Hello All:

Just be curious enough today and tried out the first time ever Italian tune-up on my S90. The Check Engine light came on just seconds after I shifted it to low gear and above 4,000 rpm range. I read the OBDII code from a local Autozone store and had it erased. All 3 faulty codes translated to cylinders misfired ....Should I investgate further now or I should wait to see if the light will come on again to isolate the problem...By the way, the spark plugs got 20,000 mi, coils condition unknown and air filter is new. Thanks in advance for any input.

If this is the first time the engine has been "cleaned" it just may have been some fouling on the plug. At high speed and load it takes more voltage to fire the charge and the plug may have been fouled just enough so that at light load it worked OK but not under a high load. Just see if the codes stay away.
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'96 965 with 16' wheels at 114K. Had '85 745 Turbo Diesel for 200K.

You might want to get some spare coil packs. Did you write the numbers down? They till tell which ones are bad. It could be arching.
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Warren Bain - '99 V70GLT G-Valve > 80K mi, 89 300SE, '96 965 >120Kmi, near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu. This post written with 100% recycled electrons.

I think there were 3 codes pulled up. The first was like "cylinder 5 misfire" and the other 2 were "multiple cylinder misfires"...The car as usual is running and idle very smoothly though. Thanks

It could be the head gasket.

Brandon

shooting from the hip, i'd say you have a fuel injector problem or a coil problem. stressing the system like that will show weaknesses. drive it normal. that also means less raw fuel into the cat convertor. they don't like that. you won't either when you have to buy 1. if the codes pop again, have someone look at it. good luck, chuck.