2001 v70 2.4t misfire issues

[precopster]

Have you tried Clearwater Heads. For around $500 including freight they can exchange a Volvo head. Far less work to replace a head than exchange an engine in my opinion

[draser]

Bad news.

[draser]

Sorry, fat finger. So head has cracks in 5 places.... hmmm.... can they show you? I mean.. 5 cracks??? Kinda hard to believe.

[naonin]

Sorry I didn't update sooner but I did go ahead and purchase another engine for $850, it had only 109k on it (according to the junkyard that has a good reputation and good reviews online). I did see the old head, it was cracked all the way through, right down the middle. Anyways, swapped them out, got it all back together and I'm still getting a misfire!

So I'm at a near loss. Here's a recap methodically:

Fuel-

Drained oil fuel and put in fresh premium today.

Changed the injectors between the ones that I had before and the ones that came with the engine. No change.

Pressure was fine before in the old injectors so I don't think I need to test the new ones either.

Pulled the injectors but kept them connected to vote the spray pattern, nice smooth even cones.

So ask this leads me to think fuel is fine.

Compression/air leaks-

Compression tested the new engine, 155 on cylinders 1,2,3. I think my gauge is not calibrated correctly or possibly damaged, but at least they were consistent. I didn't bother with testing the other two. I was tired.

Sprayed ether all around the engine while it was running, no change in idle, so no leaks.

I didn't change the timing because this came off an engine that was running and got in a wreck so I think it's safe to assume that the timing is fine (plus the plugs and oil filter was OEM Volvo so I think the previous owner may have done dealer maintenance, and the vvt hub and solenoid both look new compared to the rest of the engine). I do plan on a timing belt change but I think it's in time.



Likely not compression.

So finally ignition-

Changed coils multiple times, changed plugs multiple times.

The codes are

ECM 3503 - general misfire

ECM 3533 - misfire cylinder 3

ECM 3553 - misfire cylinder 5

I've changed the ECM, but here are the questionable details:

I figured if I'm gonna get another ecm, let's get the tune. So my dad picked up an ecm off eBay for $25 and we sent it in to ARD. They said it was not the right one for my car but he had one there on the shelf. He tuned that one and sent it to us.

So is it possible the ecm is still the issue?

The only other thing I can think of is the wiring. I was going to try these tests:

- check voltage of wires at the harness connecting to the coils.

- check the duration of the fire at the harness connecting to the coils.

- check resistance of the same wires.

Is there any other things you guys can think of?

[naonin]

Somewhere along the way in fixing this, the wires to the coils on 3+5 got mixed up. No wonder I couldn't get it in time. I know for certain I didn't do it because I'm very aware of keeping track of things like that. I'm quite certain it was the same mechanic that was supposed to do the timing belt. I changed the wires and it fired right up.

Sadly, it still didn't run perfect. There are no more codes being thrown but the idle is still rough. I'm guessing throttle body.

Regardless, just thought I'd update this for anyone coming along. It seems obvious that you'd check that the wires are in their correct spots, but you never know when someone else works on your car. Lesson learned: never trust that the other guy did the job correctly.

[abscate]

Nice!! I know it's frustrating but at least you weren't paying someone 100 bucks an hour plus...to fix their mistake...

Let's not panic on that ETB yet. Is is it Bosch or the infamous Magnetti Marelli Italian job? Yellow or white label?

[naonin]

I had a yellow label on the previous engine with 200k miles on it... I'm not certain when we got the yellow label etm. My pops got the car in '02, so somewhere along the way we must've picked it up. The engine I purchased had a white label ETM on it, which that must have 109k miles on it.

I figure the yellow label Magnetti Marelli will die if it isn't going out already. I've tested the car with both in there are there are idling issues with either body. No codes. I figure while I've already got a newer engine in there I'll just get the xemodex upgrade, it's bound to be a problem eventually if it's not already.

With the coil burning out on cylinder 3, it got so hot it melted the wiring harness for the coil on cylinder 4. Purchased a complete engine wiring harness and only clipped off the connector for one of the coils. The issue here is that the wiring harness was off a VIN 61 engine and mine is a VIN 58. My other connectors only have 3 wires in the harness, this new one has 4 wires. I've ran many tests to compare them (resistance, voltage, continuity between pins) and find no difference. The only thing I haven't been able to figure out with my multimeter (Mac Tools em710 if anyone is familiar with it) is checking the pulse voltage. I'm wondering if that 4th cylinder has low or high pulse voltage because of the different harness/connector. Is it dumb to think that because I spliced the connector from a B5244S into my B5244T3 it'd be an issue?

tl;dr of symptoms left - The car is smooth when cold but as it warms up it starts getting a slight, random misfire. Not sure if it's only one cylinder or if it's all.

[draser]

On the coil for cyl#4: if you spliced the primary correctly and have spark then you're good. Spark intensity is the same. If you're running good when cold then it gets rough you may have an air leak which causes lean condition, hence misfiring. I'd get some live data fully warm to confirm.

[chrism]

Maybe as the coils warm up, one or more of them starts to break down and misfire. You said at one point that you put in new ones. Were they new or used? Volvo or aftermarket?

Also, I may have missed it, but did you ever say what kind of spark plugs you have in there? These engines seem to do the best with plain old Volvo or NGK copper cores - yep the cheap ones.

[naonin]

I've tested with OEM Volvo plugs and coils as well as aftermarket NGK plugs and blue boot coils, whatever brand makes those (not the IPD ones). No change.

Live data:

Cold:

Air mass sensor reads 14 kg/hr and throttle position varies between 6-12 degrees.

Hot (15 minutes to warm up plus 5 min of hard driving and then I watched the data for 10 min just in case it took time for the turbo to wind down):

Air mass sensor goes between 3-10 kg/hr, mostly sitting around 6 kh/hr.

Throttle degree: between -1.75 and 15 degrees. Highly fluctuating.

The air mass seems low. I do have a k&n high flow filter, I've read that can result in slightly lower air mass readings around 9-10 kg/hr, but 3 seems like a problem. What's the correct reading for throttle position at idle?

I'm putting in a new pcv box today, I'll let you guys know if that makes a difference, but I'm beginning to think it's the ETM + air mass. Both have been cleaned by the way.