Engine Help with direction to attack issues. Evap and some wiring

claypoolxx

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Oct 13, 2013
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This is going to be pretty long but I want to be as detailed as possible. I have a 93 gt 5 speed. The previous owner put in another motor (another mostly stock 5.0). It has a cobra intake and I'm pretty sure a larger cam but don't know for sure.

It has a check engine light on so I ran some codes. I saw that it had code 15 for no memory. I read that that could be caused by a chip. I checked and there was a chip in there. I ran the codes again with the chip in and with the chip out.

With the chip in the car idles well and seems to drive fine. When I take it for a drive it takes about 5-10 minutes for the check engine light to come on. It has codes 15, 67, 85. Also, I have no idea if the chip was for this motor or not.

With the chip out, the car's idle drops to just about stalling to 1300 until it warms up, then its good. The check engine light comes on much sooner, pretty much right after I give it a little gas. It shows codes 31, 67, 81, 82, 85.

The car has no smog, evap, A/C, or heat. I just bought all the stuff to put the evap back. Although I'm unsure where the plug the the bare wires connects.

I've read that 81 and 82 can be ignored as they don't cause drivability issues. I know code 67 prevents me from running the KOER tests.

Lastly, in the area with the computer I found some wires with stripped ends. They don't seem to be ripped out of the computer or one of the plugs there, but I have no idea where they go. There is also some speaker wire in there. I'll try to post a pic.

So my questions I guess are

1. What about the chip would make it idle better. Would that rule out vacuum leaks as a cause?
2. Should I remove the chip and try to get it to run well without it?
3. After replacing the evap stuff, what would you tackle next?
4. Any idea about those wires? I the second pic, its the green and whites ones that I'm referring to.

Thanks, after a few years of corvettes, I've got my first ford. This was my favorite car from high school.
 

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Dan02gt

10 Year Member
Mar 2, 2003
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Greenville, NC
Tackle the code 67 first. It’s the neutral sensing system. There should be a switch on the trans and clutch pedal that tells the computer when the clutch is pressed or trans is in neutral. When it’s not working the EEC thinks the car is in gear with a load on it. So your idle strategy is all messed up. Fix it and your bouncing idle will probably go away.
The chip could be tuned for a different MAF or injectors. Any idea if they are stock?
 

claypoolxx

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Oct 13, 2013
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I didn't think that 67 would affect idling but I did some research and see that it does. I see that there is a sensor that goes into the tranny and another one with a plunger behind the clutch pedal. Is there a way to figure out which one is causing the issue? Also I see that there is a way to jump the computer to get the codes, but that is only for testing and has to be removed for driving. But, I see other people have jumped the plunger sensor behind the clutch pedal and leave it like that.

I don't mind not having the function of the sensor as long was the code is gone and it'll idle properly and I can check codes.

I know I have stock injectors and the MAF looks newer but I think its calibrated for 19lb injectors.
 

Dan02gt

10 Year Member
Mar 2, 2003
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Greenville, NC
Here are the wiring diagrams you will need to troubleshoot:
http://www.veryuseful.com/mustang/tech/engine/

The signal comes from the computer on pin 30 and goes to the internal EEC ground on pin 46. The switches are normally open switches (when the clutch is not depressed and the trans is in gear) and wired in parallel so that when either is closed the circuit is complete and the EEC knows there is no load on the engine. There is also another connector in the center console near/under the radio that is for the auto car and shouldn't be connected. You can use it to help you troubleshoot. Jumping it will tell the computer the car is in neutral or the clutch it depressed.
 

claypoolxx

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If I'm understanding correctly only one of them needs to be working to run a KOER test then? That why I've seen people take some wire to make a loop with the clutch pedal one.
 

Dan02gt

10 Year Member
Mar 2, 2003
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Greenville, NC
Yes that’s correct.
Also leaving the loop in would allow you see if your car idles better with the system working properly.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
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Mar 2, 2015
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Those look like aftermarket speaker wire....and the factory speaker wires for dash speaker or door speaker on that side. You can follow them up ND if they turn into the rubber grommet for the door wiring they go to the door speaker. If they go straight up they are going to the dash speaker. You can squeeze the sides of the glove box and it will flip down allowing you to get a better view. Just bush it enough on the sides for the rubber stoppers to slide past the opening.
 

claypoolxx

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That would be great if they are just stereo wires. I'll have all of the parts to replace the evap and egr this weekend, however if the snow is still here I won't be working on it. I'll be very excited if this is all that's wrong. Thanks so much, I really appreciate it.
 

claypoolxx

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One last question if I could. I ordered the canister purge valve and extension but it’s a little different than the pics of it I’ve seen on this site. The one I’ve seen posted here has the wires connected to the valve with a connector at the other end.
My purge valve has a connector on it that the extension fits into but then has bare wires at the other end.
Should I order another extension and solder them together to have one long double ended connector?
 

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claypoolxx

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That’s the plan. I’d like to be able to run KOER codes and make sure that it’s the switch that’s the issue.