Pfc. Parts

Hi Ken -This is a great write up, I have a field report to go with it.

There may be '85 928's out there with a MAF sensor inaccessible from the top of the engine. Mine was oriented with the adjustment (3mm hex) screw and multi-pin connector running left to right (passenger to driver) on the firewall side of the MAF, making it impossible to orient a tool to connect with it with the intake manifold and air box installed.

I removed the IM and AB, loosened the hose clamps on the MAV, rotated it 180 degrees clockwise and was able to re-assemble the intake in a way that let me control the 3mm adjustment screw with the engine running.

I'll send pictures later, the batteries in my camera are re-charging.

Thanks for the tips on the adjustment tool and the "blinker"! I discovered that the tool can be made using standard 10 AWG butt connectors and a Crimpmaster ratcheting crimp tool. Very nice

Regards,
Scott

PorKen

Good job!

I found there is an alignment nub to line up the MAF, see (post #40).

Also, make sure that Durchflow => on the MAF lid is pointed towards the throttle body.

I've seen them installed upside down, which makes it run a bit weird.

Pfc. Parts

Ken, thanks for the tip on the Durchflos arrow, I'd put an arrow marked "Up" on mine with a marker so now I have one pointing each way I didn't even see the arrow molded into the sensor until you mentioned it.

As it turns out the procedure never worked for me. Finally I got so frustrated I pulled the MAF out of my parts car (which starts and runs just fine) with the idea I'd swap it in. When I pulled it I found a part that wasn't on my driver; an O ring sealing the MAF to the throttle boddy. Thinking quickly, I decided the missing O ring might be the cause of my vacuum leak so I stole it off the old MAF, put it on the one in my driver after lubing it up with ChristoLube and re-installed the MAF.

Lo and behold, the cold start problem was gone. Idle was perfect. Life was good https://rennlist.com/forums/images/smilies/beerchug.gif

This is all to say that while my adventure in MAF tuning wasn't all that successful, the journey was. Of course, I'm now very worried about where the old O ring went. I have visions of it slowly deteriorating somewhere in the intake and eventually getting sucked into a valve...

Thanks again for your writeup. I had fun making the tools too.

Regards,
Scott.

ReefShark

So what was the address of that chevy conversion again?

SMTCapeCod

^^ Haha. Or go V-12 in Tx..

Guess I should give up on waiting for a batch-run of Blinkr's, have to get going locating the assembly thread and putting one together for myself. Big difference, it seems, between the recommended baseline resistance and the final adjustment reflected above.

Otto Mechanic

The only assembly thread I know of is this one, I think everything you need is in posts 1 through 5 or so? You can get the VW relay from most parts stores, the only trouble I had was taking the relay apart without cracking the case. It worked great for me. There was a manual for it on Ken's site but if it's not there anymore let me know, I have and old copy that talks about the commercial version (has two lights) but the procedure still works fine, you just have so sort of squint at the manual.

SMTCapeCod

Loirqad ^^ See post #4? ^^

And, thanks Otto. #40 had what I needed, after all.
Though the internal connetions aren't crystal clear for me yet-- I'll try squinting! Likely followed by multiple choice/trial and error..
;-)

And wth is a banana plug?

Otto Mechanic

So you found the link to the manual and post #40 shows how to make the tool. Ken used to sell them pre-made, don't know if he still does but you need a Crimpmaster swaging tool, the hex bit, a short piece of aircraft cable, a T handle hex tool and a Dremel with a cut off wheel (or equivalent) to make it yourself. The most expensive tool is the Crimpmaster (find one on Amazon). The one Ken sells already made up is cheaper than the Crimpmaster by itself so if he's got any more of them I'd buy one.

Also, see the post by Pfc. Parts on getting at the adjustment screw, you may have to remove your intakes and fiddle with the MAF orientation a bit then re-assemble the intake before you can use the tool on a running engine.

A banana plug? Where do you need one? I used an alligator clip? Anyway, a banana plug is a push in electrical connector, you can find them at radio shack.

