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Junior Charter Member
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Discussion Starter #1
When I purchased my car, it was uncompleted but the engine was in it and it would start and run. However, if the car had been sitting for any length of time - say overnite - the idle would go up and down for a couple of minutes and finally settle in. Subsequent restarts resulted in smooth idle.

Inquiries on the forum resulted in suggestions to check IAC, TPS, reset the idle by shaking chicken bones on a full moon, etc. After doing all these repeatedly, I pretty much gave up on solving this problem and marking it up to having an aftermarket lumpier cam, a bigger throttle body, and an EEC that was stock (non-compatible parameters to hardware).

In the process of trying to fix my idle, I learned of KOEO codes and quickly discovered that I had a code 67 - neutral safety switch. Again, answers solicited from the forum were either "I have this code, too" to "You don't need it, it doesn't affect anything, don't worry about it". Considering that one cannot run a KOER test with this code, I figured I needed to worry about.

The original owner sent the harness to a professional wire-dieter. After he received it back, I have no idea what changes were made by the owner. I do know that he had manged to drill through the passenger footbox into the wires resulting in repairs and had managed to hookup the alternator grounding incorrectly. What else the original owner changed or modified I have no idea.

Nonetheless, I tore apart the loomed harness and discovered a really sloppy wiring job. There were wires that led to nowhere on both ends. A wire that started off factory, was spliced with butt connectors for about a foot to a different color, then spliced with another butt connector to the original wire - and was too long. More butt connectors. The big yellow power wires going to the ignition were soldered together and wrapped just in tape for insulation. The neutral safety wiring was completely cut-out of the harness once it got past the tranny harness plug. The variable speed sensor wiring was cut at the EEC (neg return) AND tranny harness and had to be redone, and the HEGO plug was actually configured for an automatic. There were other issues, but you get the idea.

So after hooking up the neutral safety circuit, reconnecting the VSS, and putting the HEGO pins in the proper manual transmission position, I checked for codes and ol' number 67 no longer showed up. The EEC only returned "all clear" during the KOEO test.

Since I didn't like the 70 psi I was getting for oil pressure, I decides to replace it with a regular volume unit. I also took the sidepipes off for repainting and just left the cats attached.

Filled the car with oil, primed the pump, hit the key and VOOOOOOM. Idled around 1200 briefly then settled to around 800-900 with 50 psi for oil pressure. "Hmmmm" I said to myself. No hunting for a stable idle when cold anymore.

Car sat for a few days to do some other things. I thought that perhaps the stars were aligned perfectly not to have my idle problem previously and surely it would return much to my disappointment when I started it again. Hit the key and, once again to my amazement, an idle like it came off the showroom floor.

My advice to those with an idle hunting problem when cold is to make sure that you have your VSS and Neutral Safety circuits hooked up properly. There are those on this forum that have stated that they are not needed, however I tend to believe that Ford didn't put them there and program the EEC just so they could charge a few more dollars per unit.

Anyway, when stone cold, my car now idles like it is supposed to. Your mileage may vary...

[ January 13, 2005, 03:56 PM: Message edited by: Lurker ]
 

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May have to change your name, handle, here on the forum. No longer Lurker, you are now the Contributor. :D

Thanks for the insight. I think there are many of us with this problem, and we have just lived with it.
 

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May have to change your name, handle, here on the forum. No longer Lurker, you are now the Contributor. :D

Thanks for the insight. I think there are many of us with this problem, and we have just lived with it.
 

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Junior Charter Member
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Discussion Starter #6
Leonard - perhaps. However I do live in Houston and experienced this problem when the air temp was 95 degrees.
 

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FFCobra Fanatic
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4,257 Posts
I'm glad you found your problems.

I had similar symptoms and the problem was air entering the hose between the mass air meter and the throttle body. That got fixed (by quality roadsters) and it ran perfectly. I have no VSS hooked up whatsoever.

For others who see an incredibly high oil pressure, if you put in a "real" oil pressure gauge and use a 93+ oil pressure sender, your problem is that ford used an "idiot light" sender and put a peg at 60psi in their gauges. I found this with my new gauge and idiot light sender. Pegging the meter at over 100psi was a bit troubling to say the least!
 

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Junior Charter Member
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Discussion Starter #8
Jack, where do your VSS +/- wires from the EEC (pins 3 and 6 I think) terminate on your car? Curious if they are completely removed, wired in a complete circuit, neg side tied into Sig RTRN circuit, whatever.
 

