4agze stalls after a few seconds. Got me stumped!

[cam_ra40]

Just a little background first. I have an AFM version 4agze in my Aus spec ae92, its running coilpacks, factoy ecu and AFM. It has been converted to turbo by me roughly a year ago and has run fine since.

a few days ago i went to start the car while the engine was already warm, it started fine but then stalled about 4 or 5 seconds later. Every go after this would do the same thing, even if i had my foot to the floor.

Later that night i tryed to start it again and it started fine, roughly after a minute of idling it stalled and then went back in to the 'stalling efter 4 or 5 seconds' pattern. It now seems to run fine once its completely cold, and stall once the car is just begining to get warm.



Things that i have tryed are:
disconnecting cooler pipes and running the AFM directly from the throttle body, this basically eliminates the posability of intercooler or induction leaks.

replaced the fuel filter. I thought that it may have been clogged. there is fuel pressure because the car actually starts. Could the fuel pump be struggling to keep enough pressure up?

Running my old set of spark plug leads. The new ones were only put on a week ago.



Things that i have recently done on the car that may or may not be relevant:
changed the spark plugs a week prior, one of them poped slightly off the coil pack but still had enough contact with the actual coil pack to continue to function, i fixed it as soon as i noticed. the car ran for a day or so after this.

I replaced the exhaust gasket which reguired removing the turbo, exhaust manifold, radiator and some cooler piping. The only thing that i did a little different to normal was to use some exhaust gasket goo stuff around the gasket its self, probably didn't need it but i had the stuff laying about. supposably handles up to 380 degrees.

I noticed about 2 weeks prior that my CAS was making a tapping/rattling noise when the engine was cold. I'm unsure if it has always done that, wasn't overly loud.


I'm thinking towards the AFM at this point. If i start the car with the AFM unplugged it will do the exact same thing. Someone else has told me that it could be the coil packs. What other tests can i do to eliminate factors? i'm trying to locate an alternate AFM to try but don't know of any locally.





All fuses are fine & there is plenty of fuel in the tank. The diagnosis thingy doesn't give any clues.

[cam_ra40]

Beer is on offer for who ever can solve the problem

[inertia]

tried powering fuel pump directly?

As for the AFM, can you adapt one from another toyota?

[Vios-GT_07]

good luck with it..

i'm still waiting for my car to not want to start again.. one day after filling up, it wouldn't start, would crank and crank but no start.. very random.. it started up again after 5 minutes of randomly trying stuff..

the only difference when a car is cold.. erm...

1. it runs a higher rpm
2. has more timing
3. runs richer..
4. cat converter hasn't warmed up yet

so... if your ignition is fine, fuel is ok, TPS is ok... iscv is okay... how's your cat converter??

[Soarer_D00D]

Hey mate. My mate had a similar problem when doing his 4AGZE conversion. I know it may not be the case, but he accidentally wired something up wrong with the fuel pump and the brake pedal. Every time he put his foot on the brake., it closed the fuel pump relay circuit causing the fuel pump to shut off, causing it to die in the ass.. Not sure what else it would be, but that was his problem.

[cam_ra40]

hmm, hadn't thought of the cat. to be honest i didn't even realise that they changed between warm/cold. I did have an exhaust manifold leak just beforehand that is now sealed up so maybe that is highlighting the cat isues? its a second hand cat from a soarer from memory. I'll disconnect the exhaust from the dump pipe today and see if it makes a difference.

If thats still no good i will attempt to power the fuel pump directly just in case. I know the fuel pump is getting power initially but it may have a dodgey connection that i can rule out.

The other thing that i'm thinking more about is that slight noise coming from the CAS, could that somehow be screwing up the timing? next time the car starts for its minute of so, i'll go and listen to to carefully.

[Cuzzo]

If you can get your hands on a smallport dizzy. That will work the exact same way as what a 4agze CAS does. Just dont plug the leads in.

You can try one from a car that is running fine to rule that out. This meaning you will need to re-do the timing.

[JP]

the pump gets initial power when cranking to start, it then relies on the signal from the AFM flap switch to keep the circuit opening relay alive. Designed so if the engine stalls running, the AFM flap closes and the pump shuts off.

If the car is wired correctly with the diags box, bridge the Fp and +B terminals with a thick paperclip or similar. This will bypass the AFM switch and cause the pump to run whenever the ignition is on. You should be able to hear the fuel running through the rail etc when the ignition's on and engine not running. If the car starts and stays running then you're down to checking the wiring from the AFM to the circuit opening relay, and the wiring from the circuit opening relay to the fuel pump relay etc etc.

[Vios-GT_07]

^^

if that's the case (and yes it is possible), some wiring has become dodgy.. i'd look around the AFM and probably around the turbo and under the car.. most of the time i see burnt wiring near high heat sources

[cam_ra40]

Thanks heaps, I'll go try the Fuel Pump bypass bit now. No wiring goes near the turbo as its front wheel drive configuration. I'll send another reply in a few mins.

[BeRad]

As you said, check the AFM plug is not faulty, or the afm but if it was the afm, one would think that it would fail all the time, i'd point the finger at the afm but its funny that it works while its cold.

Does the stepper motor completely close for some reason as it warms up, therefore starving the engine?, not that, that would effect it at wot.

Have you checked that the fuel pump doesnt stop at that time?

It could be a million and one things, good luck mate.

[cam_ra40]

I tryed the bridging Fp +B bit with no luck. Although i can only actually hear the fuel pump going when the key is on the 'Start' position, Should it be going when on the 'On' position? I'm pretty certain that the diagnosis box is wired up properly, the conversion was done by a reputable workshop using the original 4agze wiring loom.

I then disconnected the exhaust at the dump pipe which also didn't do any good. I guess that rules out the Cat converter for sure.

Would monitoring the fuel pump with a multimeter while the problem occurs do any good? is there any way to check to see if it is losing spark when the the problem occurs?

I'm going to pull the throttle body off next to see if there is any iddues with the idle control thingy.

[cam_ra40]

What is the stepper motor? if anything the throttle body being completely open just makes the car stall quicker.

[BeRad]

the fuel pump should turn on for about 4 seconds when the key is turned to on, when the egnine fires the fuel pump will then continously run until you turn the car off or it stalls etc.

the stepper motor controls the idle to a certain extent, it lets air in from the intake but bypasses the t/b, and straight into the plenum, if its not connected to the intake or blocked it will cause a rough idle or cause it to stall. Although this is probably not your problem

you can check ignition by taking off a lead from one of the plugs, getting a spare plug connecting it to the lead and earth it out on the head, when the engine stalls/splutters or does whatever it does youll be able to see wheather its throwing spark as it should, the engine will run on 3 cylinders but wont be smooth obviously.

You can test the fuel pump wire with a multimeter to see if it switchs off a second or so before the engine cuts out.

Getting the diagnosis working would be the easiest way to rule alot of things out

Good Luck.

[JP]

if the pump doesn't run when the pins in the diags terminal are bridged with the ignition on, then either the diags box isn't wired correctly, or you have a problem with the COR etc.

The fuel pump should run when the igntion is on and the diags pins are bridged.

Wiring diagram is here: http://users.tpg.com.au/adsl0uxv/4AG...II_diagram.pdf