Sure.... the wire harness. Start there. Check to see if you can hear fuel moving through the fuel rail with B+ and FP jumped... check if B+ has a constant 12v.

A bad O2 sensor may be good enough to cause a slightly bad reading.... Usually when they go though they're so far out of range that the ECU disregards the sensor altogether.

Yeah, thanks, already jumped this and verified that I can hear fuel moving through the fuel rail. That part is good.

My current weak hope is that the super cold made it too hard to start, which I know doesn't really mean anything or make sense. I am pretty sure I've started her that cold before. I'm going to have to look into this ignitor thing too.

the car started today. it was 37 degrees out.
 

Ok, this is good, but weird. The car started on the 2nd try today.
It seemed like it was not actually running, but I let off on the starter ignition key and it chugged on it's own slowly and then ran. It idled normal.

It was probably 17 degrees that other night. A car guy I talked to tonight said it was probably the 02 sensor is shot, and the car is only in one mode - like an 'emergency' type of mode, b/c the sensor can't detect when it's running too rich and to cut back etc etc...

Does this all seem to make sense? He said if it was the ignition coils it would not run period, and it was running like it always does (not super strong and crappy fuel mileage) tonight. So maybe I just pop in a new 02 sensor and that could be the end of that?

Thanks!

How can I say this simply?


No.

Hey Cre:

Thanks for jumping in again. To clarify, did you mean that the 02 sensor won't prohibit the ECU from detecting proper levels in the exhaust to set, uh things it does like fuel mixture, air etc etc... (therefore crap mpg and maybe cranky starting in the cold perhaps with the 'wrong' settings for fuel / air)
or did you mean 'No' to the thought that if the coils were shot it wouldn't run at all.
This guy was not a Supra expert, but works on cars before as a mechanic and does know the Supra somewhat (like that it's an inline 6 3.0 liter etc...)
Perhaps he does not know there were 3 ignition coils in this car. He also did not seem to know what an igniter is in it. But he did state a shot 02 sensor that is triggering OBD means the correct levels can't be achieved for all engine temps, and this would account for not running great, perhaps bad starting cold etc...

Thanks again!

The car will run fine with a bad O2 sensor. Once the signal get out of range the ECU just ignores it. When running cold you would see no difference at all as it is as the ECU doesn't use the O2 sensor until the engine is close to normal operating temp. This is the case with almost ALL EFI equipped cars from the mid 90's and earlier. I've already covered this once... Unplug it, there should be very little difference. Your mechanic is either used to vehicles from the 60's or only new "plug it in and that neato machine will tell you what to replace" models.

Coil packs will cause intermittent misfires and if there's a break in the circuit they'll usually be fine when the engine is warm but falter when cold as the conduits shrink and the gap widens.

Have you checked the timing (both mechanical and ignition)? Have you inspected the timing belt? Have you diagnosed the transmission codes yet?


EDIT: There is VERY little which will put the ECU into "limp mode"... the only one that's really common is a code 52 or heavy knock detection.

Thanks for the explanations Cre. Before getting this car I have to admit I really did not know what an Oxy sensor was, what it looked like, and what it did - in any car let alone this one. Sorry for the newb-ness.
I did pull my CPS to repair the coolant problem before and very carefully set it back in correctly aligned the way it was supposed to be (TSRM) with the crank at TDC both visually on the pulley. So that part of the ignition is in spec.
(in also ran identically to how it ran before I pulled it out).
I have not gone any further than finding the two transmission code problems so far. Have not been around the car for several days and have not put the volt meter to different parts / wiring yet.
My car is not having knock problems, nor is it mis - firing. Although today for the first time after starting it and it was idling fine for 2-3 minutes, it did stumble heavily once during idle and then ran normal after that. (like the motor sounded like it was bogging down and like it would almost stop running for a few seconds and then went back to normal idling about 600 rpms like nothing had happened).

You might be right about the mechanic guy - could be either one of those types you suggested.

The sensors used in modern vehicles provide a LOT more information about the fuel mixture and are accurate under a much wider range of conditions; They're known as "wideband" sensors and they do serve as a diagnostic tool.

Older types of oxygen sensors (aka "Lambda" sensors) are only capable of detecting a very specific mixture; get outside of that range and it provides essentially zero data. They're useless except as a trim sensor to adjust for that 1% that the mixture may be off... Your mileage may suffer from a bad one, but it's not going to stop running.

no light out of timing gun, engine error code re-set also
 

Car stranded me after work one day and refused to start in relatively cold weather (30 F?) Would not start at all no matter what I did. If my car is cold I usually blip the throttle a little bit and back it off to start it. I've noticed if it doesn't start the first try I am usually screwed and it won't start at all. Especially if I can't start on 2 tried, I'm really in trouble.
Oh, the batt is good, the motor cranks and cranks and almost starts when it's bad and then won't run.
Jumped it the next day and it started on try #2. If the car is warm, it can start with no throttle. Down to 13.2 MPG, and running really poorly. Worse than before and harder to start. I have so little power up inclines. Even with the turbo at +6 on the gauge I can accelerate up big hills but not much. Without a lot of boost, I loose speed and crawl up them. Climbed a very steep but less than quarter mile hill and my car temp went up really high - about 80% of the gauge last night as I was going super slow up it.

To set and check ignition timing, I just borrowed a friend's timing gun and followed the TSRM online and my Haynes Celica 86 and on models manual and I had no light at all coming from the gun with the thing all connected right and the car warm and running with the T - E terminals connected. Dunno if the gun is broken or I am doing it wrong. (Sunpro timing gun with red lead onto batt +, blk lead onto batt - or grounded to alt bracket and I got no light). Other end onto #6 spark wire - cleaned and solid contact on the inductive clamp, then on #1 spark wire, then on #4 and #5 with a bad connection on #5, no light from anything.

And, I checked and all my engine error codes are cleared after starting the car about 8 times and running it 3 times a total of about 40 miles. So far the O2 sensor error is not back, nor the Igniter / Ignition coil error code.
I also found I have a spare ignitor that came from a donor car, it looks visually a little better than the igniter in my car - should I switch that out in case?

If i were you i would start Ohm'ing sensors

pick up coils
http://www.cygnusx1.net/Supra/Librar....aspx?S=IG&P=9
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=12

plug wires
[2 pages NEXT]

check igniter
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=15

check CPS
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=16

just check everything on this page. lol
http://www.cygnusx1.net/Supra/Librar....aspx?S=FI&P=1

something else you may def want to take a peek at....
http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=124