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Senior Charter Member
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3,025 Posts
I agree on the Code 67 and idle. Fixing this code seems to have helped my idle. I had bad cold idle and fast warm idle. Additionally I was seeing an 11 Continuous code, which I knew was wrong (no EGR, air pump...). After hooking Pin 30 to Sig Ret I am know seeing the expected Continuous codes and the car idles much better. I know it blocks KOER, but for me it seemed to screw up the Continuous also. I thought I was nuts.
 

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FFCobra Master Craftsman
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Is this a just completed car? I wonder if you unplugged the trans harness now if you would get the idle problem back. I have seen several causes for your type of idle problem and this could prove your fix. If you do this don't dis-connect the battery just unplug the trans harness. The car has learned how to idle and it needs constant battery voltage to remeber. Just thinking out load it would be nice for us to know for sure if this fixed it.
Jeff Hamilton
 

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Nobody Special
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608 Posts
Originally posted by Leonard Rosenbeck:
I would think the oil pump change would have contributed some. I'd think that moving that much cold (thick) oil would put some additional load on things until it warmed up and thinned out a bit.
Low oil pressure at idle allows the lifters to soften up, causing a slight change in valve timing. Ford programs this into the computer.
I've seen idle quality effected because injector timing is grossly off valve timing.
So I guess it's possible for too much oil pressure to counter what the computer is trying to do at idle.
 

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Junior Charter Member
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Discussion Starter #12
Jeff-

I drove the car for a year unpainted. When I decided to finally take the body in for paint I also decided to fix my code 67 and here we are today. I can crawl under the car and pull the VSS and see if it goes away. Wouldn't be a real test considering how it was wired previously. It wasn't a matter of the VSS not being plugged into the transmission, but wires being cut and the circuit to the EEC being incorrect. This is why I asked Jack how his VSS is not hooked up - it may be wired so the car always thinks it is not moving. I think mine was screwed up so that the EEC didn't get any acceptable reading whatsover for the VSS so it didn't know if it was stopped or going 150 mph. I didn't have a completed circuit between the VSS+ and VSS- at the EEC or even just a ground for the VSS-. I also had no signal going to the EEC for the neutral safety input.
 

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i have seen this problem on mustangs.
unless you get a chip to turn off the vss & nss
you will experience simmilar problems.
best to make these functional.
 

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FFCobra Craftsman
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2,315 Posts
Any idea who did the "wire diet" ? I have been considering getting this done but after hearing this horror story I'm wondering if I might be a better candidate to do the job...

- SB
 

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This is my first post, but having done a few years of Car Audio and Security, that wiring harness sounds like a horror story at amateur night.

If you find out who did the wire diet, you should call to make sure that those mistakes were not something the prior owner did after the fact. Perhaps the builder didnt fully understand the need for the VSS or Neutral Safety Switch and cut them himself.

Well, thanks for the first post.
 

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FFCobra Master Craftsman
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2,033 Posts
First let me say that something is going on here. I'm one of the guys that does not use any trans harness at all. I have done over 20 wire harness for FFR cars and not one of them stalls or has a poor idle. It would be nice to know for sure what causes this problem. I guess it could be the VSS and neutral input. I think a EFI car takes too long to return to idle. I like it when you push in the clutch and it return to idle like a carb car. I think with the VSS signal hooked up the computer lets the RPM fall slower between shifts or coming to a stop.
Jeff Hamilton
 

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Senior Charter Member
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3,025 Posts
I jumped the neutral input at the driver's side harness connector. The wrong wires were jumpered together at this connector, +12 Start TFI and Auto Ground (Luckily it seems the Auto Ground goes nowhere, no damage done). I don't have the VSS hooked up. When I get a chance I will experiment with Code 67.

If Code 67 will block KOER could it also be blocking some of the adaptive capability of the EEC? It all depends how the program deals with or gets hung up on it.
 

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Senior Charter Member
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First test: KOEO Code 11, Cont Code 29,33. Disconnect Neutral Jumper: KOEO Code 67, Cont Code 11. Reconnect Jumper: KOEO Code 11, Cont Code 11. Code 67 appears to have stepped all over the Continuous Codes and wiped them out. Is this expected with other KOEO codes? Comments, please.
 
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