SMG issues... ECU or PUMP replacement?

[MondoM3 0]

Hi Guys,

Having done countless hours of trawling existing SMG threads worldwide, I've decided to add to that list with what I believe is a slightly unique problem.

My '02 E46 M3 SMG has developed the common(ish) refusal of engaging 1st gear and also jumping out of gear without warning while underway. This becomes worse as the car becomes warm.

Just to clear things up, the usual suspects like hood sensor, 'salmon relay' and fluid/gear position sensors have been checked or replaced with no change to the problem.

After 5 hours of diagnostics with Jeff Gray BMW chch, I have been told that it is likely to be a pump failure. However they also said its possibly an ECU problem. The reason they believe it could be ECU is because when the the pump fails to provide sufficient pressure they were able to manually dail up the pressure using the dealers ISIS computer attached. So the pump has the ability to provide pressure when it is instructed to..

However, perhaps the pump is working fine but the accumulator is not holding pressure long enough? What I don't understand is why the ECU isn't telling the pump to work once the pressure becomes too low.

Im looking at a $5k fee for the pump incl. labour, which is far from ideal.

What do you think I should do? replace the ECU to eliminate the possibility first?

Im 90% sure the pump is the issue but not sure if I should outlay the money for an ECU just to be sure. I think I can pick up an ECU from ebay for less that $500 delivered.

I'd love to hear everyone's thoughts.

Cheers,

Simon

[M3_Power 636]

The pump fault is easy to pick up on the diagnostics menu - you can physically see pressure build up and pressure drop and then recharge.

If it's not recharging it's usualy a relay issue (bonnet switch ect) ..

Dropping out of gears can be a couple of things - gear position sensor, temp sensor and my money on your issue - Compression spring.

You'll need to lower the gearbox to get to it - but my money is on the one next to the gear position sensor being broken.

Have they tried to re-teach the gear selection in the car? The process where it shifts through all the gears to learn the travel distance and rotation? If not then they need to try that first and see if it still drops out of gear.

Usually if it's a pump issue you'll get multiple gear selection issues, not just one gear.

What are the fault codes?

Edited July 31, 2013 by M3_Power

[MondoM3 0]

Hey man,

thanks for your quick response!

The problem seems to actually be across all gears - jumps out of 4th for example, then coasts along in neutral. when car comes to a stop the car struggles to get into 1st. they can then make the pump provide pressure then engage first. So I feel there is possibly a communication issue between pump and ECU.

Sorry I don't have the fault code right now but I'm told the fault logged is for 'hydraulic pressure'. What I don't doubt is that at times there is not enough hydraulic pressure to shift but the reason for this is what I'm not sure about.

The clutch adaptation has been done as I have just had a new clutch fitted. But they haven't mentioned anything about re-teaching the gear selection...

To be honest my gut feeling is that its the pump, but I want to be 100% sure before spending $5xxx.

Im trying to track down an ECU to plug in and see if that fixes it. Mosen have quoted $295+ gst for a used ECU but Im hoping to borrow one from some generous person in the BMW community!

Jeff Gray don't seem to have had much experience with SMG's so i'm looking for as much advice as possible.

Cheers,

Simon

[M3_Power 636]

Highly doubt it is ecu related.

Sounds like Jeff Grey doesn't know what they are doing. I would re adapt the gearbox shift pattern also after a clutch change.

It sounds like the accumulator is out - but if you know how to use the diagnostic system it'll show this straight away as you can get live readings on accumulator pressure.

The accumulator itself is a lot cheaper than the full pump so i would just change that. Also given the pump is capable of manually charging the full pressure it points to the accumulator being the culprit.

There is one other possibility and this will be harder to trace - but there is the remote possibility that someone has accidentally bent the hydraulic lines when changing the clutch.

I would still check or change the indent compression spring regardless as that has been known to cause all sorts of gear dropping issues.

You'll also want to read the smg temp to see when it is dropping out of gear to confirm it's not the sensor that's cause fault.

Edited July 31, 2013 by M3_Power

[hybrid 1039]

Highly doubt it is ecu related.

Sounds like Jeff Grey doesn't know what they are doing. I would re adapt the gearbox shift pattern also after a clutch change.

+1

ECUs either work or dont function at all. Its not like the bytes wear out.

[M3_Power 636]

How much are you getting quoted for the SMG pump? Some rough overseas pricings with GST and shipping:

ecstuning NZ$3400

Schmiedmann NZ$3450

I can personally get them for cheaper through some of my contacts overseas.

Don't over complicate the SMG system, it isn't actually that complex. It's basically just an electric pump with a pressure accumulator, bunch of hydraulic lines pushing fluids around and a few sensors telling the ECU what's going on.

