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I've been searching for a solution to an issue which I believe is the AFM acting up due to wear... I have a 1990 S2 done approx 250K km and basically at approx 2000rpm at soft throttle I get the bunny-hop. From what I have read it is most likely caused by AFM wear, so I removed it today. Only thing I can go on is a YT video I found and an old post from Clarke's garage page. The YT video was of a 944 AFM but only had two contacts, & I can't see the photos on other Web pages. Since mine has three contacts I was unsure it is a 944 part but the part no. matches.
Also wondering if I should clean the resistor strip with an eraser & contracts with sand paper as Clarke's suggests or just clean it with alcohol or similar. Clarke's also suggests bending the back part of the wiper arm but I can't see exactly where it means.
I've been searching for a solution to an issue which I believe is the AFM acting up due to wear... I have a 1990 S2 done approx 250K km and basically at approx 2000rpm at soft throttle I get the bunny-hop. From what I have read it is most likely caused by AFM wear, so I removed it today. Only thing I can go on is a YT video I found and an old post from Clarke's garage page. The YT video was of a 944 AFM but only had two contacts, & I can't see the photos on other Web pages. Since mine has three contacts I was unsure it is a 944 part but the part no. matches.
Also wondering if I should clean the resistor strip with an eraser & contracts with sand paper as Clarke's suggests or just clean it with alcohol or similar. Clarke's also suggests bending the back part of the wiper arm but I can't see exactly where it means.
And finally is standard silicone OK to reseal?
Thanks heaps in advance
Go to Bavarian Restoration website. Jeff? repairs Bosch/Porsche AFM's, you send it to Bavarian Restoration on the first of the month and returned in the 30th of the month. The repair cost for a 944 8V non turbo is $215.
I wouldn't use sandpaper. Way too aggressive. Use nothing more than a piece of cardboard wetted with isopropyl.
I don't like the idea of bending the arms either. Terrible practice. You'll never get the pressure against the board right. I like removing the board, enlarging the mounting holes, and then repositioning the board slightly to start new tracks. Just be careful not to bend the arm removing the board!
and here is a photo from after I had a go at the AFM...
I loosened off the wiper shaft and moved it up ever so slightly... then gently bent the arm down until I could see and fee that the three contact points were good. You may be able to see the difference, where the arm is now approx .5mm smaller arc. I had to be careful as the lower contact point was already very close to the edge.
I also cleaned with an electrical contact cleaner using paper under the arm contacts and cotton swabs on the track... and cleaned the wiper shaft top contact point and the external plug. then made sure there was no dust or particles in the AFM using a soft air blower (from my camera bag) and all was dry.
Result is about 10 times better... the only slight bunny-hop I get is coming on and off the throttle, at any speed/gear if I'm not too steady... but ever so slight... nothing at 2000rpm anymore. Also the throttle response is much sharper and more responsive at lower rpm (where the AFM track was most worn).
So want to give a big thanks for the info and now the car is even better to drive!
Bunny hop? If by that you mean the car kind of lurches when creeping along in traffic, yeah I'd definitely look at the afm too.
However, for me, that lurching was eliminated when I changed the O2 sensor. I did not expect that, but I suppose the dme might just work better closed-loop in that sort of driving.
Bunny hop? If by that you mean the car kind of lurches when creeping along in traffic, yeah I'd definitely look at the afm too.
However, for me, that lurching was eliminated when I changed the O2 sensor. I did not expect that, but I suppose the dme might just work better closed-loop in that sort of driving.
Now after I adjusted the AFM, it only does a slight bunny-hop when I come off the throttle... it does not happen when I am on the throttle or accelerating/decelerating (engine braking and/or brakes).
Bunny hop? If by that you mean the car kind of lurches when creeping along in traffic, yeah I'd definitely look at the afm too.
However, for me, that lurching was eliminated when I changed the O2 sensor. I did not expect that, but I suppose the dme might just work better closed-loop in that sort of driving.
I have now replaced the O2 sensor, and the vehicle has less 'bunny-hop' or lurching, but it still occurs?... mainly @ 2000rpm or less, with the throttle just being feathered. Higher speeds is less evident, obviously due to the vehicle's momentum. Once I apply more throttle, or take foot off completely, it goes away.
try something...
in the moment when you're going to let off the throttle and would normally experience your bunny-hop, instead hit the clutch pedal right before letting off the throttle.
try something...
in the moment when you're going to let off the throttle and would normally experience your bunny-hop, instead hit the clutch pedal right before letting off the throttle.
does it still "hop"?
I'll give it a go... but generally if I lift off the throttle completely (where engine braking takes over), there is no hop... it is only when I am on that borderline of touching the throttle but not hard down, if that makes sense. I have read that it could be the ICM?...
06-26-2018, 06:26 PM
Another AFM thread
