Harsh Idle

[nj96z28]

my 96 z decides it want sto idle rough after long drives. More specifically it was at its worst this last weekend when i drove back form philly and had no traffic a good open run and then suddenly bam right as im getting off to teaneck cars everywhere. Starts shaking like a ***** at idle but no other time. ive had checked the codes with a professional scanner and all i get is a weird evap code. plugs are brand new, and i just did the fuel pump .... it was doing this before the fuel pump so i know thats not it. also notice when i do a regular launch out of 1st gear( meaning not driving like a nut) it vibrates....
tranny mount? engine mount.... i cant afford the labor on a distributor and wouldnt it come up in a code?

[Tru2Chevy]

I doubt that it's a tranny or motor mount....you would most likely feel the effects of either of those the most when "driving like a nut"

- Justin

[ar0ck]

Does it feel like its breaking up the higher into the RPM's you go?

[JL8Jeff]

You might have a vacuum leak at one of the evap hoses which is allowing too much extra air in at idle. Also, check the rubber intake elbow for rips or tears where air can get in past the MAF. Check to see if you can suck or blow air through the evap line up near the intake. But be careful, you might get a mouth full of dried out charcoal if the cannister is going bad. Don't ask me how I know! :wink:

[nj96z28]

hmm the code is an evap code so ill check thanks

[Pampered-Z]

Check the EGR valve too, that dang thing will make the ECM throw all kinds of oddball codes.

[nj96z28]

im starting to get ideas about a carbeurated 400 and get rid off all this silly egr/air/computer..... who knows need a job and a beater first

[nj96z28]

my cousins gonna scan teh comp and get the cde for me tommorrow night and ill post it to see if anyone is familiar with it... meanwhile im going out to the garage to see if i can find a leak somewheres

[Pampered-Z]

Look at the basics first; How old are , wires, fuel filter and PVC valve and air filter?

Maybe the ICV is dirty, might just need to take off the throttle body and clean the ports?

[nj96z28]

Look at the basics first; How old are , wires, fuel filter and PVC valve and air filter?

Maybe the ICV is dirty, might just need to take off the throttle body and clean the ports?

wires need replacing , everything else is brand new and the throttle body got cleaned out less than a year ago...er i ned to do fuel filter and wores... just did egr valve yesterday. i have the filter and wires... not looking forward to the wires lol

ok just went out to do wires and fuel filter.... dont have the patience fo rthe wires and my fuel filter is rusted on .... cant get that nut off . even sprayed a ton of yield on there let it soak for a few minutes and it still wont com eoff :(

[Tru2Chevy]

ok just went out to do wires and fuel filter.... dont have the patience fo rthe wires and my fuel filter is rusted on .... cant get that nut off . even sprayed a ton of yield on there let it soak for a few minutes and it still wont com eoff :(

spray it with PB Blaster every day for a week.....shouldn't have a problem then.

- Justin

[bobb1589]

Check the EGR valve too, that dang thing will make the ECM throw all kinds of oddball codes.

agreed i had a 24x loss of signal on the ignition system when im reality my egr was bad

[nj96z28]

well i put the new EGR in and the harsh idle situation is gone . ty all for the suggestions. They really put that EGR in a extra special place on these lt1 f-bodies lol.