MEMS is designed by Rover. The earlier versions of MEMS used Motorola hardware although Rover used Siemens engine management on the KV6 Mk2 and the G-series so they may have contracted Siemens to build the MEMS 3 hardware.

As far as I know, Emerald Engine management isn't used in any OE applications, not for volume manufacturers anyway.

What do you want to know?

 

My main issues are regardiong LIMP mode and Long Term Fuel Trim adjustment.

How often does the LTFT "update/learn" and for how long must the condition exist before the LTFT adjusts?
If the ECU goes into LIMP mode while the LTFT is still trying to "catch up", does it ignore the condition that caused it into LIMP or does it adjust?
Could LIMP be caused if the fuel trim exceeds certain preset parameters where the ECU would normally "adjust" itself?
What fuel trim conditions can lead to LIMP mode, and are there other inputs / conditions that act in conjunction with this, eg if load is high, fueling goes outside LTFT parameters at high engine speed, does it cause LIMP mode?

 

Try this link
http://www.mgfcar.de/library/ENGINE_MANAGEMENT_SYSTEM_ MPi_VVC_MEMS_3.htm

 

I understood everything up to

My main issues are

then it got a bit technical

 

For some reason I thought the systems were Lucas?

I have searched the net many times for info, particularly the communications protocol and details, but no luck, so i hope you have more.

 

The 5AS alarm/immobilser system used on eariler cars is a Lucas system.

 

Thanks for the link. Unfortunately they only mention "adaptive" system, and then moves on. It's really the parameters of this adaptive system that I am interested in most.

The communication protocol is ISO 9141 on my MEMS 3.

 

There is not just one 'limp home mode' that the ECU defaults to. The ECU will attempt to keep the engine running in one way or another, and protect the engine and associated systems (e.g. cat) in any way it can in the event of a problem. What the ECU does depends on what the problem is, for example if a sensor is open circuit, there is a value or set of values that the ECU will substitute instead. This is why in some cases the car will run better with a component disconnected, as the default values are more accurate than the measured values.

I don't know for certain when STFT starts to affect LTFT, I would think FT is monitored whenever the engine is operating in closed loop and there are no relevant faults present that would upset the LTFT but as I say I don't know the parameters MEMS uses for this.

In the case of some manufacturers, excessive STFT and/or LTFT stores a code, often before driveability is noticeably affected. MGR is probably the same although I don't know for certain.

Some Rover engine management systems were Lucas, such as on the M-series, RV8 and Maestro/Montego. MEMS uses some Lucas components, such as injectors.

 

Where can I obtain a list of limp modes with the causes of that specific mode? I know that is asking for a lot, but that is actually what I need.

When my TF goes into limp, the AFR goes extremely lean. One would think that it may have sensed a very rich condition prior to that, but when I look at my logs, the mixture was actually fine up to that point. The only common factor present before the ECU goes limp is that the engine load is high - more specifically, if I ease into the power, it seems to last longer before it goes limp, but when the power rushes in quickly, it goes limp towards the top end of the power curve. A side note is that the ECU will still be in closed loop mode as I am not using WOT.

 

No idea where you could find that information, sorry.

Is this a standard car and assuming you have checked all the live data, is the fuel pressure ok?

 

The car is not standard - it has a turbo fitted to the standard K-series engine. The first issue was the MAP sensor, but I resolved that with some circuitry.

I know that the ECU can adapt to the latest setup, as it did when I was running 0.4 bar boost. At first it kept on tripping, but after a while it stopped going into limp.

I have now increased boost to 0.5 bar and increased fuel pressure slightly from the previous setting (1.4 bar to 1.6 bar at idle), so I am expecting the ECU to adapt to the new setting like it did before, but would like to expedite the process at least.

I know asking for the LIMP info is going right down into the "DNA" of the software, but it cannot be that difficult to find the info. One can do nothing with it (other than plan and explain scenarios to yourself) unless one can write to teh ECU, which I cannot and do not want to do. The tuners that change the mapping on these ECU's might know, but none of these are offering.

 

Forgot to mention - I am running 315 cc injectors as opposed to the standard 200cc/min units, and duty cycle of injectors only goes to about 72%, so well within limits.

 

How have you dealt with the MAP sensor? Are you using a standard MGR one or a GM 2 bar sensor or similar, and does the ECU 'see' the correct MAP or does it see an altered version?

Also how are you doing on-boost ignition timing?

 

MAP sensor output is unmodified up to the point where it is clamped at a constant level (at approx 0.25 bar). Thereafter, the ECU does not see an increase in MAP at all. To cater for the required increase in fueling as boost increases, I use a Rising Rate Fuel Pressure Regulator (ratio 1:8), which increases fuel pressure. As a result, if duty cycle is x at a certain condition, the increased fuel pressure results in more fuel being delivered at the same duty cycle when boosting.

Timing is unfortunately unaltered. I run water injection to counter detonation, and have not experienced detonation at all, even when I tested at boost levels of 0.8 bar boost at low RPM and throttle conditions recently.

