Hey everyone,

So, as per the title I have misfiring issues post adjusting the valve clearances, I found all valves to be tight and suspect they may never have ben adjusted, The car has 132k miles on the clock, 2000 AP1. I also replaced the TCT at this time.

I adjusted them to the looser end of the tolerance and have had approx. 600 miles of motoring, suspecting a slight misfire at idle and wary that the engine was perhaps a little noisier than it should be (accepting that this is an inherently noisy engine and adjusting the valves loosely will result in more valvetrain noise).

Anyway, today the car threw codes P0302 (cylinder 2 misfire), P0303 (cylinder 3 misfire), P0300 (random multiple cylinder misfire) and P1399 (manufacturer control..?).

My suspicion is that as the valves were all quite tight, the valve seats could be compromised and that the issue has come to the fore with the valve now being looser.

The car also drinks oil (even by AP1 standards)(insert Oliver Reed metaphor here) to the tune of about 2 liters per 1000 miles (Mobil Super 3000 5W40).

I'm considering moving the car on as I'm losing faith in its integrity. The engine pulls very well and revs very keenly though...

What say ye oh mighty S2KIers?

 

double check your valve adjustment and make sure it is within spec., maybe you went too loose.

With tight clearances you could get burned or pitted valves but you can't really tell without removing the head.

It might be a coincidence and you may have coils going bad or some injectors, common sources of misfires.

 

I actually already rechecked the valves.. the thought of checking those clearances again is not an appealing one! It could certainly be a coincidence. Starting to get a little scary cost wise. The engine drives like it's in rude health, but it recently failed it's road worthiness inspection on emissions (and rusted inner sills, but that's another matter...).

 

Step one on valve adjustment instructions, discard instructions regarding lining up timing marks and counting rotation. Overly complicated and too easy to mess up.

Instead, do this:

Use wrench to rotate engine until valve you want to adjust has its cam lobe pointed up, 180 away from its follower. Adjust that valve.

Only ever adjust a valve if its cam is pointing up. If you are following the instructions, and are about to adjust a valve, and its cam lobe isn't pointing up, stop. You messed up timing marks. Toss those instructions and just do the lobe up method. Impossible to screw that up.

Cam position doesn't need to be super precise. The valve is closed, and adjustment gap is the same on the whole closed half of lobe. Its not like if lobe is actually 160 degrees instead of 180 that your adjustment will be wrong.

Thought 2. What torque spec did you use for the spark plugs? Old spec was too low and plugs can loosen and cause misfires. This is super dangerous as detonation causes plug tip to fall off, and can destroy cylinder wall. Updated spec is 22 lb/ft.

 

What is tight? Check all your coil connections for broken or loose tabs

 

Should we understand that all the codes etc started appearing for the first time after you adjusted valves?
If this was the first time you adjusted valves strongly advise open it up and check them again. Record your measurements. Set at loose end of spec. If its your first time it is easy to put feeler in at a slight angle that make it seem there is drag and therefore a tight gap when in fact there is really no drag. and the gap is fine.
Also, look at plugs and snap a shot of each plug out of the motor.
Also, if it was my car I would check the compression.. Burned valves leak and compression numbers suffer. Compression test is quick and easy down dirty way to see if there is air leaking.
Then - if not sorted - there are other possible causes as mentioned above.
The fact that it is burning a lot of oil is not a wonderful sign. But, don't jump to conclusions. Could be back to normal in no time. Just have to investigate the cause.

 

Download the Service Manual and follow the trouble shooting steps. Just search it for the P-codes to get the right area. Misfire can be as simple as bad spark plug torque.

-- Chuck