Idle problem with a couple codes stored

mywhite89

Registered User
I've got an intermittent idle problem with my 89 5-speed. Seems to occur more frequently when the car is warmed up but it doesn't really matter. The idle will sometimes just stay at 1500 rpms and not come back down. When its having this problem while driving, its like the cruise control is on when I am going down the road.

This morning I got it to do it on me and I changed out the IAC sensor and the problem still persisted the same as before. After changing the sensor, the check engine came on for a second while driving.

At this point I have checked the codes and they are as follows: 49 spout signal problem, and 63 Throttle position circuit fault below minimum voltage. I checked output voltage at the TPS and it was a .9 at zero throttle and increased voltage smoothly when slowly opening the throttle. I adjusted the sensor to .97, its at 4.73volts at wide open throttle. Road tested car, Problem still persists.

I believe the tps code is being set because of the idle problem, and I have no clue about the spout signal code, the spout connector is plugged in. I have heard of someone having a problem with their spout connector going bad, is that a possibility?

Lastly, I cannot find any vaccum leaks. Being that the problem is intermittent I don't see a leak being a problem.

Chris
 
What process did you use to 'adjust' the TPS to .97 V?

Clear the codes, run the car to allow the system to relearn sensors and retest. Check grounds/ground paths. Make sure the battery is up...don't use the alternator to charge a depleted battery.

Use this code chart that is SC specific.
 
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I manually adjusted the tps sensor with the key turned halfway. Middle wire on the connector to that sensor is your output signal. I did use the battery as my grounding source.
 
Erased codes from memory, drive vehicle and recheck for codes. Both codes come back. Pulled number 1 spark plug, very black and sooty. Vehicle seems to be running quite rich. Reset codes and tried the KOER test, oxygen sensors showing vehicle running rich all the time, code 42. It's a pain to do a KOER test in my car because it dies out during the cylinder balance test half the time right in the beginning.

I've been running 100 octane unleaded in my car about 50/50 with 93 octane. Being that the gas is unleaded, I'm not hurting my oxygen sensors am I?
 
>I manually adjusted the tps sensor with the key turned halfway.

The TPS doesn't normally allow for 'adjustment' - how did you persuade it to move enough?

You will most likely need to replace the plugs regardless of what else you find...might as well do it now so that you can continue testing.

Do you know how to check for plugged cats?

Make sure your air filter is clean as well.

Remove the SPOUT plug and confirm the pins & connector are clean. Examine the harness to check for any cuts, melted wires, etc.
 
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The TPS doesn't normally allow for 'adjustment' - how did you persuade it to move enough?

You will most likely need to replace the plugs regardless of what else you find...might as well do it now so that you can continue testing.

Do you know how to check for plugged cats?

Make sure your air filter is clean as well.

Remove the SPOUT plug and confirm the pins & connector are clean. Examine the harness to check for any cuts, melted wires, etc.


Open the holes up a bit and you can adjust the tps. Only way there is a problem in the tps is if it is a ground problem. Still need to check that.
Only way I can think to check for plugged cats would be to remove a oxygen sensor and screw some type of pressure gauge in and check for abnormally high pressure. My car doesn't have cats though, so you can eliminate that possibility.

I'll replace my plugs this week and see if that changes anything. My car needs re-tuned and the weather is a heck of a lot colder now. Makes me wonder if that is making my computer freak out?
 
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Ok, I changed the plugs for lunch today, yum yum. The one I checked the other day was the best looking of all:rolleyes:. The others were completely black and sooty, and the one I checked had gotten worse since I checked it. This thing is hog rich! We'll see if that temporarily fixes my idle problem and the codes it was setting. I drove it a couple miles and it ran much better, and initally started much better also.

btw, took me 30 minutes at lunch to change them out, I damned near had time to get food if I was hungry.
 
There are several issues here.

1) did you get a check engine light? If the car is so rich that it is fouling plugs you will also get a check engine light as the EEC runs pegged full adaptive in it's attempts so correct the situation. If there is no check engine light then you have not pegged adaptive and that means that it's not a rich issue (at least not one that is recognized by the EEC).

2) you pulled codes, but are those current and valid codes? Did you erase the codes correctly? Some people think that disconnecting the battery erases codes. It doesn't. If you are truly getting a Spout code and TPS code then you have issues that are not tune related. You have an electrical issue that needs to be addressed.

3) if the plugs are black and sooty then they are fouled which is causing the EEC to run even richer. Misfires due to fouled plugs will read as "lean" at the 02 sensor and cause the EEC to add fuel.

4) fuel. You are running a mix of race fuel and pump gas. The car was tuned on pump gas only, and now you have changed the composition of your fuel. It's one thing to run race fuel at the track occasionally but a totally different thing to run it all the time. Under normal driving conditions your octane is too high for your base spark map etc.

The tune is not bothered by temperature but if the motor doesn't get up to at least 160 deg it will not leave the cold start tables which can effect how rich it runs in certain conditions but it will not prevent closed loop. If your engine is not getting to 160 deg then you need to take measures to see that it does.
 
When I first started it this morning it had a problem starting and the check engine light was blinking on and off. Other then that, it came on while driving it around the block a mile or so on saturday.

2) I have a code scanner that I erased the codes with, then re-checked to make sure they were erased(they were). Drove it 2 miles and they were back on.

