MEMS 1.9 to MEMS 3 help.

[STW82]

Good morning all!

I found your very helpful forum whilst looking for information relating to converting MEMS 1.9 to MEMS 3. I did lots of reading on numerous posts before posting but there are still a few bits I couldn't get my head around. While my car is a Rover 100, I'm hoping some of the information I found will still apply. I've not had much response from the Metro community with getting any info. I'd like to do all the work myself and then I know exactly what's wired to where if I need to diagnose anything which is why I haven't yet gone down the route of paying someone to convert the loom.

I have a MG ZR 1.4 16v engine with a MEMS 3 loom and ECU. I understand I have to use both looms, that the finished loom will need to have the MEMS 3 ecu plugs and the MEMS 1.9 MFRU. The ecu I have been supplied is free running.

Am I better off -

A) using the majority of the MEMS 1.9 loom, changing ecu plugs and adding the extra sensors and wiring from the MEMS 3 loom into the 1.9

OR

B) using the MEMS 3 loom and wiring the MFRU into it?

Sorry if this has been covered already, I didn't come across the info.

[Rob Bell]

Welcome to the forum!

In answer to your question, I first have a question (sorry!): Are you looking to upgrade to MEMS3 for the flexibility of remapping?

If you're not looking to re-map, I'd actually just keep the MEMS1.9, but find a suitable ECU for the 1.4 litre engine (circa 1995-1999 Rover 214). With this solution, you'd just have to swap over the existing engine loom to the new engine for it to be plug and play, assuming that your Metro has a K-series with multi-point fuel injection. Most Rover Metros would have had either carbs or single-point fuel injection - and in which case, you might just as well go for MEMS3 if you're having to fit a whole new engine harness anyway.

However, I assume that you're looking for MEMS3 for the additional programming flexibility?

If so, you've probably already found my thread where I've spliced together the MEMS3 engine loom with the MEMS1.9 main loom connectors? (viewtopic.php?f=8&t=11758&start=240). I did a lot of reading and research, but the bottom line is that you remove the MEMS3 loom plugs from the engine loom, remove the MEMS1.9 loom plugs from a MEMS1.9 engine loom, and splice the MEMS1.9 loom plugs to the MEMS3 engine loom - largely just connecting up the matching wiring colour codes.

Yes - there are a few bits that get a little more confusing than this - and you've got to connect the correct wires to the appropriate connectors (it's possible to get this wrong). There are also multiple iterations of engine loom that I wasn't aware of, and fell slightly foul of. But in general, none of this is rocket science and you'll get there.

MEMS3 also has a number of additional sensor inputs that simply do not exist in MEMS1.9. This is no disaster: the ECU still works. Plus, you can get these extra sensors and functions "written out" if you get the MEMS3 remapped (Mark Stacey knows all about this).

Hope this helps - and do let us know how you get on

[RobboMC]

It looks to me like you're fitting a new engine to your Rover 100 that came from a ZR and it doesn't match?

I had this problem. I have a 99 model MGF that was MEMS 1.9 and I grabbed a reconditioned engine that was MEMS 3.
My solution was simple, rather than attempt to rewire half the engine bay I simply removed the cams from the MEMS 1.9 engine
and put them onto the other engine, along with the matching cam cover ( no cam angle sensor )

This of course gave me the correct distributor drive. I also brought across every single sensor from the old engine including the
entire inlet manifold.

There are 27 different versions of the K16 just in the MGF. Add the variations in the Rovers and Freelanders and you end up with a large variety.

But the motors before they are 'dressed' are pretty much all the same.
Of course if your path is to remapping and hot cams then of course you need MEMS 3 as Rob states.

Once I left the ignition ON for a few minutes for the stepper motors to reset my little project fired up first kick.
Remember a 'dry' motor will take more oil than the book says, so crank it for a minute or so to fill up the oil galleries and top
up to correct fill line before you let it fire.

[STW82]

Hi guys, thanks for the input.

I am fitting the ZR 1.4 engine to my Rover 100 which was originally a 1.1 8v MPI. A local chap sold me the engine and I didn't think too much about the compatibility side of it at the time. I hadn't really thought to much about retaining the old loom and changing the ECU. As I bought the engine package as a conversion I figured I may as well swap to the MEMS3 as it will also make life easier if I want to modify the 1.4 or go down the 1.8 route in the future. It's probably a close one (hassle wise) between sourcing and fitting the cam cover, ignition setup, and ECU from a MEMS 1.9 car or splicing in the MEMS 3 loom.

I hadn't actually seen your thread Rob (just some of the images contained within). Top work on documenting the work and even just the notes and thought process as you went. Hopefully that will help me

I think I'm just going to have to bite the bullet and lock myself away in the garage with a hot soldering iron, heat shrink and this forum and see what I end up with.

Also added a photo to brighten the post up.

[talkingcars]

Hi and welcome to the forum.

