OK this problem has been bugging me for about 1 month now.

Car starts and idles @ 1500 - 2000 RPM. If I start driving right a way it will try to die when I come to a stop. If I wait 1 - 5 min. it will rev to 2000 - 2500 RPM till I come to a complete stop. Then drop to about 1500 RPM.

While driving around the engine will boog down if I use more the 50% pedal quickly then pick up. If I roll into WOT slowly no problems.

Once it feels like it it will go into closed loop all of this self reving and high idle stops. As well as the power sag.

My Idle has all ways been a little high 1000RPM. I've done every thing under the sun to fix it with no luck.

If I let the car idle for a while hoping it will warm up and go into closed loop I will leave 2 nice black stripes on the ground. So it appears that I am running way to rich at idle.

If the temp out side is about 58 or higher The car will go into closed loop in about the regular amount of time and driving the car is much more enjoyable. If it is colder than about 58 out side the car will most likely not go into closed loop, and I have no clue why. It never had a problem going into closed loop before even if it was butt friging cold out. Maybe it would take 1 or 2 minutes longer.

Now here's what I have done to try and fix it.

Replaced wires - some were burnt. Only minimal effect in helping cure prob.

Replaced Cap and rotor - no change.

Checked and cleaned plugs - ever so slight fuel fauling ( running rich at idle). Other than that the electrodes were fine as well as gap.

Tried to set timming - Timing was at 22 BTDC. yes this was with the EST wire disconected. tried to set it to 10 BTDC with horible results. Ideled fine, nice and smoth, but if you tried to put the slightest load on the engine it stumble and die. Returned timing to 22 BTDC. Rough idle, but at least I was back to ware I strated and I could drive the car to work. Suddenly my timing light would pick and chose when the bulb would fash.

Replaced coil - due to above issue. Idle quality improved, but still had same issue with trying to set timing. Bulb would flash only intermitantly. Open / closed loop, and power sag, and running rich issue remain (SP?)

Timing chain replaced - back in early November as part of rutine maint. and car ran fine afterwards. in fact it ran so well I though to myself "hey this engin might be able to make it 400,000 miles!".

Fuel Pump was replaced - back in late October due to it up and deing on me while I was driving to work. So I know I am getting plenty of fuel. the black marks on my drive way tell me this as well.

Little info on the car it's self. '92 3.1L with 360,000 miles on it. Only minor bolt on stuff, K&N, Custom Cat back, etc.

Had to disconnect battery some time back. I couldn't remember the proper procedure for the IAC relarn and the only info I found in the Chilton / Haynes books was that the 3.1L's need to have a scan tool hooked up to set the IAC position. Even the Helms shop manual doesn't give a procedure other than using the Tech 1 scan tool.

Now I have had to remove the battery manny times in the past, and I have all ways simply started the engine let it run for 5 secounds and shut it down. then I would drive the car around for a little while. It would die at the first couple stop lights, but after about 10 or 15 min. of this it would slowly return to normal.

Does any one know if there is a procedure that I can try to do the IAC relearn. Or am I stuck with having to pay some one 95$ to hook a scan tool up for 3 - 5 min.? Seems a tad F'in over priced for a 3 - 5 min fix if you ask me!


Oh and yes I am going to be replacing this poor 360,000 mile engine with a 3.4L, but need it to last a bit longer while I am rebuilding the 3.4L I got for Christmas. 5 speed + 3.4L

 

To reset the IAC, run the car over 45mph for 30 seconds, that resets the IAC.

Sounds like you have a vacuum leak my friend. check all the lines to make sure nothing is leaking, then spray the intake with carb cleaner. if there's a leak, the idle speed will go up even more.

 

yeah but if it was a vacum leak he wouldnt be running rich i would check voltage at the tps with the throtle closed and then again at wot and see if its within range bad maf can also do the same thing

more then likely its a fualty tps if its reading out of range on idle part throttle it will tell the computer to add more fuel making the car run rich,and cause the idle to be to high, if u take a normal running engine and tip the tps switch in at idle the idle will jump up without the iac opening or moving the throttle blade

 

How are you sure that you're running rich?

 

What should the TPS voltage be? I will definetly check it. I don't go back to work till the 3rd so I have plenty of time to fuss with it.

I don't think it is a vac leak. I did have one, but I fixed it. Forgot to list it as it was such an easy short fix. The vac line running from the evap can to the throttle body had a nice hole melted into by the EGR stalk. Replaced it with flexible rubber line and routed it a way from the EGR and other hot stuff. This actualy had absolutly no effect on how the car ran.

Maf can't be bad, I have SD. The map sensor is only 1 year old.

I know I am running rich due to raw fuel that spits out of my tail pipes and leaves nice black soot on my drive way. This happens if I let idle for more than 30 secounds in one spot, unless it feels like going into closed loop then all is well.

Also my AF gauge reads rich all of the time. Of course unless the car actually goes into closed loop then the gauge will sweep when cruising.

Before all of this happened if the car was in open loop the AF gauge would only go rich if I stepped on the gas and go back to stoich when at idle or cruising.

I know the stock NB O2 sensor will only tell you if it is rich, lean, or ok, but it is a great tool for a warning when things start to get out of wack before they are major issues. This issue hit all of a sudden.

 

your idle is fine. Min launch rpm is 1500-2000, no reason for such a low harley idle. Will just make fartin n dyin easier at take off.

now if you have an auto trans, I would drop it some.

 

Nope 5 speed, but I do prefer to have it at about 1000 RPM. It uses less fuel this way. Idling @ 2000 makes it a gas hog.

 

you were all over the place but last comment about idle was.

