The Official Auto-to-Manual Transmission Swap Thread

**Mrmontecristo** · 03-16-2005, 02:30 PM

Yea, don't feel bad about leaving your car in gear and forgetting you have a manny now! I did the very same thing a few times

. You'll get used to it. Totally off the subject but worth thinking about...Something that was passed on to me from a trusted source is to start your car, let it come to idle and drive it. Don't leave it in the driveway to warm up. Just drive it keeping the rpms below 2.5-3K and be gentle until is warms up to normal operating temp. I share this with you because with that 3.91 diff, this is a chore for you, especially if you have to jump on the freeway right away....
By the way, is your cruise control hooked up, and your reverse lights working? Did you do this conversion yourself or have it done. The c/c and revlights are hot topics on this thread right now.
MrMonte

**Boosted318is** · 03-20-2005, 01:20 PM

Okay guys,
Many of you who have completed this swap and then used a relay on the clutch switch to get the cruise control to work. This cruise control fix is detailed in this thread under "cruise control fix".

One issue I found with this fix is that when you depress and release the clutch the idle would fluctuate. This was pretty darn annoying to me

The reason this was happening is because the cruise control fix tricks the car to thinking it is in "park/neutral" when the clutch is depressed and "drive" when the clutch is released. Using this logic, there is engine timing intervention circutry between the DME (engine computer) and tranny control computer. I found this out by looking at the transmission control electronics diagram in my bentley manual. This changes the engine timing depending on whether the car is in drive or park/neutral. We all know that on a manual the car is in "drive" ALL the time, so this was the goal.

Using the Bentley diagram (Tranny control electronics diagram), I found out that the DME takes a "Park/neutral" signal from the old auto range switch. This happen to be inputed on pin 65 of the DME on my 1995 car. This signal is activated only when the car is in park/neutral or in our car when the clutch in IN. You following OKAY??

After talking with a mastertech I also found out the DME "only" reads a timing intervention signal from the tranny computer when this P/N line is activated. (A reason why the DME are universal between auto and manual cars) Therefore my cutting the P/N signal to the DME will get the DME to think it is always in drive!

So this is what I did. Yesterday, I pulled the ECU and CUT the line going to pin 65 on the DME, the P/N input (this could be a different input on your car so check the Bentley manual). So far this has been Awesome!! No idle droop anymore when I release the clutch. The car DME now always thinks it is in drive. I can still start the car and use the cruise because the P/N signal to the DME as read after the cruise and EWS ignition disable. VERY EASY!!

HOPE THIS HELPS GUYS

**str8 gone** · 03-20-2005, 03:01 PM

Originally Posted by Boosted318is

Using the Bentley diagram (Tranny control electronics diagram), I found out that the DME takes a "Park/neutral" signal from the old auto range switch. This happen to be inputed on pin 65 of the DME on my 1995 car.

So this is what I did. Yesterday, I pulled the ECU and CUT the line going to pin 65 on the DME, the P/N input (this could be a different input on your car so check the Bentley manual). So far this has been Awesome!! No idle droop anymore when I release the clutch. The car DME now always thinks it is in drive. I can still start the car and use the cruise because the P/N signal to the DME as read after the cruise and EWS ignition disable. VERY EASY!!

Nice work Boosted

For the 325 owners this will be pin 81 (drive range wire Brown/Black OR Red/White)

**al_r** · 03-20-2005, 03:36 PM

Kudos to Boosted!

Info like that makes this forum worthwhile.
But my 328 doesn't have this issue...

**Boosted318is** · 03-22-2005, 06:38 PM

Ok Guys,
Following my fix for the idle droop I have noticed that the idle speed now fluctuates up and down (a.k.a surges) when I come to a stop.

I think this is because the ECU thinks it is in "drive" all the time and has a specific idle control for an auto tranny set in "drive". My thinking is that this idle control loop requires a large rotating mass such as a torque convertor to maintain speed. Now I am driving around with a much lighter flywheel which does not provide enough inertia to keep the engine idling properly.

