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MG MGB GT V8 Factory Originals Technical - Rover FI

A revival of a previous thread- I was asking about FI for the Rover 4.2 & was on the fence as to Rover or Ford systems. A Rover wiring harness & ECU has found its way to the work bench, the Rover plenum has been machined to reduce height.

Now I need some Rover info showing all the various vacuum lines & a wiring diagram. The harness is complete & uncut & has plugs for unknown components. I also need a source for the correct resistor for a non-cat stick shift & lots of info I don't know yet that I will need.

Anyone out there that has done the FI willing to share?
Jim Stuart

I'll scan you the wiring harness diagram and get a copy to you. It's pretty straightforward. Actually, it's REALLY straightforward. If you lay the harness out on the floor of your garage, you'll see the two veins -- one for the passenger side, one for the drivers side. basically, just plug everything in, in order going down each vein. I know, sounds archaic, but it's exceptionally effective. I can't think of anywhere where there are two sensors close enough together where the plugs are interchangeable. What you'll need the diagram for is the 5 or so wires that connect to the car.

Over near the plug for the Mass Air Flow sensor, you'll see a black wire. Plug that into the " - " side of the coil. You'll need a feed from the ignition, a power feed from the starter motor (or somewhere else that can handle the amperage you'll need) and a connection to the fuel pump. The rover fuel injection runs the fuel pump, so don't try to just leave it wired to your existing wiring harness. It won't be happy. There are a couple of grounds over near the drivers side of the harness. but those are pretty self explanatory. As for the oxygen sensors themselves -- you can A)buy rover sensors which are MAD expensive or B) cut off the tips and use a generic oxygen sensor. The oxygen sensor you want is (I believe) a 96 nissan sentra, but I'll double check that against my files, and let you know. It should be a 12mm TITANIA sensor, but once again, I'll double check. You CANNOT use a generic zerconia sensor, and get the kind of results the system is capable of. It will run, but not as good as it possibly could.

Have you purchased all new sensors yet? If you haven't, do it now, and be done with it. Over time sensors inevitably go bad, and you'll rack your brains trying to get the car to run good with a bad sensor in the system. Ford 19lb injectors out of a mustang are what will work in our cars, so don't go buying rover injectors.... not necessary!

I think that's everything, if you want, e-mail me at Justin(at)jjgraphics.com

Justin

p.s. I'll let you know how the ford eec-IV system with EDIS works out ;-)
Justin

Hi Justin,
I have a harness from a 1995 Hot wire Rover 4.2 and it is a LOT more complex than you mention. I assume I will have to strip a lot of it out to get back to the essentials you mention above. For example, it looks like there are plugs for 4 relays,the main power and the fuel pump and I don't know what else. Also as you move from the main ECU plug, there is a blue multi pin plug, then two more (a white one and a yellow one) etc etc. My harness seems to also include all the AC connections, power from the alternator, horns, and who knows what else.
Tony Bates

There were small changes to the hotwire looms - you really need to identify which and get the right diagram
Roger

Justin,
I am also working on an FI for the Rover. Just in case I miss something, can you e-mail me also that wiring diagram.
I have a home made ECU that seems to work well. It's an experimental one but has been proven its succes in many hundreds of applications.
I have the Federal injection set up so hood clearance is not so much of a problem. Also it uses the MAP sensor(Vacuum pressure sensor)
Werner
Glad to have your new e-mail
Werner Van Clapdurp

I have the harness layed out & have all the plugs hooked to the sensors, but have lots of unused plugs & no hookups for the temp sender in the thermostat housing or the temp sender (small) on the front of the intake manifold.

As you say, the ground wires are obvious. There are 2 relays present & 2 blade type fuse holders. One I know is for the fuel pump, & I assume the other is power for the ECU???

I spotted the wire to the negitive coil & the O2 sensors. Why does the system require 2?

If I use other than Rover O2 sensors, it appears that they need to be of the heated variety- which wire is the sender? Are the other 2 wires interchangable as to power & ground?

Justin- send me everything. Thanks to all for taking time to help.

How about the vacuum lines?

Any good sources for the Rover senders I will need to replace with new?

