Speed & Reference Sensor Removal

[onZedge]

The last time I had the intake manifold off, the male connectors on both sensors crumbled and remaining pieces had to be picked out of the female harness connectors.

I did have new 3-pin connector kits on my parts shelf, but installing them on the teeny wires with shields did not give me a warm fuzzy feeling (the sensor cables are not long enough to properly cut back to very clean wire). These also appeared to be the original 34 year-old sensors.

Fast forward about 6 months to now - have minor starting (longer cranking time), and now, minor running problems (momentary ignition cut-out), so replacing the Reference and Speed Sensors seems a prudent place to start before trouble shooting further, if required.

I've read a lot of posts citing the difficulty in removing the sensors, so I will share my experience as part of getting my S&R Sensor merit badge.

Looking from above and below, I decided to follow the Standard Porsche Rule of removing two things to get to the thing you need to work on. Intake Manifold and Air-Oil Separator in this case.

With those out of the way, I had much better access. Not ideal, but cuss-free access, if you know what I mean.

Using a wobble extension, I was able to remove both of the special bolts without much fuss. By twisting the forward "BG" reference sensor, it came out with no problems (the o-ring was gone). The rear "DG" speed sensor came out about half way and stuck. There wasn't enough room to try the "long" vice-grip trick without removing more stuff (heater control valve), so I squirted on some Aero-Kroil. After soaking for like 2 minutes it pulled right out with one finger!

I did not touch the pivot or pivot lock bolts. New and old sensors are exactly the same length, however I will check the gap by using various thickness washers glued on on the old sensors to verify. I also noticed that my bracket does not have the metal sleeve that is supposed to shield starter motor electromagnetic interference.

Just checking and reassembly left, but I'm done for the day:

[944 Ecology]

Do yourself a favor and remove the bracket, then use some emery paper to open up the bores a bit to give the next person to work on them an easier time.

In order to adjust the height, glue a piece of .8 mm cardboard to the end of the sensor, install until it touches the starter ring gear, lock the bracket and you're done.

[onZedge]

Replaced with the "longer" cable version of the Bosch speed & reference sensors. The FSM says you don't have to re-gap if you are just replacing the sensors, but I did check using two alternate methods:
1) A S&R sensor gap checking tool that came with my Arnworx Maxi Kit (older version).
2) Glued a 1 mm washer to one of the old sensors and measured the under-head gap with a 0.2 mm feeler gauge.
Both "indirect" methods showed I had a 0.8 mm gap.

Also replaced a suspect Oil Pressure Sensor.

My car now starts immediately, instead 3-4 rotations, and I don't appear to be having any more hot restart issues.

My oil pressure is back normal readings: 5 bar cold and 2-4 bar hot depending on RPM.

[onZedge]

Well, that didn't last long. Hot restart issue is back; and now cold start, idle and stalling issues as well.
Pulled the DME connector and tested the entire cable for continuity and shorted loop resistance. Everything OK there.
No vacuum leaks because all hoses replaced 6 months ago with a new AO$ (but inspected closely anyway).
Tested each component required to make the car go (and DME happy) one at a time to see exactly what was causing the issue:
- Bypassed the MSD 6A. No improvement.
- Fuel pump was replaced 6 months ago, and tested fine (pressure & flow), so no surprise there.
- FPR / Injector (all replaced 6 months ago) leak-down tests were within limits, so OK.
- S&R Sensors were just replaced a month ago, and tested fine, so no surprise there.
- Blaster II Coil tested fine.
- TPS adjusted correctly and tested fine.
- Cap & rotor were replaced 6 months ago, so they both looked almost new and rotor was not loose, so no surprise there.
- DME Temp Sensor was replaced 6 months ago, and tested fine, so no surprise there.
- ICV was toast. Replaced it. No joy - starting/stalling issues remain, but idle was much better.

And now we get to the air flow sensor, which is the MAF type that came with the NA Tune kit. There really isn't an easy way to bench test and all the (2005 Mustang) MAF sensor troubleshooting guides and videos require a running car and backprobing the connector for proper testing. I skipped all that and just installed a brand new shelf spare Delphi AF10140 MAF sensor and AHA! this cured the hot cold starting and stalling issues, BUT still idles a little rough.

This morning I swapped the NA Tune daughter board out of the (factory original) DME, in into a brand new Focus 9 Technology 944/951 Sport DME and installed it.

Installing a new DME should not have made THAT much of a difference, but it did.

First time in my 17 years of ownership that the tach and "economy gauge" needles held rock steady at idle. Idle is smooth. Throttle response instantaneous.

Thank-You Joe B for a fantastic "new & improved" aftermarket DME product!! ...just kicking myself now for not getting the OBD option at the same time...

[Rasta Monsta]

Solid state DME is a solid source of a peaceful state of mind.

Combine with SS relay....great products.

[onZedge]

Yes, I have had a F9T SS DME Relay with pump-prime installed since 2/2016, and I only checked to make sure the relay socket contacts weren't being pushed out the back of the socket with the relay plugged-in. This does happen, and is even mentioned in the Service Manual. The pump-prime feature is more useful than I ever thought it would be (purging the air out of the fuel rail after injector or FPR servicing, for example).