The failure fashion tends to have a rough ranking in the following:

1. Infamous Salmon relay

2. hood switch

3. gear selection sensor

4. indent spring

5. temperature sensor (this has been known to cause accumulator like failures - because what it is basically doing is telling the SMG ecu that the pump fluid is overheating so it stops charging even when it isn't) - there's now really good resistor mods online that you can do to trick the system into never seeing an overheat.

6. SMG accumulator

7. SMG pump (there are businesses now overseas that do rewinds of these pumps) A few have attempted a self rewind DIY and failed, as apparently the brushes are quite special so to speak.

8. hydraulic lines.

There's an accumulator test and pump test in the GT1 - those should be the first port of call to see if the tests pass or fail before you spend the money to replace the pump.

Edited July 31, 2013 by M3_Power

[MondoM3 0]

Great, thanks for the info guys. Heres where I currently am with those 8 points listed:

1. Infamous Salmon relay - Has been replaced with no change

2. hood switch - Been told by Jeff Gray its ok. And I believe the car would not even start if this was faulty?

3. gear selection sensor - Was replaced by previous owner. Work done by BM Workshop.

4. indent spring - Not yet checked. Will definitely check when the 'box is pulled!

5. temperature sensor (this has been known to cause accumulator like failures - because what it is basically doing is telling the SMG ecu that the pump fluid is overheating so it stops charging even when it isn't) - there's now really good resistor mods online that you can do to trick the system into never seeing an overheat. - I have specifically asked them about this and Jeff Gray say that the temp sensor has been reading about 75 deg C consistently and they believe that is normal.

6. SMG accumulator. Very likely. Im currently thinking that if I replace the accumulator I should probably replace the pump at the same time, I don't want to go through the same labour costs in 50,000k's to get the pump replaced.Im planning on owning the car for 3+ years

7. SMG pump (there are businesses now overseas that do rewinds of these pumps) A few have attempted a self rewind DIY and failed, as apparently the brushes are quite special so to speak. I can source a rebuilt pump for around 1650 USD. (minus 250USD core exch so 1400). Its a lot less than the $3695.00 + GST by Jeff Gray! BUT is it really worth the risk?

rebuilt part: http://www.invasionautoproducts.com/01bmwm3smgpu.html

8. hydraulic lines. Hmmmm, there could-well be a bent line...unlikely but possible. but the fact that the issue gets worse when the car gets warmer doesn't makes sense with that... I would have thought that the warmer the fluid, the easier it would pass thru the lines?

In addition to those 8 points there is another interesting point I was told by Kayne at Kayne Barrie Motorsport. He mentioned that if the SMG system is not calibrated regularly, out of sync gear selection can cause the gear selector forks to wear on one side. If it gets bad enough the gearbox wont be able to hold gears. Im going to check this when the box comes out but its unlikely to be related because of the haydraulic pressure fault and that the symptoms aren't quite right for it to be this.

Hybrid. I agree that its unlikely the ECU. The only reason im considering it as issue is because its such a cheap repair! lol. Although theres Im still confused as to why the pump can be made to bring pressure by an external computer, when the ECU should really be activating it as soon as pressure is down.

Right now im considering two options:

1. Replace ECU to see if there is any change. ($400 incl labour). Still hoping ill find someone to lend me an ECU

2. Drop gearbox, check springs, check gear selector forks, check hydraulic lines. If no faults there => replace pump.

Edited July 31, 2013 by MondoM3

[MondoM3 0]

There's an accumulator test and pump test in the GT1 - those should be the first port of call to see if the tests pass or fail before you spend the money to replace the pump.

What do you mean by 'GT1'? is that a diagnostic unit?

[M3_Power 636]

I have specifically asked them about this and Jeff Gray say that the temp sensor has been reading about 75 deg C consistently and they believe that is normal.

That's pretty high actually (once again shows JG don't know what they are going on about) .... 80 is when it throws a fit ... normally should hover around 40 to 50. If it's constantly at 75ish then I think that explains why it is not charging. I would change this first and see - as it's easy to get to and reasonably cheap part.

6. SMG accumulator. Very likely. Im currently thinking that if I replace the accumulator I should probably replace the pump at the same time, I don't want to go through the same labour costs in 50,000k's to get the pump replaced.Im planning on owning the car for 3+ years

I tend to agree ... although you are talking $3500 vs about $600 ...

The shitty bit is you can't buy the pump without the accumulator, so if the pump goes you are stuck with an extra accumulator that no one wants to buy.

