Nate's 1998 Z28 Project

[nascarnate326]

Thanks guys.

[JoeliusZ28]

I'll hand it to you, that sounds great! Unfortunately cats would ruin the sound on my car though.

[nascarnate326]

Given my current exhaust setup it just had to be done, your car is perfect the way it is.

It is a bummer that the air conditioning pulley is making tons of noise now, going to need a new condenser. This car sitting for so long just caused so many more problems than I ever intended on. O well.

[nascarnate326]

Well, this weekend marks one year that I have had my car. Looking back I 100% am glad that I ditch my LT1 car and upgrade to the LS1 car. My only regret is that I didn't get a trans am but this thing is tons of fun and I love it.

Some pics that Scott took a few weeks ago:

[nascarnate326]

Remember a year ago it looked like this:

[meissen]

Great transformation Nate!

[nascarnate326]

Anyone have any info or diagrams on the vacuum system for this car?

Randomly it will just idle really high. Last night it went to new levels - 3k. Yes, a 3k idle while moving. Come to a stop and it mellows down.

I pulled into a gas station and turned it off, after I restarted it the 3k idle issue was gone but it just wasn't running good. Seems more and more evident that I have a vacuum leak some place, just can't find it. d

[kammi10]

Anyone have any info or diagrams on the vacuum system for this car?

Randomly it will just idle really high. Last night it went to new levels - 3k. Yes, a 3k idle while moving. Come to a stop and it mellows down.

I pulled into a gas station and turned it off, after I restarted it the 3k idle issue was gone but it just wasn't running good. Seems more and more evident that I have a vacuum leak some place, just can't find it. d

did you ever get the issue in the tune taken care of that was making it do this too?

[nascarnate326]

did you ever get the issue in the tune taken care of that was making it do this too?

Anyones that rode in the car doesnt think its the tune. I don't either, its got to be a vacuum leak.

Cant take it to a tuner because its got an issue and its been made pretty clear not to take junk to Phil.

[Superman09]

Anyone have any info or diagrams on the vacuum system for this car?

Randomly it will just idle really high. Last night it went to new levels - 3k. Yes, a 3k idle while moving. Come to a stop and it mellows down.

I pulled into a gas station and turned it off, after I restarted it the 3k idle issue was gone but it just wasn't running good. Seems more and more evident that I have a vacuum leak some place, just can't find it. d

I don't have a diagram but check:

TB, front of Intake manifold, Rear of Intake manifold at brake booster, HVAC port, and MAP sensor. PCV ports on valve covers, grommet in back right of valve cover. Check PCV lines for a crack or one collapsing on you.

[Schuby87]

Vacuum leaks don't typically happen randomly. Check the IAC sensor.

[nascarnate326]

Vacuum leaks don't typically happen randomly. Check the IAC sensor.

Replaced that a few months ago.

If it was a vacuum leak, would it happen all the time or just when I'm moving and push the clutch in?

[nascarnate326]

Any other ideas? Cant see a vacuum leak, sprayed each of the areas with carb cleaner and the idle didn't change.

Now it stalls.

What the heck happened?

Here is a video:

[landstuhltaylor]

I have the full official service manual for the 98 if you want me to grab anything out of it.

[hoogiesngrinderz]

Your tune looks to be off just by the numbers on the scanner. With air temp above -10 degrees, the system should be in closed loop when coolant temp hits 94°F (O2S11 and O2S12 should swing and STFT should change) and LTFT should kick in around 149°F. I can tell that your open loop is running lean. Timing looks like it has been adjusted for the cam. I bet RAFPN are a little high and throttle cracker needs reduced or get zeroed out, assuming there are no vacuum leaks.

Very common leak area the y connector in the PCV system right behind the intake manifold.

I can send a message to Darius and see if I can borrow EFIlive for a little while, might be able to get the street manners a bit better. I also have a Zeitronix ZT-2 that integrates WB02 with EFIlive for datalogging, great for VE and MAF tuning.