Hi there,
anybody know the fire order for 2004 S80? my car check engine light is on, it is said both of 5 and 6 cylinder misfire detected. i need to check those two. thank you.

 

To answer your question - 153624

I would check plugs and swap coils on those two cylinders (with coils from 1-4) to see if your missfire moves (replacing plugs if they are old/worn/fouled)

 

thanks, didn't figure out yet, will continue to try.

 

happy new year, everyone.
now my s80 testing result shows cylinder 5 misfire, and then i swap spark plug and coil between orer 2 and 3, according to the following order
153624
i swap 5 and 3, however, the testing result shows it is still cylinder 5 misfire, that is saying this cylinder order is not right? anybody has clue for this type of debugging? thanks.

 

You are overthinking this. Firing order does not matter. The only thing that matters is the cylinders fire properly.

Cylinder 1 is on the right side of the engine, 6 on the left side.

If miss-fire is on 5 and 6. Swap 5 and 6 to any other 2 cylinders. Drive car. Does the miss-fire move to the the cylinders you moved them to or stay in the same place?

If miss-fire moves you probably have a problem with a coil or plug. If miss-fire does not move there's probably a problem with compression or injector.

A simple thing that can cause a miss-fire would be an air leak - maybe at an intake manifold asket (a non-turbo has 2)

 

@hoonk, thanks for your replay. this is what i am doing now,
facing to front of engine, i swap 2 & 3, 4 & 5, keep 1 and 6 unchanged, i will test it, thanks again.

 

"If miss-fire is on 5 and 6. Swap 5 and 6 to any other 2 cylinders."

Why are you moving #2 to #3? there is no miss fire code for those cylinders. Just for fun?

 

, according to order you show to me, 2 is cylinder 5, right? 3 is cylinder 3, cylinder 3 is working good, that's why i switch 2 and 3, or i still mis-understand you? i wanted to isolate this issue, it will cost me at least 500$ if i drive to dealer for fixing, thank you very much.

 

Forget about the firing order - it means nothing! You asked for the firing order and I answered - but that has nothing to do with your miss fire problem. It would if you had a distributor cap and wires you were trying to replace (and did them all at once without marking what was what) But you don't have wires and a cap.

The cylinders are labeled 123456, #1 is on the right.

It does not matter what order they fire in! It only matters if the cylinders are firing!

If you have a miss-fire on a cylinder - move that coil (and plug if suspect) to ANY other cylinder - it does not matter which one. IF it's a bad coil (or plug) the miss fire will move to that new Cylinder.

 

Hi Hoonk, Happy new year! thanks so much for detail information, now i understood cylinder order is just physical location, see the picture i attach here, after i switch 2 spark plug and coil to 3(the same, 3 to 2), swap 4 and 5, after driving several miles, the testing still shows the same message, P0305#11, Cylinder 5 Misfire Detected. look like it is not plug and coil problem.

 

Did you check compression when you had the plug out?

 

Hi Hoonk, thanks again for your help. i just redo the testing after driving, i found the code disappear, the check engine light is also off, this is very weird, i will keep watching it.
actually i don't know how to do compression check, thanks again for providing debugging tips.

 

Hi Hoonk,

did i mark cylinder order correctly? today the check engine light is on again, i test it, it is still showing that cylinder 5 misfire detected, actually i have swapped #5 and #4 last time. during testing, i did another thing, i run diagnosis, then error code disappear, do you have any clue? thanks.

 

some codes are averaging or accumulating faults so if you scan / clear a code it may take a few miles to reset. There are 3 things that can cause a misfire a) fuel trim (rich/lean mix) b) weak spark (plug/coil/coil harness) c) compression. When it comes to compression, particularly if you have two adjacent cylinders reported, I'd do some basic tests for a possible head gasket issue (compression, check oil/water etc). For fuel trim, lots of things can contribute - intake air /exhaust leaks etc, wonky ECT or other sensors, vacuum lines/intake air tubing. Also dont rule out fuel pressure, fuel quality and injectors. For spark, you have plugs, coils and the harness/connector to the plugs Did you notice any discolor on the plugs? Are they the correct type and properly gapped? When in doubt, I'd install genuine Volvo - they come pregapped and are correct for the car.

So to Hoonk's point, you need to be systematic about your diagnostics - swapping coils is a way to determine if the coil is bad (rarely does more than one fail at any given time) and you can also inspect the plugs for color and the harness/connectors to make sure they are still good and not cracked. After that you may want to do the compression test, then do some testing for the fuel mix = ie look for air/exhaust leaks, check the coolant temp sensor's resistance etc. Lots can be done without guessing at parts to replace. You may also want to see about collecting some run time data via a full featured OBD 2 scanner to see what's going on with fuel delivery etc.