7. SMG pump (there are businesses now overseas that do rewinds of these pumps) A few have attempted a self rewind DIY and failed, as apparently the brushes are quite special so to speak. I can source a rebuilt pump for around 1650 USD. (minus 250USD core exch so 1400). Its a lot less than the $3695.00 + GST by Jeff Gray! BUT is it really worth the risk?

rebuilt part: http://www.invasionautoproducts.com/01bmwm3smgpu.html

Personally I would buy new, send the old one to be rewound and flick off on ebay as a rebuilt unit. Or hold onto it till somebody comes up with a rebuilt kit (which I am sure they will eventually).

8. hydraulic lines. Hmmmm, there could-well be a bent line...unlikely but possible. but the fact that the issue gets worse when the car gets warmer doesn't makes sense with that... I would have thought that the warmer the fluid, the easier it would pass thru the lines?

I did say unlikely ... haha!!

In addition to those 8 points there is another interesting point I was told by Kayne at Kayne Barrie Motorsport. He mentioned that if the SMG system is not calibrated regularly, out of sync gear selection can cause the gear selector forks to wear on one side. If it gets bad enough the gearbox wont be able to hold gears. Im going to check this when the box comes out but its unlikely to be related because of the haydraulic pressure fault and that the symptoms aren't quite right for it to be this.

Kayne is correct ... I recommend a reset every month actually - which is what I do with mine. You'll be amazed how different it drives with each reset.

That's why I said it was strange that JG didn't try to re-teach the gear selection function with the diagnostic tool (ISIS is the new one but more fiddly, GT1 is the old system).

Right now im considering two options:

1. Replace ECU to see if there is any change. ($400 incl labour). Still hoping ill find someone to lend me an ECU

2. Drop gearbox, check springs, check gear selector forks, check hydraulic lines. If no faults there => replace pump.

Option 1 is a waste of time and money in my opinion - nothing that a proper diagnostic can't pick up. If there's a CAN issue it'll show up.

I would - change the temp sensor first, do a gear selection re-adaptation and see if it solves it. At the same time test accumulator and fluid temperature on a live reading and test schedule on a diagnostic machine with someone that knows what they are doing.

If it still doesn't work - lower box and remove selector unit to see if it is worn.

While the box is lowered you should be able to get to the indent spring - I would check that ...

If above two shows no signs or wear or damage I would then buy a new pump from the States and replace, sell the SMG pump if it tests okay as a second hand unit with a faulty accumulator - you should get at least US$500 for it ...

Edited July 31, 2013 by M3_Power

[HELLBM 1530]

We have all parts discussed at least 50% less than quoted prices. A pity you are not closer,we would work thru with replacement parts until problem diagnosed. As Tom said basically a simple system.

Call if we can help.

[MondoM3 0]

HI guys. just to give an update.

I have informed the service team at JG of my concerns about the fluid temp sensor. They confirmed again that they found it to be reading at about 75 deg. Once I told him that the sensor will shut off the pump when 80 deg is reached he said 'that's interesting'... hes going to talk to his techs and get back to me.

Have found a temp sensor on ebay for very cheap so this will be awesome news if it is the temp sensor.

http://www.ebay.com/itm/SMG-Transmission-F...6-/310672976927

fingers crossed!!!

Cheers,

Simon

[mrphil 1]

abit off topic

but may i ask how many km's has the car done when the issue came about? was the car nz?

[MondoM3 0]

Hi there. 128,000 k's.

NZ new. seviced at Team Macmillan and BM Workshop.

Have just been through a Vanos nightmare so the timing couldn't be any worse!

[mrphil 1]

Hi there. 128,000 k's.

NZ new. seviced at Team Macmillan and BM Workshop.

Have just been through a Vanos nightmare so the timing couldn't be any worse!

damn! Vanos problems too...i feel for you man

i hope the temp sensor fixes your smg issues

[MondoM3 0]

yeah I haven't had much luck with this car that's for sure. have owned it 8 months and have only drive 1000km!...

anyway, I have heard back from JG. They have admitted that either of two temperature sensors are likely the cause..

I was hoping it would be the separate sensor that I mentioned earlier (http://www.ebay.com/itm/SMG-Transmission-Fluid-Temperature-Sensor-for-BMW-m3-Series-2001-to-2006-/310672976927) BUT what I overlooked initially is that that sensor is for the GEARBOX OIL TEMPERATURE. not SMG HYDRAULIC FLUID.

So I feel it is more likely to be the SMG fluid temp sensor which is actually a part of the hydraulic unit. Can anyone confirm for me that this sensor inside the pump is the ONLY temp sensor related to the SMG Hydraulic fluid? Or is there a separate sensor also?

This sensor is not serviceable/replaceable by Jeff Gray.

Tom mentioned to me the possibility of doing a small re-wire of the sensor at the pump to trick the computer into receiving lower temperature readings. I think this is my best bet.

