Idle hunting issue

[Durandal]

Pulled all my spark plugs today, and they were all soot black so I cleaned them with a wire brush and some brake cleaner (they are iridiums with less then 10k on them).

I tested my intercooler piping with a homemade boost tester and it wasn't leaking.

Took the car for a drive after resetting the ECU. It started up cold at 2500 RPM and slowly came back down to around 1800. While driving I noticed when the clutch is pushed in the revs bounce from 1000 to 2000 continulously. (An ongoing problem that comes and goes that i've been trying to solve)

Come back to the house and right before I shut it down the MIL and CEL come on. I shut it off thinking that I will have a code that will point me in the right direction. Put my paper clip in and turn the key and my CEL light isn't flashing just on solid with my "SLIP Cont off" light flashing. 30 mins later I try to check the codes and the CEL light is flashing steady telling me there is no codes.

I start looking into my electrical system checking the plugs at the ECU which look fine, they are tight and none of the pins are bent. (The car is pretty much stock)

Upon looking at the large bundle of wires that come through the firewall from the ECU I find this.


There four wires (3 black and red stripe one and 1 thicker black one all spliced into one black and red wire and also another 2 wires spliced into 1 where the blue electrical tape is. That's not standard I'm assuming?

I had a greddy emanage ultimate that I used to have hooked up only for the speed limit removal and speedo adjustment for bigger rims. I disconnected it awhile ago trying to eliminate possible problems while troubleshooting but it wasn't the problem. I'm thinking I could hook it back up and use it to datalog some data to troubleshoot with although I've never used that datalogging part of the EMU, hoping its straight forward.

Anyone have any ideas?

After looking at some electrical diagrams, I'm starting to think I have some grounding problems.

[pwpanas]

Originally Posted by Durandal

Pulled all my spark plugs today, and they were all soot black so I cleaned them with a wire brush and some brake cleaner (they are iridiums with less then 10k on them).

I tested my intercooler piping with a homemade boost tester and it wasn't leaking.

Took the car for a drive after resetting the ECU. It started up cold at 2500 RPM and slowly came back down to around 1800. While driving I noticed when the clutch is pushed in the revs bounce from 1000 to 2000 continulously. (An ongoing problem that comes and goes that i've been trying to solve)

Come back to the house and right before I shut it down the MIL and CEL come on. I shut it off thinking that I will have a code that will point me in the right direction. Put my paper clip in and turn the key and my CEL light isn't flashing just on solid with my "SLIP Cont off" light flashing. 30 mins later I try to check the codes and the CEL light is flashing steady telling me there is no codes.

I start looking into my electrical system checking the plugs at the ECU which look fine, they are tight and none of the pins are bent. (The car is pretty much stock)

Upon looking at the large bundle of wires that come through the firewall from the ECU I find this.


There four wires (3 black and red stripe one and 1 thicker black one all spliced into one black and red wire and also another 2 wires spliced into 1 where the blue electrical tape is. That's not standard I'm assuming?

I had a greddy emanage ultimate that I used to have hooked up only for the speed limit removal and speedo adjustment for bigger rims. I disconnected it awhile ago trying to eliminate possible problems while troubleshooting but it wasn't the problem. I'm thinking I could hook it back up and use it to datalog some data to troubleshoot with although I've never used that datalogging part of the EMU, hoping its straight forward.

Anyone have any ideas?

After looking at some electrical diagrams, I'm starting to think I have some grounding problems.

No that doesn't look right. That's definitely not an oem splice.

[Durandal]

Yah removed the tape today and there are crimp connectors and all the wires are red striped black wires which are grounds i believe? I don't know why it is the way it is though.

[pwpanas]

Originally Posted by Durandal

Yah removed the tape today and there are crimp connectors and all the wires are red striped black wires which are grounds i believe? I don't know why it is the way it is though.

Crimp connections in general are good (Toyota never uses solder - it's a less relaible connection over time on a moving/vibrating vehicle than a proper crimp). That said, I'd guess you're referring to a cheap plastic press crimp.

Regarding the wire colors in the harness, it's best to refer to the TSRM:
http://www.mkiv.com/manual/1995_elec...ual/index.html

[Durandal]

No the crimps were all metal and seemed very secure. I have seen mentions of some splices in some factory wiring diagrams so maybe they are normal.

After some more testing my recent problem of the CEL and MIL coming on after driving for awhile has got me thinking it could be something as simple as the O2 sensor on the way out. It seems to always come on after driving for about 15 minutes after the car has warmed up a bit. It still doesn't explain why when I check for codes it says there are none, or the trac off light flashes and my CEL doesn't even blink. The car definately runs rich when this happens. Ox1 reads above 0.9v, exhaust smells almost like straight gasoline. Can oxygen sensors work bad when warmed up but fine when cold? I always pegged them as a failing unit.

[Durandal]

I think the crimps are labeled on this picture as "E24" splices.

[Durandal]

At long last I traced all my problems to a bad battery. It had never been below 12 vdc when I checked it but after doing some testing, I found that it wouldn't hold a charge much past 12.15 volts. If you charged it up to around 12.7 volts with a charger and hooked a multi meter up to it with nothing else connected you could watch the voltage drop and in about 10 minutes it was at 12.05. It would never drop below 12 volts so I never thought much of it until this test.

Replaced it with a new battery and after a test drive the voltage is reading 12.9 and not dropping. Roughly 1 volt makes all the difference in the world after factoring in the resistance of the wires.

[pwpanas]

Originally Posted by Durandal

At long last I traced all my problems to a bad battery. It had never been below 12 vdc when I checked it but after doing some testing, I found that it wouldn't hold a charge much past 12.15 volts. If you charged it up to around 12.7 volts with a charger and hooked a multi meter up to it with nothing else connected you could watch the voltage drop and in about 10 minutes it was at 12.05. It would never drop below 12 volts so I never thought much of it until this test.

Replaced it with a new battery and after a test drive the voltage is reading 12.9 and not dropping. Roughly 1 volt makes all the difference in the world after factoring in the resistance of the wires.

So it idles 100% consistently now?

[Durandal]

I haven't done as much extensive testing as I would have liked yet since I got hit with a down pour. However starting the engine from a cold start gave me 1300 RPM while it warmed up and then dropped down to 900 RPM when the engine had reached operating temperature. So I do in fact now have a working cold start system.

[Durandal]

Updating this since it's been fixed for awhile now. The problem came back and after looking inside my ECU found some burnt components, most likely from the time I boosted my car awhile ago when my battery died. At least that's what I think caused it. I got a second hand ECU from England to replace it. Really hard to find a JDM ECU around here.