famed S13 idle problems

[emperor_lunchbox]

Hello, this is like the 5 or 6 time I am posting about my idle problems. I have nearly had it with this crap. I have brought it to 3 mechanics, the last one had the car for 8 days and didn't find ANYTHING, what the hell is that....He said he cleaned out the IACV and that didn't work, then he put one from another KA on and that didn't work either.

What it will do is when I am at a stop light, the car will seem to idle OK for a second then drops rapidly to about 300 RPMS then bounces to 700 RPMS or so. It will do this until I put the car in neutral (automatic). The only time the car idles like crap is when I am in drive at a stop light. It will sit fine in park and in neutral, just not in drive.

Does ANYONE know what the hell is going on with the damn S13 idle?Any friggin ideas?

[teddy]

vacuum leaks...check for vacuum leaks. Even though you may have done it already, or think there is no leaks, check it again. I had the same problem when I put a supercharger on a civic. The idle would bounce up and down from 400rpm to about 1000rpm only in drive. In park and neutral it was fine. I checked, double checked, and triple checked vacuum lines and couldn't find anything. Found out later that my throttle body gasket was jacked and air was leaking out between the TB and manifold.

[emperor_lunchbox]

I dont mean to sound defeatist or anyting, but it would be impossible for me to find a hose off or a hole in a gasket. Is there a typical hose that causes this or a typical gasket that could attribute to this?Thanks for your suggestion, I will have another go with those lines.

[S13inBatnRuge]

buy a bottle of carb cleaner and spray different hoses while the car is running. when it hits the hose you have a leak in you should hear the engine rev.

[trulyphly710]

DID you find out what the reason was? thanksI'm currently having the same problems also!

Thanks again!

[emperor_lunchbox]

I never did find the problem. I have given up, this car is for sale. I have spent too much time and money to make a stock car idle properly. I am done.

[sil80drifter]

Hey.... if your car idles NORMAL in neutral gear and it drives fine as well, without shuddering or hestitation, and ONLY has issues when you are in DRIVE, stopped, maybe something is wrong with the transmission, which may be engaging the clutch (or whatever automatics have) and makes your revvs drop. Automatic trannies can do odd stuff like that. They are also controlled by the ECU and they themselves can go haywire sometimes.If it idles fine in neutral, there are no problems with the engine. Look into transmission issues.

sil80

[trulyphly710]

DID you find out what the reason was? thanksI'm currently having the same problems also!

Thanks again!

[rogoman]

I dont mean to sound defeatist or anyting, but it would be impossible for me to find a hose off or a hole in a gasket. Is there a typical hose that causes this or a typical gasket that could attribute to this?Thanks for your suggestion, I will have another go with those lines.

To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. A good place to connect to is the charcoal canister. There should be three hoses connecting the carbon canister. Two of the hoses go to a purge valve that's built into the canister. The second larger hose off the purge valve should be your vacuum line. With the motor fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg.

If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.

The idle hunting can also be caused by the following:1 - Sticking EGR valve.2 - TPS harness connector pins. Look at the pins and see if there's oxidation on them. If so, clean them with fine steel wool then lightly coat them with 'dielectric lubricant' which you can get at most autoparts stores.3 - Dirty air filter.

[rogoman]