Simon

[M3_Power 636]

So I feel it is more likely to be the SMG fluid temp sensor which is actually a part of the hydraulic unit. Can anyone confirm for me that this sensor inside the pump is the ONLY temp sensor related to the SMG Hydraulic fluid? Or is there a separate sensor also?

This sensor is not serviceable/replaceable by Jeff Gray.

Tom mentioned to me the possibility of doing a small re-wire of the sensor at the pump to trick the computer into receiving lower temperature readings. I think this is my best bet.

Simon

As stated on the phone and TXT - contrary to what BMW tells you, this sensor IS replaceable.

Item number 7 below:

BMW Part number (blue plug on the back of the sensor) 13-62-1-709-966

It's a Bosch sensor - Bosch part number 0 280 130 026

Or apparently the VDO one works also: Part number 805/9/1

Full sensor spec:(-40-+130C, NTC 2.5K@20C log curve +-5%, 1.0amp max M12x1.5mm, 19mm wrench, 25 NM installation torque)

The system throws a fit and shuts down the pump from recharge when temperature reaches above 80 degrees C - normal operating hydraulic fluid temp should be between 30 - 60degrees C. (It faults often because the bloody pump unit is right next to the engine block (clever design BMW !!!))

The SMG pump operates at 80Bar and starts recharging when it drops below 45bar. The accumulator has a volume of 150ccm (two cambers in the accumulator, separated by a piston, one side filled with nitrogen at 39bar). There's a pressure relief valve in the system that opens at 100bar. When reading the hydraulic pressure the voltage is always between 0.5v to 4.58v (0bar to 100bar respectively).

The resistor modification splices into a wire on the 18 pin plug tricking the system into thinking it's always within range. I believe the resister is suppose to be between 500ohm to 1K which will put it within range (most have reported the 680ohm works well even in very hot climate).

As you are introducing air to the hydraulic system, you WILL have to bleed the SMG system afterwards (I hope JG knows how to do this!!! Given how they've been diagnosing your car I am not so sure ... lol)

^ Jokes aside:

The sensor is the right hand side one with the baby blue plug (below the dark blue dot)

Said sensor:

Resistor mod:

http://www.radioshack.com/product/index.js...;utm_medium=CSE

Good luck Simon!! Hope this sorts it for you and then you can finally start to enjoy the car!!

Edited August 1, 2013 by M3_Power

[APT 179]

This should be sticky'd

[westy 614]

This thread is beyond awesome.

[M3_Power 636]

This should be sticky'd

Technically speaking BMW techs should know how to fix the SMG system ... a lot of it is in the training manual

Edited August 1, 2013 by M3_Power

[hybrid 1039]

Unfortunately not a lot of BMW dealerships around the country send the right technicians on training.. they either leave after a year because they dont want to be a mechanic that and the SMGII system is old technology these days. Most of the 'old boys' who have had the traiing have moved on and out. We also live in a replace it and fix it generation. Not too many people who can be assed or can actually fix these systems. Simplicity aside.

Welcome to bimmersport This is what its good for.. Lots of knowledgible OWNERS who have been there done that and are willing to share information.

[_ethrty-Andy_ 2122]

I dont even own an M3 and here I am reading it all, it all might help in the future you never know! Thanks Tom

[MondoM3 0]

DUUUUUUDE. You're an absolute legend.

Im not sure how I couldn't find all that info on the countless existing threads!

One more question:

If I JUST do the resistor splice, might that take care of the problem?? I believe that wire is quite accessible right?, so if I just add the resistor, leave the existing sensor and see what happens I have nothing to lose? if the fault comes back then I will fork out the cash to access the sensor, get it replaced then bleed the system.

Still, its not 100% certain that this sensor is the problem. Even so, this possibility should have been eliminated before Jeff Gray quote me for over $5k of work!!! If I didn't raise this issue with them, I probably would have ended up replacing the pump..... which would have fixed the issue. BUT I would have unknowingly been shafted 5k. It makes me wonder how many people out there have just spend buckets of cash for no reason.

I have talked to Jeff Gray and I am meeting them in the morning. They have agreed to cut the wire to the sensor and test the car. If it gets rid of the problems then BINGO. If it doesn't, then on to the next solution.....

Will keep you posted.

Cheers

[MondoM3 0]

Welcome to bimmersport This is what its good for.. Lots of knowledgible OWNERS who have been there done that and are willing to share information.

Thanks mate. I think if this pays off then I owe everyone and particularly Tom a round of drinks!

[Tristan 338]

Great work as always, Tom.

[nath 128]

Whether it fixes the problem or not, this thread has some of the best, most considered and deduced advice I have seen in a long time. No "its definitely the pcv/icv/replace everything it will bean offence if you don't spend a ton of money" statements to be seen.

I'm a (green behind the ears) mech engineer and this the kind of problem solvibg ability that not many people have.

Keep up the good work