4AGZE troubleshooting

[cjeff]

Shitter, so the fuel tank was only half the problem. Something wiring wise is up imo. Mechanic rang today to say he's at a loss as to the cause. He said it was running fine last night and was going to call me this morning to pick it up only to find it wasn't running properly again. Haven't got any codes out of the car yet. So planning to try and get it home somehow tonight and see what I can find.

But I'm wondering what worse case scenario would be $$$ wise if I just took it to an auto electrician tomorrow. I'd really love it if I could have it running by Sunday for a Motorkhana event, but if the job is massive, rather than fork out a grand in re-wiring, i'd rather just give the event a miss and take the time to do it myself.

or should I just try and get a mobile auto elec out to my mechanics tomorrow and get them to go over it there, then if they find anything else that's buggered, my mech can swap it?

Craig

[punkture]

def sounds like your AFM/MAP what model GZE is it? id say get the BGB and start checking the control inputs..i.e AFM, CAS/DIZZY etc

[Kebin]

Get your mechanic to check fuel pressure at the fuel rail if he already hasnt.
Check alternator charge rate at the battery, Check voltage at the fuel pump, check voltage supply to ecu, etc. Could be a voltage drop/bad earth issue

I assume your check engine light comes on when the idle drops real low and the engine starts to hunt?
What other troubleshooting has the mechanic done?

[cjeff]

hey, just going down to the mech with my multi-meter to test some things and bring the ecu back to check for dry joints. Can someone confirm for me 2 things?

1. How do you know if the engine is warm enough to be "at operating temperature" to get the diag codes out of the ecu? or will they just read out anyway if the engine is cold?

2. Car is map sensored - can someone confirm what type of map sensor this car has - voltage type or frequency type - ie can I probe it to test it? anyone know proper testing procedure for map sensor on this thing?

Craig

[cjeff]

also which pin is voltage from battery to ECU is the BATT pin from battery or is it +B1 and +B from EFI main relay? or is it VC (wiring pinouts say VC is alternator with a question mark next to it)

[TERRA Operative]

I wait until the fan turns on, that way you can be sure the engine is warm.

[cjeff]

Ok, so this what is happening. Car was starting fine, but idling a bit rough, revd it and it was leaning out and mis firing badly. A couple of times it just wouldn't start, but would crank ok. Changed the fuel tank and pump. Now when it starts, it idles fine for 20 secs ok then dies. Fuel pressure has been checked and is ok. When you try to rev it, it dies. However, my Mech had to try and move it, so tried revving it with the key on start and it went fine, release the key and it's stuffed.

B and B1 have just under 12V. Batt has 12v on back of ecu. All of a sudden again, just won't start again. I tried bridging diagnostics on back of ecu. I saw it flash briefly but couldn't hold the connection long enough to read the code. Tried again with someone watching and it just wouldn't flash. Now what do I do? Borrow an ecu?

[cjeff]

Ok, so this what is happening. Car was starting fine, but idling a bit rough, revd it and it was leaning out and mis firing badly. A couple of times it just wouldn't start, but would crank ok. Changed the fuel tank and pump. Now when it starts, it idles fine for 20 secs ok then dies. Fuel pressure has been checked and is ok. When you try to rev it, it dies. However, my Mech had to try and move it, so tried revving it with the key on start and it went fine, release the key and it's stuffed.

B and B1 have just under 12V. Batt has 12v on back of ecu. All of a sudden again, just won't start again. I tried bridging diagnostics on back of ecu. I saw it flash briefly but couldn't hold the connection long enough to read the code. Tried again with someone watching and it just wouldn't flash. Now what do I do? Borrow an ecu?

[punkture]

sounds like possibly relay/loom issues...auto elec job unless you want to waste lots of days. try another ecu but i doubt itll fix it

[Kebin]

Fuel pressure has been checked and is ok. When you try to rev it, it dies. However, my Mech had to try and move it, so tried revving it with the key on start and it went fine, release the key and it's stuffed?

Sounds like your injectors are blocked.... maybe runs fine when cranking cause the coldstart injector is firing... which you can see in under the plenum.

[cjeff]

Ok, update, while I'm cranking it (now that it's cranking but not starting), the injectors aren't pulsing. A bit losses atm...

Can't find the circuit opening relay on it either. Can find only 1 fuel pump relay

[cjeff]

Also, when you turn the key to the on position, before cranking, the check engine light won't even light up. Shouldn't this be on before starting. Check engine light wire out of the ecu isn't sending any power to it either.

[cjeff]

Can confirm that when it's cranking, the fuel pump relay is working too.

[Kebin]

check lamp should be on with ign on. wire from ecu is a negative signal output not a positive power if you don't know.
Probably doesn't have a c/o relay being a conversion.
Check your wiring around the crank angle sensor.

[cjeff]

So my workshop has closed for the entire weekend as they've got to go away. So can't look at the car until Monday. BUT...

Took the ECU home, took the covers of it this morning to find that there's at least 3 capacitors that have leaked significantly, and when you sniff near them it smells like burnt rubber. My electrical mate is going to replace the capacitors this weekend.

I'm also going to see if I can borrow somebody's ECU to try on Monday to make sure that even after we replace the capacitors that the whole ECU isn't stuffed.

Cheers - Craig

Also - thanks for everyones help - I really appreciate the time you've all taken to reply - it's really great.