4AGE won't start after overheating

[banana_socks]

Long story short I may have been an idiot and not properly bled the cooling system before going for a drive. Everything was running fine, when it sort of misfired under load so I instantly pulled over and noticed the temp was pretty damn high. I had been adjusting the TPS on the fly to try and sort some dramas with it, which previously has caused it to run hot even when properly bled.

Luckily I was one street from home, so I left it for about 90mins. After which it still won't start. Turns over, but doesn't wanna kick. Pulled the oil cap and it looks decent, dipstick looks perfect. Ran a compression test, and I'm getting 190-195 in all cylinders (if anything seems higher than the last test). So I'm pretty stumped as to what might be wrong with it. What should I be checking next?

[Hen]

Check the usual:
- Is it getting spark?
- Is it getting fuel?

If you're running stock ECU check for codes. If you're running aftermarket then plug a laptop in and make sure all signals look right. It could be as simple as a blown fuse or broken wire, but it's hard to say from the little information you've given about your setup.

Personally I wouldn't be at all worried about major engine damage.

[banana_socks]

I cleaned up the plugs when I pulled them, but I haven't checked for spark and fuel yet. Mainly because they were working fine until it started overheating, so I thought it would be related to that. But it doesn't seem like i've cracked a head or HG, so maybe it purely is coincidental. I guess I'll start troubleshooting from the beginning. Cheers.

[pandaah]

id start with fuel pressure and spark aswell.. 195psi across all 4 is plenty enough to get it going..

[jondee86]

Pull the top timing cover, and check that your timing belt hasn´t jumped
a few teeth.

Cheers... jondee86

[Billzilla]

To give you a bit of hope, here's the story of when I overheated my 4AG in 1995.
I was driving along the motorway south of Brisbane, coming up on the Logan Hyperdome, and was talking on a mobile phone. This was in 1995 so it was a cool thing to do.
While I was talking on the phone I noticed the car 'felt funny', in that when I got off the throttle is didn't seem to want to slow down as much as it did usually.
Anyway I was going to pull over at the Caltex at the Hyperdome anyway and when I pulled in the engine was idling at something like 3,000 - 4,000 rpm. (Shitty Microtech D4 computer) I figured the bolts holding the distributor in place had come loose so all I'd have to do it turn the distributor backwards until the engine sounded like it was idling properly and that'd be close enough for the spark timing, then find a bolt from somewhere else to strap it down then keep heading home.
Opened the bonnet with the engine still running quickly and was hit by a huge cloud of oil smoke. The smoke was caused by the engine being so hot that it was boiling off the synthetic oil on the side of the block, so pretty damn hot.
Okay put the car on a trailer, got it home, fixed the stuff that needed fixing, etc ..... compressions were all about 150psi, that's all. I could turn the engine over by hand, by grabbing the front pulley and turning it!
Anyway it started and ran okay but was obviously down on power. The engine stayed in the car for another six years and hardly needed any other work.

Useful trivia - The cause of the loss of water was hard to track down, and it was this - The pipe that runs from the back of the water pump to the back of the engine for the internal heater, etc, has a small metal strap that bolts onto the side of the block to support it. Where the spot weld was, it'd corroded through from the inside so you couldn't see it and was slowly squirting water out. But not at idle! It took a bit of searching but the only way I could make it visibly dump water was by running the engine at about 3,000rpm for a minute or so, and ONLY then would a stream of water start to come out of it.

[old_mr2]

check your EFI fuse?

[mullett]

And fusible links!

[banana_socks]

Hey guy, thanks for all your responses. Halfway through my diagnostic checks it decided that it would start up, and run perfectly fine. Had been perfect for about a week, but now throws up another issue. I'll go to start it after sitting for a little while, and it'll just keep turning over without firing, with the temp gauge at the absolute max. This is definitely not a correct reading, as in one instance it had been sitting for 3 hours after running normally. Also the gauge stays at max with the key out, but when working normally it goes off.

Pretty sure its a buggered sensor, but I need to know which one to replace. AFAIK, there are 4.
Single wire, white plug on thermostat housing - fan control?
Two wire, greem plug, side of block - cold start injector?
Two wire, orange plug, side of block - unsure
Single wire, black plug, back of head - unsure

Which should I be replacing? Also are the sensors same for a bigport, even if the plugs aren't? Cos I have a set of those.

[30psi 4agte]

prob find that your no start issue is due to that sensor. With the temp that high its prob causing the ecu to adjust mixtures and timing etc to compensate. Could also be causing it to go into limp mode if it is a factory ecu