Thans again-

Jim
Jim Stuart

Jim, the vacuum lines are kind of up to your discretion. the passenger side of the trumpet stack has 3 spots for vacuum hoses, and the drivers side has one spot. I plugged 2 of the passenger side connections, and used the 3rd for my brake booster, and the drivers side connection is plumbed into the throttle body, and the flame trap on top of the valve cover. I'll take pics of my setup and e-mail them to you tonight.

The oxygen sensor you want is Nissan part number 226A0-40U60. Have your local auto place do a reverse search on that, or go to a nissan dealer. Should be about $60.00 each. You'll need to have a 12mm boss welded to each of your exhaust manifolds as high up as you can. The rover system basically tunes each side of the system, allowing for more or less fuel, based on the results of the reading from that sides O2 sensor. That's why you need two of them.

Tony, my harness is out of a 91 3.9L rover, and I'm sure there's not toooo much difference when they upped to 4.2L. I've actually pulled a 4.2L rover engine harness out of a truck before, so I've seen them first hand. The major difference between yours and mine is the inclusion of the cooling fan relays, and I think the heater relay to your harness and that pesky alternator connection. I chopped a lot of that out of my harness after I read the diagram and confirmed what I needed to make the injection run. There may be other small additions, but for the most part, I think it's pretty straight forward. If you need it, I can e-mail you the wiring diagram that I have, and it should help you keep things straight.

Roger Parker gave us an AWESOME help section in this archive for the rover injection, and I'm going to paste a section of it here. It TOTALLY got me up and running in my fuel injection setup.

Roger Parker wrote:


Basic Rover wiring colour codes apply.

You should have a single 7 or 9 pin connector that doesn't have a home. The wires that come to this will be as follows...

Brown, white/slate, white/purple, black/yellow, black/orange, yellow, yellow/blue, brown/purple.

Some secondary colours vary with different model years and markets, but the basics will be the same.

The main connections are as follows...

Brown to main battery supply - permanently live.

White/slate to ignition switch for the 'ign on' signal.

White/purple feeds power to the fuel pump, but ensure that this then goes through an inertia swicth for safety.

The above are the main functions that apply to this connector. The others there are for ancillary functions as follows...

Black/yellow is the feed wire from the ECU to the dash warning light for EFi faults. Not an essential fit.

Yellow is the sensor wire to the ECU from the road speed input sensor. This assists the correct implementation of the idle speed, but is not that much of an issue if not fitted. However if the sensor IS fitted then the standard inbuilt speed limiter in the ECU will be active and kill the fuelling at between 110 and 112mph.

Black/orange is the sensor wire from the auto gearbox to indicate when the gearbox is in neutral and so the load on the engine is less. This is to enhance idle speed control and with a manual box is superflous.

Yellow/blus is the sensor wire from the air conditioning unit and again is an idle speed control function to ensure idle speed is maintained high enough when the aircon loads the engine and drags speed down. Not used unless your car retains aircon.

Both these latter two functions can be reallocated to other very heavy load functions that can drag the idle speed down and risk stalling.

Brown/purple is a function not used in the UK, but is going to be an additional sensor function for idle speed control.

In addition to the wires in this plug you will find a number of other connections. There are several separate earth connections. The ones nearest the injector end of the loom are intended to be bolted to the engine and not the body of the car. This is to allow for potential poorer earth paths from engine to body later in life. There will be additional earths nearest to the ECU plug end.

There are also a couple of standard relay holders which are for the main system relay and the fuel pump relay. You can see the colour codes of the wires from what I mention above.

A very important single wire connection that is separate and found near to the airflow meter plug is a single white/black wire which is the sensor connection wire for the negative side of the coil. This provides the ECU with engine speed information and has to be connected to the ECU through a 6.8k ohm resistor. This should actually be in the loom so a simple resistance check from the end of this wire to the ECU plug, pin 39 will reveal whether the resistor is in circuit. If not get one and use it to protect the ECU from spikes.

There will also be another couple of connectors. One should have a sealed resistor in it and is known as the 'tune resistor'. This alters the actual map in the ECU that is used.

