Hey all, I recently took the 86 240 wagon to the local Volvo mechanic and was advised that my MAS and throttle sensor were in poor (read not) working order and need to be replaced. While they were asking a pretty penny to do the job, I figured that is easy enough to swap my self. My question pertains to the MAS brand, as I am trying to stay away from the Bosch due to the high cost. Are there any aftermarket brands you would suggest for a MAS that might save me some money and that you have had an alright experience with? Also, where the hell is the throttle sensor, as my research to date has yielded no results. Thank you all for the feedback and help as I get big blue back on the road.

- Joe

 

Hard to say with aftermarket electronics... How about a rebuilt? How about a used one on ebay? I have had good luck with used MAFSs.

I bet you need ONE of the two, either aMAFS or a TPS, and you are getting the usual mechanics spiel! What are the chances of both being bad?

I'd replace one, see what happens. What are your symptoms?

The TPS is on the side of the throttle body, by the intake manifold. Easy to change but it takes a minor adjustment.

 

Thanks Lev, Ill check into the Ebay route. Symptoms are stuttering/stalling while accelerating. If the car is parked or in reverse, the stuttering won't occur when i apply the throttle, the car also idles fine. Only when it is in drive and usually only accelerating from a dead stop, the car stutters and will occasionally die. She starts right back up ... I'm leaning towards MAFS as the issue... but if you have any other ideas I'm all ears.

Thanks again!

 

Not sure about that diagnosis-- your symptoms don't point to TPS and MAFS problems. I hope your mechanic did some testing/swapping to arrive at what he told you. TPS? Definitely not! The MAFS? May be, but not typical. Did they swap in a working MAFS to see if it made any difference? Should do that before expecting you to fork over or a new one! A lot of things can produce what you are experiencing.

 

New problem developed and the Bently manual has not been helpful for this one either. While I was tooling today I noticed a loose hose attached to the air hose running from the MAFS to the throttle body. There are two, one running up and to the left (attached) and another running out of the right side (not attached). I'm not sure if it has been loose or if I knocked it loose but I couldn't find where it should be reattached to and what it does. I'm sure this isn't helping my cause, as now I have unmetered air past the MAFS. Any clarification would be great! in the picture ripped from Google below, the hose attached to the top left opening (how much more confusing can I make this?)

Mechanic said the Mafs was tested, not sure how he did it but I took it to him because he is an older volvo specialist, been working on only volvos since the 70s so I'm kinda praying he is right. I had him replace a wiring harness, but when he told me about the other stuff he wanted to do I figured I could do it myself.

I ordered a new mafs on eBay, should get it this week and will go from there I suppose, cross another thing off the list if that dosnt do the trick...

 

MAFs easy to change, whatever you do though DO NOT unplug/plug your MAF with the key in, it'll either fry it or your ECU.

Good luck with your ebay MAF though, I tried ebay once and I got a MAF that didn't quite match the original other than the plug.

 

rebuilds are all over the place quality wise. many cheap ones will die in a couple months. best bet probably is taking the advice of a reliable older-volvo-only mechanic as he'll know what works from the experience of having done lots of them. the new Volvo ones are made in china :-/

 

Thank you for the heads up on the key trick, and yeah I figured eBay would be hit or miss. Apparently the one I ordered has a year warranty so worse comes to work she will be sent back.

Any help with the two hoses running from the air intake hose just before the throttle body? Where the heck is the one closest to the firewall supposed to be running?

 

But really, can anyone help clear up my unplugged hose issue? Still in the dark.

 

btw, the 'throttle position sensor' on a 240 LH 2.x car is just a idle switch, and maybe a full throttle switch. the idle switch can easily be tested with an ohm meter, it should be 0 ohms with the throttle at idle, and open circult at anywhere other than idle.

re hoses to the MAF, I don't think there are ANY vacuum lines connecting to the MAF, just the intake hose from the airbox, and the intake hose between the MAF and throttle body. Of course, there's an electrical connection to it.

Primary vacuum hoses include brake booster, chrysler ignition controller, heating/air controller (in dash), and the charcoal cannister (under the airbox). I'm probably forgetting a couple. oh, cruise control, if you have it.

 

oh, that fitting near the throttle body, I believe thats for the crankcase ventilation aka flame trap.

 

The hose that attaches to the upper-left nipple shown in your image is supposed to be connected to the flame trap - which should be located between the 3rd & 4th intake manifold runners. Indeed, if this hose is missing, there is unmetered air entering the throttle body that could lead to drivability issues. I would make sure that your accordion intake hose is leak-free first, then adjust the throttle position sensor as per the Bentley manual before springing any money for the new MAF. For the flame trap hose, IPD sells a relocation kit for your model. Check it out here:

Volvo Flame Trap Relocation Kit - LH 106506 9658K

 

I needed a new MAF and found a new Python on craigslist for $50. Been running amazingly well for about 6 months now without issue on my 90 240. MPG jumped up by 20% as well. Recommend taking a look at Python brand.

http://www.amazon.com/Python-Injecti.../dp/B000CK2D76

 

Or send your old MAFS to Python, they will rebuild it for you, send it back to you.

 

Update: replaced the MAFS and still having the issues. Still stutters when the accelerator is pressed while the car is in drive. It idles fine and in reverse there is no issue. Just in drive. Could the TPS be the issue? Any other recommendations? It's such a strange issue and it's driving me crazy!

In regards to the flame trap, I believe that's the one. I tried to take a picture, as it looks like I need a clamp and a longer hose than what I currently have. Will look into the ipd relocation kit suggested.

Thank you all so much for the help/support. Look forward to hearing some ideas.

 

the TPS is just an on/off switch on idle, and maybe another one on full throttle.

the idle switch is sensed and used to enable the idle control loop, while the full throttle switch is used for full throttle enrichment.


both are very easy to test with a ohm meter. the idle switch should be closed with the throttle at idle, and open as soon as you give it any gas.

 

Thanks Pierce, I'll look into grabbing an OHM meter next time I'm out so see if I can test it out. Any other ideas on what the issue may be? It may seem dumb but could some bad motor mounts cause the issue? The engine seems to shake/twist quite a bit when throttle is applied....