I have a 1997 S90 with 200k miles; replaced the MAF sensor two years ago.

Recently, I am finding that the MIL lit every morning; the scanner says it's P0102. While cold, with the MIL lit, the engine stumbles; it will eventually stall if I don't do anything special (like rev the engine).

If I clear the code immediately after seeing the MIL, the engine runs fine, and I won't see the MIL until another long cold soak. BTW, several hours of cold soak at 45 F is not enough; seems like it has to be overnight at that temperature before I get the MIL the following morning.

I did clean the sensor and the connections with MAF sensor cleaner, replaced the air filter, and searched for intake air leaks (none found).

The only other thing that might be related is that I was getting P0410 codes (secondary air) about once a month or so, right before the MAF problem. I had replaced the air pump relay last year because of the P0410 code, and subsequently had no problems for about 10 months.

Any ideas?

 

Secondary Air system and MAF aren't really related. Actually they are, but very remotely.

I am assuming you are cleaning the MAF correctly. If cleaning MAF doesn't do anything, a new sensor must be installed. No way around it.

But before you do that, I would either make sure that thermostat for the preheat hose is working properly, or shut the flap closed. If stuck open, this malfunction would fry the new MAF in short order.

 

Thanks for your note.

I replaced the MAF sensor and all is well.

Two questions:

1) If the pre-heat flap is stuck open, should I see a code?
2) Is there a way to disconnect the secondary air system?

Thanks again.

 

No. It's not part of the electrical system. The easiest and free method is to close its flap shut; before it fries the new MAF.


Why do you want to disconnect it? Do you know its benefit / cost? Does your car have emissions testing in your State?

 

- Can you describe how to close the flap, or recommend a reference for me to read? Actually, a picture would be best.

- I asked about disconnecting secondary air due to the error codes that I occasionally get. Replacing the relay fixed the problem for about a year, now I'm getting the code again. I had a little leak in the coolant expansion tank which could have dripped down on the air pump...any chance that is part of the problem?

As far as the benefit (if I remember correctly):Tailpipe HC, CO, and aldehyde levels can be decreased when air is introduced into the exhaust gas. I believe that oxygen in the air promotes oxidation in the exhaust gas. BTW, My state does not have emissions testing.

Appreciate the feedback; thanks.

 

PAIR (Pulsed Air Injection = SAS or Secondary Air System): is a very simple, yet very beneficial system. Fixing it is cheap, parts are cheap. DIY time to fix it is also minimal. I would not recommend you getting rid of it. It does extend Catalytic Converter's life and provides better MPG, because it helps the Cat warm up faster, which means open-loop is shorter, which means less fuel used.

You can read a brief description here

Parts Diagram here

Several people have eliminated the SAS (search google with "Volvo SAS delete" keywords), results have been mixed. I find that deleting the SAS is actually more work than fixing it.

The most problematic part is the SAS Valve. This is a normally-closed, vacuum-operated air Valve. SAS Solenoid (which you replaced) is the one to control the Valve. When ECU wants to open the Valve, it grounds the Solenoid, which opens the vacuum passage in the solenoid and, via the purple vacuum hose, Valve is sucked open. In about 10-80 seconds depending on conditions (see above link), ECU shuts down the system and keeps it off until next start-up.

This Valve undergoes the most extreme temperature swings. Exhaust soot gets baked inside the valve, and with time it gets stuck partially-closed, when it is supposed to be fully-closed. I think that's your problem. Take it out, spray some Carburetor Cleaner and loosen it. Every Oil Change spray some WD40 thru thru the vacuum hole.

Pump: take it out. Apply 12V. If pump works, drill a 1/32 or 3/64 hole at the bottom plastic housing. This is to drain any water if accumulated (see link above). If you need new pump you can buy another pump for about $ 45.

Thermostat on pre-heat hose: I don't have any diagrams handy. You can go thru the Volvo Parts Webstore (linked above).

You need to take the airbox out and you will see the thermostat. Mine was rusted thru, and if I tried to replace it might have damaged the airbox. So I (like many others) decided the shut the flap closed, by drilling a screw thru the plastic housing of the airbox and stuffing something there. A new thermostat is about $ 11 at FCP Euro. If I was using my car daily in cold climate, since the pre-heat hose is a good thing, it would have been worth it for me to fix the thermostat.

 

Secondary Air System codes can be triggered if the vacuum signal isn't getting to the valve. Double check the right-angle rubber connectors at the valve and at the vacuum switch at the other end of the vacuum line. If they are crumbling your fix might be quick and cheap.

 

If my 97 wagon gets hit will the motor shut off on me or will the engine keep running so I can get off the road ????? Plz help I just bought the car and don't know much about it