4AGE wiring problem

[cosi]

Im wiring up a bluetop 4age into a kp61 starlet. I actually had the engine running ok a couple of weeks ago but since then I took the car in to get the driveshaft shortened and the exhaust hooked up. I got the car back and this weekend set about trying to get the engine going again.

My problem is that the engine fires up, starts for maybe 1-2 seconds and just sort of shuts off again. I have searched the forums, net etc, and found some useful information. I would really appreciate some advice, things to look for etc. Im keen to fix this myself because I know an electrician is going to charge like a wounded bull for it, if it comes to that.

I have the air filter off and at one point while I was turning the key over a burst of flames, maybe 5-10cm long came out the throttle body of the manifold. It rumbles, sounds loud and shakes around in the engine bay quite hard. Hope its not stuffed. haha

[slighty_sykotic]

Check the timing....both ignition and cam timing.

Search how to do ignition timing if you don't know, you have to put it into diag mode.

After that I would be looking at fuel if it won't keep running, is your fuel pump working during "on" key? (and running the right way...).

Thhhhhhhhhheeen, I would check for codes and go from there.

And somewhere in the middle I would check for massive vaccum leaks.

Remember, all you need is spark and fuel at the right time for it to go bang.

--Sykotic

[cosi]

... a few more things;

- I had to remove the tvis butterflies, that was the only way to fit the intake manifold in the engine bay
- There are no leaks in the intake manifold
- Im using a new battery, the voltage drops to about 10v while the engine starts and gradually comes back up to 12.5v. By the time its up to 12v again the engine has shut down.
- The alternator is disconnected. Tried connecting it and that makes no difference
- Lastly the engine might have a tiny bit of 2 stroke oil in the petrol. I went to fill up the petrol tank and poured maybe 100ml of petrol into the tank, only to realise I was using a petrol can mixed for a motocross bike! Doh. By my calculations, 100ml of petrol at 36:1 is about 3-4ml of 2 stroke oil. That would be diluted in about 20L of petrol now. Not sure if that would make a difference

[cosi]

Fuel pump is coming on, and stays on for the entire cycle. Its running during start and shortly after the engine cuts out I can still hear it going.

Will look into the timing, thanks ay

[slighty_sykotic]

I have the air filter off and at one point while I was turning the key over a burst of flames, maybe 5-10cm long came out the throttle body of the manifold. It rumbles, sounds loud and shakes around in the engine bay quite hard. Hope its not stuffed. haha

That sounds timing related to me....

Check that first if I was you

--Sykotic

[cosi]

Im keen to try that, but I dont seem to have a diagnosis plug in the loom.

I adjusted the distributor forwards and backwards gradually about 1mm each time and tried to start it. Went all the way forward and all the way backwards in 1mm steps. It doesnt make a difference for keeping the engine running.

Ive got a feeling the injectors are not firing and that the fail safe relay is switching on. Without the cold start injector plugged in the engine will not start at all.

Is there any way I can test that the injectors are firing or not blocked?

[slighty_sykotic]

To check injector firing put a LED across one of the injector plugs.


Put that doesnt mean fuel is comming out, can you hear the pump running during on?


And you dizzy...

How do you know that its in the right way? Like, the cog isnt a tooth out on the cam? (if you know what I mean).

You really need to get a timing light on it to check that, which you need a diag connector for.......

And cam timing, have you checked that?


But if what you saying, with the cold start unpluged it won't start, then I would say you arn't getting fuel.

--Sykotic

[cosi]

Im pretty sure that the dizzy is on correctly. I bought the engine / gearbox as part of someone's abandoned project. Apparently it was running fine up till a couple of months ago but I cant be sure.

I did actually manage to get it running a couple of weeks ago - thats the annoying part. I had it running for about 2-3 minutes. Since then Ive taken the intake manifold off to fit a new gasket, had the exhaust connected up and driveshaft done.

