The air filter I prefer is the type that is fitted into the standard air box. The filter size dictates that it has more than enough filtering and flow capacity, and keeping it in the box means that it will not become noisy. I have found the K&N replacement element to be excellent, the one in the car lasting for over 10 years without needing a clean! The Pipercross (and others) should provide the same basic flow/filtration but I can't say whether they would last as long before needing a clean.
Exhausts
The exhaust system will not provide any more power unless the head is modified to suit. On that basis the only change that you are likely to see with a performance type exhaust is one of a diferent noise - read louder! I have found that the Bell stainless systems are very good, especially if you have the type of silencers that can be opened up and repacked with rockwool in a few years time. This is always the failing of stainless systems, losing the filling over a period of years leading to a very boomy and noisy exhaust. Simple repacking will provide a very significant increase in system life, which is good to start with! Another bonus with the Bell systems is that they are efficient and have provided good power on cars that have been converted to 16 valve
engines, as well as those that have been given a Burgess head. This gives the Bell a significant advantage.
Motobuild used to use PCS for their exhaust systems and I found that on the EFi they weren't as effective as a Janspeed and only cost a little less. The current systems are 'said' to be from another supplier, but I'm not so sure. Fit of the PCS systems is poor, Janspeed and Bell is spot on.
Ignition
In the best traditions of old 'mechanicing' replace the plugs for NGK or Bosch resistor type plugs as listed for the model (NGK BPR6ES) (Bosch WR7DC) with the gap set at 0.9mm. Check the dizzy cap and rotor. The
cap can suffer from tiny cracks from the electrode posts inwards through towards the centre, and the rotor erodes under the tip. If in doubt just change them for new.
Suspension
The Turbo suspension bushes are applicable for both Maestro and Montego and late cars (1989 model year on) use the Turbo spec bushes as standard all round.
Montego tyres and steering
The steering wheel removal follows the same route whether you have the early nut (large) or later bolt (small) fixing. To access this use a small screwdriver to lift out the 'MG' in the wheel centre, it is lipped in to the left of the M and right of the G. Pull off the plastic nut cover (if it is still there) and undo the bolt/nut. Before removing the wheel line up the car so that the wheels are in the straight ahead position so that you can easily place the wheel back in the right position. Now you have to ease the wheel off by tapping (Hammering even) the underside of the wheel to break the seal off the spline. There is a tool for extraction but gentle persuasion always succeeds with no damage.
As you are going to change tyres leave the steering wheel till after the new tyres are fitted. With new tyres you want to ensure the tracking is correct, as this often drifts out of true. New tyres and resetting the tracking very often brings back the steering wheel to the correct position.
As to tyres use a 185/60 x14 if you have the earlier 14" dismeter wheels. If you have the 15" versions then go for 195/50 x 15. Both sizes are slightly wider and lower profile than the OE fittings, but will give virtually the same accuracy for the speedo. Being common sizes they are much much cheaper and you will have a very wide choice.
Montego wheel arches
The wheel arches are easily cut away with an angle grinder and you can buy replacements at virtually any motor panel suppliers. I am not sure of the price for Maestro ones but I recently did the ones on my Montego and got the new arches for £18.30 each. You could probably get someone to weld them in pretty cheaply too as they are very easy although some care has to be taken due to the close proximity of the petrol tank to the drivers side arch.
Rear shock absorbers
Stripping the thread won't be the problem but distortion of the inner part of the frame nearest to the bolt head will be! Quite simply the corrosion weld between the bolt and bush steel sleeve will be almost impossible to break. The quickest and easiest route is to liberally spray the threaded area and wind the bolt in and out as much as possible to free off the thread. With this done cut through the bolt either side of the damper and remove. The threaded part will still be in the H frame, but now use the saw to cut a screwdriver slot in the cut end. You can now insert a screwdriver in through the frame and simply unscrew the remains of the bolt. This is where the easing of the bolt to start with pays off.
