Rough Idle

[MSz28]

For the last week or so I have noticed a rough idle in my Z28, After driving when I put it in park the idle seems to get rough, not bad but not "normal". I have changed fuel filter a month ago or so. Any ideas?
also, it's an automatic

[prietodogg]

How bout spark plugs and wires????

[sunsetorangess]

How many miles are on the car? Plugs and wires? Are any of the wires burnt? I would reccomend pulling out your iac motor and clean with some crc maf cleaner, and also pull off your maf and give it a good cleaning with the same method.
J

[70RScamaro]

i would check ur EGR , when they get stuck open it makes ur idle little lopey and sometimes they really bad and almost acts like u got a huge cam in it, i would look here first.

[MSz28]

mileage is 72,xxx , wires look okay, but I probably need to change plugs and wires soon, will check egr, also I plan on cleaning maf, but what is iac motor

thanks for a the help and advice

[MSz28]

found out what it means, idle air control motor, but I have not found any pics, maybe just did not know correct name for it

[sunsetorangess]

Its what controls your idle, here is a pic on my 01 SS
J

[MSz28]

thanks abunch for the pic sunsetorangess
I will try cleaning this weekend, on the maf do you just spray and let it dry, you don't touch the wire or sensors is what I remember hearing

[SSpdDmon]

It could be the O2 sensors on the way out too. Best thing to do is find someone with some software and have them scan the car while you go for a drive. Otherwise, it's a guessing game as to who's right (IAC, NBO2s, Plugs/Wires, Vacuum leak, etc.).

[sunsetorangess]

It could be the 02's but they normaly throw a ses light. Not too shoot down your idear but too have someone hook it up too a Diag. comp it will cost about 100 bucks, so cleaning a few parts would be alot cheaper.
Just get some crc maf cleaner from your parts store and spray it down and it should be fine. You can clean the iac the same way.
J

[SSpdDmon]

It could be the 02's but they normaly throw a ses light. Not too shoot down your idear but too have someone hook it up too a Diag. comp it will cost about 100 bucks, so cleaning a few parts would be alot cheaper.
Just get some crc maf cleaner from your parts store and spray it down and it should be fine. You can clean the iac the same way.
J

Depends on where you go. I have software and I know a few people with software. If someone just wanted me to take a look at their car, I wouldn't charge 'em. If they wanted to slip me a $20 out of the goodness in their heart for taking the time out of my day, I'd be ok with that. You just have to ask around...there are quite a few people in Texas that post up in the Tuning section over at LS1Tech.

[MSz28]

I am running a k & n, so there may be some oil in there that needs to be cleaned out? The cleaning will not cost anything right now so I am going to try that and want to change plugs soon. Then if I get a contact on some software it would be good to see how everything is running

thanks again with all the help

[sunsetorangess]

Yepp, thats the reason i yanked my K&n and put a stock filter back in there. Had oil on the maf twice so i was done dealin with it.
Hope all the info helps ya
J

[blue02Z]

clean your TB as well, it can make the idle ruff if there is buildup around the throttle plate

[MSz28]

I am thinking of taking out the k & n, I have a SS hood from suncoast creations with the functional air box, it came with the k & n, does anyone have this kit and would a oem SS filter work
I do not have part number on the k & n, so not sure if same set up as original ss's

[sunsetorangess]

yes and oem filter should fit just fine, If you have any doubts just take the old filter in with you and match them up.
Shouldnt have a problem thou
J

[Steve Crowe]

Cleaning the IAC:

Unplug the electrical harness from it then remove the two mounting screws (usually Torx)

Gently rotate and slide it out. You will probably notice a buildup of carbon &/or varnish on the pintle, a paper towel and a bit of B-12 or other carb cleaner will do the trick. It's also a good idea to clean the seat the pintle rests in, a few blasts of carb cleaner or better a Q-Tip soaked with cleaner will work here.

NOTES:

If you eliminated the easy things and changed the plugs & wires it could be one or more of your injectors has a poor spray pattern thus a professional cleaning is in order. We sell an injector cleaning kit that will hook up to the cans of professional cleaner and do every bit as good a job as the $300 - $600 kits.

Also, and I'm not sure if it's this way on an LS-1, but many GM engines will miss a bit at idle IF IN PARK but not if in gear. In essence since you're in Park the PCM knows you're not going to be moving anywhere so it really pulls the idle mixture and timing to the extremes - pollution thing.

[MSz28]

cleaned iac and maf sensor, they had some build up on them, also cleaned throttle blade and housing as good as I could. drove car and seem to run a tad better but then when I came to a stop idle was not smooth, still a little rough, took egr deal off and cleaned, crank it up with hood open and heard air sound.
I guess it is a vacuum line, it is just under hose that runs to top of throttle body. The piece had a hole melted in bottom and looked dry rotted and when I squeezed it the motor almost shut off. It is only 2" long and connects to a line that runs back on the valve covers. any idea what the correct name is for this? One end has a lip on it.

[SSpdDmon]

The hose that connects the top of the TB to the front of the passenger side valve cover is just a vent hose. If you need to replace it, stop by the local Autozone/Napa type place and ask for a few inches of 3/8in. vacuum hose that can be used on your PCV system. Cut it to size and slip it on.

[MSz28]

it's actually a hose underneath the hose that connects to top of TB, I figured any vacuum hose would work, just this one has a lip on one side, maybe just to help pull it off. will try napa on way home