With this in mind I think instead of tricking the ECU to think it is in "drive" all the time I need to make it think it is in "park/neutral" all the time, essentially what we started with before the cruise control fix. I would think the idle control for a auto in park/neutral would be much more akin to that of a manual.

Here is what I am going to do. Pin 65 on my car is the P/N signal input to the ECU. 12v signal indicates P/N, and 0V indicates drive. I previously cut the wire to let the ECU think it is always in drive. To get the ECU to think is is P/N all the time I am going to run a constant 12v signal to the line. Therefore it will always apply that idle control loop.

For those of you with the relay clutch fix -- Does your car idle better with the clutch in??? When you release the clutch you get an idle droop followed by surges??

If so, then this might be the reason why. Please comment!!!

**SecretAznSauce** · 03-22-2005, 07:57 PM

Originally Posted by Boosted318is

Ok Guys,
Following my fix for the idle droop I have noticed that the idle speed now fluctuates up and down (a.k.a surges) when I come to a stop.

I think this is because the ECU thinks it is in "drive" all the time and has a specific idle control for an auto tranny set in "drive". My thinking is that this idle control loop requires a large rotating mass such as a torque convertor to maintain speed. Now I am driving around with a much lighter flywheel which does not provide enough inertia to keep the engine idling properly.

With this in mind I think instead of tricking the ECU to think it is in "drive" all the time I need to make it think it is in "park/neutral" all the time, essentially what we started with before the cruise control fix. I would think the idle control for a auto in park/neutral would be much more akin to that of a manual.

Here is what I am going to do. Pin 65 on my car is the P/N signal input to the ECU. 12v signal indicates P/N, and 0V indicates drive. I previously cut the wire to let the ECU think it is always in drive. To get the ECU to think is is P/N all the time I am going to run a constant 12v signal to the line. Therefore it will always apply that idle control loop.

For those of you with the relay clutch fix -- Does your car idle better with the clutch in??? When you release the clutch you get an idle droop followed by surges??

If so, then this might be the reason why. Please comment!!!

I've been quite happy with the wire to starter wire gig, at idle or driving its think it in drive(no voltage) and when start it think its in P (only time its receiving voltage) much easier than tapping DME. so no more looping issue

**Boosted318is** · 03-22-2005, 09:51 PM

I finished updating per my last post tonight. I just tied the 12V switched line input (red wth white stripe) to the ECU to the pin 65, so now the ECU is always reading the idle control as if it were in park/neutral.

The idle improved greatly and now sits smooth. I think it is a little higher that before. I attached a picture. Let me know if this is too high.

SecretAznMan4u - I think your idea is brilliant. I just wanted to keep the clutch disable capability with my cruise control. In addition, my issue was that that having the car idle thinking it is in "drive" gave me a surging idle. I assumed this was due to improper idle control programmed for a heavy torque convertor (which is engaged in "drive" in an auto car). By making the ECU think it is in P/N at idle, the idle smoothed without surges.

My issue was that that having the car idle thinking it is in "drive" gave me a surging idle. The guys who complete the swap and do not car about the cruise functioning will have there cars configured so that the ECU thinks its in P/N all the time so they can start it.

SecretAznMan4u, are you having any surging idle issues??