Obtain a replacement bolt from either a dealer or bolt supplier and replace as per mainual. Liberal use of coppaslip helps prevent this problem in the future. Rover part number for bolt is ADU 8347
Fuel
From the 1989 model year cars, fitted with the 20HE series engines and either ERIC or MEMS Mpi integrated engine management system, (silver fluted / silver ECU in engine compartment) are all designed to use 95RON unleaded. If they care to open the bonnet or petrol flap of one of these cars they should see the tell tale green unleaded labels as fixed by the factory. Failing that check the engine number which must read 20HE99, the E99 being the engine code for 1989 and on unleaded engines.
ECUs, fuel consumption and related problems
The throttle switch on the pedal is integral to idle speed control and if the bracket has bent, which is not unusual, and the switch is not being operated then this early MEMS is not intelligent enough to compensate smoothly. Basically the pedal arm should come to rest and just push onto the switch to operate it. Although it is in the most difficult of positions to get at, it may be worth pulling off the two spade connections and checking operation with an ohmeter.
The surge at idle you have is another common problem which is usually down to two things. 1, idle mixture incorrect
2, incorrect mechanical setting between the stepper motor and the throttle linkage. Adjustment is via the tuning interface I mentioned before.
The operation of the throttle at the engine will induce a flat spot on acceleration for exactly the reason you suspect. Once you have created an 'error' situation the engine will almost certainly run rough from that point. As a guide when you hit this switch of the engine, count to 20 (which allows time for the ECU to deactivate the main power relay) and then switch on just the ignition. Count to 3 then start the engine and allow the idle to settle by itself. Keep feet away from the throttle during this process.
This is the equivalent of saying to the ECU, 1 + 1 = 2, 2 + 2 = 4, etc. As I said it is a simple device easily confused by odd inputs - poor thing!!! This proceedure should allow the MEMS to reset all parameters to 0 so that when restarting it stats from a known position so it doesn't 'get lost'.
Manifold leaks & rough idle
ANY leaks on the manifold will throw the idle speed and smoothness out of the window. At idle the throttle is closed and only a fixed small ammount of air is allowed to pass. The manifold vacuum is at it's highest so any gasket leaks will allow air to be drawn in weakening the mixture and raising the idle speed. As you open the throttle the amount of air entering the engine is increased considerably so the air leak through the gasket is proportionally much less than it is at idle, so has less of an effect. This is why as the engine revs rise the engine smooths out.
Replace the manifold gasket and then also do the exhaust, even if it is just a temporary 'Gun Gum' job. You will then be able to see wether the problems have gone. It may be that the idle setting of the throttle mechanism in the stepper and the MEMS unit will have to be reset. This is a job requiring a module that plugs into the round three pin socket near the MEMS unit. Idle speed and mixture is set with the assistance of one of these interface modules. I have one and most tune up operators should also - whether they can use it is another question!
Question.
Does anyone know why my Aug '87 MG Maestro Efi is only doing about 60 road miles to £10 of 4 star petrol. This seems rather hard compared to my previous Apr '88 Efi Maestro which did about 120-130 miles to £10 of 4 star?
Answer
Make sure that the basics such as plugs, air filter, leads, dizzy cap and rotor arm are spot on.
Does the temerature gauge read normal and steady (ie a notch or two before the centre position.)
The temp sensors (screwed into the thermostat housing by the servo) have a reputaion for failing and leading to false temperature readings. As the ECU's read this information they may be 'fooled' into believing that the engine is cool. They then apply 'correction factors' leading to extra fuel being injected all the time.
For the same reasons the thermostat also has a similar effect when not working properly. An 88 degree unit is the correct one. Does the heater work well or not? A poor heater and perhaps a slightly low tem reading are sure indications that the thermostat has probably failed.
These first two problems account for about 95% of these types of problems. If these are ok then you have to look deeper. Is the inside of the exhaust very sooty and do you have difficulty in achieving the 2 to 3% CO level that it should be set at?
If so then you may well have a problem within the fuel ECU. These sometimes have a failure on the circuit board, leading to a permanent rich mixture. Often the cause of this is an electrical spike through the wiring.
