7mgte - Starts only with throttle slightly open then stalls

[Kedderz]

Just finished repairing a bhg on my mz21 project car, It will start but only if I have the throttle open slightly. Am I right in assuming this is unmetered air getting into the intake system?

Also there is a miss in the engine when it is running should my troubleshooting be the following;
- pull the plugs to see if they are fowled
- regap the plugs to 0.8?
- check leads for damage
- check grounding of the ignitor?

Also check codes put out by ECU

Please bare with me im new to troubleshooting all this so if I say something stupid please point it out ;-)

[thechuckster]

might mean the aux air valve (aka idle or ISC valve) is not opening up.

lack of AFM results in engine stall shortly after starting (no air flow detected usually means fuel pump turns off after starting) and opening the throttle results in engine stall as the motor does not know that more air is being allowed in and it doesn't provide more fuel.

air leak post AFM makes motor run slightly lean and will probably stall if you stab the throttle.

[Kedderz]

Now that you mention the ISCV it was difficult to get the one way valve in its slot inside the iscv. The rubber oring caused this but I thought nothing of it. I will source another one way valve thing and try that as well.

Its not stalling if I hold throttle say at 700 rpm only when i back off does it stall straight away.

[thechuckster]

before replacing it, watch/listen to it when you power up the ECU - it should make some sounds when it positions the valve at startup ... you may have to turn off other stuff to hear it (use a hose-pipe as a stethoscope).

[Kedderz]

Is another way of checking its operation to start motor then cut it, should I not hear the "ticking" noise of the iscv motor reseting?

I dont hear the normal sounds of it because theres lots of clicks/beeping from the stupid EMV(tv system) and the airbag solenoids.

The ISCV I can replace this arvo as I have a mate whos wrecking a 7m so i will compare my oring+valve to his.

[thechuckster]

Is another way of checking its operation to start motor then cut it, should I not hear the "ticking" noise of the iscv motor reseting?

yes you should.

but if you have a mate turn the IGN on, and you have a long screwdriver or some 11mm black garden pipe with one end wedged in your ear and the other firmly pressed against the ISCB, you should hear some noises at startup.

[Kedderz]

last night I checked the codes there was none
ISCV motor/solenoid operates but im still not convinved its functioning correctly due to the pressure needed to insert the oring and one way valve.
I couldnt replace any vaccum lines as no decent auto store here stocks lenghts of silicon hose suitable for replacing the lines so ill have to wait.
Tonight im going to take the 3000 pipe off, coil packs and inspect the plugs and double check the gap see if that helps.

[Jin~Jah]

I reckon check the ISCV a bit more - is the one way valve in backwards? mine have always literally *just* sat inside the lip, and there's no pressure whatsoever needed to get it out. In fact, when taking the ISCV out, it'll sometimes sit in the manifold, and sometimes fall out!

then you have to fish the bastard out from wherever it lands

but yeah, I'd be looking there first, especially since it idles around the normal idle speed when you crack the throttle a bit.

As already posted, if you have a fuel metering issue (afm) then it'll still idle, but as soon as you try to bring it above idle, it'll just splutter and die since it's not sure how much fuel to put it. They know how to idle though

[Kedderz]

You know i completely discounted the afm *stupid* because I have a spare one at home which is known working as it came from my old 7m I went to 1uz afm.

Iscv will be replaced tonight providing I can get my other shit done!!!

+rep jin

[Jin~Jah]

haha good luck!!

It's so satisfying when it's running on it's own

[RyleyMA61]

yeah that happened to me but i was a dipshit and forgot to plug the AFM in again har de har har