Engine Idle RPM for a 02 Manual

[kool-aide]

I have noticed ever since I took ownership of my 02 z28 the idle RPM seems high.

I am almost positive after my old 99 z28 warmed up it would idle at about 600 RPM, ish.

The 02 z28 is a constant 800-900 RPM, from cold to hot, all the time.

Is this normal?

[kool-aide]

so i started to dig around for other similar posts.

i neglected to mention the car as an after market exhaust and tips. As far as I can tell it is not a cat back, muffler and tips. The intermediate pipe steps up twice just before the muffler connection. It steps up to a diameter that looks pretty close, if not same, as the tail pipes. The tips are only a little bigger the the tail pipes.

So I disconnected the battery. The car has had three owners before me and the batter is dated 7/09. It may be safe to assume with such a new battery it has been unplugged since the muffler install.

I also read some one mention it could be a dirty MAF. I can say this car had all kinds of dirty and bugs all over the upper area of the radiator and A/C coils. I had never seen dirt and bugs caked on like that before.

I noticed the screen for the MAF caught its small share of debris.

How do you clean the MAF without busting the wires? I would think TB cleaner shoots out with too much force. Do you spray it with something from like 3 feet away or what?

[Firebirdjones]

Stock tune shoots for 550 rpm.

I set both of our cars higher, didn't like the 550. I have one at 700 rpm and the other with a small cam I have at 850 to help smooth it out a bit.

Maybe someone has changed yours in the tune??

[Firebirdjones]

I use MAF cleaner that can be found in any parts store.

[kool-aide]

i also noticed some one mentioning an idle control motor on the throttle body. Maybe that needs a cleaning. So of course i will ask what does it look like and exactly where is it on the TB?

considering the amount of dirty and nasty stuff all of the radiator. I'm guessing i need to clean a bunch of stuff.

If I had a vacuum leak would I hear it? I just replaced the PCV. The hose was cracked and I had to use new rubber and the ole brass fitting replacement gig. Now one thing I noticed about that PCV setup is the metal ground that sticks out. That is not exactly making a nice air tight freezer fresh seal there. I seriously question the air tight fit of the factory hose too.

still searching for ideas of why the car idles at 800-900. I am only guessing this is higher than what it should be for a non-mod car.

[00z28bubba]

does it run bad or strange at all. or is it just the rpm that makes you worry. mine idles at 650ish after the battery was changed. i dont remember what it was when i initially got it tuned.

[Wesman]

An idle of 900-1000RPM sounds about normal to me, thats where my car idles at. Manual transmission equipped cars idle higher than the automatics to prevent stalling.

Was your '99 Z28 an automatic??

[kool-aide]

personally i think it has excessive knock. I call it piston slap but full time, not just on the cold start up.

Its to early to tell if my MPGs are suffering. I haven't driven "nicely" enough to measure the MPGs. I can tell you i just spent money on 10.2 gals and only got 172 miles out of it. I would say that is far below what my Auto ever did. I was pretty solid with 19-20 MPGs on the ole 99 Auto.

[kool-aide]

at first I thought maybe the knock sensor was bad because it knocked longer than i thought it should. I guess i was spoiled with the 99. It had zero piston slap, . That engine rocked, oh my, what have i done, lol....

[kool-aide]

I also think the car rumbles more like my 99. I know the 99s had a different CAM. But this seems like it is a nice CAM idle, but since this baby is bone stock. I am curious why it would give a little shake like my 99. Again, I don't know how much of this is normal vs me being super picky over sensitive.

[redbird555]

I think the 02 tend to have a bit more piston slap than the other years mine and a friends have more than my buddies 2000 did and another friends 98. The mileage varied between all cars too. But from other 02's ive heard it just seems like theyre noisy lol. Mine goes away after about 15 min of driving, weird but Ive also found dino 10w-40 pennzoil oil takes it away the most and quickest even better than german castrol.
Dan-

[Mr. Luos]

Stock tune on my 1999 M6 had warm idle at 800 RPM.

[Firebirdjones]

Wow, sounds like alot is going on with your car. Poor MPG according to what you posted (170 miles and 10 gallons) is 17 mpg. Plus the car shakes at idle but it has stock camshaft. Possible vacuum leaks etc...

I don't know, maybe sounds like tuneup time. I'd go through the whole car, plugs, wires, clean throttle body, iac pintel, maf, filter, and look into changing the front pair of 02 sensors if it's been 50,000 miles or more.
I'd also run a good quality injector cleaner through it for 2-3 fillups. Something like Lucas fuel treatment.

See where that gets ya.

[kool-aide]

I think the 02 tend to have a bit more piston slap than the other years mine and a friends have more than my buddies 2000 did and another friends 98. The mileage varied between all cars too. But from other 02's ive heard it just seems like theyre noisy lol. Mine goes away after about 15 min of driving, weird but Ive also found dino 10w-40 pennzoil oil takes it away the most and quickest even better than german castrol.
Dan-

Ah. Yeah on my 99 I always used 10w-30 Dino. I bought it w/ ~90k miles so I figured no way I will ever know what the prev owner did.

On this 02 it has had 3 owners and one of them lived somewhere with a ton of dirt little rocks and bugs.

[kool-aide]

Wow, sounds like alot is going on with your car. Poor MPG according to what you posted (170 miles and 10 gallons) is 17 mpg. Plus the car shakes at idle but it has stock camshaft. Possible vacuum leaks etc...

I don't know, maybe sounds like tuneup time. I'd go through the whole car, plugs, wires, clean throttle body, iac pintel, maf, filter, and look into changing the front pair of 02 sensors if it's been 50,000 miles or more.
I'd also run a good quality injector cleaner through it for 2-3 fillups. Something like Lucas fuel treatment.

See where that gets ya.

yeah, this car definitely lived in some dirty place and I don't me dollar bills. I have a bottle of STP waiting for the car. Maybe I will splurge for the Lucas.

Change plugs and wires, ah man...It took me like 3 hours and a pint of blood on the 99... Can't I wait a little longer, lol...

How do you clean the IAC pintel? And where the heck is that?

[kool-aide]

I dunno, maybe an idle between 795 and 815 is normal.

I finally remembered how to pull up the data using my scanner. It had a pretty steady 795-800 with occasional 805s, 810s. 800 seemed to be the most often number.

[Wesman]

I dunno, maybe an idle between 795 and 815 is normal.

I finally remembered how to pull up the data using my scanner. It had a pretty steady 795-800 with occasional 805s, 810s. 800 seemed to be the most often number.

Sounds 100% normal to me.

[kool-aide]

guess i was so used to a lower idle cuz my 99 was an auto.

i thought the manuals idled the same.

[Mr. Luos]

i thought the manuals idled the same.

Stock setting is at 800 RPM for the manual.

[hutch1999]

My 98 idles around 800, I haven't had any problems in the last few years. So you should be fine.