98 S70 t5 missing after replacing cps., P0300 etc

BRONCMAN · Post by **BRONCMAN** » 22 May 2012, 22:19

My car has always seemed like it would have a small miss while driving. It would only do it maybe once or twice in a 100 mile trip. Last week it started missing very badly & i stopped to turn it off & it would not start. It had fuel pressure & after I moved the spark plug wires around & tapped on the coil it started back up, but was still missing. I got it to the auto parts store & scanned it. I got the following codes.

P0304- cylinder 4 misfire.
P0335- crankshaft position sensor A circuit.
P0305- cylinder 5 misfire.
P0300- random misfire.
P0103- mass or volume air flow circuit high input.

I erased the codes & drove it some more to see which ones would come back. I drove it home about 30 miles & it seemed to run better, only missing once in awhile. The next morning i drove it back to town & it started missing very badly again after driving about 4 miles. I scanned it again & got P0300 & P335. So I ordered a new crankshaft position sensor & replaced it. I made sure the wires for it & the camshaft position sensor were not close to any spark plug wires or the distributor as I know that's a common problem. When I started the car it was immediately missing and sputtering, so I disconnected the battery to erase the codes since I don't have a code scanner at home. I let it sit 5-10 minutes & reconnected the battery & started the car. It was idling nice & smooth. I took it for a drive & noticed a slight miss every now & then while under light throttle. Under heavy throttle it has never missed. When I got back, I noticed if I give it light throttle in park at about 1800 rpm it will miss & the rpm will drop to about 1200 then jump back to 1800. It will continue doing this unless you let off the throttle or increase the engine speed.

On Thursday I'm driving the car back to town to see if any other codes come up, but I doubt it. Last year I replaced the mass air flow sensor, plugs, wires, cap, & rotor. Could this be an ignition coil issue or would that just not work at all if it was bad? What else would throw a po335 code??? Thanks in advance for any help. This has really got me frustrated as I probably just replaced a part I didn't have too & I'm very short on funds at the moment.

Post by **steve850** » 22 May 2012, 23:01

I had very similar issues with my 850 a couple of years ago; turns out the "tune up" done the year before was done with Champion plugs and bargain store wires and that was the issue. It threw all kinds of misfire codes. Volvo original plugs, bougiecord wires and volvo cap and rotor, problem solved. The specialist i dealt with (I was away on vacation at the time) suggested that plugs cap and rotor are the first thing to change if you get a miss.,,

mrboogaty · Post by **mrboogaty** » 23 May 2012, 10:10

Same here on a 1998 V70 T5, had multiple codes/misfires, turns out the guy before me had installed Autolite plugs so I ordered this http://www.ipdusa.com/products/4688/115 ... une-up-kit, I think they have a kit with just plugs/wires/cap/rotor button thats a little cheaper. Installed and problem solved.

Post by **jblackburn** » 23 May 2012, 11:46

P0103- mass or volume air flow circuit high input.

This may be a clue to the problem.

Unplug the mass airflow sensor (engine off) and see if it runs any better.

What brand did you replace it with last time?

BRONCMAN · Post by **BRONCMAN** » 23 May 2012, 17:03

I don't remember the brand name off the top of my head. It was an autozone one with lifetime warranty. I'll try that tomorrow if that code is back when I scan it. I guess it could be the plugs acting up. I think ill pull some & see how they look. I was thinking about it & I have put about 30k miles on the car since I replaced all that stuff...

Post by **erikv11** » 23 May 2012, 18:37

The Autozone MAF is going to cause problems very soon if it isn't already. Really, a non-Bosch MAF simply will not work in your car.

E.g. https://www.matthewsvolvosite.com/forums ... 4&p=234100 but there are dozens of threads like this.

BRONCMAN · Post by **BRONCMAN** » 25 May 2012, 16:13

What's strange is that it hasn't thrown anymore codes for the maf. Also it only misses like hell around 1800 rpm.

Post by **erikv11** » 25 May 2012, 16:20

Can you get one from a junkyard? Almost always those are still OK. The MAF is an expensive part, but until you eliminate it as a problem, well, it isn't eliminated. They don't always throw a code.

But if you are saying it still misses like hell at 1800, even with the MAF unplugged, well then OK that is pretty good evidence that the MAF is not the main or only problem right now.

Post by **erikv11** » 25 May 2012, 18:12

Hey another thing - could the catalytic converter be clogged?

Post by **steve850** » 27 May 2012, 13:04

Clogged cat usuallly feels like you stuffed a sock in the intake... It produces an overall loss of power, not a miss