There is also a diagnostic plug that should have four wires. Black/slate, white/light green, white/pink and white/yellow. Leave this untouched as it will alow for any Rover diagnostic unit to be plugged in and system faults read. Very useful if you have a problem that you can't get to the bottom of.



Enjoy!
Justin
Justin

If you don't wish/need to fit oxygen sensors - change the tune resistor.
Roger

What value Roger ?

Mike
Michael barnfather

Mike
PRC 8182 (green wires) from any LandRover dealer -
Jim
sorry; forgotten resistor coding and can not give the value of the resistor needed to 'compensate' for manual gearshift - anyone else ????.

Also - For the record - the colour codes (above) may vary
Also - speed sensor important to maintain minimum revs while the car is still moving (otherwise there is a risk of stalling in the over-run - slowdown situation)

Roger
Roger

I recognize it is wholly possible, and relatively easy to leave out the oxygen sensors, but at that point you're relying on the pre-programmed fuel maps within the ECU. It will work just fine (as many have proved) but I don't think it will allow the ecu to do all it's capable of, and really limits your options when it comes to tuning. That's just my two cents
Justin

Hi Justin, thanks for all the sound advice, can you email me any and all info you have that may help with my installation.
tony@batesfamily.net
Tony Bates

Justin
You mention that you used Mustang injectors, do you ahve any more info/part numbers etc.
Regards
Tony
Tony Bates

Should be a mustang d9b injector. I bought mine at http://www.fiveomotorsport.com I think around $180.00 for the set.

Justin
Justin

Justin-

Thanks for the additional information.

Where is the source of Roger's FI info? Is it in the archives?
Jim Stuart

All-

If you want O2 sensors that plug into the harness without modification, try www.oxygensensors.com. I recently purchased a set for $95 per injector. I just checked and they are still offered at that price.
Scott Miller

Hi All,
Here's a real puzzle. I have just checked out my harness (1995 Hotwire off a 4.2 Range Rover)and there is no pin 5 in my harness plug that connects to the ECU. I have taken the plug apart and there is no pin or wire for pin 5, just a blank hole. I also cannot find the tune resistor anywhere in the harness.
Is it possible that some setups had no tune resistor?
Regards
Tony
Tony Bates

Before this thread dies,does anyone have answers to the following ? I have a small cannister (1.5") diam. with a black direction arrow on it . It mounts near the #3 injector. I think it allows more air into the plenum when there's a sudden drain on the electrical system, I'm not sure.It has a black lead which connects into the car's loom , not the EFI's, but where ? Also the press. return valve has 2 wires ( blue & black) which connect to the EFI loom. The corresponding wires seem to be both white. I'm wondering if these leads are polarised or just a series switch ? I can't find any reference to either. Thanks for any replies. Barrie E.
Barrie Egerton

Man Tony that's a tough one! I know some of the car had the tune resistor built right into the harness (as opposed to a removeable plug) but a lack of a pin #5.... yikes! Did you pull the harness yourself or where did it come from? Around 95 rover was making some "half breed" motors that had the old timing cover with the external oilpump, but were running the gems engine management system (i.e. no distributor) maybe you have one of those? Otherwise I'm completely clueless!

Barry, maybe the canister is some sort of shutoff valve? i.e. dumps more air into the motor so it runs lean and dies... I'm not really sure w/o looking at one. "Press return valve..." I'm not following you on what that is either.

Justin
Justin

Justin, it's the valve between the fuel rail & the & the return line to the tank. Barrie E
Barrie Egerton

Hi Justin,
The harness definately came off a 95 4.2 engine. It was installed on the engine when I got it. The engine had the crank driven pump and serpentine belts and a distributor, now all changed for early Buick parts etc.
It has been suggested that by 1995, maybe all vehicles had cat converters so there was no need to mount the resistor in the harness any longer?
Tony Bates

Tony, according to my ShopKey program, U.S. models after Vin #..451518 use ecm PRC8747 which does NOT use a tune resistor and therfore no pin #5.Also a corresponding fault code #21 is no longer stored by ecm. I believe this change occured in late 1994.
Joaquin

Barrie, it would seem to me that your fuel pressure regulator has some sort of connection to the EFI warning light. If fuel pressure drops, it probably triggers the light on the dash...

