Car wont start hot

[carfanatic89]

I just did a ignion rebuild. New distrubutor, cap, rotor, NGK wireset, and bosch platium 4 spark plugs. I ran good for about 300 miles then started messing up again. I was told that sometimes the transistors inside the ecm start going bad and are sometimes affected by heat.

Im not really sure this is the cause, but it would make sence it runs bad and good at random times. sometimes it takes 3 trys to start my car and other times it starts right up and revs to 1500 like its suppost to. Everything is really random and it seems to get worse the hotter the engine gets. (I just checked the coolant and cold start injector time switch yesterday and the ohms are within spec)

oh and it gets better, my car now for no reason at all idles at 400 rpm. Ill pull to a stop light and it idles at 400. green light Ill go to the next light, stop and it will idle at 700<---- this part here has me confused and the idle screw wont raise idle any.

[MK3PIMP]

take those bullshit bosch platium plugs out and get ngk and it should fix it or atleast help u out alot

[carfanatic89]

My friend has a video camera so im gonna get some videos and post them that way yall can see what im talking about. Internet troubleshooting isnt gonna help if nobodys had this problem and cant see what the car is doing.

If I dont fix it in the next 2 months im thinking about selling the car and getting a truck. Supras are badass cars and all, but im not experiencing the badassness my car once had. Ive been trying to fix it for over a year now and im running out of money and patience. Im in a tech school for auto mechanics. Doesnt really leave money leftover for my car.

[CyFi6]

try asking your problem over on Supramania - Home of the Supra
Its not that they have better people or anything, they just have much more activity than this site.

[carfanatic89]

I finally got a timing gun and checked it on the supra. I warmed it up, and jumped the te1 and e1 terminals, and was Idling at 800 RPM. It read about 20 degrees BTDC, which is way out of spec. So I adjusted it to 10 BTDC like the book says, and now it runs even worse. 1000 to 3500 rpms is fine, but no full throttle and no power above 3500 RPM. If I do give it full throttle it missed really bad and wont even accelarate and above 3500 RPM it misses bad but will accelarate as long as I ease into full throttle. WTF is up this doesnt make any sense, I put it where it needs to be and it runs worse than when its out of spec. Its a JDM motor, would that make a difference??? Any ideas? Please help

[TheMark3]

>carfanatic89 says: Im in a tech school for auto mechanics. Doesnt really leave money leftover for my car.

>If I dont fix it in the next 2 months im thinking about selling the car and getting a truck. Supras are badass cars and all, but im not experiencing the badassness my car once had.

Then stop throwing parts at it and diagnose the issue. This is going to be your career - right? Get to the bottom of it or quit - the world does not need more sub-par mechanics. Sorry to be down on you but honestly you should see this as a challenge and not act already defeated by it.

Since you already replaced the ignition you need to do some diagnosis work before you go out and replace the fuel system. Put a fuel pressure guage on the fuel rail and see what pressure you get. It could be a clogged filter or good old fashon vapor lock causing the issue.

[carfanatic89]

30 psi. and hold that for 3 hours. The vsv's are working and the fuel pump regulator is recieving vacuum. I have built alot of engines and fixed many of my friends vehicles, but their easy to fix problems. Nothing like wont start when hot and will when cold. Makes no sense, Im just frustrated with this car ive been trying to find out whats wrong with it for over a year now. I have taken the car to toyota, and they couldnt find anything. The school im going to has a toyota program and they are clueless as well. Just because I want to get a reliable car inorder to get a relaible job doesnt mean im a shitty mechanic. everything else as far as maintenance has been done by the book. Nobody can help me with the problem and im currently on 3 forums to find the problem.

[TheMark3]

So the 30psi on the fuel rail is stable - meaning the same reading when it is hot, cold, running well, running like crap?

The vacuum solenoid valves are working - under what conditions were they tested? Back in the day I had a 280Z that acted similarly. A temperature sensor was faulty but bench tested OK - meaning it had the right resistance cold and hot - but it did not remain correct under prolonged heat. The end result was that the engine was enriching the mixture until it thought it warmed up - which it never did. It was eventually found after sitting on a diagnostics machine for about an hour.

[TheMark3]

Another thought is to monitor your fuel trim and see what the engine thinks is happening with the fuel mix while this is happening.

...or stick a wide band sensor in the exhaust and see if it is rich or lean for yourself when this happens.

I would also recommend the NKG plugs - even a cheap set until you get this solved. When my 280Z was running as I described in my previous post - the NKG plugs were the only ones that could shake off the rich mixture - the rest would just foul until they died.

[carfanatic89]

Thanks that was more helpful, I just took off the timing cover to make sure the cam gears haven't jumped a tooth. everthing checked out and I started it and ran ok. The fuel pressure is to high right now to crack the line, ima let it bleed off some pressure. Then ill put the guage back on to check and get a fuel curve of all conditions and see what I find. As far as a wide band goes, do they make a wideband sensor that will bolt inplace of the old sensor to run a guage and send feedback to the ecm. If so can you tell me where I could buy one. I have ngk wires on right now. I have to wait till next paycheck to get ngk plugs. Im also going to put on a new intake. I think the old ones fine, but it is old and has some stress cracks in it and might be letting un-metered air in the engine. Thanks again, I know im really close to find out whats wrong with her.