With a cam like the 306 with its lazy lobes and high overlap you most definitely need a tune. Preferably a proper dyno tune, not a mail order.

KyleW707

I do plan on getting a dyno tune, but have to get an obd1 pcm first. But like I said, outta town until next weekend. I'll get the tune done and report back

96TransAmboosted

iTrader: (8)

My 306 car needed a tune before it would idle at all.