Several Electrical Issues: any help?

[rick8928]

I'm driving the snot out of my car and am having a blast, but do have several electrical issues.

I have a WireDieted harness, and have several minor electrical issues, all of which I attribute to my own actions. I think when putting the dash back on after getting the painted body installed, I disturbed some of my electrical connections. However, my dash is a bitch to take off, so I'm going to wait until winter to pull it off and see what I see.

1. The first two times I drove it after paint, I ended up losing alternator charging (the meter was just showing 12v, rather than 14v as it usually does when the charging system is working). This popped a fuse each time. I found that the wires from the 500 ohm resistor, installed in parallel to the charging light, were shorting out on the steering column, so I wrapped the column with electrical tape and bent the resistor wires out of the way-no repeat since then.

2. Instrument lights aren't working, but the needles are lit. Don't know if those lights ever worked or were damaged by the above "short", since i never tried the lights at night before.

3. and the real problem is that the engine doesn't return to slow idle immediately when the throttle is released, but stays at a high idle (1700 rpm) for about 5 seconds, then you'll hear a small "pop" (like gas burning in the exhaust), then the idle will drop down to 900 or so. If at a stop, the speedometer will simultaneously show a pulse (at the "pop") up to about 30 mph and then continue to slowly oscillate between 15 and 30 mph. On overrun, say coasting down a hill with zero throttle, you hear a contiuous patter of those soft pops coming out the exhaust. The ramifications are that I get minimal if any engine braking when I let off the throttle, because of the temporary high idle.
It has been suggested that the idle problem could be caused by an intake leak, exhaust leak, the idle air bypass valve not working properly, or the throttle position sensor not working properly.

4. My last symptom is that I can no longer connect to my engine computer and pull codes through the OBD connector with my Diablo Predator engine tuner. I was able to do it before. It's possible that I've compromised my grounds, including to the OBD connector, the last time I mounted my dash.

My questions to you all:
*do you think I've fried my ECU/computer?
*Would the car run and maintain perfect operating temperature with a fried ECU?
*Basically, do you have any ideas what some or all of the above issues could be caused by? (I understand that diagnosis would be a lot easier if I took the dash off, but will wait until cold weather to do so).

Thanks,
Rick

[JKleiner]

Originally Posted by rick8928

2. Instrument lights aren't working, but the needles are lit. Don't know if those lights ever worked or were damaged by the above "short", since i never tried the lights at night before.

FFR/Speedhut gauges? If so there are two separate lighting connections; one for the needles and the other for the faces. Sounds like you're good on the needles so look at the small gauge, siamesed pair of black wires that have mini-connectors to chain all of the instrument lights together. I labled this photo for someone else recently but it shows the pigtail I'm talking about:



At the origination of the chain one wire gets power, the other goes to ground.

Good luck,
Jeff

[RE63]

Originally Posted by rick8928

I'm driving the snot out of my car and am having a blast, but do have several electrical issues.
3. and the real problem is that the engine doesn't return to slow idle immediately when the throttle is released, but stays at a high idle (1700 rpm) for about 5 seconds, then you'll hear a small "pop" (like gas burning in the exhaust), then the idle will drop down to 900 or so. If at a stop, the speedometer will simultaneously show a pulse (at the "pop") up to about 30 mph and then continue to slowly oscillate between 15 and 30 mph. On overrun, say coasting down a hill with zero throttle, you hear a contiuous patter of those soft pops coming out the exhaust. The ramifications are that I get minimal if any engine braking when I let off the throttle, because of the temporary high idle.
It has been suggested that the idle problem could be caused by an intake leak, exhaust leak, the idle air bypass valve not working properly, or the throttle position sensor not working properly.

4. My last symptom is that I can no longer connect to my engine computer and pull codes through the OBD connector with my Diablo Predator engine tuner. I was able to do it before. It's possible that I've compromised my grounds, including to the OBD connector, the last time I mounted my dash.

My questions to you all:
*do you think I've fried my ECU/computer?
*Would the car run and maintain perfect operating temperature with a fried ECU?
*Basically, do you have any ideas what some or all of the above issues could be caused by? (I understand that diagnosis would be a lot easier if I took the dash off, but will wait until cold weather to do so).

Thanks,
Rick

3 Did you adjust your idle at the throttle plate? This is a no no, back it off where it was and try it again, it should come down to idle as it is supposed to. BE aware these cars do not idle down like a carbureted or early EFI car, they do come down slower than you would expect. But it should not be bothering you and hanging at 1700 does not sound right. The idle is controlled by the computer not the screw on the throttle plate.

4 Check ALL your fuses, even the ones out front in the second fusebox, sounds like the OBDII port lost its power.

It is extremely unlikely that you fried the computer.

Hope this helps.....

[rick8928]

I was aware of the two separate gauge circuits on my FFR black classic Speedhuts. I also hope that the gauge light circuit now has a simple disturbed connection, rather than having been severely injured due to my resistor short.

I didn't intentionally mess with the idle screw, but I'll check it out tomorrow to see if its an unintended consequence of something else i did.

There is no longer a separate engine bay harness and fusebox. That was eliminated in the WireDiet. There are several fuses going to the starter, but since the car starts I'll presume they were not compromised.

What mystifies me is the oscillating speedometer while at a stop after the exhaust pop and return to low idle. There's obviously some signal crossing that shouldn't be there.

Thanks Jeff and RE63.