"My Idle has all ways been a little high 1000RPM. I've done every thing under the sun to fix it with no luck."

the higher idle surges and stuff is just the close loop mode waiting and trying warm up the O2 so it gives a reading. A 3 wire O2 mod can help cure that.

that IAC relarn is BS or so everyone says.
The books does say the 3.1 cars need to do this but it varies on the time of month if people will believe it. It comes to mind every time I hear of a 3.1 with a funky problem but then 30 3.1 guys will show up and say its BS. They never had to bla bla bla

But that info is here some where.
Was a big thread here in the V6 section long ago about how to do it right. gonna need to search n dig some.

 

5 volt idle i beleive lol benn so long since i checked mine i forgot but im pretty sure its 5 volt

 

Cool I will check it and see ware the voltage is at.

I was all over the place becuase there are so many symptoms that it is driving me a bit crazy trying to pin point the problem. There might even be several different issues going on as some of the things I have done have helped improve things a little, but not much.

It never acted like this over the last 6 years even when it was cold, and in open loop. The power sag is so bad that if I press the gas pedal half way or more the RPM's will drop to about 900 than pick back up. I have to be really genttle with the pedal. Especialy when shifting gears. Plus it has never ran this rich when it been in open loop. Raw fuel literaly spits out of the pipes, and the idle is rough as hell.

I'm just not sure what to go after at this point, but I am definetly checking the TPS out. It sounds fesiable.

 

did you check the car in the dark for spark leak?

had similar problem once as my coils were leaking but after 3 new ones it still didn't fix anything. they would soon start to leak also. then a full tune up of all new parts did something even though it was not time for a full tune up.

I ended up sticking my original coil back on.

2nd n 3rd gens eat ign parts like candy. might not be time or they might look good, doesn't matter. It wants new ones.

 

uhh.. no. Very no.

The TPS is a 5 volt referenced circuit. Idle is .54-.56 volts, WOT is generally around 4.5 volts.

Setting the sensor should be done using a digital multimeter, however testing the sensor for dead spots is best accomplished with an analog unit since the needle will respond instantly to any inconsistencies in output.

 

opps thnx man i remebered that after posting that it was like 0-5 after i had posted it but couldnt get back to repost

 

The TPS checked out ok. .56 at idle and 4.4 at WOT.

Coil, spark plug wires, cap, rotor have all been replaced. The plugs were fine, but I did run them through the cleaner just to be sure. Plus they are only 1 month old. Even checked for spark at each plug nice strong white spark. Also checked at night for spark leak. Nice and dark.

All of these problems go a way once the car goes into closed loop, but it has never acted like this in open loop. Maybe a slightly high idle, but driveability has never been effected.

I have been going over the service manual reading about every sub system on the engine/ ECM hoping to find some insight, but no luck. It just doesn't make since that the engine would be running so rich at idle while in open loop, but then correct it's self once it goes closed.

Found out that my Timing light was shoot. Whent out and bought another one. Checked the timing and it was @ 12 BTDC. Backed it back down to 10, but it had no effect.

I checked to see what vaccum I am pulling. It came in at 17 InHg at idle fully warmed up. Only slightly jerky on the needle, jumps maybe .5 up and down. Needle is steady at 2000RPM @ 24InHg.

Not sure if any of this helps give any one ideas. I don't know to much about what the vaccum should be. I belive it should be at about 18, but 17 is not that far off. I have run out of ideas of what to check.

 

Also: Thermostat sounds like it's sticking open, MAP sensor may be fragged (or wiring glitch in MAP harness). Do not fool yourself into certifying any part as good based on its age.

 

you might also want to check the ECT voltage. If it's repoting a low temperature, for instance if the ECT itself is internally open or something in the wiring is open, then it'll show it's super cold and increase Pulse Width accordingly. It's not likly that it's totally open, but could be out of spec causing the same problem. The ECM only sets an ECT code if the circuit is either open, shorted, or grounded.

 

Cool I will check all of those. Right now the rain coming down pretty hard so it will have to wait a bit. Man I wish I had a 2 car garage!!

 

You know the ECT idea may be the problem. Some times inorder for it to go into closed loop I have to let the car warm up to 245 then kick the fan in. Once it starts to cool down to 210 it will sudenly go into closed loop. After that I don't have any problems till the car is turned off and it fully cools down.

I have a manual switch for the fan since it doesn't like to kick on at all on it's own for the last 3 years. Over the past 3 years I have had to replace the ECM and the fan still won't work on it's own.

360,000 miles of heat cycling doesn't do wires much good. So I wouldn't be suprised to find an intermitant short.

Thanks for the ideas it at least gives me some hope of finding the problem!

 

OK, I notcied that my temp would go up to about 250 then suddenly fall back down to 190. My first thoughts... Stuck thermostat.

I replace the stat and while I am filling the rad back up I kick the defroster on high just help burp any air that is traped. Well I hear the AC compresor kick in.

Now this causes me to scratch my head in confusion so I call my wife out the verify that it is running when the defroster is on.

Now I know one of these control levers are controlled by vaccum, but witch one. The mode selector or the temp adjust lever?

I am still trying to figure out how to keep the AC from comming on when it is in defrost mode. If I put the lever in heater mode it goes into defrost mode. IT's all f'd up!

 

Thats normal for the AC to kick on when in defrost mode. Its supposed to do that because the Air Cond. Takes moisture out of the air, or something like that.. But its supposed to be on when is defrost mode. The only way to stop it from turning on is to disconnect the A/C wiring completly

 

An ac is also a dehumidfier.

does the ac work?

 

Cool.

Well the AC sort of works. I need to refill it every year. It has a very slow leak ever since I switched to R134a.

All though after replacing the stat my problems have gotten better. It doesn't run nearly as rich as it did before. Now instead of 2 black streaks, it's just to blacks splotches.