FixedWing

Merry Christmas all!

I get a "check engine" light with the following error messages:

16815 - Warm Up Catalyst: Bank 2: Efficiency Below Threshold
P0431 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16690 - Cylinder 6 Misfire Detected
P0306 - 35-10 - - - Intermittent
16689 - Cylinder 5 Misfire Detected
P0305 - 35-10 - - - Intermittent
16685 - Cylinder 1 Misfire Detected
P0301 - 35-10 - - - Intermittent

The random missing at idle has been an on-going problem. I usually see it most when the car is warming up. I just swapped to a chipped ECU but was seeing these sorts of error messages on the previous un-chipped ECU (though it didn't previously trigger the check engine light - I'm guessing that the catalyst error caused that).

I earlier found and fixed a pressure leak. And I've also changed spark plugs (before factory - looked ok when they came out - now Bosch Platin).

So how do I diagnose the cause? I'm guessing that it is the MAF but is there any way to tell before buying and swapping parts?

I'm also guessing that the catalytic converters are on their way out (car has 135,000 miles). If I'm right, then I will have to figure out what my options are later.

Thanx.

Stephen

VonK :: Retired

If it doesn't misfire with the MAF plug disconnected, it's likelly the MAF.

FixedWing

Thanx for the advice ... can you tell me why this is so?

VonK :: Retired

---> to determine fuel quantity based on throttle position, engine speed and others I can't remember. Usually, the engine performs quite well that way, even if not at optimal efficiency. In your case, it might eliminate the MAF as the cause of your misfires, if it continues to occur.

FixedWing

and watch the engine warm up to see if I am getting the same degree of missing. Makes sense to me.

I'm also thinking that the catalytic converter issues could be related in that their getting an overly rich (or unburned lean) mixture could be affecting them. But first to solve the missing problem.

Thank you VonK. :-)

Stephen

VonK :: Retired

N.P. :-)

masterguildtech

APB engines have a few misfire issues...

1. Primary ignition power stages overheating due to lack of grease on the heat sink (They're on the air box)

2. A few cases of head gasket problems

FixedWing

Now I'm noticing (by feel) missing at idle even after the car is fully warmed up and has had a good run. So whatever is causing it has got pretty bad at this point.

I am really thinking it has to be the MAF. But I really would like to figure out for sure what it is before I start replacing parts.

I really doubt it would be the head gasket. No symptoms of a problem like that.

Thanx. :-)

Stephen