fivepointo

I have a 1998 M6 Z/28 with 150,xxx on it. simple bolt on's. LS6 intake, ported and polished tb, long tubes, !cats, full exhaust(don't remember which one), lid, bellow. Since I have owned it (about a year and 10,xxx miles), I have installed nothing else. changed nothing but the fuel filter.

My Problem: After I've driven the car and it warms up to normal operating temperature, it acts like it doesn't want to crank. It ALWAYS does, but turns over for about 3-4 seconds before it does, and it sputters to life while sounding like it has a monster cam in it for about 3-4 seconds. Then clears up and runs great. not lacking on power, I'm outrunning new auto 'Vettes and new stick shift 5.0's all day. no miss fires, overheating, smoking, etc. No check engine light(It is there, comes on when you turn the ignition on just like it's supposed to). Please give some direction because I really don't know which way to go.... Thanks, Kenny

Burken01

iTrader: (88)

If your out running new vettes and 5.0 mustangs then you have to have a cam in there, at least...

You might have mods that your not aware of, did he dyno tune it (previous owner)

fivepointo

no mention of dyno. just that it was tuned. no loping idle at all either. heads are factory casting. seems stock, but i can't really know for sure

Burken01

iTrader: (88)

Hmmm what's the head casting number

3rdCoastPowerSports

iTrader: (5)

i know you said no misfires but did you scan it with a scanner (not scan tool) and look at the misfire count on each cylinder? don't get to excited about smoking auto C6 corvettes, they are slow as ****. GM really missed it on the trans gear rations on the auto C6's

fivepointo

I'll have to look at the head casting when I get home. Don't remember. which two were offered that year? i would remember between the two.lol

03Sssnake

iTrader: (20)

perimeter bolt heads, 806?

fivepointo

think so. i know its not the 853s

fivepointo

I havent looked at it with a scanner. I can borrow a snap on solus if need be.

ds98formula

iTrader: (3)

I agree he could have more then he know. However bolt on cars can and do out run the new stock 5.0 it won't be by a lot but they do.

fivepointo

I would say it's because of the E.T. Streets, but they were roll races. but anyways, anybody have any experiences similar to what I'm having? I've been told coil packs are worn out, been told crank sensor, cam sensor, etc. but I really don't wanna just go start changing parts ya know

fivepointo

any ideas? please?

Burken01

iTrader: (88)

Its almost impossible to diagnose it over the internet... But pull a spark plug out and see what it looks like...

I just did my wifes eclipse and they were all burnt out lol no wonder it had a rough idle and under acceleration it would sputter for a sec and then take off.. new spark plugs and spark plug wires fixed it $25 bucks

If all you have done is a fuel filter change on it since you owned it, then it couldnt hurt to do spark plugs..

fivepointo

this true. the only thing it could hurt is my nuckles.lol

fivepointo

knuckles

fivepointo

I wish I could get in touch of the guy I bought it from. he is on here somewhere but don't know his sn. lives in Mobile Al. supposedly the car came from arizona or new mexico or something.

Burken01

iTrader: (88)

yeah it sucks espcially if theres not check engine light on to help you pinpoint the problem... but if you plan on keeping the car for a long time then a little money thrown at it won't hurt..

fivepointo

im actually trying to sell it.lol

PAGregSS

iTrader: (10)

I'd put a fuel pressure gauge on it. Sounds to me like your fuel pressure is bleeding off and the car needs to crank a few times to build it back up. With those kind of miles, without a new fuel pump, it could be the issue.

fivepointo

that was the first thing i could think of. but it wouldnt make sense to me because it would bleed off over time, but when you let the car sit overnight it fires right up. after you drive it and shut it down for 5 or so min, it doesnt want to crank. I may be wrong though, and any insight on that if im wrong would be greatly appreciated..... thanks to everybody so far btw.