[RE63]

Originally Posted by rick8928

I was aware of the two separate gauge circuits on my FFR black classic Speedhuts. I also hope that the gauge light circuit now has a simple disturbed connection, rather than having been severely injured due to my resistor short.

I didn't intentionally mess with the idle screw, but I'll check it out tomorrow to see if its an unintended consequence of something else i did.

There is no longer a separate engine bay harness and fusebox. That was eliminated in the WireDiet. There are several fuses going to the starter, but since the car starts I'll presume they were not compromised.

What mystifies me is the oscillating speedometer while at a stop after the exhaust pop and return to low idle. There's obviously some signal crossing that shouldn't be there.

Thanks Jeff and RE63.

Is ther a purple loop on the back of the speedo? If so snip it so it does not have continuity

[dukegrad98]

All the popping is probably an air leak into the exhaust, not an electrical problem. Check your j-pipe or headers and make sure everything is tight and sealed. I was never able to get them adjusted very well on my 4.6, and this is a common complaint. I later had a custom exhaust built, and I now have no popping or backfiring.

Cheers, John

[Art Cuesta]

Rick and I have already talked about these issues and my thought was part of this must be due to something changing behind the dash as he told me he had been driving the 'snoot out it' for about 1500 miles.

As he says with the WIREDIET he no longer had to use the battery junction box harness which was eliminated and the power and grounds he needed from it were relocated to the PCM harness. That power is firing up the CCRM with it's relays for PCM, Fuel Pump and Fans. As he says the car is starting and running fine except for the idle issue and popping so electrical seems unlikely at this point for those issues.

His DLC that once worked but now doesn't is powered from the Mini Fuse Panel of his EZ Wiring chassis harness in the foot box with the power wire leading to DLC so I would be looking for loss of power or the dedicated DLC ground I set up. Rick I don't think I mentioned it at the time but I should have had you check for 12V at the DLC power pin on the DLC (light green w/ red #1047 wire at pin # 16) and you would know right away about power - that wire on that pin should be 'hot all the time'.

Problems with the PCM at this stage of troubleshooting wouldn't be real high on my list as others have said.

Rick and I communicated a lot during his build and I was dissappointed to hear he is having these issues after it seemed he had everything sorted out and was driving the car. I have confidence once he has a chance to drop the dash it won't take him long to figure out what happened back there and correct it.

Again I am happy to hear the comments of some of the forum's finest and see my own thoughts are in the same ballpark.

Art

[rick8928]

Thanks Art, and again I want to make it clear to everyone that these are my issues, not yours, since everything worked fine when I was driving around in primer. I have no doubt that in squeezing my wiring (heater hoses take up a lot of room behind the dash) during final dash install, I must have disturbed one or more circuits. And, these are minor issues and not compromising my fun with the beast!

PJ and I are taking our cars to Mark Doughtery's shop for setups this Friday, and I hope to check exhaust connections while car is on a lift.

Thanks again to all responders.

[rick8928]

Have got about 7000 miles on the car by now, loving it. Got stranded the other day (loss of power) and had to be towed home. Thought I had a bad starter (again) and had it tested at Advance Auto. The first time they tried it, their entire test station blew a fuse. Trying again, they got a green light but commented that the starter was making an unusual noise. So, I bit the bullet and bought a remanufactured one from the Ford dealer. He gave me a discount so it was actually cheaper than the knockoffs at the auto parts stores.

Still, only partial juice. I had checked all connections and fuses previously and was at my wit's end. Called Mark Doughtery and he suggested that I take my battery safety switch out of the circuit via a bypass, but still no luck. Then, hours later at about 10PM he called and left a voicemail suggesting that my symptoms sounded like bad grounds. Several hours earlier, I had had the same thought while driving home from a friend's house, but it was great to hear my thoughts seconded by an expert.

Next morning, connected my negative remote terminal to the quickjack bolt with a battery cable and clamps and voila! Solution!. Thanks Mark for your conscientious follow-through! I opened up my trunk access panels and saw that my sheet metal screwed ground strap was loose and causing a loss of current. Tightened it up big time and added another connection between remote negative terminal and quickjack bolt-this connection will not loosen.

While I had the dash off for the first time since completing the car, addressed my earlier issues: found that during the last dash installation had pulled the gauge light connections off the dimmer rheostat-soldered additional wire on and gauge lights fixed. So cool to drive at night with them brightly shining. Per RE63s suggestion and confirmed by a call to SpeedHut tech, cut the speedometer purple loop (taping up the ends) and the speedometer oscillation issue was resolved (purple loop acted as an antenna and was picking up interference). Decided not to mess with Art's suggestion yet about checking the DLC out due to the pain in the ass factor and I was jonesing to get back on the road after a week in the garage. By the way, the high idle issue has gone away and I now just have a slightly slower return to idle than I would expect, but perhaps as RE63 stated, it may just be normal.

I'm now ready to embark on a "Tour de USA" this summer, starting out at Factory Five's open house, heading west to the London Ohio Cobra get together, and spending about 3 months circumnavigating our country counter clockwise visiting friends, family, museums, national parks and monuments and other things. Will mix up camping out in parks with tent and cheapo hotels. I'll be starting a thread in awhile with some details of my itinerary and a shout out to fellow forum members seeking potential lifeline support if I run into mechanical issues.

[RE63]

Sounds like good progress, I would put a nice heavy ground strap between the block and the frame.

[dale]

Aaahh, ground connnections; had my share of these problems with last build, all corrected. Next build, I'm going to stud-weld threaded connections to chassis for all chassis grounds, as someone here recently advised.