**SecretAznSauce** · 03-23-2005, 12:26 AM

Negative, none at all. at idle, i site right at 750-725 range

**Mrmontecristo** · 03-23-2005, 12:34 AM

boosted 318is Great work man! One issue that Secretazianman brings up is that our installed relay working off of the normally closed clutch switch, everytime the clutch is depressed and that relay makes up the pin5 to pin 7 connection on auto range switch it also energizes the coil for the starter immobilization relay (or a similar device depending on your year). I agree with you that having the clutch disable feature is a good thing, and that also disabling the cruise by using this scheme is useful. However, the coil on the starter system is getting a serious work out. If it burns up, it's not going to be cheap. The Bentley page showing where the pin 7 wires go to (starter relay, cruise control, auto trans comp, and ECU) is where the answer lies. I'll work on a solution for bypassing the signal to the starter coil after initial start, and keep the rest of the circuit in tact. I was thinking of running a 12v signal from the run position of the ignition switch with a relay that would open that pin 7 wire going to the starter coil. THat way, after hitting the start position and energizing the starting coil and starting the car, the key would go back to the run position on the ignition circuit and disable the pin going to the starter while allowing the cruise to be disabled using our originally modded relay (still with me?) As far as the surging goes, I did not experience any of that until I installed the cruise control fix relay, thus sending the 12v signal to the ECU. I understand your theory about the torque converter and timing anticipation, but I like my idle speed the way it was before I installed the relay. I'll try cutting the wire to the ECU and let you know what my results are.
Regardless, this is all good research and many variations to suite many different modes of operations. And I can tell you, I've learned a ton about this entire circuit just researching and reading what's been written here. THanks to all who have contributed.... Just think of the poor bastards coming into this green like we all were and how much time we'll be saving them. Another victory for this forum!

MrMonte

**Boosted318is** · 03-23-2005, 12:59 AM

Note that the cruise control fix only sends the 12v signal to the ECU when the clutch is in (P/N). The question is how does the car idle when the clutch is out, hence in "drive". As a side note I have a 318is, which could also have an entirely different idle control. My car idled perfect in park/neutral setting but surged in the drive setting.

I think I will switch to SecretAznMan4u's solution as well. I guess we could just hook up a relay in parallel with the brake cut circuit, allowing the clutch or the brake to disable the cruise on the same circuit....

I guess I am missing the critical nature of the relay we are energizing. Is it easy to replace?? I will have to check out the bently again. Could you point me to the correct page for a 95 318is??

**Trentos** · 03-23-2005, 05:48 AM

An answer to that would be to buy a good relay or buy one that sits in a seat. so that if it did go you would just swap it out in a matter of seconds.

Imho if you buy a decent relay this is what they are designed for. some relays spend there life energised without problems its just finding one that is over engineered for the job. Over relays spend there life swapping between the two. Im sure there is a fair few relays already on the car that spend there life in the energised state???? Fuel injection pump relays?

**SecretAznSauce** · 03-23-2005, 06:24 AM

Originally Posted by Trentos

An answer to that would be to buy a good relay or buy one that sits in a seat. so that if it did go you would just swap it out in a matter of seconds.

Imho if you buy a decent relay this is what they are designed for. some relays spend there life energised without problems its just finding one that is over engineered for the job. Over relays spend there life swapping between the two. Im sure there is a fair few relays already on the car that spend there life in the energised state???? Fuel injection pump relays?

a........this isn't just a simple relay. Do you even know what relay we are speaking about? and you are missing the logistics that we are talking about, the idle droop issues

**SecretAznSauce** · 03-23-2005, 06:25 AM

Originally Posted by Boosted318is

Note that the cruise control fix only sends the 12v signal to the ECU when the clutch is in (P/N). The question is how does the car idle when the clutch is out, hence in "drive". As a side note I have a 318is, which could also have an entirely different idle control. My car idled perfect in park/neutral setting but surged in the drive setting.

I think I will switch to SecretAznMan4u's solution as well. I guess we could just hook up a relay in parallel with the brake cut circuit, allowing the clutch or the brake to disable the cruise on the same circuit....

I guess I am missing the critical nature of the relay we are energizing. Is it easy to replace?? I will have to check out the bently again. Could you point me to the correct page for a 95 318is??

its sits right next to the comfort relay, its huge you cant miss it, its yellow. btw your brakes already kills your cruise control. in my book, ELE-99??

