billy bronco

Cleaned my throttle body last night and car starts better and seems to run much better but the idle is now at about 1000 and seems a bit high. The first thing I noticed was when I first start it cold it goes to 1500, didn't do this prior and drops off as warming up, but only down to 1000, any ideas?

mzmtg

iTrader: (11)

Reset the idle speed. Follow the procedure in your Haynes manual.

Julchen

Same thing happened to me. I had to adjust the idle. You'll find the procedure in the stickies. The high idle when the engine is cold is totally normal. Almost all newer cars do this in an effort to warm the engine and catalytic convertor as soon as possible to reduce emissions. My car will actually hit 1800rpm for a couple seconds if its really cold out, then drop down to 1500rpm, 1000rpm, and finally 700rpm when fully warm. There is a cold-idle component system designed specifically to perform this fuction.

Greg

caudio51

yes mine does the same as well

billy bronco

Thanks I'll read up on the idle adjustment, I want to do a few other things too seeing I'm playing arround. I want to replace the plugs and slap in a K&N that's all for now. I noticed the air filter was pretty dirty last night when I pulled things appart to clean throttle body.

caudio51

any links on how to clean the throttle body?

VQuick

iTrader: (17)

You could also try resetting the ECU, that's what I did. It might need to adjust to the cleaned TB. After I cleaned mine, my idle went up, but I reset the ECU soon after and now it hits 1500 on cold starts before falling to 650.

Motorvate.ca has the write-up on cleaning the TB.

billy bronco

I can't seem to find the idle adjustment procedure, is there a quick link to it?

blaze0ne

i will be doing this today cause im sure my tb is diiirty
here's a link on how to clean your throttle body
http://www.motorvate.ca/mvp.php/517

blaze0ne

http://forums.maxima.org/showthread....dle+adjustment
http://forums.maxima.org/showthread....dle+adjustment
have some info on adjusting your idle

caudio51

this looks simple gonna do it right now

caudio51

Just to make sure I know how to do this before I clean my throttle body:

The proper way to adjust the idle speed on 95 - 99 is as follows:

Warm the engine up to operating temp, at leaset a 15 min. drive.
Shut engine off and disconnect the TPS.
Restart the car, the CEL should NOT be on.
Adjust the idle speed to ~650 RPMs, neutral, no accessories on.
Turn engine off and reconnect the TPS.
Restart engine, if the idle speed is not correct adjust it using the IACV bypass adjustment screw to approx 700 - 750 RPM.

You need to set the default idle speed at the throttle body first, then adjust the IAVC only if necessary to correctly set your idle speed.

Where does the initial adjustment take place before the IACV bypass adjustment screw? Is it at the cables on the throttle body?? The CEL is what?

billy bronco

I can't find the computer, according to above there is a lot of steps, to adjust the idle, what is the TPS and IAVC, holy crap I'm lost! I can't even find the spark plugs, help!

ALC252DM

The best way to adjust idle speed is after the engine has warmed up. I did mine after running a few errands.

According to Chiltons for 95-98 Maximas (VQ30DE):

1) Make sure all accessories are turned off, even the radio,radar detector, etc., anything that will increase the load on the electrical system. Ensure that both manual and automatic transmissions be on the neutral position. Steering should be centered.

2) Visually check air cleaner for being clogged, hoses and ducts for leaks.

3) Unplug the throttle position sensor, and then start the engine. Rev the engine 2-3 times up to 3k rpm and let idle for 1 min.

4) Check idle speed. According to Chilton's, idle speed should be 625rpm (95-98 MT), 700rpm (95-98 AT), give or take 50rpm. If you need to adjust the idle speed, make sure that the cooling fan isn't cycling. If it is wait til it stops as this affects idle speed.

5) Once you're satisified with the adjustments turn off the engine, plug the TPS connector back in. Restart the engine and check the idle speed again.

ALC252DM

If yours is a VQ30DE which I'm pretty sure it is, you don't need to mess with the ECU and IACV. That only applies to VE30DE engines but check your engine type first by looking at the metal plate located on the firewall in the engine compartment. Steps may differ depending on engine type.

billy bronco

Okay confirmed its a VQ30DE and changed plugs too. The spark plug set up was a little different than my 1983 Chevy Impala, how things have changed!

The above post does not tell how to do the actual adjustment. Is it just a matter of tweeking that plastic screw on the ECM?

Terran

iTrader: (6)

It's a plastic screw on the IACV, but yes.

billy bronco

Okay cool, what does IACV stand for?
And I assume it is the wire off the TPS I'm to disconnect? That's it?

FishyMan

tagging

what does it mean by CEL should not be one? sorry for some abbrivateions.

ALC252DM

I don't remember what direction does what to the idle speed, just turn the plastic screw just a tiny bit and see what happens. I'd take a black sharpie or marker with a fine tip and draw a tiny line on the screw and on the TB. That should give you a reference point just in case. IACV = Idle Air Control Valve.

caudio51

clockwise is lower

2 Da Max

iTrader: (2)

i left mine high

caudio51

how come you left it high??

billy bronco

I can see why my car stalled when first started prior to cleaning TB. It never jacked the RPM up high enough to keep it running when first started cold. Now it cranks up to 1500 when cold and slowly backs down, not far enough though. I will attemp idle adjustment today.

billy bronco

Okay getting a bit confused here. Seems this has happend to others too. I've been digging in to how to do this idle adjustment, so many ways told. My IACV (the box under console) does not look the same as pictures in these links. I have a 98 SE, and there seems to be talk of 99 being different (are these pics for 99 only). Mine does not say anything about idle adjustment only "SELF DIAGNOSIS MODE SELECT" then I read just adj set screw on TB, what is the right way on a 98, quick & simple please.

ALC252DM

First of all, the IACV is NOT the box under the center console (inside the car)...that's the ECU. The IACV is next to the TB (in the engine compartment, close to the firewall) and it has 3 electrical connections on it. The steps I provided is off of a Chilton manual for VQ30DE engines. I'll repeat...you don't need to mess with the ECU. The only thing you have to do is disconnect the TP sensor while the engine is off. Then start the engine and check/adjust idle speed.

billy bronco

Was it luck or just a fluke. I removed the grey plastic screw completely while the engine was off from the TP area. I assumed there was an adjusting screw under that and the plastic thing was just a cover, wrong! So I screwed the plastic thing back in all the way, kept my fingers crossed and started car, It runs perfect at 650 RPM, was this luck or what?

Gen8888

...

billy bronco

This seems to be the deal, when you disconnect the tps and start the car the ecu finds 650rpm, then when you shut off and connect tps, start car it idles at 650. I wanted it a little higher so I just turned the plastic screw out while it was running and tps connected, wala 750 rpm ...

eturnl

WFT?! either way no one ever answered the initial question! why does the engine rev higher with a cleaned throttle body?

caudio51

I'm guessing but increased air flow?? Or the throttle body position changes slightly when the black gunk is removed. Or a combination of the two.