3rd gen cold start = Total crap., Any ideas? Options

[Silver94CelicaOw...]

Time for troubleshooting.


My ST205 swap was running fine for about 2 days, but startup was always a little rough from the get-go.

When I cranked the motor to start it the first few days, it would take a little while but then fire up....but when it did start it sounded as if it were only running on like 3 cylinders momentarily (think Subaru with an exhaust sort of sound) then once I gave it some gas and blipped the RPM's to around 2k for maybe 30 seconds or so, it sounded like the cylinder that was missing came in and it sounded perfectly fine and idled great. Once the motor was warmed up, it seemed to start much easier and smoother though. I also drove the car for the first two days and it boosted great and ran very smooth the whole time.

After those two days of starting rough, I went to start up the car the morning of the third day and it wouldn't fire up at all. The starter worked fine, and it sounded as if one cylinder was firing and trying to go and that was it. Later that day i played with the ignition timing, and it took advancing the timing almost all the way in order for the motor to sound like it even remotely wanted to start up. I eventually got it to sputter once the ignition timing was advanced and by pumping the gas it slowly started up and once again was running on maybe 2-3 cyinders until I revved it a little, and then all four would kick in.

I let the engine warm up to normal operating temperature and shut it off. Once warmed up, the car will start up on a dime like there was never an issue. But from a cold start, it seems that the motor hardly wants to fire up sometimes without cranking it for like 20 seconds.



The car has a brand new battery, new cap and rotor, and I'm using NGK BKR7E copper plugs at stock gap. I checked the plugs yesterday and they all seem to be fine. I don't believe the 3rd gen 3SGTE uses a cold start injector either, so I don't think that is an issue. ECU was checked for any CEL's or stored codes and it all appears just fine. Only things I can even think of anymore is that maybe its one of the air temp sensors (either manifold or airbox) sending out a bad signal when the engine is cold. Otherwise the only factors to having correct idle on the 3rd gen that I can tell is having proper spark, fuel pressure and injector pulse, ECU signal, TPS voltage output, and temp sensors or O2 sensor maybe?




Any ideas as to what may be contributing to the really poor startup conditions I'm experiencing? I'd appreciate any ideas or perhaps similar experiences that may yield me an answer to the problem.




-Corey

[lagos]

bring it to the philly meet today and i will diagnose it

oh, and.... its a common problem on all 3s motors. you need a new Cold Start Time Switch.
try to score one from a junk yard, cause toyota wants over 100 for them.

[lagos]

edit:
just finished reading the entire thread. adjust your timing with a timing light and TE and E1 bridged. you cant just do it it by feel. it should be at 10tdc. very important!

even tho the 3rd gen doesnt have a cold start INJECTOR. it should still have a time switch. they just used the stock injectors at a higher duty cycle for cold starts. so you should still have a switch on the drivers side coolant neck.

This post has been edited by lagos: Oct 13, 2007 - 10:25 AM

[Silver94CelicaOw...]

Thanks for the advice Art. (I wish I could drive it all the way to Philly right now....soon though.)

I'm trying to score myself a timing light as we speak so that I can set the timing to where it should be, at 10 degrees btdc. I'm too cheap to go out an buy my own because I know I could just borrow one...ha.


I'll definately look into a cold start time switch though, sounds promising.



Any other ideas?

[phattyduck]

I'll definately look into a cold start time switch though, sounds promising.
Any other ideas?

Give up on the time switch. The 3rd gen doesn't have one. Cold-start is completely based on the water temp sensor (or is it sender?).

Did you completely replace everything in the ignition system? (wires, cap, rotor - it sounds like you already did the spark plugs)

Any check engine lights? Check the resistance on the water temp sensors while you are in there...

-Charlie

[lagos]

Give up on the time switch. The 3rd gen doesn't have one. Cold-start is completely based on the water temp sensor (or is it sender?).

then his coolant temp is bad.

[Punisher]

I'm 80% positive it's the head gasket..

[Silver94CelicaOw...]

I'm starting to feel the same way.

Horrible start up, bad overheating issues, white smoke even after the engine is warmed up....not looking so good.



I'll do a compression test tomorrow morning just to confirm my fears, but looks like I might be tearing this bastard down already. Oh well, I'll just be sure to rest up and buy lots of beer for the occasion.

[phattyduck]

I'm starting to feel the same way.

Horrible start up, bad overheating issues, white smoke even after the engine is warmed up....not looking so good.

I'll do a compression test tomorrow morning just to confirm my fears, but looks like I might be tearing this bastard down already. Oh well, I'll just be sure to rest up and buy lots of beer for the occasion.

That sucks.

Once you get it back together, you will absolutely *love* the motor. Keep on it!

-Charlie

[Punisher]

*drools* beeeeeer.. we're going to get really sloshed and put the head on backwards lawl

[Silver94CelicaOw...]

Yea, so its definately a head gasket issue.

Just did a compression test today and the figures speak for themselves:


#1: 150psi

#2: 110psi

#3: 140psi

#4: 150psi


Lots of coolant on the plugs of cylinders 2 & 3, so there was definately a head gasket failure somewhere between those two cylinders. I have a feeling that my motor, as incredibly clean as it was, had a brittle head gasket when I bought it for whatever reason and running it a little bit hot a few times sent it over the edge and the head gasket failed. At least now i have an answer to the problem and I can get it fixed and boost again.


I'll take lots of pics when I tear down the motor. In the meantime, I've got a lot of work to do.