If there's no tune resistor, and the ecu isn't programmed for one, then I'd say you don't have much of a choice when it comes to cats, and oxygen sensors. Next question: If the oxygen sensors came after the cats, and now you don't have any, is the computer going to freak out at all the exhaust gasses passing by the sensors?

Justin
Justin

Joaquin-

Perhaps you can shed some light on my situation. I also have a harness that has no tune resistor and no PIN # 5. The ECU I have is PRC7081. Do I need to either a) add a tune resistor to my harness or b) find a new ECU (PRC8747)?

Thanks
Scott

Hi Joaquin
The Land Rover ECU label states it is a 14CUX, there are two other numbers on the label, AMR3729 and 80506A, any idea what these are, I cannot find a PRC number anywhere, where would it be? The date code is 8/94 so it would fit with your date comment. There is alos a small white label that say: Tune #3652, any ideas what this might be?
Regards
Tony
Tony Bates

Will be back in office on Monday.
Joaquin

So, I have an '80 SD1...if I just lifted the engine/tranny & instruments/wiring loom/fuel pump could it all put transplanted into an MG without much modifications?
anthony barnhill

Tony, been there done that. No big deal. If you back the motor up the 1 1/4" for the A/C & get a set of my F/I mts. that drop the motor down you do not need to do anything to the F/I manifold, it all goes under the steel hood
Glenn Towery

Glen...will call you Monday...I'm gonna junk the SD1 & put the entire drivetrain under a '68 GT I have...quick & dirty, not like my long-term V8 project...need something I can drive in a couple of weekends - cheap!
anthony barnhill

Spent some time on the bench today with the injection unit & wiring harness, eliminating the superflous. I found the plug for the tune resistor, but none is present. The plug is not like the picture in the Rover manual, but the wire colors are correct. My info says I need a 180 ohm tune resistor for "Austrailia, rest of the world" as opposed to Saudi, Europe, etc. Any corrections or other input? Sources?

Next, I tried to locate the resistor #11A in the diagram which has different values depending upon manual or auto tranny, cat or non cat, but cannot find it in the harness. Any words of help?

I am looking for the plastic elbow that connects the plenum to the hot wire unit, so if anyone has a spare or a source or an alternate piece of plumbing, please speak up. I do not want to use flex hose.

Thanks for all the help so far.

Jim Stuart
Jim Stuart

Justin,

I also am struggling with the wiring, mine's off a 1990 Range Rover ( I think) .Can you e mail me a wiring diagram, as the snipped wires don't seem to have the right colours.

Mike
Michael barnfather

Jim,
Not exactly how it's meant to be used, but I went to Lowes and bought a rubber 90 elbow for 4" pvc pipe. The ends of the rubber elbow are about 4 3/8" which is too big for the plenum connection, but it's darn close to the size of the MAF. I used a hack saw and cut off the neck of one end of the elbow, which left that end at about 4" inside diameter, which fit comfortably over the plenum opening, and the other end fit the maf without modification (IIRC) I'll take a close up, detailed picture of it, and e-mail it to anyone who wants it.

Mike,
I'll e-mail you the diagram tonight. Is your computer the 14cux model, or the 14cu model? Both have differences in their wiring harness.

Justin
Justin

Justin,
Don't you mean 3" pipe? how did you attach the elbow to the plenum and the MAF?
Tony
Tony Bates

Jim, have you stripped away the protective sleeve around the wiring harness near the ecu plug? I bet if you removed the pvc wrap back a couple feet it might reveal some of the things you're looking for. If you still can't find 11a, you could probably locate its wires in the loom, and follow them to their end, or even just cut them, and insert your own resistor and be done with it.

Tony,

I'm pretty sure it was 4", but I'll measure tonight. I attached it with some really stinking big hose clamps.

