View Full Version : Idle problems... Code question

08-28-2002, 04:22 PM
Good afternoon folks,

Let me see what you folks think;

Your having problems with your car, you throw your handy dandy little code reader on there and get a KOEO code of 18 and 29... The car does start but turns over, what I would consider, to many times to be right before it finally starts... When it does start it's idle is lower than it should be and when you put it in gear it drops well below the base idle..

I know what the codes mean, but what's y'alls first guess... Cam sensor?? or DIS unit??

09-01-2002, 07:49 PM
nobody has an opinion on this ??

09-01-2002, 09:10 PM
Ya gotta tell us what the codes mean. We don't all have them memorized.

18 - SPOUT circuit open or loss of tachometer input/IDM circuit failure.

29 - Insufficient input from vehicle speed sensor.

Not sure if any of those are related to your problem. You should check and make sure the SPOUT plug is still plugged.

Idle air control valve could be sticking and having trouble metering appropriate air flow.

Fuel filter, and/or fuel pump could be giving you low fuel pressure. I'd check the fuel pressure at the rail.

Describe the slow start. Do you hear the fuel pump starting up right away?

09-03-2002, 09:12 AM
Good morning Mike, sorry I was out working on the car all weekend doing cosmetics things. Didn't get back to the computer..

Yes it sounds like the fuel pump is starting right up, the car does start it just turns over, oh I'd say 20 times or so before it catches and takes off... It idles just a hundred or so below normal idle but when you put it in gear it drops real low, especially if the A/C is on... I know the leveling circuit that's supposed to take up the slack whenever the load is heavier on the engine is working... When I turn the A/C on I can see the idle come up a little and then down farther.. Same thing when I put it in gear, the idle comes up for a minute and then settles down below base idle..

I'd read somewhere that the cam sensor, when bad, will cause the system to go into a guessing game with which cylinder is actully number one, then it will guess till it can fire, I was wondering if that could be what's causing the extended crank start issue..

thanks Mike


09-03-2002, 09:29 AM
How has your fuel consumption been?

I would check the vacume hose on the fuel pressure reguator for signs of fuel. If the diaphram in the FPR fails, it will leak fuel into the intake system. Creating a too rich condition can cause that type of low idle speed. Just replaced a FPR on a 90 Olds Custlas for a nephew this weekend with a similar issue.

Also, just because the idle changes, doesn't mean that the IAC is at 100% function. The computer could be sending a signal for the IAC to adjust, but do to wear or dirt the IAC is not able to adjust enough.

Crank sensor failure, the car won't start period. You should also notice the UpShift light on when cranking if it's the crank sensor. Cam Sensor shows up as a car that starts randomly. I.E. Key On, Start.. nothing. Key off, key on start... nothing, key off. key on start... Brrrrooommmm. Basically the computer guessing when cylinder 1 at TDC. But having it have to turn over 20 times to catch sounds like something else.

Hook a timing light up when that's happening and make sure spark is occuring. If you have spark, then it must be fuel. A weak fuel pump perhaps. You need to check that with a fuel pressure gauge.

09-03-2002, 11:24 AM
Fuel consumption!!! It's been fantastic!!! heheheh cause it ain't left the yard since I got the thing... It was purchase as a project car, and it is without a doubt been that all right... I appear to be the fourth owner on it, the kid before me only had it a month and found out how expensive things were to repair on it... The guy before him had just had the head gaskets and heads redone.. Belts and pulleys are all bad, bought them this weekend but haven't been able to get them on yet...

I thought since the heads were done maybe we had a vacum leak but, did the carb cleaner trick on everything and no leaks.. Have done several little things to it and mostly cosmetic issues so far waiting on the Tranny to get here from Ryan... I only titled it no tag till I get it closer to being on the road. I'm trying to get a house built, momma told me I'd better not over spend on this "Project" or there'd never be another one!!!

You are right though it does seem to be running very rich... exhaust fumes are absolutely terrible..

Thanks, I'll check these things, more to follow...


09-06-2002, 05:21 PM
Ok, Mike, is the IAC that everyone is talking about on the side of the TB and kind of got the connector over there TPS ?? The Ford manual calls it the air bypass idle control??

I can't find IAC anywhere in the factory manual...

09-06-2002, 05:36 PM
Yep, that's it. There are two sensors there. One right on the shaft of the butterfly for the throttle plate. Thats the Throttle Position Sensor (TPS). The other is just past the butterfly and is the Idle Air Control.

09-06-2002, 05:39 PM
That must be the one that the factory manual says don't clean with carb cleaner.... does that work?? do I pull it and clean it It also say something about a little fine diaphram in there to be careful of, not to brush it and puncture it...

Or do I just break down and replace it?? dealer item or parts house??