4age starts, then stalls 1sec later

[MRMOPARMAN]

howdy guys, got a bit of an intermittant problem with my jdm 4age in my ke25. i go to start it, it starts fine, runs for about 1 or 2 secs, then slowly dies, similar to a fuel blockage/dud pump, or similar to an imobiliser operating on a car that hasnt been disarmed.

ive checked fuel pressure cranking and running, that sits on about 35-40psi, ive obviously got spark as it runs. ive had the coil arcing to ground while cranking, its got strong and consistant spark until the battery gets down on power. ive had it jumped off another car whilst trying to start, same thing happens.
its got an aftermarket alarm+immobiliser? in it, ive disconnected that and it hasnt changed anything. also checked all the earths i can find, still doing it.

basically im thinking 1 of the fuel pumps is cavitating when the engine is running, although that should have shown up on the pressure gauge?

or either the dissy hall effect sensor is dropping out, or the ecu is switching off the cold start injector for some reason?

ive got an ae82 twinky here that i can start swapping parts with. does anyone know of something else i should look for?

i cant find the diagnostic port (dodgey butchered wiring) so i cant check for codes. im running out of ideas. its been doing it for ages. usually it will start, sometimes not, and when it doesnt, you have to walk away and leave it for a week or so and then it will run again. not so now.

oh ive also rebuilt the engine recently, but had it running fine since then.

thanks, cameron.

[Devils]

Hi Cameron,

I'm not too familiar with Toyota's as yet, but it sounds like it is running too rich or too lean...

What ECU are you using? Have you got a MAP or AFM?
Do these engines use a cold start valve to bypass air around the throttle into the plenum?

When it starts i assume it's fully kicking over then going barp barp baaarrrp barrrrrp bap bap DUF.

If that's the case, will it do it IDENTICALLY the second time round straight after? Or does the situation change.

Can you hear your fuel pump/s atall?

Not out of fuel are ya?

What happens if you try to keep it alive by blipping the throttle?

[skiddz]

i had the same problem with my 20v check all vac hoses n shit esp ones that could suck a shitload of air into your engine

[Devils]

Hey Skiddz *waves* from Nissan to Toyota aye (good move or what?)

That's a very good point, if you've got a big enough vac leak it will do exactly that BUT then it would do the exact same thing every time you try to start it, you should be able to keep it going by using the throttle, and you wouldn't need to leave it for a week before re-starting it (indicates a over-fueling issue).
Also why i asked if it was MAP or AFM controlled ECU, as if it's a MAP it should compensate for a vac leak, but an AFM wont!

[Mos]

You didn't say specifically that the fuel pressure gauge remains at 40psi during the dying condition - at first glance is sounds like the pump is being primed but not sustained, turning off after cranking.

Cold start injector is not ECU controlled - it only runs during cranking at lower temps - but it is possible that the engine running is due to the cold start injector only. The engine should start without the cold start injector - disconnect the plug and if it doesn't start then your injectors are not firing.

What do you mean by intermittent? Does this problem only happen sometimes and other times it runs fine?

Mos.

[wilbo666]

Just to put another vote in for a fuel pump issue (Circuit Opening Relay Issue)...

If you connect the fuel pump to the battery constantly does it have the same issue?

Cheers
Wilbo

[Poggy]

Hows your ignition timing etc? map sensor communicating with the ecu?

[Cuzzo]

Just to put another vote in for a fuel pump issue (Circuit Opening Relay Issue)...

If you connect the fuel pump to the battery constantly does it have the same issue?

Cheers
Wilbo

This could be a good thing to try first up. Even off a relay connected to your ign.

If you wanted to pull codes you can also do it at the ECU. Just need to find out what wires normally get jumpered at the diagnostics plug and do it at the ecu. However being in a ke25 id assume there is no light to display the codes so you may have to wire one of them up too.

[30psi 4agte]

Try pulling off the intake pipe at the throttle body and spraying some from of fuel ( aero start etc ) down the throttle when cranking it over..........------- It helps to have two people.

If it starts and continues to run .......then you know you have a fuel prob and to start looking at the fuel side of things

If it still dies you will have narrowed that side of the system down and know to look at ignition.

[Pure_In_Sanity]

thanks for the replies guys. somevery good theories there! its a map car, the car has been running since i rebuilt the enigne and if there were any leaks they would have been tiny, not enough to make it stall/run weird.

30psi i actually tried that one time when it was doing it previously, and it did keep running, so thats the ign side sorted i spose.
im leaning towards injector circuits/ fuel pump. i disconnected the return line last night and cranked it, and fuel absolutely bucketed out. but whether its cavitating under pressure is another question. the fuel pressure when cranking was 40psi, and running to stall it was at 35psi.
i disconnected the cold start injector last night, and it refused to start at all, and i backed into the cold start plug with my mutimeter on duty cycle and ithad duty, tried the same on no3 injector and there was nothing. my multimeter a bit dodgy so ill recheck with a noid light tonight.

thanks again, cameron.

[Pure_In_Sanity]

sorry, on phils computer atm.. this is actually mrmoparman!

[parrot]

Check you have voltage at the injectors when cranking. Specifically between an injector terminal and ground. Should be battery voltage.

Sounds like they are not firing to me thus it stalls when the cold start injector stops.

Detailed diagnostics can be found here in the 4AGE diagnostics manual

http://www.aeu86.org/index/technical...t/9/topic=5158

Covers all ECU and engine electrical diagnostics.

I had a similar problem in mine that drove me insane for a long time. Turned out to be a bulky solder at the EFI relay No.2 causing the terminal to have only intermittent contact with the relay.

[EldarO]

doesnt the ECU ground the injectors to fire them?

so you should have 12V on one side as long as the ignition is switched on, and the other pin should be grounding while cranking.

fixed this in a cressida last night actually, it would stumble and start but dies straight after.

turned out an intermittant loss of contact to the IGSW pin behind the glovebox, 12V power to it, it started right up...

EXACT same symptoms to fuel pump only priming, and not supplying full fuel.

[Cuzzo]

On the 4age's the standard earth for the injectors are on the inlet manifold. One small bolt which can possibly be forgotten to tighten up

[AEhachiroku]

4Ages earth to switch the injectors and have constant power to them through the black/organe wire.

The two wires that come from the ECU are blue and yellow. Yellow will feed ones set (1,3) and blue will feed the other (2,4) but im not sure if the numbers are correct.

Ive had the same problem with people doing the conversion and only running for a few seconds. Ive added power to a wire and it ran. Can't remember off the top of my head which wire though.

So deff check the power supply to the injectors first