 

Interesting solution to the boost fuelling, I've not heard of that before. Presumably the fuel pressure regulator has a larger surface area on one side than the other, so that when manifold pressure increases by x, fuel pressure increases by 8x.

Is the fuel pressure fixed (relative to MAP) up to atmospheric pressure, or does it rise exponentially all the way, if that makes sense?

I'm surprised about the ignition timing, it's a shame they never put a knock sensor on the K-series as it sounds like the timing definitely errs on the side of caution, no wonder they're not particularly economical for their size. I can only assume the K-series block doesn't have enough meat to transfer the vibration, as T-series always had closed loop ignition.

 

Is the fuel pressure fixed (relative to MAP) up to atmospheric pressure, or does it rise exponentially all the way, if that makes sense?

The fuel pressure is more or less constant at idle - it used to be approx 3 bar before I adjusted it down to 1.4 bar when I fitted the bigger injectors. Logic is that at the MAP increases above atmosphere, the fuel pressure increases by a factor of 8:1. At o.4 bar boost, the pump would have had to supply pressure of 3 + 0.4 x 8 bar = 6.2 bar. I was concerened about pump capability, so turned RRFPR pressure at idle down to 1.4, which means max pump pressure would be 4.6 bar which is a lot lower and more within the pump's capacity.

christ, is yours vvc too?

I take one look at my ems and it ****s out, how the hell have you got it running seeing boost.

is your rising rate a fse type, they rise by 0.9bar instead of standard 0.6 bar.

I think it has VVC, as it is a 2004 model 160TF. Not sure what you mean with it seeing boost - maybe it does not see boost?

I built a Fuel Cut Defender circuit to fool the ECU in not seeing boost on the MAP sensor. At 0.3 bar boost with the FCD out of circuit, the ECU goes limp. With the FCD in circuit, the head gasket is the limit

- had it at 0.8 bar and FCD works perfectly.

I am using Malpassi RRFPR.

Where do I find Davy Wishart, other than driving to Ireland? Is he perhaps a forum member?

 

christ, is yours vvc too?

I take one look at my ems and it ****s out, how the hell have you got it running seeing boost.

standard fuel pressure is 2.4 to 3bar (closed throttle to open throttle) i.e. 1:1 ratio fuel pressure increase to atmosphere to closed throttle difference. Or do you run lower pressure? or am i confusing absolute with gauge being 1 bar different?

is your rising rate a fse type, they rise by 0.9bar instead of standard 0.6 bar.

try davy wishart, i think hes in ireland, i read somewhere hes like neo from the matrix.

 

god this gets well confusing and i obviously know a gazzilionth you do but:

standards mems is used to only seeing between vacuum and atmospheric it should definitely see no boost or positive pressure.

you run boost but clamped the circuit basically so mems see no more than zero (atmosphere or 1 bar about 99.4 kpa iirc looking at map signal on scanner). So mems is seeing say 35-100kpa then?

so mems cant compensate the timing or fueling at all for any of the boost and revs rise it will be trying to lean out, no?

no knock sensor on mems.

BUT, assuming you are running the standard later 160 vvc map sensor, iirc its not just a map sensor its also a maf/iat type sensor i think, 4 wires, is this aspect of the sensor sending things funny when the airflow picks up as boost overpowers 'standard' vacuum air flow rates?

hth, but probably not!!!
why not run a dta ecu or an emerald, they have pwm drivers to run both vvc and turbo, swap out the map sensor for a proper job

 

standards mems is used to only seeing between vacuum and atmospheric it should definitely see no boost or positive pressure.

you run boost but clamped the circuit basically so mems see no more than zero (atmosphere or 1 bar about 99.4 kpa iirc looking at map signal on scanner). So mems is seeing say 35-100kpa then?

so mems cant compensate the timing or fueling at all for any of the boost and revs rise it will be trying to lean out, no?

BUT, assuming you are running the standard later 160 vvc map sensor, iirc its not just a map sensor its also a maf/iat type sensor i think, 4 wires, is this aspect of the sensor sending things funny when the airflow picks up as boost overpowers 'standard' vacuum air flow rates?

hth, but probably not!!!
why not run a dta ecu or an emerald, they have pwm drivers to run both vvc and turbo, swap out the map sensor for a proper job

I clamped the MAP signal just below the point wher it caused the ECU to go limp, with the hope that maybe they have extended the map slightly to allow for a bit of positive pressure at least. If they did not, then not an issue anyway.

The MAP sensor is actually a dual MAP/IAT sensor as you said (4 wires). The FCD only deals with the MAP sensor though.

Because the fueling nor the timing is modified when I boost, the RRFPR sorts out the fueling side (sort of in a crude way) and the water injection contains any detonation (to a point) if I am running timing too far advanced.

I am planning stand alone ECU setup, but part of the project's aim was to keep the conversion as simple as possible with standard components on the TF to proof that it can be done.

