I worked on an old supra where the owner swore up and down he had checked every last detail and couldn't figure out why it sort of start but but die.

Turned out to be the key to the cam gear broke off so the cam gear was turning but was out of timing alignment.

 

Did the full 12v mod directly without FPC, same behavior.

I pulled the TB and looked at the wiring going to the coils. They are very brittle and the colors you can barely make out. They had attempted to re wire them (black tape everywhere) and just pinned them into the coils without connectors.

So tomorrow I'll pull the wiring harness back to see the original colors and make sure they are going to the right places. The spark plug wires are all correct (1-6) (2-5) (3-4).

 

All coil wires are in order, though the front 2 had the ground upside (if that matters).

Another test start and it idled a little longer this time, perhaps the ECU is making some adjustments.

However, something strange to me. I hooked up my scanner to get a live view of sensors and there is NO voltage reported from either o2 sensor. Also one of the short fuel trims is at +99%. So I don't know if that is a misread by the scanner (cheap one) or maybe something in the ECU is F'ed up to trying and dump 99% more fuel on 3 cylinders.

My other thought. I had a Volvo that was giving this same erratic behavior for a long time could never get it to start and stay running. Turned out to be a clogged catalytic converter.

 

if the front two coil connectors were misplaced, it would cause a P1300 code. Also, yes, those 99% values are reminiscent of a cheap scanner, mine has them too. Its basically just fill in numbers for values that don't exist, those values are pretty much for cars with 4 O2 sensors (such as a v8). Also, if you think it is a clogged catalytic converter, just run it open headers bro! Also, the O2 sensor readings could be a sign that perhaps the O2 sensors are unplugged (lol) since the engine won't run without them, just like the MAF sensor.

 

WHERES WALDO?



SOOOO It is starting to be more and more timing related. I went down to line up the crank pulley and cam gears and there is NO crank pulley bolt? So, this is not good. Also it looks like someone was jabbing in there. So did the ding dongs at the shop who messed with it sheer off the bolt in the crank?

I'll have to get a crank puller tool and possibly remove the radiator to get access. Whether or not it's related to the start issue, this is not good!

 

What the actual hell, those folks weren't mechanics, they were clowns with a badge. After seeing this, its pretty much guaranteed that it has at least SOMETHING to do with the timing. There is no way that is timed up at all. Seeing that there is no harmonic balancer bolt you should pretty much be able to take it out without removing the radiator (perhaps?). Never done it on this car so I don't know.

 

I did timing belt jobs on a few SCs back in the day, I had to remove the radiator to make room for the puller tool without jabbing into the radiator. I hope the pulley is still good, that will not be fun to replace. Possibly the keyway is damaged or missing. I did notice that the crankshaft IS moving with the pulley so that is good news.

I'll have to search back I remember years ago a couple of people posted about a sheered off crank bolt.

 

I was able to line up timing marks and everything seems dead on. I was hoping that was the problem and we would be done.

So, I removed the pulley and the keyway is there (figured it might be missing and the pulley was off timing).

I also have a closer look at whatever is inside the crankshaft front. I can't quite make it out. Maybe a sheered off crank pulley bolt?

 

Wow, that's a first. Maybe they drilled it to try to get an EZout in there? Going to really suck getting that out, if it's even possible. Project Farm did a video testing for the best extractor, from what I recall the Irwin brand that I've always used came in near the top. But I've also broken them on a lot less than a crank bolt. You would need a special service tool to hold the two bolts you'd put in the pulley while you crank on the crank bolt. Probably easiest would be to weld a piece of plate with a semicircle cutout and drill two holes for the smaller bolts to go through.

There's also an electrical process called metal disintegration but you'd likely have to remove the shaft for that.

 

IT LIVES!


I took a few days to reflect on how we came to this point. The person I let *borrow* the car, said it was misfiring then died. Upon inspection years ago, I found that the intake pipe resonator had burned a hole in it (the heat shield was missing). So who knows how long they were driving the car running super lean. When I replaced this part, it did start but died. The lean condition must have burned out one or both of the catalytic converters. I towed to to my friends shop where it looks like he broke the crank pulley bolt off attempting to change the timing belt.

Fast forward to today, the car would still start but not stay running. A clogged catalytic converter has this same behavior. So I removed the front o2 sensor to see if I could get some different behavior. I couldn't reach the rear one. I started the car and VROOM! Starts and purrs like the kitten it used to be.

So end result, clogged catalytic converter, one bad driver, one idiot mechanic.

Thanks for the help guys! Now, one to the crank pulley bolt problem.