I never took the dizzy off or touched the cam belt.

I know the fuel pump is pumping and there is good flow in/out of the tank.

It just seems to be the injectors dont want to fire. I'll try an LED like you suggest although Im not sure what to do if they happen to not be firing?

[l1ttle_d3vil]

although Im not sure what to do if they happen to not be firing?

if they aren't firing it will be either a) because you've got no power going to them or b) because the ECU is stuffed and isn't telling them to fire.

maybe they knocked the ecu or something while they had the car? how do you mean the exhaust was connected up? was it welded at all on the car? if it was mig welded they may have forgotten to disconnect the battery which will stuff your computer.

what sort of loom are you using and what ecu are you using etc? i had quite a few problems with my bluetop 4age and one of them was similar to this. where abouts are you located too, could come check it out if you're close enough?

[jondee86]

if they aren't firing it will be either a) because you've got no power going to them or b) because the ECU is stuffed and isn't telling them to fire.

Yeah.... what he said All the injectors should have 12 volts going to
them when the ignition is on. The ECU switches the injectors to earth to
make them fire. The 12 volts is there all the time, so I'm not sure that a
LED would tell you anything. Better to stick your finger on the base of
the injector and see if you can "feel" it clicking.

Cheers.... jondee86

[slighty_sykotic]

of course an led will. When the ecu grounds the contact, and the other has 12v, it will light, just try it both ways around if it doesnt light up as LED must have correct polaitly....

--Sykotic

[cosi]

maybe they knocked the ecu or something while they had the car? how do you mean the exhaust was connected up? was it welded at all on the car? if it was mig welded they may have forgotten to disconnect the battery which will stuff your computer.

what sort of loom are you using and what ecu are you using etc? i had quite a few problems with my bluetop 4age and one of them was similar to this. where abouts are you located too, could come check it out if you're close enough?

I disconnected the computer and didnt take it down with the rest of the car. I was actually worried that might happen.

Using AE86 engine/box/loom/ecu into a KP61 starlet, got basically everything that I needed from one car. Im in Auckland near Lynfield/Mt Roskill

Ill try the LED, there is definately 12v to the injectors but my belief is the Fail Safe Relay is probably coming on. Not sure why.

By the looks of it, from the diagram the computer has the option to short out the injectors to shut down the engine using that relay.

[matt dunn]

dumb question but,

are all the HT leads in the correct place? not a firing order problem.

[jondee86]

Just take a temporary 12 volt supply direct from the battery, or any
circuit switched on by the ignition switch, and stick it up the injector
power circuit. That way it doesn't matter if the failsafe relay operates
or not.

AE86 has an ECU input for that relay, but the AE92 ECU does not. Gave
me no end of grief trying to figure out why the injector circuit wasn't
powering up

Cheers.... jondee86

[cosi]

dumb question but,

are all the HT leads in the correct place? not a firing order problem.

Yup ... they are now

Ok so that explains why it was backfiring out the inlet manifold, this afternoon I clumsily reversed 2 & 3. Thanks man. I feel like such an idiot, haha

Unfortunately the engine is still doing the same thing. It does sound much nicer now - but still dies after a few seconds.

[l1ttle_d3vil]

I disconnected the computer and didnt take it down with the rest of the car. I was actually worried that might happen.

Using AE86 engine/box/loom/ecu into a KP61 starlet, got basically everything that I needed from one car. Im in Auckland near Lynfield/Mt Roskill

have you tried testing a new computer anyway? I've got a computer here which fires the engine every time I crank it over the first time then it won't fire again until I switch the key off and try again. its as if only the coldstart is firing or osmething and not all the other injectors; that could be a similar problem. there would be other things you could try first though before buying a new ecu!

i wired my 4age up with the exact same loom and ecu, but I only had the engine loom, none of the failsafe relays, nothing to do with the fuel pump etc etc. sounds like your wiring is alot more complicated than mine!!!