Misfire issues

[Grumble and Grouch]

Hi all, new to forum and to ZTT ownership. Car purchased fairly cheaply about three weeks ago and not much history but generally sound. I'm not great with cars but have a basic grasp and helpful nephew!Will need rear brakes and a few minor things but ran okay then had slight misfire on acceleration that seemed intermittent before driving home last night when she turned into a violent kangaroo and was clearly not firing at all well on at least one cylinder and close to stalling several times. I'd had a T4 test when I bought her to try and solve the classic airbag light fault( apparently the " firer sensor) which showed a misfire but as it was minor was hoping to address when I got the brakes sorted.
Not being able to have a diagnostic run today and needing transport for work I gambled and bought sparks, leads and coil packs. Fitted and no difference at all, still essentially undriveable. Gutted.
As last act of desperation disconnected battery for an ecu re-set and after 30 minutes reconnected, turned key and hey presto- running okay. I'm delighted but bemused- can anyone explain why it worked? Can't help but be slightly suspicious!
Got her booked in for T4 diagnostic in May to check that misfire fault is fixed and get brakes sorted but wondered if anyone had any advice about the misfire and if anyone could advise as to how tricky the airbag firer is to do/ what it should cost. Thanks in advance. It's a 1.8 on a 03 plate by the way!

[T-Cut]

Hello Mike,
Most airbag warning lights are due to faulty connectors under the front seats. It's the most common problem found in these cars. The airbags themselves are unlikely to be the cause. The two pull out connectors clipped under the passenger seat should be checked/cleaned/lubricated/zip tied/replaced in that order. If that doesn't fix it, repeat with the driver's side. If that doesn' fix it a T4 will identify the location. Maybe the steering wheel gizmo.

Always fit the Fabled Orange Clip (search 'FOC') to the in-tank fuel filter case on later petrol models to prevent Fuel Filter Syndrome (search 'FFS'). Yours may have one, but be sure to confirm it.

You may find reducing the spark plug gap to 0.5-0.7mm will improve a gritty acceleration.

A battery off reset can resolve all sorts of issues involving the ECU.
Always ensure the plenum is free of rain water.
See this: http://www.the75andztclub.co.uk/foru...d.php?t=125864

EDIT: Be sure to embrace the terminology used around here. This will help: http://www.the75andztclub.co.uk/foru...ad.php?t=53394

TC

[planenut]

Originally Posted by Grumble and Grouch

Hi all, new to forum and to ZTT ownership. Car purchased fairly cheaply about three weeks ago and not much history but generally sound. I'm not great with cars but have a basic grasp and helpful nephew!Will need rear brakes and a few minor things but ran okay then had slight misfire on acceleration that seemed intermittent before driving home last night when she turned into a violent kangaroo and was clearly not firing at all well on at least one cylinder and close to stalling several times. I'd had a T4 test when I bought her to try and solve the classic airbag light fault( apparently the " firer sensor) which showed a misfire but as it was minor was hoping to address when I got the brakes sorted.
Not being able to have a diagnostic run today and needing transport for work I gambled and bought sparks, leads and coil packs. Fitted and no difference at all, still essentially undriveable. Gutted.
As last act of desperation disconnected battery for an ecu re-set and after 30 minutes reconnected, turned key and hey presto- running okay. I'm delighted but bemused- can anyone explain why it worked? Can't help but be slightly suspicious!
Got her booked in for T4 diagnostic in May to check that misfire fault is fixed and get brakes sorted but wondered if anyone had any advice about the misfire and if anyone could advise as to how tricky the airbag firer is to do/ what it should cost. Thanks in advance. It's a 1.8 on a 03 plate by the way!

Well done in finding a solution, I hope it's long term.

[Grumble and Grouch]

Not long term sadly! Fine first thing today, then not but nowhere near as bad, then fine again. Bemused! Booked in for t4 on 9th of May but is there anything I should check before then? Had my head under the bonnet today whilst it was misbehaving and then it just resolved itself before I could really tinker with anything. Wondering if it is a damp ecu- haven't yet had chance to get a look at the plenums and it's been pretty wet for a couple of days. Job for the weekend perhaps.
Randomly the slight misfire under acceleration seems to have gone, just randomly very lumpy sometimes.
Garage just round the corner stuck a heat gun sensor on the cylinders today whilst it was a bit lumpy and they seemed uniformly hot and as when I was looking at it it suddenly settled and was fine.
Points towards ECU? Maybe injectors?
Any advice much appreciated.

[Grumble and Grouch]

Originally Posted by T-Cut

Hello Mike,
Most airbag warning lights are due to faulty connectors under the front seats. It's the most common problem found in these cars. The airbags themselves are unlikely to be the cause. The two pull out connectors clipped under the passenger seat should be checked/cleaned/lubricated/zip tied/replaced in that order. If that doesn't fix it, repeat with the driver's side. If that doesn' fix it a T4 will identify the location. Maybe the steering wheel gizmo.

Always fit the Fabled Orange Clip (search 'FOC') to the in-tank fuel filter case on later petrol models to prevent Fuel Filter Syndrome (search 'FFS'). Yours may have one, but be sure to confirm it.

You may find reducing the spark plug gap to 0.5-0.7mm will improve a gritty acceleration.

A battery off reset can resolve all sorts of issues involving the ECU.
Always ensure the plenum is free of rain water.
See this: http://www.the75andztclub.co.uk/foru...d.php?t=125864

EDIT: Be sure to embrace the terminology used around here. This will help: http://www.the75andztclub.co.uk/foru...ad.php?t=53394

TC

Thanks very much, will explore and get round to all of the above!

[marinabrian]

The likelihood of it being ECM related is extremely unlikely

I would be inclined to look very closely at the wiring to the MAP/IAT sensor to the left of the inlet manifold as viewed from the front of the car.

It is quite common for the four wires that go into the plug housing through the rubber bungs to work harden and break where they enter

Also check the condition of the vacuum hoses from the turbocharger to both the inlet hose, and the boost control solenoid.

I find plugs gapped at .7mm to be best suited to the 1800T.

Best of luck

Brian

[Grumble and Grouch]

Originally Posted by marinabrian

The likelihood of it being ECM related is extremely unlikely

I would be inclined to look very closely at the wiring to the MAP/IAT sensor to the left of the inlet manifold as viewed from the front of the car.

It is quite common for the four wires that go into the plug housing through the rubber bungs to work harden and break where they enter

Also check the condition of the vacuum hoses from the turbocharger to both the inlet hose, and the boost control solenoid.

I find plugs gapped at .7mm to be best suited to the 1800T.

Best of luck

Brian

Thanks, the wires do look a little brittle. I'll take a closer look and check the hoses. What confuses me is it runs perfectly well then doesn't! I'm no expert with cars and haven't tried to fix anything since I had a BGT a decade or so ago. Things have got complicated since then! Thanks again.

[suzublu]

Don't forget that well known & common fault, a leaking inlet manifold gasket

[Grumble and Grouch]

How do I check that? Whip it off and look at the gasket?

[suzublu]

Originally Posted by Grumble and Grouch

How do I check that? Whip it off and look at the gasket?

Or, look for coolant around the bell housing, or a damp spark plug, usually no.4