misfire only at tick-over

[lib]

Hello all

I have a 1997 ROW Boxster 2.5 which when it gets up to temperature will misfire at idle and put the cell on.

When I first had this problem of misfire at idle the Durametric showed misfire on bank 1 and cam adjustment fault.

I subsequently removed the variocam adjuster and changed the slipper shoes as they were slightly marked but could not find any thing wrong with it.

I fitted it all back together and road test. te car went really well but after a few miles i stopped at a junction at idle the engine started to misfire again.

when I checked it with the Durametric I discovered to my amazement bank2 had the misfire and bank 1 was OK!!!!!

I then fitted another o2 sensor to bank 2, I had previously fitted one to bank1

I also changed the maf sensor as durametric showed fault with maf hot film.

Today I checked with the Durametric and find that the fault has changed back to bank 1.

I have done nothing to the car other than clear the faults and test it again to See what faults will show up this time.

I have added the fault codes in the hope that someone can interpret them for me.

P0102 Porsche fault code 115 - Hot film MAF sensor

P1530 Unknown DTC: 1530

P1115 Porsche fault code 13 - Resist. limit O2S ah. of cat. conv. B1 exceeds limit value

P1119 Porsche fault code 5 - Resist. limit O2S ah. of cat. conv. B2 exceeds limit value

P0301 Porsche fault code 508 - Misfire cylinder 1

P0302 Porsche fault code 510 - Misfire cylinder 2

P0303 Porsche fault code 512 - Misfire cylinder 3

Many thank for reading my tales of woe.

Regards Lionel

[Loren]

P0102 Mass Air Flow Sensor - Below Lower Limit

possible causes:

- Open circuit.

- Short circuit to ground.

If you are still getting this code you need to check the wiring to the MAF.

P1530 Camshaft Adjustment, Bank 1

- Short to ground.

- Actuator faulty.

Unless you think you might have bad coils or more wiring problems I would fix this first as it could be causing the misfires.

P1115 Oxygen Sensor Heating 1 Ahead of Catalytic Converter - Below Lower Limit

P1119 Oxygen Sensor Heating 2 Ahead of Catalytic Converter - Below Lower Limit

Contact resistance.

- Heating resistance too high.

- Open circuit in heating current circuits.

- Open circuit in H02S signal wire.

- Short to B+ (output stage cut off).

Odd that all of these would occur are one time - have you visually inspected the wiring to these items and the harness.

Almost makes me think the DME connector is loose or damaged. Or even a bad ground from engine to chassis?

[lib]

P0102 Mass Air Flow Sensor - Below Lower Limit

possible causes:

- Open circuit.

- Short circuit to ground.

If you are still getting this code you need to check the wiring to the MAF.

P1530 Camshaft Adjustment, Bank 1

- Short to ground.

- Actuator faulty.

Unless you think you might have bad coils or more wiring problems I would fix this first as it could be causing the misfires.

P1115 Oxygen Sensor Heating 1 Ahead of Catalytic Converter - Below Lower Limit

P1119 Oxygen Sensor Heating 2 Ahead of Catalytic Converter - Below Lower Limit

Contact resistance.

- Heating resistance too high.

- Open circuit in heating current circuits.

- Open circuit in H02S signal wire.

- Short to B+ (output stage cut off).

Odd that all of these would occur are one time - have you visually inspected the wiring to these items and the harness.

Almost makes me think the DME connector is loose or damaged. Or even a bad ground from engine to chassis?

[lib]

Thanks Loren

I will check out the wiring and let you know.

Regards Lionel

[pk2]

Loren's on to something, awful lot of codes. It might be a central problem that cascades and throws everything out of whack.

Most Codes seem to point to heat, shorts (shorts make heat, or heat can look like a short) resistance (more heat), heat, heaat, and more heat.

Don't know how technology has progressed, but I remember a thing call arcing where bad ignition components, especially plug wires, would arc, at running temp. and run like 'ell. You could actually see it like lightening if it were bad enough and dark enough.

Could be the equivalent of bad the bad coils Loren mentioned.

Regards, P-

Edited March 20, 2010 by pk2

[lib]

Loren's on to something, awful lot of codes. It might be a central problem that cascades and throws everything out of whack.

Most Codes seem to point to heat, shorts (shorts make heat, or heat can look like a short) resistance (more heat), heat, heaat, and more heat.

Don't know how technology has progressed, but I remember a thing call arcing where bad ignition components, especially plug wires, would arc, at running temp. and run like 'ell. You could actually see it like lightening if it were bad enough and dark enough.

Could be the equivalent of bad the bad coils Loren mentioned.

Regards, P-

Hi PK

Thanks for your info. The Porsche centre pu 6 new coil packs in a few months ago and said that would solve the problem but alas NO

This is a real stinker of a problem just cant seem to get yet.

Regards Lionel