[Newbi] First time poster [Solved], Already I need help Options

[Chanassa]

Hi everyone, first time poster with a keyboard in the other end here, and of course I have a problem.
I got my Celica ST20 1.8 one week ago, a good car and I like it a lot already.
Unfortunately the motor don't run on all four cylinders when it's on idle and hot.
When the motor is cold there is no problem at all, and same goes when I'm revving it, all four is on board and do their workload as they should.
I have found out that it is cylinder number four that is the problem, and tho whole motor have been taken apart and reassembled, we cleaned to cylinders, and pistons (Also the pistonrings, they were stuck and I thought this was the problem) but this didn't help.

I have now bought an used top to this engine, but do you have any tips for what this can be?
Thanks all.

This post has been edited by Chanassa: Nov 25, 2013 - 1:00 AM

[njccmd2002]

not an expert, but could the spark cables be bad, or you have a bad distributor. but someone with more knowledge will help out...

[SwissFerdi]

Maybe a faulty ECU? Your issue seems electrical to my untrained eyes, since you mention engine temperature making a difference. This makes me think that when the a/f is controlled in open loop and reading from sensors, the error is caused.

This post has been edited by SwissFerdi: Nov 20, 2013 - 5:44 PM

[Box]

Try swapping plug wires and injector wiring around to see if the problem moves or stays.

[Chanassa]

"Maybe a faulty ECU? Your issue seems electrical to my untrained eyes, since you mention engine temperature making a difference. This makes me think that when the a/f is controlled in open loop and reading from sensors, the error is caused."

- Then it should run on only three when I drive aswell, shouldn't it?

Did try swapping cabels, problem stays on cylinder number four.

[malpaso]

Did try swapping cabels, problem stays on cylinder number four.

I simply expect you checked sparks when swapping wires so would:

- check distributor cap. there are four "pins" (damn how to describe it). Called "individual contacts" in the picture of v6 distributor below:



the one for #4 cylinder can be burned/cracked

- in case you end with "no solution" and trying that ECU just let me know. I have one spare AT200 ECU at home (from European model ST). Can sell it for 50€ if you want . I have no use for it anyway.

[Chanassa]

Yes I checked sparks and all four looked fine.

I'm at work now, and don't think I will have the time before tomorrow to check this, but thank you for all your help. Will check it out as soon as possible.

[Poonicus]

It might be a problem with the wires, dizzy or the cap. Go to the junk yard and find an wreaked car with the 3sfe motor in it and pull the dizzy out. Go to your local auto store, o'reilly's or something and get a new rotor they're only like 2$ and check to see if there's any blown fuses or relays. You can find out how to test your relays on google. Make sure that AM2 and ecu are fine. The am2 is a 30amp fuse and the ecu is a 15. Could also be the ignition coil inside the dizzy, but then again this is speaking from my expreience with my 5sfe motor, haven't work on a 3sfe yet..

keep us posted.

This post has been edited by Poonicus: Nov 22, 2013 - 12:09 PM

[Chanassa]

Hi everyone! This weekend we switched out the old top with an another one, this was the last piece in the restoration and guess what! The valves on the old one, in cylinder four did not seal the cylinder off completely, we could se a gap on two of them.
After we changed the top it sounds so much better, no more running on three cylinders, now all of them are doing their job as they should.
I want to thank all of you guys for your help, this seems like a great forum.

[Smaay]

so the valve clearance was way too tight holding the valves open. this would cause you to have no compression.

[Chanassa]

so the valve clearance was way too tight holding the valves open. this would cause you to have no compression.

Yes, the valves was so dirty. I think this was due to a old woman having the car before me.. Driving on 3/4 gear in low speed.

[Poonicus]

so the valve clearance was way too tight holding the valves open. this would cause you to have no compression.

Yes, the valves was so dirty. I think this was due to a old woman having the car before me.. Driving on 3/4 gear in low speed.

Yeah, that'll do it. Because of that reason I have to redo the top end of my block, or go get a beams, just need to find one..