car suddenly wont start - never ran great anyway, esp. cold, now cranks, but won't st

[rjSupra]

Thanks Cre.

I hear you. That might not be a bad place to start. Also, for some reason I don't think my ECU is bad, just a hunch nothing more. But my O2 sensor looks pretty old and dirty on the outside, so I bet it's old and dirty on the inside too.
I wonder if the 02 sensor is so bad and dirty and old, and the temp was so cold here yesterday, maybe it just couldn't work (air temp in the teens, maybe lower). And maybe trying to start the car the 14 + times without it starting prompted my #21 error of ignitor / ignition pack failing to start after "A" times (which for my Turbo is 3 times in a row). So would that make sense?
Can a trashed O2 sensor cause some power issues by, what, messing up combustion or timing, and account for lowered power and crappy fuel mileage?
What do other folks get on their older Supras for MPG anyway? I think I read 14-30 mpg range. It would be very nice to solve this problem, have a running car, and a break from the headaches. I haven't even had time to think about the nasty PS leak with all the other stuff.

[cre]

Your O2 sensor isn't going to cause much other then slightly poorer mileage than normal. The average mileage I've seen would be about 18MPG with mixed highway and city and a slightly heavy foot on occasion. You can unplug the O2 sensor and should see little change in the operation of the vehicle. If there is a significant change then there is a problem with a more critical trim sensor somewhere else in the system (such as the AFM).

The code could be the result of low voltage due to the cold temp and drain from repeated cranking... test the battery, the alternator and test the ignitor.

[btwilson86]

Originally Posted by rjSupra

What do other folks get on their older Supras for MPG anyway?

I'm averaging about 18-19 city driving, and that's with a somewhat frequent heavy foot.

[rjSupra]

Hi guys, thanks for the assistance!

I have a battery charger with a 50 amp starting setting, to start the car with the battery in it from your garage A.C. This worked pretty good with a bad battery before on the car, before I bought a new (cheap) battery. Autolite Silver series $67 with core on sale direct internet. Probably not a great battery, but I was not sure at that point I could keep the car (had that unsolved mega coolant problem that grounded it for 2 months at the time, and had thought if the steel line under the headers was toast I'd probably sell the car as is with disclosures).

So, I am guessing I should be getting enough juice. I am separated from the car's location for another day, hopefully when I get back it will warm up a bit and I can re-try. The car sat about 24 hrs overnight in fact (not same day), in biting cold since it had last been driven 30 miles / 45 minutes. So far, the alternator has been keeping the battery charged. The car has sat for 7+ days in bad cold before and fired right up as always.

I have not done the spark plugs. They looked, well used, but not terrible. No real oil that I can recall, although it's possible one was wet a little bit. Mostly I remember normal carbon deposits (at the time no plug gapper tool, so could not check the gaps). Have not done the wires, no idea when they were done last, although visually they look ok (i've seen a lot worse).

Any thoughts what that wisp of smoke behind the motor, close to the firewall could have been? And the slight plastic-y burning smell? That happened the last time I tried to start her, with a paper clip jumping either the engine error code check terminals, or the fuel pump 12v bypass I can't quite remember which one I had it in.

It sounds like the 02 sensor can't be at fault for all these issues, so I appreciate knowing that now. Don't really know what they do aside from I gather measuring oxygen levels in exhaust to send setting info to the car for fuel rich / lean levels etc... I do have a multi meter so next step would be to test a few of the components that way. It was just too cold and dark the other day to deal with it.

Thanks again.

[cre]

Originally Posted by rjSupra

Any thoughts what that wisp of smoke behind the motor, close to the firewall could have been? And the slight plastic-y burning smell? That happened the last time I tried to start her, with a paper clip jumping either the engine error code check terminals, or the fuel pump 12v bypass I can't quite remember which one I had it in.

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.

Originally Posted by rjSupra

It sounds like the 02 sensor can't be at fault for all these issues, so I appreciate knowing that now. Don't really know what they do aside from I gather measuring oxygen levels in exhaust to send setting info to the car for fuel rich / lean levels etc.

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.

[rjSupra]

Originally Posted by cre

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.

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

Originally Posted by cre

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.

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.

[rjSupra]

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!

[cre]

How can I say this simply?


No.

[straight6power]

Can the 7mge ingnition system b put on a 7mgte...

[cre]

The distributor/points system? It may be manageable, definitely not possible the other way around but controlling it and pulling the three separate ignition signals into one may prove to be more effort than it's worth.