Not sure if you have seen this: http://forums.mg-rover.org/showthread.php?t=215965&highlight=xr3tf

 

With this setup the fuel pressure is increased, so the ECU doesn't know about the extra air or fuel being delivered when on boost.

No MAF with MEMS, I'm not sure whether the IATS is part of the MAP sensor or further down on the inlet manifold near the ports on this setup.

MEMS used a knock sensor on the T-series but not the K-series.

 

With this setup the fuel pressure is increased, so the ECU doesn't know about the extra air or fuel being delivered when on boost.

No MAF with MEMS, I'm not sure whether the IATS is part of the MAP sensor or further down on the inlet manifold near the ports on this setup.

MEMS used a knock sensor on the T-series but not the K-series.

i hear what your saying but it is a maf, thats its technical term, not a map sensor. it does measure map too but its used by ecm to calculate mass air. my turbo diesel for example has a pure map sensor and a separate maf, the 160 doesnt it has a single maf that also reads vacuum if that makes sense.

 

i think earlier mems2j used a separate iat and a map?

 

It measures Manifold Atmospheric Pressure which is used in a calculation with intake air temperature to calculate the air mass per cycle.

An Air Mass Meter or Mass Air Flow meter measures the air mass directly, which then must be divided by engine speed to calculate the air mass per cycle.

 

what happens when you hit limp mode, sounds like the setup is exceeding the map parameters for the vvc timing calculations as the ecu uses map/maf (engineload) to determine cam dwell.

 

Performance drops dramatically and AFR goes to 18+:1. Huge risk if you do not monitor AFR, as it can sometimes go into limp where you do not realize it (aspecially the first few times it happened), and if you then just applies more boost it still goes, but runs very lean - piston melting lean...

Started logging ignition timing and will see what happens with timing when it goes limp.

 

so your probably exceeding the adaptation limts of the ecu for fueling, it then substitutes default values which are probably a bit lean for your setup!

brave man! for the money you spent wouldnt it be better to spend a bit more and buy a DTA ecu, they could probably give you a map to get it running. Apparently their tech support is very good.

 

which ecu have you bought, i assume it has pwm drivers for the vvc solenoids?

 

on the other hand, with forced induction is vvc worth a toss?! probably not, you might be better with a solid cam conversion and a higher rev limit!! go baby go.

 

Bought a local system called Go-Tech Pro X which should cater for all my needs.

This conversion is almost at the point where I wanted it to be - just a low boost conversion.

Project TF360+ needs to get underway - 2.0 16V big turbo setup mated to 6-speed gearbox

 

Hello,

I am an ex-longbridge engineer - I actually was part of the team developing the Mems 3 calibration for TF, and Z models including the 1.8 turbo.

In reply to some points in the thread - Mems does not use a MAF input, relying on a 'speed density' mass air flow conversion from the MAP sensor which also provides an intake temp input.
Regarding knock sensors - these were tried in development but general noise from the block made accurate isolation of a knock event too unreliable - so no knock sensing in production..


Another point to clarify is that Mems does not have a limp home strategy - the only torque limitation is a large retard offset to reduce power above 150 degrees oil temp... Your running issues are down to elementary combustion problems, probably due to component incompatibilty with the ECU.

Mems software includes maps covering injector flow rate/volumetric efficiency and target lambda as a fundamental part in system fuelling calculations. Without accurate compensation your component additions will mean AFR and ignition values way out of control..

Remember the K series turbo involves lower compression, wider range tmap sensor and modulated wastegate control etc. Not to mention a fully revised ECU cal.
Running a VVC with a turbo is another novelty - its possible the wider overlap at higher loads is also giving combustion problems as boost builds.

I now run a support service for Mems issues which includes the ability to rewrite the calibration, for instance to provide the wider range of man pressure inputs needed for a turbo.
However in your case the list of cal areas to be amended would be pretty significant and would also be best developed on a test bed..

For a simpler route for interested parties - I have just begun to investigate the possibilities in offering a calibration for fitment of the K 1.8 turbo in the TF/ZR models which may be the simplest route to turbocharging...Ill keep you posted.

In the meantime have a look at www.zandf-tuning.co.uk
for more info on the service.

 

Hello,

Another point to clarify is that Mems does not have a limp home strategy - the only torque limitation is a large retard offset to reduce power above 150 degrees oil temp... Your running issues are down to elementary combustion problems, probably due to component incompatibilty with the ECU.

Hi, thanks for the information. I do not know what it is called if it is not "limp", but my MEMS 3 definitely "trips" at a certain point for whatever reason. I could get the ECU to adapt to my configuration after driving it for a few months which casued it to stop "tripping" but as soon as I changed the parameters of my setup, it started to trip again whan it is under load for a while / boost rushes in too quickly.

Conditions prior to tripping are that most is well up to that point - AFR at 12.5:1, 70% duty cycle on injectors (not sure about ignition timing) and then all of a sudden for some unknown reason it trips, causing it to run very lean. This condition persists until ignition is switched off and on again.