Unichip and HFM installed and tuned, dyno results.

[Chris E30 Cab]

Congrats Jordan, and glad you got the MAF/Unichip sorted. Proper tuning pays big ;)

[andrem5]

Air temp sensor

Very interested in your results.

From the photos of your project it looks like you added the OE temp sensor (from inside the AFM) to the harness for the MAF. Did you salvage this sensor from an AFM or buy it new somewhere? If the latter, may I ask for the P/N and source?

Where did you mount the temp sensor? In the elbow?

Many thanks.

Mike A

[Jordan]

The temp sensor was salvaged from a dead AFM. I do not think you can buy it seperately.

I drilled a 1/2in hole in the intake pipe (before the HFM) and mounted the temp sensor there with a tight fitting gromet.

[andrem5]

Thanks for the very speedy reply, Jordan.

I have 3 working AFM's (M20 and M30) but it seems a shame to waste one. I guess I could shop for a dead one or even get one free somewhere.

Nonetheless I am going to continue contacting some service centers I located and see what I can find.

Mike A

[rwh11385]

If someone uploads a picture, I have one M20 AFM I pulled the electronic board out of, and another I am about to, so I might be able to help you out.

[Jordan]

If the board is out you can't miss the sensor. It goes down through the "floor" where the board mounts, and into the AFM tunnel. Its at the very front of the AFM inlet sticking in the air path.

It is held in with 2 rivits, just drill them out and gentley pry it out with a small flathead.

[andrem5]

If someone uploads a picture, I have one M20 AFM I pulled the electronic board out of, and another I am about to, so I might be able to help you out.

We can use two air temp sensors if you don't mind removing them. Let me know what you would want for them. One will be used with a Split Second the other with SMT-6.

As I understand it, these rarely if ever fail on the Bosch unit so they are likely to be just fine. There are differences in ohms/deg calibration for different models AFMs but it should not be an issue for M20's or even M30's.

Thanks!

Mike A

[rwh11385]

This is off be-boarded M20 AFM #1. The 2nd just arrived this week and I haven't cracked it open yet.

I actually would desire your M30 AFM if you could part with it. Whats the PN btw? I could send you the two temp sensors + $ for the M30 AFM.

Let's reply from now on in PMs to not further hijack Jordan's thread. Thanks for your help J.

[diegom6]

The temp sensor was salvaged from a dead AFM. I do not think you can buy it seperately.

I drilled a 1/2in hole in the intake pipe (before the HFM) and mounted the temp sensor there with a tight fitting gromet.

Isn't the MAF has itself hte temp sensor, I mean doesn't calc the temp air by the flow of mass? I tought read that somewhere so no needed to install a air sensor temp

[Jordan]

I don't have a MAF, I have a HFM.

And while it does somewhat resemble the function of a temp sensor it isn't usable as one.

The factory temp sensor and wiring must remain intact.

[diegom6]

I don't have a MAF, I have a HFM.

And while it does somewhat resemble the function of a temp sensor it isn't usable as one.

The factory temp sensor and wiring must remain intact.

Jordan, could you explain what is the difference between those, I always had the impression were the same thign for some reason called different just.

[andrem5]

You may need the air temp sensor for the reference value with an MAF. It is part of the calibration. Not all MAFs are alike though and some need a temp signal for reference.

More importantly, when you convert from AFM to MAF or even HFM your DME is still expecting the reference air temperature since it does not know how to read units of "mass." A piggyback system is supplying signals converted to the DME to simulate volume.

If you simply disconnect the air temp sensor, I expect the DME will be very unhappy to receive 0 volts where it expects to see a signal proportional to temperature. A negative temperature coefficient sensor with an output of 0 ohms (or 5 V) would correspond to extremely high temperature (higher temp -- lower resistance). An aftermarket temp sensor could be used but it would have to exactly match the range of the OE or be fed to a piggyback that could map the values correctly.

Diego: I spent a lot of time climbing around the Peruvian Andes. Do you also have an M6 as your username implies? If so that must be an incredibly rare car on HWY 1.

[Chris E30 Cab]

it defaults to 18C

[e30sd]

mike a posting on r3v? has hell frozen over/!?!

[andrem5]

it defaults to 18C

I have asked several sources and read the Bosch shop manual but I could not confirm this. It makes sense Bosch would do this, but I could not find it in writing. I was planning to just splice in a 2.5K ohm resistor.