1998 V70 GLT Throwin' codes, wife's freakin'

shadetree_v70 · Post by **shadetree_v70** » 21 Mar 2015, 21:03

So the wife is on a Thelma and Louise road trip this month (hopefully without the crime spree and driving off the cliff), and she really wanted Marilyn, her beloved viggen to make the trip. So that meant many hours on my part making sure she was up to the task. Everything has been fine so far, but here's what's going on:

Twice, and all at the same time, she's getting P0410 (air pump), and misfire codes for random (P0300), and specific cylinders, 1,2,4,5. Once was under really wet conditions, and once was really dry conditions. As far as I can tell, air pump has little or nothing to do with misfires, but wifey is convinced otherwise. BTW, she has a code reader with her to report Marilyn's condition as it happens and reset the MIL.

To date, here's what I've done:
Front O2 sensor (Bosch)
Plugs, wires, cap, rotor
Exhaust
Genuine Volvo PCV system, complete. That fixed what I thought was an oil leak, turned out to be a rotten elbow (the 1" one from bottom of oil trap to crankcase)
Cleaned throttle body
Fuel filter
Air filter

Plus a lot more not engine related, but you get the picture: She needed some attention before I was going to feel OK about her hitting 48 states and going 9-10000 miles over 4-5 weeks.

Sorry about the rambling, but I wanted to tap the vast universe of experience here, and maybe see if there is some troubleshooting to be done. She is going to be at her brother's for a few days, and he's a capable mechanic, especially with some direction.

The only thing I could come up with was maybe the coil is starting to show its age? Vibration, moisture, sheer mileage?

The air pump codes have come up before and it passed inspection 3 weeks ago, so I'm not too worried about that, but again, she's thinking that and misfires are related somehow.

Thanks in advance!!!!!!!

crlande · Post by **crlande** » 21 Mar 2015, 21:18

The P0410 code refers to the emissions system. The AIR pump puts air to the exhaust to lower emissions. It takes in outside air and pumps it through two one-way check valves into each bank of the exhaust. About 90% of the time that this code is set, the one-way check valves have worn out or failed and allow water (which occurs naturally in the exhaust) back into the pump. In any cold climate, especially in climates with higher humidity, this water may be more excessive. The water partially fills the AIR pump, it can then freeze. When the PCM commands the pump on, if the pump is frozen it cannot turn, thus overloading the circuit and "popping" the fuse.

Read more at: http://www.obd-codes.com/p0410
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Post by **erikv11** » 21 Mar 2015, 21:51

I'm with you, p0410 almost certainly unrelated. Tell her you can fix that when the car is back home.

Among causes of multiple misfire codes that come to mind: fuel supply (has the fuel pump relay ever been replaced? Hopefully it is not a dying fuel pump), vacuum leak (especially inspect the all of the intercooler hoses, cracks in these can be tough to spot, the one with the funny elbow at the throttle body is a likely suspect) or oil or moisture in the cap due to a blown cam seal (have bro in law pull the cap and inspect for moisture or oil under there).

Post by **jreed** » 22 Mar 2015, 07:02

For what it's worth, on my '97 855 GLT, the two times that I've had a misfire code were caused by a sticking idle air control valve that would cause the engine to stall or nearly stall. When the engine nearly stalled, the computer set a misfire code. I replaced the IAC valve and the problem has not returned. This may not be related to the problem you're having, but it might be worth checking.

shadetree_v70 · Post by **shadetree_v70** » 22 Mar 2015, 08:09

Jreed: haven't noticed or heard complaints about stalling, so the IAC hasn't been on my radar, and no codes have been set to that either.

Erik: I wondered about the fuel pump too, especially when the 0300 pops up, like there was a hiccup in the whole supply to the rail. I always thought that electrical parts work until they don't, so throwing new parts at it isn't the best approach. But no, neither pump has been replaced as far as I know. I thought it was interesting that #2 never popped up

Vac lines were mostly replaced, and at least inspected when I was swapping in the 15g turbo, and cams were done when I did headgasket last year, and again when the head went out for exhaust valves in November.