jkennedy2004

I've got a 1993 Ford Mustang 5.0L 5-Speed. I'm having an issue with the check engine light. When I start the car when it is cold, everything is fine (no check engine light comes on). If I take the car for a drive, then park for 30 to 120 minutes or so, and then restart the car, then the check engine light comes on and stays on until I let the engine full cool (generally over night).

I recently took it to my mechanic and he tuned it up as it was bogging down under heavy acceleration. He replaced the plugs, wires, throttle positioning sensor, air filter, fuel filter, and was supposed to clean the fuel injectors. All of that made the car run great (except for the check engine light issue I described above). I've just learned he didn't have the equipment to read the engine codes. One other thing I've noticed is the plastic overflow "bin" for my radiator seems to not stay full. Not sure if it is supposed to. Regardless the check engine light doesn't appear when the car is started from cold and doesn't seem to come on until the car is turned off and sits for a while.

1) Any thoughts on what might cause the check engine light to come on under the conditions I've described?
2) Is there a specific piece of equipment I can buy to read the engine codes?
3) Is there some sort of reset my mechanic needed to do after the tune-up?

I'm guessing I'm going to need to find a mechanic with the right tools to figure this out, but wanted to see if I could get a head start here or with my own tool to read the codes. It's running great, but the check engine light may cause me to fail the smog test.

JK

dawson1112

Check the codes , only the ecm knows why its coming on at the moment.

http://www.dfwmustangs.net/forums/showthread.php?t=7908

88 orangepeel notch

+1 ^^^

Special tools needed……………paper clip, pencil and paper.

And about 15 min. of your time to do it twice. Then report back here with the codes. Good luck

jkennedy2004

So I gave it a shot, and was not successful. Needless to say this type of thing isn't a core skill for me! I suspect that I never got a good connection between the signal return and the STI with my super duper paper clip. I read through the instructions and also found a video on youtube of someone doing this process on their Ford truck. It seemed simple enough. My issue seems to be getting the correct connection with the paperclip in the first part.

Issues:
1) I wasn't sure how to complete the connection on the STI. I pulled out a small red part on the STI (and proceeded to lose it inside the engine) and tried pushing the paper clip inside...most places it would slide through, one area, it felt like it stayed "stuck" in. Wasn't feeling confident.

2) The shape of the STC was a bit different than the picture. #3 seemed to line in between both rows. So I assumed the signal return was in the row with of two connectors (assuming #1 and #2) in the connector furthest away from #3 (aka #2). I was able to press the paper clip into here enough that it felt connected (*note: there was yellow wire here) . I presumed this was the Signal Return.

When I tried the KOEO nothing happened other than what you would normally expect. A few gauges and lights turned on and the check engine light came on and stayed on. Same with the KOER attempt...normal response, no test.

A) I'm wondering what the little red item is that I lost from the STI is called, and and if I need to replace it. If I know what it is called I can obtain one!

B) Anyone have any suggestions on how to get a good connection between the signal return and STI. Seems I need some very basic instructions (or maybe a better jumper). I may be best off finding a mechanic bit am willing to give it another shot.

JK

Maxwelhse

If you're having a problem with getting the paper clip to make contact for some reason there is a "tool" that is just a little metal guy that you can buy and use instead. It's about $4 and is a little easier to use.

This guy is using the "tool" to check codes. (and yes, I bought one of the "tools"). You can use a test light in place of the meter if you want. I've never had a need to pull codes on my Fox (bought tool years ago for other OBD-1 vehicles) but I was always under the impression that the dash light would flash the codes. That's what has always happened on my other OBD-1 cars.

https://www.youtube.com/watch?featur...q-NUzWs4#t=656

And no, your overflow bottle shouldn't be empty all the time.

jkennedy2004

Thanks for the info on OBD1 tool! I also took a quick look at a few available code readers from Amazon. I'll report back if/when I get the engine codes. Thanks!

Maxwelhse

Unless you have other OBD-1 vehicles those code readers are really not worth it since everything takes its own software and connector (GM/Ford/Chysler/Mazda/etc). You're better off getting a decent quality multimeter and learning to use it. I've also never encountered an OBD-1 vehicle that you couldn't pull the codes from with a very simply appliance (paper clip, $4 metal thingy, whatever).

Now, for OBD-2, a code reader is nearly the best money you can spend and I would even recommend you spend a fair bit so you can a full on scan tool that data logs (and since it works on everything OBD-2, no harm in spending some cash). I would have NEVER figured out a weird O2 problem on my TJ without data logging it. It never threw a code and was an intermittent problem. I had to go back through the playback and later the spreadsheet in Excel to find it.

Good luck!

yurizx6r

I bought mine from autozone and it works just fine. There is no need to over think it at all. Read the instructions, do the test twice, and google the codes. If you are not sure about the codes, tell us what they are. I have all data on our cars, so I can tell you what it is.