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Q: What could cause my car to shake and lose horsepower when accelerating rapidly? on 2001 Volvo V70 XC

I've only owned it for 4 months so I'm not sure about past maintenance. I replacedthe coils and spark plugs when iI got it. I felt it sputter a few times, like a misfire, so I took it to my Volvo mechanic. He told me the only issue he could find was low/dirty oil. So we did an oil change. It is still having the same issue. When I get on the freeway or speed up to go around someone the engine struggles and the check engine light flashes. City driving is perfect. I do get electrical fluctuations when I use my AC, so I stopped using it, but I still get the shaking on acceleration. I was thinking if I can get help in the forums I can tell my mechanic specifically what to fix so my car doesn't die. I love my car. Its been my dream car for the past decade.
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You just need a MECHANIC with a good scanner! Check, got to be one around,, not necessarily a Volvo tech!
I've been to 3 mechanics. Two non Volvo mechanics who work on my jeep, and my Volvo mechanic who I've been going to for 3 months. None of them see a problem..
Have they test driven the car? Have they test driven the car with an active scanner on board? Under the conditions you drive!
No they revved it in park and said it was fine, possibly low oil pressure, thus an oil change.
I stand by my first answer! One more thing, where did the new parts (coils & plugs) come from? What kind of parts?
I got them from the volvo mechanic. It was misfiring and burned 2 coils. The spark plugs that were in it were really worn and he said the cheapest ones he has ever seen, so he replaced all of them and 3 of the coils, the other 2 he said looked good. He also did the alignment, AC compressor, brakes, and struts. He said he did the timing belt for the guy who sold it to me and the transmission is newer than the car, but he didn't do that.
Replace remainder of coils with NEW volvo parts!!! If the others were not new, replace those as well to FIX this problem! One of the coils is breaking down under load, more pronounced on the highway than in town because of extra load on the eng. from the higher gears!!!!!!
New me hanic is replacing spark plugs and coils. He thinks this could be my problem. Fingers crossed. NEW parts, the last ones turns out were not new :-/
Car seems great now. My last mechanic put used parts (which I didn't know about, I thought they were new). I took it to a different mechanic this time, recommended by repairpal, and he knew what to look at right away, tested the vvt, checked my fluids, and fixed it. If I had taken it to him when I first had the issue it would have saved me this whole headache. Looks like I have a new mechanic. Closer and nice isn't always better.
So... Shaking and loss of horsepower, and power dips with the AC on, are all coil/spark plug issues. THANK YOU GUYS!
jennjenn137, that's exactly what i thought! - So, installing used or inferior ignition parts is never a good idea!! When any engine with the Coil On Plug (COP) ignition system needs one of the coils replaced due to age or mileage breakdown, replace 'all' of them with new OEM parts. While it may be pricy initially, it actually saves money in the long run. Especially IF you plan to keep the vehicle. Evidenced by this page!!
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A flashing check engine light is a definite "Misfire" and a catalytic damaging issue as well. There are many variables that can cause a misfire. Its very broad, you can have issues with ignition, fuel, air intake, exhaust, timing issue to name a few. My advice is to have it diagnosed and tested by a reputable shop that works or specializes on volvo's.

let us know once you figure out your problem. So somebody else with the same issue can be helped. :)
The shop did plug it into the computer. The only code it had was for a misfire in cylinder 8, which is impossible on a 5 cylinder car, and a mirror temp sensor error. And this is a volvo specialty shop.
ECM-1100 Outside temperature sensor- signal too low
ECM-644A Camshaft control - faulty signal (was yellow the mechanic says this means it is not causing any problems, is he lying?)
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Camshaft trouble code can be causing ur issue. Have ur vehicle's timing checked. V70 uses a belt so they wear overtime and is recommended to be replaced every 100k miles. Check ur owners manual for the right interval. Also check ur cam vvt which adjusts ur timing depending on driving conditions this vvt is electrically controlled and allows oil to pass Thru small orifice in the vvt which can be clogged by oil sludge and debris. A not uncommon thing to happen on a 12 year old car. A clogged vvt or bad electrical connection to the vvt can cause issues as well.

Also, i think yellow means the problem is not currently present. But was stored as a history code.
Update us with the fix as i am curious. Im sure someone wil be help by this thread somewhere down the road.
It has a new-ish timing belt. But I will have him check out the vvt. Thank you so much for some sort of direction to go in. Hopefully this helps. I'll let you know. :)
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