**str8 gone** · 03-26-2005, 08:47 PM

Originally Posted by SecretAznMan4u

Did no one read my post on just hooking the park/nuetral wire to the blk/yel ingiton wire? it provides 12vdc while cranking any never else

therefore you are never excercising that big yellow AT relay everytime you push your clutch in.

thats what fixed my problem

Hey secret.....nevermind,I figured it out

**joe325i** · 03-28-2005, 06:34 PM

Mabye I missed it in the thread.. If so please tell me..
But was anyone able to figure out how to make the cruise control work.. w/o the idle or rpm surge probems.. and not working out the pre-existing auto relay??

Joe

**Mrmontecristo** · 03-28-2005, 10:23 PM

I think SecretAznMan4u has the cleanest solution so far. This is a lengthy thread, so if you can't find the answer you're looking for, PM me and I'll walk you through it. Also, the Bentley manual is your bible for this. Hopefully you have one, cause it makes life soooo much easier.... That and some knowlege of print reading helps.
MrMonte

**joe325i** · 03-28-2005, 11:19 PM

Yeah.. Ive just been lookin through my bently for the past hour and 20 tryin to figure out these diagrams.. sadly high school physics and my lack of knowing how the electronics are interlaced dosnt help

**str8 gone** · 04-01-2005, 09:51 PM

Okay,I've started my swap....The starter bolts are a major pain without an obstruction,(starter), wrench.You will have to remove the rear trans crossmember and tilt the engine downward to access the upper bellhousing bolts.Keep in mind that I have a 94 325 which does NOT have the threaded starter.When you get to the bellhousing bolts that also hold the starter you need to hold the nuts from the opposite side with the aforementioned starter wrench.
BTW I got the wrench at sears....It is curved and has 9/16 on one end and 5/8 on the other(the 5/8 side is the one you will need)

**TopSpeed328i** · 04-16-2005, 06:55 PM

Dont let this thread die! I am now convinced on doing this swap to. Now my question is this: Anyone have a final solution to the OBDII fault code problem with the new MT? I understand the electronics aspect of the brake light switch, cruise control etc, but fill me in on the CEL, I dont want this light to be on, so I can tell when I REALLY DO have a problem, instead of ignoring it. Also, where is the best place to buy the pedal assembly w/ master cylinder? My final thoughts are this: I know that I can manage the grunt work and assembly of this project BUT, a clear explaination of what needs to be changed with the computer (or whatever to fix idle probs etc) would be greatly appreciated.

DONT LET THIS THREAD DIE!!!!!!!!!!

**TopSpeed328i** · 04-16-2005, 07:04 PM

Oh, one more thing I forgot. I have a '96 328i auto w/ sport package and LSD diff, which I believe is the 3.91. Is this gear going to be too tall?

**JLac** · 04-17-2005, 12:40 AM

That gear seems too SHORT if anything. You'll probably top out at 125.

**CrazedBMW** · 04-17-2005, 05:03 AM

Originally Posted by JLac

That gear seems too SHORT if anything. You'll probably top out at 125.

A little under 125

**CrazedBMW** · 04-17-2005, 05:04 AM

Originally Posted by TopSpeed328i

Oh, one more thing I forgot. I have a '96 328i auto w/ sport package and LSD diff, which I believe is the 3.91. Is this gear going to be too tall?

Honestly... 3.91 diff is a blast to drive. I don't really want to swap mine out, downside = lower gasmileage...
upside = Quick ass car

**TopSpeed328i** · 04-17-2005, 10:53 AM

sweet! So about what rpm are you running at at about 80mph? I have heard something like 4k - 4.5k. Diffsonline claims 4250rpm, this about right? I am slightly concerned with unneccessary ware on the motor. But hey, if its fast off the line what the hell.

**UKFan4Sure!** · 04-17-2005, 02:42 PM

Originally Posted by Sacramento M3

GRAND TOTAL: $2,822

Dang! I only paid $4000 for the car. 94 325i 5 speed. Whew!

Thread: The Official Auto-to-Manual Transmission Swap Thread

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