The cure is to replace with another ECU. As before with the gearbox, you can source ANY ECU from any 2 litre Maestro or Montego. They will all work the car well with no other changes. The very early Efi Montego's ECU (Lucas number code 84399, found on the stick on label) was not quite right for all engines and may be a little weak, so given a choice avoid it. The number on your ECU will be 84498, or depending on the build date, it may even be the later 84598. Either of these are equally good as far as performance and economy are concerned.
There is also the strong possibility that your injectors are well past their best and may be leaking. Checking is a case of removing the fuel rail, complete with injectors, yet leaving the fuel line connected. With much rag underneath turn on the ignition and pressurise the fuel rail. The book says that any injector that drips more than 2 drips per minute is scrap. Don't believe that, they can be brought back. The other probability with the injectors is that the spray pattern will be shot. This is more fiddly to check as you need a milk bottle or similar. Disconnect all but one electrical plug to the injectors and place the bottle under that one. Get an assistant to crank the engine and watch the spray pattern. It should be a find mist in a conical shape. Anything less that that will lead to poor running, performance and economy. Repeat for each injector and note how different each pattern is.
Rectification follows one of two routes.
1, remove injectors from rail and take to an establishment that has an ultrasonsic cleaning machine. This will remove all deposits and maximise flow and patterns.
2, take whole car to establishment that has an 'on the car' cleaning service. In this case the injectors are left fitted to the engine and only the fuel feed and return hoses are disconnected. The fuel rail is then connected to a machine that provides a very very strong cleaning fluid which also acts as the fuel to run engine. The passage of this fluid has a very similar effect to the firts method in disolving the deposits causing problems.
Advantages?
Method 1,
You only take the injectors which are fully cleaned tested and balanced as a set, any odd flowing injector is identified. The internal filter baskets and rubber seals are normally changed within the price.
Method 2,
You simply drive the car to the garage and leave it with them, no dirty hands. The whole process involves less disturbance to the engine. The cleaning fluid is very effective at not only cleaning the injectors, but also cleans the inlet tracts, valves and seats. There is also a cleaning effect inside the cylinders and even in the exhaust. (Just like a good decoke)
As the costs are similar (£50/60 ish)I would plump for the 'on the car' treatment with it's extra benefits. The ultrasonic cleaning really comes into its own where injectors are seriously restricted or even blocked. Other than the above just amke sure that all the wiring connections are clean and tight.
On doing some further reading on this subject it could also be the fuel temperature switch which is located in the fuel rail. Disconnecting this when the engine is hot is a quick test you can do. If the mixture goes back to normal then the switch will need to be replaced. The coolant temperature switch can be tested with a multi-meter which should register 3.5V cold and .5V when hot. The air flow meter could also give this problem but is less likely than the switches. If you let me have your address I can send you some articles from Car Mechanics which deal with this subject specifically.
As the system start up involves the energising of the pump for a second on initial feed of 12 volts to the system none of the external sensors will at this time have any bearing on the system operation. Anyway as far as the pump is concerned there is the starter connection to bypass the pump resistor during cranking so that this will automatically provide battery power to the pump. The fact that you can hear the pump working by earthing pin 16 confirms the system is intact.
I have come across more cases of ECU failure in recent years as the units get older and are subject to damage, water/damp ingress, 12 volts where 12 volts shouldn't go!, as common problems. There is usually a sign on the circuit board to indicate problems. The simplest check is to change your ECU for one that is known to work and with the numbers of 2 litre injected 'O' series engined cars in breakers there is a good supply of sound parts.
Coventry is well served by breakers specialising in Rover/Maestro/Montego and there are plenty of general breakers that will also have cars. Have a look in the Salvage section of the Midland Auto Trader for dozens of specialists. What you want is ANY fuel ECU from any Maestro EF1/2.0i from 1984 to 1991, or Montego EFi/2.0i from 1984 to 1989. Depending on the specific date your car was built the ECU will contain two identity numbers, one a Rover part number starting with ADU and the other a five digit one which is the Lucas part number. I can only remember the Lucas numbers which are 84498 (most likely for yours) or later 84598. These are the most common unit numbers,and are the most suitable. The very early cars used 84399 and 84400 but these I would suggest are only suitable to confirm you have an ECU fault since there were problems with very weak running on early cars using these ECU's.
