no injector pulse on #2,#3

[lockwoodfe]

Thanks for the input. Starting to sound like the ECU is deliberately shutting cylinders down because it thinks something is wrong. Guess I need to figure out who I can borrow a code reader from and see what clues that reveals. Another piece of info that I have not shared yet is that we replaced all the spark plugs the day before this all started. Before then, we actually did get a code read for some misfires on #3 but after we changed the plugs (and they really needed it) it ran great, at least for a day... Since these latest troubles begin, I have checked spark on all cylinders several times and I definitely have spark everywhere. I also have some extra coilpacks and was playing swapsies when I was troubleshooting before I figured out is was the injectors. Not sure if any of this could somehow be related but the timing sure is suspicious.

Truth be told this is kind of a side project for me. It is my sons old car and I want it out of my garage. It doesn't make sense to dump much money into it but it could still be a decent car for someone who needs cheap transportation. I hate to scrap it if it only requires a simple fix but it is getting close to that.

[mrbrian200]

is this really wired with individual constant12 VDC and common ground switched by ECU?

This arrangement isn't uncommon within vehicle systems. I don't know the specific technical advantage of doing it this way, but I'm sure there is one.

[mrbrian200]

I'm on board with the idea the ECU shutting down 2&3 for some reason not yet discovered. Coil pack grounds through several ring terminals and are attached through more than one ring terminal (either 3 terminals coil packs grounded in pairs with one oddball having it's own terminal, or two terminals 3/2). In changing the spark plugs you would have potentially disturbed these. Resistance through a weak connection is usually tied to heat (as heat rises resistance rises or continuity is lost). Problem may be where the wires are crimped at the back of the terminal and/or oil and corrosion between the ring terminal and the aluminum manifold.

[oragex]

How is the circuit board of the fuse panel located inside the engine bay? I read about an owner having to resolder this panel.

[lockwoodfe]

So I got a code reader. P1620 and P0507. 0507 is Idle Air Control System RPM higher than expected. No text for 1620 and conflicting info when searching internet. However, finding stuff about ETM (electronic throttle module) or MAF problems for these two codes and think I have a new problem statement. This is a known problem for my model year and symptoms of ETM failure include rough idle, hunting idle, going into "limp mode" which is sounding like a match. I pulled the intake hose off and sure enough the butterfly valve does not open when I press the throttle. For kicks, I wedged the butterfly open with a screwdriver and gave it a quick test drive and presto, the engine ran smoothly, the car responds to the throttle and has power now. Still welcoming advice but it appears there is lots of searchable info on ETM/MAF problems. Still researching but maybe just clean ETM or replace MAF. Also sounds like bad ETM would be curtains for the car. $1000 part that requires keying to ECU.

[abscate]

You can get away for about $500 on the ETM via FCP and a Volvo software match.

P1620 is some sort of Comm error - you really need the ECM code read to get this right.

[lockwoodfe]

Well now that I am narrowed down to the ETM, I discovered that the fuse for the ETM was blown. Replaced the fuse and crossed my fingers and everything ran fine for about a minute, then the fuse blew again. Not looking good for the ETM. I have also cleaned the ETM and while a little dirty it didn't seem terrible and the valve did not seem to be sticky in any way. I have read that the most common failure for the ETM is that the position sensor is a mechanical wiper that wears through. Not so sure if this would cause the fuse to blow though, sounds more like an actuator problem to me.

[lockwoodfe]

Well did not have another 10A fuse so did what any other hack would do and put a 15A one in there. Drove it around the block a few times and the 15A fuse has not blown yet. I have cleared the codes a few times and the P1620 keeps coming back but other than that I am clear. The check engine light is off. Suppose I can inspect the wiring harness to the ETM to look for any intermittent shorts.

[abscate]

Is there other stuff on the ETM fuse circuit? I seem to remember someone having trouble with the accelerator pedal position sensor being on this same circuit some years back...

[mrbrian200]

A little googling I can't say for certain what P1620 description is supposed to be, but that it pops up with ETM failures on the years that Volvo use this style ETM, and disappears on its own when a good ETM is installed.

It's a "SBDS Interactive code". What exactly that's supposed to mean (Interactive?) I have no idea. With some digging I figured out SBDS refers to a diagnostic computer system developed for Ford Motor Company. Being an '01 I'm not surprised there of signs of Ford floating around in there somewhere.
http://www.engenius.com/SBDS.html