850 Studder and Fluctuating RPM at Idle

alexk243 · Post by **alexk243** » 18 Feb 2013, 14:10

Just moved into the city and after parking on the side of the street I noticed that my Volvo was dropping RPM at idle and occasionally was hesitant with throttle response, but seemed to have the same amount of power. I scanned all "A" ports on OBD-1 and all I got was A3 (213, 141) and A7 (231) which I could not located in the database on this site and I have no idea what these codes mean. I am starting a new job tomorrow and this is my only car so I am really nervous about it leaving me stranded.

Any ideas on what the issue is and what I can do to fix it? Seems like the car is just struggling to idle.

Post by **Ozark Lee** » 18 Feb 2013, 16:07

The port A-3 codes are for the ABS and the A-7 code is for the instrument cluster. Clear both of them and see what, if anything, comes back. Neither code will cause the problem you describe.

The ports of interest to you are A-2 and A-6.

Try unplugging your MAF sensor and see if the idle smooths out. Unplugging the MAF will set a code and turn on the Check Engine Light but it is easily cleared.

...Lee

Post by **abscate** » 18 Feb 2013, 17:42

Im having trouble with the same symptom on my 1999 V70T5 after I had the air system open (radiator R/R)

I got two codes P0327 (knock sensor) which has been occasionally showing on this car for two years

P1238 "trouble code definition not found"

Cold running is undriveable, but it settles down once hot. It ran great for one day after the radiator job. Water in fuel or gunk in MAF ?

On edit - I will start a new thread as my issue is growing its own cancerous tumor...link to new thread here

alexk243 · Post by **alexk243** » 18 Feb 2013, 18:17

Pulled MAF plug at Idle and the car died.... Dont why I thought it would do anything but that. Plugged it back in, cleared the CE light/code and started it again. Same issue. Any other thoughts or ways I can diagnose this?

Also the car is running much rougher now. fluctuates at idle and hesitates on acceleration until 3500+ RPM.

Post by **jblackburn** » 18 Feb 2013, 23:16

Don't disconnect it while idling. Disconnect it, then start.

My bet is on a bad MAF as well.

alexk243 · Post by **alexk243** » 20 Feb 2013, 18:01

ok, Disconnected it while the car was off and restarted. Still had issue and now car died at idle with the MAF unplugged. Plugged it back in and same issue, but wont die at idle.

I really need to fix this car this weekend and I am willing to dump money into it, but I dont know what to do. Ordered a new MAF but I dont really think thats it.

Car has no power under 3000 RPM on highway either, but can go highway speeds. just rough starting out. Thoughts?

Post by **erikv11** » 20 Feb 2013, 21:06

It's a longshot but almost free to try: have you cleaned out the IAC valve?

alexk243 · Post by **alexk243** » 21 Feb 2013, 19:18

What is the IAC valve? and how would i clean it?

Post by **xHeart** » 21 Feb 2013, 20:15

alexk243 wrote:What is the IAC valve? and how would i clean it?

/viewtopic.php?f=1&t=47533

alexk243 · Post by **alexk243** » 24 Feb 2013, 18:04

So... Figured it out. Went home this weekend to work on it and got some new spark plugs (just in case) and ordered a new wire set. Planned to check the distributor cap and rotor as well. Well when I pulled off the spark plug boots I discovered the issue. The spark plug "wells" or whatever you call them had 1" or so of water in them on cylinder 1 and 5. This was most likely caused the last time I washed the car as I neglected to run the car before or after to dry out the engine (as recommended), which I usually do. I am assuming that the spark plug/boot was grounding through the water and shorting to the engine block and most likely cylinders 1 and 5 were not firing or were intermediate.

Replaced the spark plugs (NGK Platnium), Spark plug wire set (Bosch, only $65 from Autozone), and got the distributor cap and rotor replaced under warranty from Autozone (just under 2 years old. Also cleaned the throttle body and IAC valve, plus added a few more hose clamps on loose fittings near the intake. After this started it up and it was good to go. No more issues at all. Kinda feel like an idiot, but at least it was a cheap fix and prevented issues in the future.

Here are some pictures of the spark plug "wells" and the old boot/wireset