4agze misfire

[LO01UX]

hey all

my rolla has a pretty bad missfire all throughout the rev range and feels like there is no power! its a 4agze AFM and DLI out of a ae92

it use to happen intermittenly and if u gave it a squirt it would go away for a while, no it does it non-stop

ive changed the plug. leads, checked the timing belt is correct, checked the ignition timing

does anyone have an ideas as its quite annoying

cheers

[Grega]

check that you have good proper clean earths. i had a similar problem years ago

[LO01UX]

all the earths are new as the engines just been put in but ill check them anyway,
any other ideas?

[TERRA Operative]

Could be coilpacks?

Also, have you checked the condition of the capacitors in the ECU? I always replace them as a matter of course when I have a chance because 100% of the Toyota ECU's I've opened up of this age have had stuffed capacitors. It causes all sorts of weird problems.

[LO01UX]

And how does one go about checking the capacitors?

[inertia]

Open ECU casing,

Look at capacitors and see if any are bulging, leaking/oozing build up of crud etc.

Normal caps are uniform cyclinder with a flat top, if the top and/or bottom is bulging (like the cyclinder is under pressure, then they'll be candidates to blow.

See below for an example. the row on the left bottom look ok, far right small ok, middle are stuffed, especially MR unwinder
http://upload.wikimedia.org/wikipedi..._capacitor.jpg

[pandaah]

what gap did you set the plugs at?

[LO01UX]

1.1mm I think it was, I pulled the fuel rail and injectors out today to see how they were firing (which they are firing fine) and after putting them back in its running fine with a slight hunt at idle....

I played around with the fuel pressure a bit and if you lower it the miss comes back but if you up the pressure then the hunt develops more??? Im confused

But its atleast driving better now

[senn]

check for vacuum leaks etc is my first thought...maybe also o2 sensor wire/voltages (don't know what they're meant to be, should be in service manual)

[LO01UX]

Ok so as I said It was sorta fixed after playing with the injectors yesterday

Then tonight on the way home from the monthly meeting it started missing really badly again.....

What the hell is going on with my car?????

[pandaah]

try gapping plugs to .6mm 1.1 is sometimes too big for boosted engines, even on stock boost ive seen that heaps of time at work

[Dimmy]

Do you have a bonnet scoop? Water in the spark plug galley?

[pandaah]

possibly aswell the rocker covers leak between the cylinders and oil gets all over the leads, but im guessing you would of noticed that

[Dimmy]

It would have to be a significant amount of oil though to interfere with the spark

[pandaah]

nah even a little bit of the oily moisture inbetween the lead and the plug will be enuf to misfire it... my honda daily does it pritty often but im too slack to give it a rocker cover gasket lol

[inertia]

Coilpacks, Ignitor, Leads.

Check them off your list.

Then as above, check ecu for blown caps.

[pandaah]

try gapping plugs first... its free lol

[LO01UX]

Nope don't have a bonnet scoop n there's no water or oil in the sparkplug valley, was the first thing I checked

The leads and plugs are brand new but ill check for any oily residue tonight and check the plug gap,

Is there anyway to check the ignitor and coil packs?

[TERRA Operative]

try gapping plugs first... its free lol

But the gap shouldn't be an issue if it's at stock specs and the rest of the system is ok.

[LO01UX]

Its a stock engine besides a pod filter, fuel pressure reg and a metal head gasket,

Would the capacitors in the ecu cause it to stop n then happen again?

And could it be anything on the fuel side of things?