2006 S60 R #3 and #4 misfire [Coil wiring fitment] Topic is solved

[Corrado]

Have a 2006 S60 R 6 sp No injector pulse on cyl 3 and 4 and misfire codes 303 and 304 , was able to use scanner to actuate those injectors and verify with test lamp...but the PCM will not fire them by itself.
Replaced PCM and had dealer flash it and now injector pulse is OK.....but still two bad holes #3 and #4 misfire. All the time hot or cold.....dead holes .....injectors are spraying ok on all cylinders now

compression is 125 to 135 on all cylinders and leakdown is low..double and triple checked....in fact the dead cylinders are maybe even less leakdown and 5psi more compression,than the ones firing OK . Valve timing is bang on, replaced injectors,coils, spark plugs, exhaust back pressure is 1 psi , but I dropped it anyway to check. Sprayed alcohol around intake and breather to see if there are air leaks.....

I can verify during leakdown rolling the engine over by hand and can confirm proper valve events.....leakdown is fine

swapped and replaced coils plenty of spark....

35 yrs experience tech here.....completely miffed ? any thoughts

[abscate]

I would look for a wiring fault between 3,4 and ECM. A short to supply could have blown the gates in the old ECM , and will blow the new one too.

[Corrado]

Thank you for responding

When I first diagnosed the faulty 3 and 4 injector control....I was also able to remotely control the injectors with my scanner which confirms the wiring is functional with old PCM I have full injector pulse and spray on all cylinders now with new PCM wiring is ok

I had a thought and I`m going to check this now....the coils 3 and 4 wring cannot be interchanged because they dont extend far enough to reach the wrong coil....but perhaps before I diagnosed this, someone unwrapped the tape and swapped some wires....

[Corrado]

Update

This is what a modern tech has to deal with these days.....customer brought car in said `` I just drove to the mall and suddenly the car ran poor and would barely move`` As I diagnosed it... It had spark on all cylinders and no inj pulse on 3 and 4...we changed PCM and dealer flashed it and the car ran no better and the Volvo dealer admitted to us their previous records showed we told customer previously the engine is faulty......hmmm He never told us he went to the dealer......at the end of the day...

The PCM was the original problem.....but whomever (volvo tech) diagnosed the car before the customer brought it to us ..... mixed up the coil wiring so that 3 and 4 were mismatched and taped it up so they appeared to not be interchangeable.....

compounding this ...the coil wiring is same colors for all coils...the PCM cannot be removed without proper tools making diagnoses problematical......

all good now Thanks for advise

[abscate]

Oh, that is a nasty bit of work,...well done getting that sorted.

On P80s, the original wiring harness does color code the coils - I documented this in a thread. I bet they do in P2s as well, but the replacement wires probably didn't preserve the color code.

And, I like that my fault suggestion above would have caught this, because you would have had open circuits between the coil 3.,4 and the correct pin on the ECM.

If the Volvo Horns were available , I would claim them, but you get them for this effort...

[Corrado]

Green white is power, Black is Ground, trigger wires are all tan...though my data base says they are color coded.

other than a few inches taped up ...the wiring looks like its never been touched ? Wonder if CDN models are different

Customer said it ran fine till he drove to the mall....laugh !!

I appreciate your input ....I've come here from time to time to sort things out over the years

Hopefully Ive offered some input too

[Corrado]

One wouldnt have suspected open coil circuits when it had perfect spark on all 5 coils.....