James

[Rob Bell]

Great job - it fits in there as though it was supposed to be there in the first place

Yes, I think this will be a task of making good friends with your soldering iron with a good supply of shrink wrap! I confess my project stalled as other things cropped up along the way (as they do). And I may end up fitting a ZR160 engine, but using MEMS2J in the first instance. Even if I do go MEMS3 for the 160, I'll need to make a new loom as the VVC loom is different from the MPi 16v. D'oh!

Do let us know how you get on!

[STW82]

Well I got stuck in and separated the MEMS 1.9 loom to remove the ECU plug and sensors I won't need to use on the new loom.

I spent this evening splicing the looms together matching wires and using screw terminals to match them up (mainly as I forgot to buy some heatshrink).

I seem to have got most of the wires sorted but I have a plug i can't identify.
It has a white/orange that runs to the interior loom, a powered brown/pink and a black with a ring terminal on it.


Location on interior loom plug.

Also, will I need to use a downstream lambda sensor?

[quick_spider]

That’s the speedo sensor - you won’t be needing it on the Metro unless you have the skills to convert the dials from mechanical drive to to electronic drive.

[STW82]

Ah I thought this one was the speedo sensor plug.

[quick_spider]

I don’t recognise that one at all. Was it an auto gearbox on the donor car?

[STW82]

I don't know the answer to that one unfortunately.

Soldered my connections and fired it up. Started first time but the idle control valve is making a constant electrical buzz/whine noise.

[quick_spider]

It sounds like it’s normal - the idle control valve will chatter for a few minutes after the engine is turned off while the main relay is still live.

[Rob Bell]

I don't know the answer to that one unfortunately.

Soldered my connections and fired it up. Started first time but the idle control valve is making a constant electrical buzz/whine noise.

Great result!

Have you taken it for a drive yet?

[STW82]

Not yet unfortunately. I'm still waiting on my suspension being finished. The valves in the top are tapered whereas my threaded boss is parallel so I'm waiting on some adapters to arrive.

I realised today I have no fan and have the fan relay and wiring on the old loom. I have been going over the diagrams trying to make sense of where my grey/blue wires connects to on the ECU but then started getting confused as the wire is already connected to the small plug on the MFRU but to my lambda relay. Then I noticed on the Rover 100 diagram it is listed as a fan relay (Not the lambda relay? Am I essentially changing the old lambda really in the MFRU into a fan control relay or do some MFRU control the fan?

[Rob Bell]

May well be different depending on application - did your Metro even have a Lambda sensor? Some would have pre-dated the need for a catalyst. I had a Metro 1.4GTa that proudly sported a "Catalyst" badge, acknowledging that it was one of the cars so fitted!

It was great - only SPi, but went like a mini rocket. I expect your 1.4 MPi to be even better. Just make sure you have a ZR throttle body - the Rover version limited performance by not opening fully

[STW82]

It had a lambda when it was a 1.1. I guess time will tell if the relay is going to work as a cooling fan relay (it should do in theory)

I'm looking forward to driving it. I have only actually driven it once to get it home after buying it. The engine came from the ZR. Caterham tuned the 1.4 to 120 bhp so I'm currently trying to find our what they did to the engines to get it there.

[talkingcars]

The post cat lambda probe can be deleted in MEMS3, it is only there to monitor the cat anyway.

Did you change the coolant temp sensor, MEMS 3 needs the black one, if it has the brown one it may explain the lack of cooling fan. Un plug it and the fan should start.

[STW82]

I hadn't changed the sensors so I but both in from the donor engine. I connected the blue plug(single wire) to the blue sensor. When I unplugged the blue the fan didn't kick in, when I unplugged the black one, it kicked in.

[2woody]

I've converted from MEMS 2 to MEMS 3 in my 200 BRM.

it is much easier just to lift the entire loom from the donor car and connect out from there. That way you get all of the functionality that comes with the later car. I was specifically after cat health monitoring and ability to use OBD-II, rather than to be able to reprogram it - its easily fast enough already

the tricky points (if you can call them that) were as follows:-
a difference in vehicle speed sensor output style
ABS block needing changing to MEMS 3 style
difference in relays, MEMS 3 uses separate relays, but MEMS 2 uses a relay box with a number of functions

I started with the wiring diagrams for both and marked up the differences - in that way you can keep track of what you've done as you go along

for yours, MEMS 3 is expecting either a signal from the ABS block OR a signal from a single wheel speed sensor. It uses this to suspend misfire detection if the car is on a "rough road"

I'd be prepared to mark you up a wiring diagram if you needed.....

[STW82]

Ok, so I have got the car on the road and done a few miles in it to work and back for a week or so and it all seems to be running okay. Not as nippy as I'd have liked but I'm impressed by how its turned out. It's just a nice little car and a great starting point for future modifications. When I did the wiring one of the wires was for the diagnostic link. Am I able to run a diagnostic check in the same way as when it was MEMS1.9? Also secondly is it worth wiring in an OBDII port (if so is there any good diagrams). I mainly want to check now that the ECU is receiving and processing all the signals correctly before looking at carrying out any further work.

Thanks for all the advice you have been able to offer. It really wasn't as hard as I'd read on the internet in the end.