1998 V70 - Rough idle, hesitation, stalling

robisindy · Post by **robisindy** » 04 Apr 2016, 12:43

Thank you again for all of the suggestions.

I have looked at the vacuum hoses and I don't see any that seem to be in poor condition. The only thing I noticed the other day while looking things over that wasn't as it should be was that when I went to check the air filter, the air cleaner box was not completely snapped shut. The 3 clamps in the back were not snapped on.

Today, the car idled perfectly on a 60 mile round trip. One time on the way to my destination it hesitated at light throttle while cruising at around 55, like it had done previously, but only for about 10 seconds. Giving it a little more throttle smoothed it out and after the 10 seconds or so it never did it again on the rest of the way down. Then it did the exact same thing, again for about 10 seconds, on the way home. When this had happened last week, it never stopped doing it for the rest of the trip and also was followed by idling/stalling problems, but not today. It was a momentary thing, and then the car ran perfectly.

The MAF doesn't appear to be a Bosch. At least I see nothing on it indicating that it is. It has a white sticker on it with a number (not the Bosch number you guys already gave me) and an abbreviation that appears to me to denote that it's remanufactured. I am thinking that it seems I should start there and see what putting a Bosch unit on will do.

Where is the fuel pump relay? I looked in the main box and did not see it in there.

I do not see black smoke from the exhaust. It does smell like it's running rich, though, and although I haven't actually checked the MPG it definitely seems to be getting poor mileage (I'm under 1/3 tank on the gauge right now and have only driven about 180 mostly highway miles since filling it up).

EDIT: By the way, I have also ordered a scan tool so that I can pull the codes. I'll report back when I've got them.

robisindy · Post by **robisindy** » 14 Apr 2016, 10:52

Here are the codes:

P0455 - Evaporative Emission system large leak
P0102 - Mass Air Flow Circuit Low Input

Also, in case it helps: the one consistent thing I seem to have found out about this problem is that anytime I get in the car when it's cold, if I start it and just let it sit and idle until it gets up to operating temp, it will stall. It's happened to me three times in the last week. And every time, once I start it back up after it has stalled, it will run perfectly the rest of the time I drive the car.

Revolvor352 · Post by **Revolvor352** » 15 Apr 2016, 18:30

Hello. The fuel pump relay is hidden in the fuse box up by the windshield wiper. There's (4) T25 Torx screws holding the cover on. Pop the cover off and you'll see it in there. Mine actually says Fuel pump relay on it. I was looking at the codes you posted and I get the P0102 code every time I unplug the MAF and run the car. Hope that helps. I've only had my Volvo for a few months and I have similar problems. I'm looking forward to seeing how this turns out.

Post by **theWIFES_S70** » 15 Apr 2016, 19:08

I hope that putting in a Bosch MAF fixes your issues. Please keep us posted with how this turns out. Have you gotten started on any Stage 0 stuff on the car? (e.g., Bougicord wires, Volvo plugs, new air filter, fuel filter?) Don't worry about that P0455, there's so much rubber that could be causing that. But from what I've read on here (and I've gone through all the pages...) I don't think it would contribute your idle/stall issue.

Guys, should he check out the resistance on that connector to make sure there isn't a short anywhere? If so, what should that read??

Post by **erikv11** » 15 Apr 2016, 20:25

I agree with Marco on the P0455, wait that one out.

P0102 is consistent with the very first diagnoses: vacuum leaks and/or bad MAF.

Your initial tests indicated a bad MAF, the MAF is not a Bosch; you sort of have no choice but to replace it. You could first hunt down and replace all the vacuum lines, which is not a bad idea anyway, but likely the reman MAF is no good. You can often get a good, used Bosch MAF from the junkyard or from other users here at MVS, for a lot cheaper. For diagnostic purposes that can be a very good thing.

robisindy · Post by **robisindy** » 16 Apr 2016, 13:40

Thanks, guys. I was thinking MAF, but wanted to see what everyone says. A new symptom today has made me even more convinced. This is the hottest day we've had in my area, and when I went to start my car after a brief time (engine still warm) it would not start. So I unhooked the MAF and it fired right up. Seems fairly conclusive that it's a problem, even if it's not the whole problem.

I also noticed for the first time (not sure how I missed this before) that the bottom one of the two vacuum nipples on the back of the air cleaner box has no line hooked to it. After researching on here a little bit I'm still not sure where that line goes, but my understanding is it has to do with an air box thermostat andprobably isn't really part of my problems except for perhaps contributing to my poor gas mileage. Am I getting that right?

Post by **erikv11** » 16 Apr 2016, 16:16

To figure out all of the vacuum lines: check the sticker under the hood and https://www.matthewsvolvosite.com/forums ... hp?t=65002

robisindy · Post by **robisindy** » 22 Apr 2016, 15:57

Just to update: I ordered a used Bosch MAF off of eBay. It came today and I installed it. I discovered 2 things. 1. The used one I ordered had a rubber seal on the side going into the air cleaner box, but the one I took off did not. 2. The one already on the car actually was a Bosch. Looking under the white remanufactured number sticker I could see with it on the car, I found the Bosch logo and part number.

Anyhow, I disconnected the battery during the installation and ran the car through the relearn procedure. I put about 6 miles on it, and so far so good. Idled smooth, no surging at cruising speeds, and it actually felt like it accelerated smoother and had more power than at any point since I bought the car.

Obviously with the problem having been intermittent before, I won't know for sure that it is really solved until I drive it more. Fingers crossed.

Post by **erikv11** » 22 Apr 2016, 16:39

When the MAF was reman'ed, it was probably not with Bosch electronics. Just the plastic housing was from a Bosch.

Anyway knock on wood, so far so good!

robisindy · Post by **robisindy** » 22 Apr 2016, 17:43

When the MAF was reman'ed, it was probably not with Bosch electronics. Just the plastic housing was from a Bosch.

That actually makes perfect sense, because the electronics did not look the same. That would explain it.

1998 V70 - Rough idle, hesitation, stalling

Re: 1998 V70 - Rough idle, hesitation, stalling