Justin

p.s. I attached an "L" shaped bracket to the inner fender under the MAF and let it rest on that. I know, not the most asthetically pleasing method, but darn effective.
Justin

Justin, was this elbow hard PVC type material or rubber type?
Regarding the 510 ohm resistor (11a) used to identify a manual gearbox, it would appear from your circuit diagram that it would be outside the loom, connected to it via a pin in the white plug with small pins to the main harness? Would it possibly be in the main harness rather than the EFI one?
Tony
Tony Bates

On my harness (1994 Lucas CUX) the 510 ohm resistor is fitted outside the harness between the orange and black wire and ground.

The tune resistor are red, yellow, white (3,900 Ohm), green (470 ohm), and blue. White is cat tune and green is non-cat tune for UK. Don't know about the other values but think they are for different fuel quality in non-UK markets.

By cat tune it means that you need to run with oxygen sensors - but you dont actually need catalytic converters. The sensors would be fitted in the manifold ahead of the cats so it makes no difference if the cats are not fitted. With non-cat tune you do not need oxygen sensors.

Other wires as per Justin's earlier post except fuel injection warning light is red/slate; speed sensor yellow/pink; purple/yellow is a load sensor intended for heated rear window but can be used for any electrical load; three wires that have something to do with a a/c fan timer module and can be left as open circuit(black/slate, black/green, yellow/black).

On North American looms you should find an extra 4 pin connector that can be connected to a fault code display.

Geoff
Geoff Richmond

Jim, I've found that Hot Rod or Street Machine shops sell convaluted tubing or ducting & elbows for EFI or after market turbos.Also ready made surge tanks with various mountings & sizes. I looked at 3" 90 degree PVC elbows in a Plumbers shop, but I think the heat under the hood would be too much for PVC.

Justin, would you please email me an EFI cct diagram ? I'm using a 14CU ECU.

Anyone, my car is an auto, so I need any info on how to connect the auto tx inhibit switch into the system.
Barrie E
Barrie Egerton

Justin-

I have stripped the cover completely & found no resistor.m Also, no cut wires, so I wonder if it is in the ECU?

Geoff-

I found the connectors as you describe. Thanks for the explaination of cat & non cat. As I will be using O2 sensors, I would have chosen the wrong resistor.

Barrie-

Off to my favorite Street Rod shop one day this week.

Thanks to all.

Jim Stuart
Jim Stuart

Justin,
you are an officer and a gentleman ! Its a 14cux 1990 model.

Mike
Michael barnfather

Ok guys, I went ahead and posted about 7 photos on the internet at http://photos.yahoo.com/bmanetd and the folder "rover fuel injection" The 14cux wiring harness diagram is there, as are a few photos of various parts of my injection system.

Tony, You were right, it is a 3" rubber elbow, not a 4" elbow. Sorry!

Jim, The resistor for the manual gearbox was on the outside of my wiring harness, so I'm a little confused about yours not being there.... I suppse you could just splice it into the wires when you locate them.

Justin
Justin

Perhaps my program here has wrong info, but it states the following for Land Rover Range Rover 14cux systems.

1990 systems had 3900 ohm resistor.
1991 -1995 as follows
Red wire (180 ohms)-Australia and rest of world.
Green wire (470 ohms)-European, non catalyst.
White wire (3900 ohms)-European, catalyst.
Yellow wire (910 ohms)- Saudia Arabia, non catalyst.


Also showing engine control computer numbers
start with AMR37...
And also Fuel injection control module with PRC7...

don't know if this helps anyone.
joaquin

Perhaps it is the tune resistor that is external & the other resistor-11a- is a resistor wire, not an external part.
Jim Stuart

Jim - for what its worth, I was advised to install the resistor externally (to convert the signal from auto to manual).

You will remember to connect up your fans and a/c won't you.
Roger Walker

A/C & fan are installed & working, & will remain seperate from the Rover loom. A trianary switch in the dryer turns on the cooling fan when the A/C is operation & a seperate adjustable sensor controls the cooling fan when the A/C is not running.
Jim Stuart

The ECU has a couple of advisory links so that it can take account of voltage dips from say the fans or a/c starting. It is advisable to use these if there is a connection to avoid revs shunting.
RMW

This thread was discussed between 24/11/2003 and 04/12/2003

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