Alright, my 1992 SC400 with 180k miles broke down a couple of months ago and I'm just getting time to work on it. The problem is when I crank it, it idles bad like it is misfiring or not running on all cylinders and it only stays alive if I keep my foot on the gas. Also got a burning metal smell in the week before it broke down. So my guess from reading on the forums here is that it is a problem in the ignition system. I've replaced the plugs, wires, caps and rotors to no avail.

So my next guess was coils. So I got new coils from Autozone to see if that was the problem. I hooked them up and no difference. Before I went and bought the new coils, I tested the old coils. The primary resistance according to my manual should be between 0.4-0.5 ohms, and the secondary resistance should be between 10.0 - 14.0k ohms. The stock ones measured 1.0 ohms for the primary resistance and passed the secondary resistance test. The ones I bought at autozone measured the same as the stock.

So my question is, are the specs for the coils right in my manual? And if they are, what are the odds that both of my coils went bad [I]and[I] Autozone gave me bad coils?

 

Fouled plugs from a head gasket leak?

My first thought was ignition as well.

 

May be that. I'm going to do a compression test sometime this week. But are the specs for my coils okay? I also failed to mention that I have also tested the MAF, TPS, IAC, and the EGR valve and they are all fine. And I haven't noticed any vacuum leaks either.

 

Any smoke coming out of the exhaust when you are able to keep it running?

 

I get some white smoke. Also smells like it is running rich. And I am not getting any codes at all.

 

White smoke usually happens with a blown head gasket, and as someone else said it could have fouled your plugs. I would take it to a shop and at least get it diagnosed by a mechanic before spending any more money on parts. That sucks man, good luck.

 

I AM NOT SAYING THIS IS YOUR PROBLEM.
I have 92 sc300 and It did almost the same thing and it was the ecu. The car had about 212,000 .
If you have a friend with a sc400 you might try and swap out the ecu to
see if that is the problem.

 

Alright, so the compression numbers are all in range. I think the white smoke I got was from the car sitting for a while in the humid weather. The plugs, however are blackened, but I've read this is caused by fuel or ignition problems. Also had a friend look at the ecu, and none of the capacitors are bad, which from what I've read is usually the problem with these computers.

So the next question is where do I check the fuel pressure from? I've already replaced the fuel filter and can hear the pump when I turn the car on.

 

Okay I finally got the car to pull a code. The codes are 24 and 31, both pointing at the MAF sensor. However, unplugging the MAF sensor makes the car die immediately. So would this still mean a bad MAF? Unplugging the TPS also makes the car die. So would this be a bad MAF? I'm leaning toward replacing the ECU.

 

anything anyone?

 

reset the ecu, start it up and try unplugging the maf again.
92 sc400 should run with maf unplugged, but not all of them do so its not a positive on the maf. resetting the ecu will give it a better shot and if it runs even worse after you reset it then that could mean the maf went out recently. those codes point at the maf though so you may want to try and swap it for a known working one. other than that i would guess ecu.