3) probably need to stop putting race fuel in it! Didn't think that would affect anything but I must have been wrong. That may parially cure my plug issue.

Well, I guess I need to check the output wiring for the TPS at the eec and the ground, because I am not seeing a problem at all from the sensor itself.

Where do I start, checking for a spout issue other then making sure the contacts are ok?
 
Ok, so the check engine light is a new issue and logic would indicate that the check engine light is not caused by the tune so it would be imprudent to attempt further tuning until this issue is resolved. The Spout connector is nothing other than a jumper wire so it can hardly fail. Instead I'd look for a bad or missing ground wire (seems you mentioned something about that before.....). A bad sensor ground will cause all sorts of seemingly unrelated issues.
 
Well, I guess I'll try driving the car for a couple days. I took a cute young lady out driving with me for a while tonight and it didn't act up at all, 15-20 miles worth. codes have not come back after resetting them earlier today. Maybe it just doesn't act up around the ladies, I don't know:rolleyes:.

seriously though, I took a good look at my wiring schematics (pg.66 1989 electrical troubleshooting manual) tonight and if I can get the car to start acting up again, I believe i'll figure this thing out. I'll test wiring later this week.

I was told that a tps problem will make the computer trick the car to run rich, does this sound correct? If so, it may play with timing also for all I know. I think I'm at least headed in the right direction.
 
Ok, I did some work tonight. Checked the 5-volt reference wire to the tps, checked out just fine. Rather than using the negative battery terminal as my ground source, I used the sensor itself ground wire which was a black/white wire. Using this sensors ground source I showed lower voltage at closed throttle then what I had just set the thing at the other day! It now showed .82-.83. I adjusted the tps using this actual ground source back up to .92-.93.

Did not drive the car or even start it before I decided I wanted to trace the output wire straight to the eec and make sure I didn't have a wiring issue from that standpoint. That checked out just fine, same voltage as it was at the sensor, happy about that.

Drove the car, seemed to drive much better but that may just be psychological. The real test will be the drive to work tomorrow, and rechecking for codes.

To conclude, I may have a slight ground issue or the wiring is just so much thinner than the grounding wire I was using that it affected my voltage reading slightly.

Anybody have any thoughts on what I did tonight, I'm not sure if .82 volts at closed throttle is borderline for setting a code or not?

Chris
 
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>not sure if .82 volts at closed throttle is borderline for setting a code or not?

I had .93 set a 122/TPS related code...
 
TPS voltage allowable range is from .4v to 1.3v (according to my memory) so clearly you do not have a TPS issue. Normally I shoot for anywhere from .85-.99 and call it good. I've tuned plenty of cars outside that range and never had an issue.

That your EEC sensor reference ground is not reading the same as battery ground is a little disturbing though. You need to check your grounds very carefully. Start with the one next to the EEC.
 
I'll re-check the difference tonight just to make sure, and I know the ground you are talking about also. Seems to be the main ground for the computer. The car has run great to work and started like it always had previously, checked for codes none have come back since putting new plugs in the other day. If nothing changes, I'll try running the KOER test tonight and see if the car will actually stay running this time. If it throws a code for running rich all the time again, I am lost. At this point I still have a little 100 octane left in it, but not a lot.
 
Well, I fixed my blower, so I'm back at trying to figure out this problem I have. After 2 weeks of sitting, I started it up and my idle problem that was gone for 2 couple days of good driving was back. It idles at 1500rpms and wont stop until I shut it off. After turing the car off and restarting, it seems to reset itself part of the time and may not do it again for a couple drives. It just intermittent.

Checked my codes today after it did it again when I went to lunch and the only code set is code 49. In my little ford code reader book, this code signifies a fault in the spout connector system. KMT's link shows, 49 C Default spark error (3.8L SC only). TPS did not come back which is a mystery, unless my re-adjusting did something??? Thats doesn't explain why it still idles high when the problem occurs though.

Today I checked my ground at the battery and it is tight and does not appear to have any issues. The fact remains that when I test my sensors output signals I show about .2 volts more consistantly from each output from my different sensors when I use the battery as my ground source rather then the black/wht wire that is a common ground wire for several sensors. I guess I can rough up the surface that my computer ground bolts to and see if anything changes, but I don't see any wierd fluctuations of voltage like break in the wire or anything.

Only peculiar thing that I have noted is when I took my spout plug out. The spout plug has just the black/wht common ground wire that runs through it. When the computer sees the ground is interupted, it retards the timing. I used the output wire on the BAP sensor as my positive reference on my multimeter and used each one of the terminals on the spout plug connector as a ground source.

On the terminal that I beleive goes to the computer, I showed 2.4 volts which is what I beleive to be a decent ground. When I use the other terminal on the spout connector as my ground source just to see what happens I get a reading of 6.1 volts or so. Anybody know what this is all about? Could this be a short in the system? I figured I would not get a reading from this terminal, because I figured the ground source would now be a open in completing the circuit.

Couyld it be that the difference voltage ground one ground source to the other is causing all this havok? I wonder if someone else could check their own car and see if they note a difference when using the battery as a ground source versus using...say the blck/white wire on the BAP sensor as their ground when checking output from that sensor. You'll need a digital multimeter to note a difference I'm sure.
 
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