Check Engine Soon-Faulty PCM?

I have a BMW x5 3.0; 2 different diagnosis: 1) bad coils and spark plugs, 2) #6 cynlinder misfire-compression and plugs good; intermittent loss of signal to #6 fuel injector. Faulty PCM. See dealer for computer and reprogramming. Help? Anybody seen this type of problem?

I replaced all 6 spark plugs today. it ran pretty smooth, slight rough idle when stopped. I drove it about 7 miles. I went in the store; came out; drastic rough idle again. Drove home, barely. It barely accelerated, ran rough.

- What to tell newbies who ask why their SES/CEL light is on but who don't have DTC scan codes or why they have a misfire or stumbling, hesitation, rough idle, etc., but who don't post codes from an OBD scanner with their question (1)

The codes are PO 1351, PO 1353, PO 0313. Any help you can provide is most appreciated. I have replaced all 6 spark plugs and 2 ignition coils (#5 & #6).

P0313 is misfire with low fuel. P1351 is misfire cylinder #5 with fuel cut-off. P1353 is misfire cylinder #6 with fuel cut-off.

Where did you get the information that you have an intermittent signal to cylinder #6?

My mechanic and the dealer gave me this diagnosis. Today the coils for cylinder #5 and #6 were replaced. After a drive around the block, the CES light came back on. The mechanic checked the codes. They were the PO 0313, PO 1353, PO 1351 that I shared earlier...

Originally Posted by smittiff

the coils for cylinder #5 and #6 were replaced

I don't see any indication of the coils being the problem so you may have replaced perfectly good coils. You can test them following procedures here:
- How to test a BMW ignition coil (1) (2)

Originally Posted by smittiff

PO 0313, PO 1353, PO 1351

I had the exact codes, among others:
- Does the order of the misfire OBDII DTCs diagnostic trouble codes actually matter (1)

Very important to check:"P 0313" Potentially - low fuel pressure. Reasons - fuel pump, fuel filter. Secondarily to check P 1353, P 1351.

Would the CES light come on if there was an issue with the fuel pump, fuel filter? I do notice that when I give the car gas, I don't have the rough idle. When the car sits at a stop light or in park, the idle gradually becomes rougher the longer it sits.

Do not think, it is necessary to check...

Originally Posted by Polikarpov

Do not think, it is necessary to check...

It's not necessary to check WHAT?

Originally Posted by smittiff

to check WHAT?

Understood the question correctly? If yes: fuel pressure.

Got it! Any suggestions on what to check? Everybody I've been in communication with are stumped. Here's my original post:

I have a BMW x5 3.0; 2 different diagnosis: 1) bad coils and spark plugs, 2) #6 cynlinder misfire-compression and plugs good; intermittent loss of signal to #6 fuel injector. Faulty PCM. See dealer for computer and reprogramming. Help? Anybody seen this type of problem?
I replaced all 6 spark plugs today. it ran pretty smooth, slight rough idle when stopped. I drove it about 7 miles. I went in the store; came out; drastic rough idle again. Drove home, barely. It barely accelerated, ran rough.
The codes are PO 1351, PO 1353, PO 0313. Any help you can provide is most appreciated. I have replaced all 6 spark plugs and 2 ignition coils (#5 & #6).
My mechanic and the dealer gave me this diagnosis. Today the coils for cylinder #5 and #6 were replaced. After a drive around the block, the CES light came back on. The mechanic checked the codes. They were the PO 0313, PO 1353, PO 1351 that I shared earlier...

Help!

Don't cry, i'm mechanic. The whole problem - my bad language.
Your mechanic may check fuel pressure? Pressure good - next step. Pressure low - found problem.
P0313 Misfire Detected with Low Fuel.

Yes, Polikarpov, an excellent idea to check fuel pressure.

The six has a Schrader valve in the fuel rail. Have the mechanic rig up a fuel pressure test gauge and tape it to the hood. Drive around and observe the pressure. It should stay at 50 psi+. If it drops when the symptoms appear, further fuel system diagnosis is in order.

Maybe you need a better mechanic.

edjack,

Thanks, Guys! That's not something I've checked...

Originally Posted by Polikarpov

Don't cry, i'm mechanic. The whole problem - my bad language.
Your mechanic may check fuel pressure? Pressure good - next step. Pressure low - found problem.
P0313 Misfire Detected with Low Fuel.

Polikarpov,
your English is fine, we appreciate your contribution, spasiba!