A good day to dangle under the car with stuff falling in one's eyes. I'm changing the front O2 sensor on our GLT. For the life of me, I have not been able to figure out how to open the connector on the bell housing. One small side of the upper portion of the plug slid out, but the other side did not and snapped off. Still no movement. What's the trick? That is, aside from just getting to the thing--that was a trick in itself.

Thanks,
DS

Just a further update for those following. About a week ago I ordered all my under-intake sundries from Volvo and they arrived a couple of days ago. Then of course one needs a maintenance appointment (!). With the car under the sun shade this AM I started dis-assembly. Simply could not believe it. I checked this a couple of months ago. Not one but two missing vacuum caps on the thermo switch under the throttle cover.

This brought up an interesting discovery. I snag the big packages of vacuum caps and plugs on the HELP shelf at the auto parts whenever there is one to be snagged (not often). In digging through my collection, I find that the most common sizes are either just a little too small for these connections and have to be forced on a bit, or just a little too large, and don't really grab. I know I've replaced these before. Found one broken early in this whole mileage debacle. I would not have used the loose caps, I don't think. I'm starting to think the tighter ones are cracking, possibly causing a leak and then falling off, definitely causing a leak, at temp. I replaced both caps, checked the rest and we are going to run another mileage test. One missing cap was at the bottom of the switch, the other at the top, so I was getting vacuum at a range of temps. I was able to find two caps on an intake I have sitting in stock that are the correct size.

DS

it's a weird connector.

The one side slides out, but it's only one side that slides. The other side stays put.

The hard part for a 'first timer' is that in order to get the plug to disengage you have to pull the slide a bit more and pull on the plug a bit at the same time. The last little bit of movement kind of ejects the pins from the O2-side of the connector and pushes it out of the 'car-side' of the connector. It's a bit hard to explain. I looked for a diagram or something but didn't come up with anything.

This will be much easier next time if you really grease the plastic connector up with silicone grease before you put it back together.
--
1998 V70 AWD->FWD->AWD Turbo 215k+

I did finish up yesterday and you are absolutely right. The connector slid out about halfway, then jammed. A shot of foaming silicon and lots of wiggling and pulling finally got things moving again. I had the same problem getting the plug back together. Especially with the very limited access, I think the engineers do us a serious disservice when they create things like this. But it's done. I will post back with mileage improvement information!
DS

Said I'd post back with mileage results, and here I am! First, serious difficulty getting data from a car with multiple drivers.

Initial tests were questionable, but eventually I did get a couple of tanks where mileage was "up" to around 17. Still very disappointing, but a big improvement over 13.

I did another once over on the various vacuum elbows and hoses. Changed several things. The next trip was one I made in the car, almost strictly highway. Mileage came in at 23+. Good, but still not where I think it should be, and compared to the 17 for city, comparable.

Next two tanks were down around 17-ish again. Just from general use, we still feel we are using more than we were six months ago, and if the readings are any indication, that's probably right.

This car is running a replaced AMM. Our original failed a couple of years ago. New, clean air filter. Plugs, wires, cap and rotor all changed less than 30k ago. New front o2 sensor. ECU was chipped by SpeedTuning over two years ago. Skip 'n dip fault has never been fixed, but rarely shows up, and the car runs and drives very well--just this niggling mileage thing. I'm thinking of sending the ECU to Rob Arnold to see if he has any suggestions. Maybe something is wrong there.

Any tips will be appreciated. No codes showing. I'm going to do an air test on the evap system and see if I can locate any leaks.

DS

Modifying the computer could be a slight problem, but usually less than 2mpg from fleet average. You should be getting around 28mpg highway with factory tune, 20-22mpg around town.

The Evap system will have very little to do with MPG. You need to check the vacuum lines that go to the intake manifold, turbo, and fuel pressure regulator (on the subframe behind the engine - 2 lines). Any unmetered air will mess up your MPG. Don't forget the invisible elbow below the #1 cylinder.

Klaus
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1967 220 belonging to C.A. lives on

Hi Klaus. I agree about the ECU, especially since the car seems to be running no differently and any error would probably show up in some fault. Rob says he has the software to fix the skip 'n dip though, as well as improve mileage, so a good opportunity to possibly make some other tweaks and who knows what he'll find. The SND was supposed to be fixed first time around. When I told the proprietor it hadn't been, his reply was "Oh, it wasn't?"

I want to pressurize the fuel and vacuum systems. Nothing I've checked that was visible has shown any failed lines. The elbows and hoses I changed were more because I thought they could be a problem soon, rather than because they are one now. I'm betting that my problem lies under the intake. I've heard about that "invisible" connector, and I'm wondering about the whole "pcv" system. Ugh!

Dave

To check that vacuum line under #1 cyl, with a cold engine, feel for it with your fingers so you know where it is. A small portion should be visible close to the PS pump. One of those pressure clamps is holding it to the manifold.

Start the engine, and then feel again for leaks. When I replaced my oil separator lines about 3 years ago, the connections looked good. When I replaced the line going to the PTC nipple, the internal vacuum line 'cracked' probably due to age.

The entire proicedure to replace the oil separator and lines should take about 5 hours, note that all work is done from above except looking for dropped nuts. It was suggested that the front of the car be up on ramps to save bending over so much!! I also used an OEM manifold gasket, the one from FCP was a piece of garbage.

Klaus
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1967 220 belonging to C.A. lives on

I've heard nightmare stories about the procedure being far too complex, but I'm prepared. Work like this is always worse with my blasted, sloped driveway. No matter what I put in the way, things always wind up rolling just a little too quickly to catch them...into the street. I'll bet I find something cracked or broken once I'm under the intake.

Thanks Klaus, I always appreciate your input on the FWD stuff. Being mired as I am, mostly, in RWD mud.

Dave

The only things under the intake manifold runners are the oil separator, knock sensors and the starter. Just don't be like me and leave the battery connected, I lost a 10mm ratchet extension and it fell in the starter connections!!! Boy, did I feel like a dummy!

Klaus
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1967 220 belonging to C.A. lives on

I like Klaus' suggestion on using genuine Volvo parts when you are in places you don't want to go again soon. Volvo parts fit and give long good service. I am speaking mostly about engine parts that are hard to get to.


dick