98 S70 - problem with MAF sensor?

martz010185 · Post by **martz010185** » 10 May 2009, 16:34

I have a 98 S70 (non-turbo) with 193,000 miles on it. I've been reading a lot on the posts here about MAF sensor failure; I've been having issues with my car that have reappeared since last summer, I posted a topic back in September, here's a link to it, and it outlines all the problems I'm having.

https://www.matthewsvolvosite.com/forums ... =1&t=16355

My car has been acting up again since it's gotten warmer; all fall and winter, I had no stalling trouble.

My question is, could I have a troubled MAF sensor? Can I try to clean it before I get a new one? I also noted some suggestions about the same trouble caused by fuel pumps and fuel pump relays. Is there any way I can diagnose the difference between the possible two?

At the same time, I want to get new spark plugs, wires, rotor and cap, and an air filter, so if it's that, I'll know after replacing them.

I can tell, though, that the problem is getting worse since last summer. Does anyone have any suggestions?

Post by **misha** » 10 May 2009, 17:35

Is your check engine light on?
If it is,read the codes and post'em here and then we'll try to help you to solve your problem.

MikesS70 · Post by **MikesS70** » 10 May 2009, 21:17

martz010185 wrote:I have a 98 S70 (non-turbo) with 193,000 miles on it. I've been reading a lot on the posts here about MAF sensor failure; I've been having issues with my car that have reappeared since last summer, I posted a topic back in September, here's a link to it, and it outlines all the problems I'm having.

https://www.matthewsvolvosite.com/forums ... =1&t=16355

My car has been acting up again since it's gotten warmer; all fall and winter, I had no stalling trouble.

My question is, could I have a troubled MAF sensor? Can I try to clean it before I get a new one? I also noted some suggestions about the same trouble caused by fuel pumps and fuel pump relays. Is there any way I can diagnose the difference between the possible two?

At the same time, I want to get new spark plugs, wires, rotor and cap, and an air filter, so if it's that, I'll know after replacing them.

I can tell, though, that the problem is getting worse since last summer. Does anyone have any suggestions?

Cleaning the MAF sensor is pretty easy. I do it as a regular maintenance item on all my vehicles. There is a special MAF spray cleaner that's marketed but I've used Wal-Mart's "Tech" brand aerosol brake cleaner successfully. I've heard of guys using plain carb cleaner with no ill effects. You'll need to carefully disconnect the electrical lead, disconnect the rubber intake duct and remove the MAF from the airbox (I believe it's held in place with two 10mm bolts). The business end will be the end that's stuck into the airbox; hold it in bright light and look into that end of the centrally mounted "bullet". You should see two very fine, very delicate wires each held between two posts; *do not* poke or touch those wires with anything other than the spray from the cleaner. Using your cleaner with the little plastic straw, barely insert the straw into the open end of the MAF and blast away being careful not to touch the fine wires with the straw. Two or three good blasts should get 'er done ....check and see when the cleaner evaporates that all is shiny inside. Let the MAF air-dry completely before you reinstall. Make sure you reconnect the electrical lead, start the engine and hopefully you've solved some of your problems.

Mike

steelfish · Post by **steelfish** » 10 May 2009, 22:47

I feel your pain. I disconected my MAF and my 98 s90 runs fine without the stalling. Probably not the best advice but try it and see what happens. Good Luck.

martz010185 · Post by **martz010185** » 10 May 2009, 23:13

Thanks for all the advice. In response to the post from misha, my check engine light has never come on through having this problem.

Another question - when cleaning the MAF, do I actually remove the sensor from the cylindrical tube body, or do I get it by putting the cleaner straw in from one of the ends of the tube? The two bolts would require a strange torx bit with a hole in the center of it.

MikesS70 · Post by **MikesS70** » 11 May 2009, 05:59

martz010185 wrote:Thanks for all the advice. In response to the post from misha, my check engine light has never come on through having this problem.

Another question - when cleaning the MAF, do I actually remove the sensor from the cylindrical tube body, or do I get it by putting the cleaner straw in from one of the ends of the tube? The two bolts would require a strange torx bit with a hole in the center of it.

Okay ...I assumed your '98 S70 MAF was the same as the one in my '99 S70. I Googled a picture of the '98 MAF ....shoulda done that first ...I get the idea that you cannot see the small wires by looking into the MAF. The Torx bits are special "security" bits (I found a set at a local Northern Tool store) but you need not remove the "core" to clean it. From the inflow side shoot the cleaner into the opening on that side of the sensor core ...then do the same thing on the outflow side ...essentially you want to flood the inside of the sensor core with cleaner and give it a good shake after you squirt the cleaner into it.

BTW, the sensor core on the '98 MAF (unlike the one on the '99 which is one peice) can be removed and replaced seperately providing you have the security Torx bits ...they sell "rebuilt" sensors which do not include the tubular housing and these are much less expensive than the 180 or so bucks for a complete new one.

Mike

Post by **wheelsup** » 11 May 2009, 06:58

I used a pair of small vice grips to remove those screws. Mine were weird, I actually just thru out the unit so I can't take a picture but it wasn't the security torx, it was something that couldn't be undone once it was screwed it.

Post by **misha** » 11 May 2009, 16:42

martz010185 wrote:....In response to the post from misha, my check engine light has never come on through having this problem..

That's very strange!

Is bulb of your check engine light ok?Maybe it's burned off.Does it appear when you turn key to ignition II?
It's been almost a year when your car started to have issues.
Try to read codes anyway,i bet that there are some codes stored.

martz010185 · Post by **martz010185** » 15 May 2009, 15:34

Update: last night, I did a tune up and replaced spark plugs, wires, cap and rotor, and filters. I also replaced the MAF sensor with a new one. So far, I haven't had any stalling (even though it's pretty warm out right now), but now my check engine light HAS come on. So I'll have to have the codes read.