3TGTE ECU probs

[Hulk]

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You might have a dry or cracked solder joint on the socket connecting to the printed circuit board.

That sounds logical. I will check that out tonight when I get home.

Will I damage anything if I take the cover off the ECU and move the circuit boards to see inside?

[GasedT18]

Will I damage anything if I take the cover off the ECU and move the circuit boards to see inside?

Not if you are careful There's unlikely to be any static risk as they are analogue. But I'd watch out for Japanese design booby traps. I've seen Jap electronics designed in such a way that if you got the screws mixed up (different lengths) and put a long screw in the wrong hole you'd end up destroying a circuit board track. This assumes you can get the screws out in the first place and they aren't glued in or that there isn't a hidden screw under a lable - sneaky buggers

Haven't looked inside myself. You're going to have to play it by ear. I'm interested in seeing the guts of these units, a schematic would be interesting. There's not very many of these units around even though everyone seems to get rid of them in favor of newer fuel and ignition tech - damned if I know where they end up - whenever they are up for sale they seem pricey.

[Hulk]

Was fairly simple to take apart. 4 screws and the top was off:



The row of soldered points on the far right looked brownish compared to the others.


When you look at the other side of that circuit board, the brown row is directly connected to the plugs.



Does this mean those ones are burnt/damaged?

[boris]

Jules,

I had a look for the receipt but it was well over 3 years ago and it seems I had a distinct lack of organisation back then. My parents actually collected the car from the mechanic which is why I can't remember exactly what was wrong. Typically Mum & Dad don't remember either.

The best information I can provide is that it was a sensor (possibly temp related) that was causing the engine to overfuel and then stall. Sorry I can't be more helpfull but I hope you figure it out.

Jake

[TA22 GT]

The internal joints appear ok. I think if it was a joint its more likely to be on one of the ECU plugs themselves.
Check they are all clean. Also those plugs have a small internal tab which stops the pin from coming out of the plug. If this is broken it will stop the pin connecting properly and externally it will look ok.
To test simply unplug the connection and then check all individual pins/wires don't pull out from the rear of the plug.

Hope that makes sense. Did you check the PC sensor?

Cheers,
Simon

[GasedT18]

So, do all the joints from the yellow socket look good? You have to look closely.

Can you see any reason why your jiggling of the wires/plug/socket might have upset the unit?

Have a look over the rest of the circuit board (the brown staining is laquer or flux - don't work about it. Look for cracked ceramic capacitors, discoloured resistors, dry joints etc

If you can't see anything, cracked joints/frosted joints, at this stage I'd put it back together. Ensure the case has no dings and doesn't foul the circuit board.

Now Inspect the plugs that plugs into the yellow plug. Are all of the wires in good nic? They are crimped into pins no doubt? Any wires hanging on by a few threads?

OK, assuming there's no physical damage and that the plug & socket are fine why the hell would jiggling the wires near the ECU cause the symptoms? I'm ruling out stray capacitance effects and unless you can continue to reproduce the symptom reliably I'm going to move on. So with everything plugged in and engine running - hold the ECU down firmly and gently jiggle the wires to the plug.

With phyical things rulled out you will need to start to look at electrical. Start with power. Is the earth wiring good? ECU to body, body to engine? Is the supply wiring good, are voltages correct? Is the supply properly regulated?

Are all sensor wires/plugs good?

Once you've gone over the plugs/sockets and wiring - ensuring that everything is wired up the way it should be you can then start to look at signalling from the sensors.

The only reason I've looked at the physical stuff first is that you reported jiggling made an effect - with everything secured - ECU mounted to firewall and wires tied down - if the effect continues you will have to look at sensor voltage values OR swap in a known good ECU. If after swapping in a known good ECU you still get problems you can start to work through the sensors. Having another ECU allows you to rule out quickly an electrical problem with the ECU.

That's all for now.

[GasedT18]

Pressure switches

The EFI itself uses 2 pressure switches. First one is used for enrichment (connector PE) above 0.15 bar (2.2psi) of boost. This pressure switch measures the pressure through a vacuum line (ok, ok, it's not in this case always under vacuum) from the intake manifold. The second pressure switch is for fuel cutoff (connector PC) above 0.5 bar (7.3psi) of boost. This one is measured before the throttle body. There are two reasons why this does not seem to be a good idea to keep functioning: the fuel cutoff is not complete, it will lead to a very lean condition under high load and is BAAAAD for the engine. It had not caused any damage, but it did render high-speed drivability to unbearable.

From this (Matti's web site) it would be worthwhile disconecting the PC switch. However, it sounds like to me you are getting fuel cut out rather than leaning. Over fueling is a possibility I guess but I don't think it would cause the engine to die so swiftly.

Does the engine run rough and splutter before dieing or is it simply acceleration. boost to a certain point and then a clean cut off?

Difficulty on restarting - too much residual fuel? Wrong advance? Thermal issue with injector drivers/ignitors? If everything is allowed to cool down does it start well?

Air flow meter. When the flap is totally closed, meaning no air is entering the engine, fuel pump is not running. This is achieved by a switch connected to the flap, which connects the fuel pump ground (connector FC) to chassis ground (E1) only when it is open at least partially

So is this switch working properly?

Another possibility is that wide open throttle switch isn't working propely and when you are at WOT the switch isn't closing/opening (don't know if it's a NC or NO)

A 3T-GTEU wiring schematic would really come in handy. Can anyone post a scan of the relevant page of the Workshop Manual?

[Hulk]

Please don't hate me guys but I just changed the battery to one from my brothers V8 and I haven't had the problem since.

Will keep an eye on it as this seems too simple.

[sillycar chick]

Please don't hate me guys but I just changed the battery to one from my brothers V8 and I haven't had the problem since.

Will keep an eye on it as this seems too simple.

LOL dont worry mate im renowned for doing this sort of shit so dont feel so bad

Just tonight I was about to relocate my fuel pump cos it was giving me so much trouble... turns out it was just a split fuel hose leaking hehe happens to the best of us.... hope it fixes your problems!

[Hulk]

What was worse is that I even took it to an Auto Electrician and tried to show him what it was doing and the mofo wouldn't die!

[GasedT18]

Being able to reproduce a fault is key to being able to find a solution.

With phyical things rulled out you will need to start to look at electrical. Start with power. Is the earth wiring good? ECU to body, body to engine? Is the supply wiring good, are voltages correct? Is the supply properly regulated?

That the fault has not occurred since swapping the battery suggests to me that your regulator and/or alternator is suspect.

D

[RiceburnaGTV]

hey mate Ive got a bare ecu lying around somwhere if you wana give it a shot,Ill send it up and if it works just throw me 80 bucks..

cheers
Nath

[Hulk]

That the fault has not occurred since swapping the battery suggests to me that your regulator and/or alternator is suspect.

What's a surefire way of testing this? All I have for electrical testing atm is a pocket multimeter.

hey mate Ive got a bare ecu lying around somwhere if you wana give it a shot,Ill send it up and if it works just throw me 80 bucks..

Thanks Nath, I may take you up on that if the symptoms resurface.

[GasedT18]

Pocket multimeter is all you need.

Time for some study:

http://www.alternatorparts.com/under...lternators.htm
http://autorepair.about.com/cs/elect.../aa122700a.htm
http://www.familycar.com/Classroom/charging.htm

There are no doubt better guides.

If your ECU is truly dud can I please have it? I have an esoteric interest in working out how it works.

Nath, if you've got the knock unit as well could you PM me?