2006 V8 "Slow Down or Shift Up"

Chonk · Post by **Chonk** » 05 Dec 2019, 08:31

Hello all,

I have been receiving this message, “Slow Down or Shift Up”, for the past week. It happens mostly at lower speeds (30-40mph) or when I really gun it.

I ran into this same message a year ago, and I received these results from the VIDA readings:
ECM-P030000 Random Misfire Detected
ECM-P030200 Cylinder 2 Misfire Detected
ECM-P030300 Cylinder 3 Misfire Detected
ECM-P030600 Cylinder 6 Misfire Detected

And so I replaced all 8 ignition coils that go over the spark plugs, as well as cleaning the throttle body and MAF sensor. I also replaced ONE spark plug that was dirty and corroded and looked horrible. That seemed to fix the issue until now.

Since receiving this message again last week, I replaced all 8 spark plugs. Interestingly enough, the worst spark plug was the spark plug I had replaced when I replaced all 8 coils. Coincidence?

So the message still persists. The car idles roughly, and as I drive I can feel a slight give/pull due to the cylinder misfires. The engine temperature stays perfect, and the RPMs are really good as well, no sudden burst in RPMs. Plugging into the VIDA after I got the message to appear gives me these results:
ECM-P030000 Random Misfire Detected
ECM-P030200 Cylinder 2 Misfire Detected
ECM-P030500 Cylinder 5 Misfire Detected
ECM-P030700 Cylinder 7 Misfire Detected
ECM-P030800 Cylinder 8 Misfire Detected
ECM-P035700 Ignition Coil G Primary/Seconday Curcuit

More interesting info (not sure if it’s helpful): Three times over the last week the engine has shut off (with lights and dashboard displays still on) after I am driving and come to a stop and put the car in reverse. I don’t know if this has to do with the cylinder misfires as well?

Thank you for any help you may have. Please let me know if I can provide more information.

Post by **jimmy57** » 05 Dec 2019, 09:36

First thing to do is to inspect the harness for the coils to see if there is a chafed spot shorting to metal. That could explain multiple cylinder misfires. Also make sure the ground wires you find by the top of the struts in engine compartment are secure and not corroded. The motion of motor when it goes in reverse and the engine dying sure sounds like a touching and shorting wire. I can't recall that the coils have a connector in the harness. The engine control module is on air cleaner box and there is no need for a connector for that close mounted ECM.

Chonk · Post by **Chonk** » 05 Dec 2019, 11:17

@jimmy57 Okay I will check the wiring and update once I do. Thank you for the suggestion!

Post by **oragex** » 06 Dec 2019, 04:45

Chonk wrote: ↑05 Dec 2019, 08:31 Since receiving this message again last week, I replaced all 8 spark plugs. Interestingly enough, the worst spark plug was the spark plug I had replaced when I replaced all 8 coils. Coincidence?

I would monitor closely that precise cylinder. May also look at the wire for its coil, as mentioned above. To me, that cylinder has some sort of issue that may even be mechanical

Chonk · Post by **Chonk** » 06 Dec 2019, 16:54

@jimmy57 I see that the harness has the connectors for each coil, but I’m not sure where to look for “chafing” of the harness. Some spots on the plastic harness that covers the wires are broken and I can see the wires inside, but they aren’t touching metal. Should I check each connector? How do I tell if the harness or wires are bad?

Chonk · Post by **Chonk** » 07 Dec 2019, 17:59

UPDATE 1

Okay. Replaced both terminal loops that are over the valves, and made sure the wire was clean and touching clean shiny metal. And cleaned the other two terminals that didn’t need to be replaced.

Same results. Idles a little rough. Still drives like normal besides going about 35-40mph has that slight shudder/misfire (sometimes). The “Slow Down or Shift Up” message came back on while I was idling and while I was going about 35-40mph. If I gun it and get up to 60-70mph it runs just fine with the RPMs staying normal as well as engine temperature.

When I come to a stop and put it in reverse it almost dies, but only when I crank the wheel all the way to the left or right. If I straighten the wheels out the engine returns to normal, with a slight rough idle.

The wiring around the harness seemed good to me, and all eight of the connectors that connect from the harness to the coils looked good too.

Any suggestions? It could be that cylinder that had the bad spark plug that was the only spark plug I replaced when I replaced all eight coils?

I would monitor closely that precise cylinder. May also look at the wire for its coil, as mentioned above. To me, that cylinder has some sort of issue that may even be mechanical

Thanks again for any help

Chonk · Post by **Chonk** » 08 Dec 2019, 09:14

Has anyone been able to get to the harness on the backside coils of the V8? It seems to be underneath/behind two tubes? I was able to get to the ground wires back there, but not sure how to get to the harness wires. I am wanting to get to all of the harness wires and inspect them.

Chonk · Post by **Chonk** » 08 Dec 2019, 13:01

I’m also seeing here that it could be due to either the alternator, Volvo-specific spark plugs (mine are brand new Bosch double iridium), or OEM crankshaft position sensor?

Does any of that make sense?

https://forums.swedespeed.com/showthrea ... -misfiring