Otto Mechanic

Oh, and BTW, I ended up setting my MAF to 380 (baseline) and the Blink'r lit up on my first attempt so it probably depends a lot on the age of your O2 sensor and MAF. I'd just put in a new O2 sensor and cleaned my MAF, which only had 65K miles on it so that's probably why setting it to factory spec was all I needed.

My problems where elsewhere...

Otto Mechanic

One more note: before you drop a large chunk of change on a new O2 sensor, check the 944 forum for the Bosch equivalent universal part, which is a 15725 or 15735 I believe (same sensor as the 944). Instead of $180, Amazon sells them for about $45. Big savings

928NOOBIE

Hey SMT..one thing I found is that I started with the correct setting per Ken's instructions and actually found I could get better power by adding more fuel (O2 sensor will show as running rich)...I kept adding more fuel till performance started falling off then went +/- in smaller increments until she was as aggressively fueled as I could make her. I found that as I make adjustments and drive it I need to give it about 15 - 25 minutes of driving before the full effect of a change in fueling is felt...I can feel it when it "takes"...I guess..if that makes sense....but it isn't immediate..it needs a little time to work the change through everywhere...

Driving it aggressively now uses a ton of fuel...but shifting into 3rd at 6,500 with ken's chips is a thing of beauty as you glance down and see the speedo cruise past 90 like it was 40....

And I've finally given up on the silicone intake boots..you're right..they're impossible....got a full set of correct rubber ones on order with the guys at 928 Int'l...thank goodness I at least thought ahead to save the old clamps..

Let me know if you have questions on fueling....I have tinkered with it endlessly to push as much fuel through it as I can....it just keeps going faster!

One thing I did also...I replaced the air box temp. sensor with a faster acting unit per suggestion from a rennlister..Bosch part number 0 280 130 085 it was one of the biggest positive impacts to performance I made to the car...it woke it up big time Ken's chips love it. You will need to do a little drilling to the air box..it's a little wide..I used flexible silicone to keep it in there.

I am still running original injectors..had them rebuilt and flow-matched by Witch Hunters. There are no cats on the car and no emissions testing in my state...your results may vary
Some assembly required. Batteries not included.

SMTCapeCod

OK, so being electrically illiterate...I've squinted at the diagram, even looked up some electric symbology- are the switch and led wire in series? I'm not following that part....

I'm surprised you are getting more power/performance adding fuel. Very often best output comes from being a little lean...but it comes at huge potential consequences. IT's odd that it takes some time to have full effect, the LH is supposed to be non-learning and if you're trouncing on it the effect of the O2 sensor and the fuel trims should be moot. Maybe it is moving the baseline setting and that is reflected in WOT curve?

For the boots- I had a bad experience with stock-- though I don't recall whether OE or URO in that a full new set started to fail after about six months.
I just ended up getting an order of flourosilicone lined Samco hoses. Trimmed to fit. I was a little too generous on the small boots, at about 49mm there is some interference with the 90' on the air cleaner lid. The "T" boots are a nice improvement thought.
I was interested in the thread on the air temp sensor, but not fond of the install solution. Have to put my thinking cap on, I do like the results you report- do you know for sure that the one that was replaced was good and that the change was due to the different specs, rather than due to replacing a failed sensor with a good one??

PorKen

It's a resistor and a LED, is all. You also need a separate wire or switch to bridge B and C.

If you have add a bunch of fuel to make it perform better your WOT switch may not be working. Most original ones are filled with oil.

John Speake

The alternative air temp sensor was recommended by me, I have compared the specifications and they are identical.

SMTCapeCod

Thanks, John!

NOW I get it-- thanks Ken, clarification that the switch is separate to manage the B/C bridging is what I didn't get at first, I was mulling over how the switch in series with the LED was accomplishing the testing procedure. Now I get it. Simple. I fear how I'll do in my fifth decade when I get there!

Otto, I know with the S300 chips the recommendation is to go with the factory O2 rather than universal. I don't recall the thread on that, whether it is variability introduced from the universal terminals, or with the calibration of the sensors or what. Good tip if the factory 944 is the same as 928, there are a few things that are the same Bosch numbers but cheaper for the 944.