Maestro 2.0 EFi 1989 98000miles (NOT MEMS!)
Qestion:
Symptom: Start up is fine, but once warm, and more so around town, when I come to pull at up lights and juctions etc, the revs drop right down and I lose the engine, so I have to restart. It will sometimes then run ok, (@ 6-700rpm) but normally I have to feather the throttle to keep the engine running. The question is should I adjust the idle, when warm, at the carb? Or should I take it up on the throttle cable?
If I take the car for a run, and get it really warm, it does seem to maintain sufficent idle when pulling up. The problem came on quite suddenly, at first I thought it was dodgy petrol, but its gets some healthy Esso 4*, and I have discounted the dodgy fuel!!
Answer
1,Remove the 4 pin plug from the stepper and then remove the stepper. The cone shaped valve at the end of the spring will be all sooted up. Get some carb or choke cleaner in a spray can (both the same substance just different titles) and clean up the stepper. Then spray out the aperture in the throttle housing. Whilst your at it remove the main air pipe from the throttle and say 'UGH' when you look at the horrible mess around the throttle disc and beyond! Give this a good spraying then clean up with absorbent material. Allow a few minutes for the cleaning fluid to evaporate before reassembly.
2,Check your breather pipes and flame trap as when these block it affects engine running, especially at idle.
3,Change plugs and set the gap to 0.9mm (36 thou). Check air filter and change if heavily soiled. (the air filter will have more of an effect at wide throttle openings when large air volumes are demanded by the engine. At idle only the really heavily soiled filter would have an effect.
4,Give the car a run to warm it up and clear out any residue of the cleaning fluid. See how it now runs.
5, If the idle is still low, and especially if it is very 'lumpy' check the CO. Adjust to between 2 and 3%.
6,At this stage you are into resetting the idle manually. Use the throttle stop screw to achieve the desired idle. I suggest around 850 rpm gives best results.
7, Check that the throttle pot is still at the correct value, 0.325v (+ or - 0.01v) at idle, by using a multimeter between the green/yellow (red wire from multimeter) and pink/black (black wire from meter) wires coming from the pot. The best checking point is at the plug found about six inches down the wires from the pot. Things should now be much better.
Modified heads
For help and advice on Performance Tuning such as gas-flowed heads then speak to Peter of Peter Burgess Performance Tuning. You can telephone him on 01773 520021
Why is everybody spending £'s on modifying ignition & fuel ECU's on the 2.0 EFI engine? The engine management uses a Lucas hot wire system which, basically, measures the amount of air going in and fuels accordingly. Hence, if you mod the head or block to get more air in then the engine management bungs more fuel in. Peter Burgess of rolling road fame has had a Maestro up to 130 bhp - at the wheels on a standard injection & fueling system. I am running a Meastro which is bored out to 2066cc which produces 102 bhp at the wheels but more importantly has approx. 8 tons of torque.
A head change for me is very simple, taking a leasurely 2 to 2.5 hours. This may well not be the case for others without the knowledge and tools. Read the Haynes manual and judge for yourself how you feel you can cope with the job. This is for a straight forward head replacement, not one that involves re-shimming the cam. That job even takes me most of a day as you have to go out and get the right thickness shims.
If you do the job yourself then remove the head complete with the inlet and exhaust manifold attached. Swapping these off the car is so much easier and quicker. Expect potential problems with the three studs / nuts holding the downpipes to the exhaust manifold. Heat and corrosion takes it's toll here and a check a few days in advance to see whether they are going to move will allow you to obtain new studs / nuts before you start. If you do shear one then changing them can be difficult and the assistance of someone with oxy/acetyline heat makes for a much easier extraction.
Change the cambelt as a matter of course, and the alternator and power steering belts if they show any signs of wear. Make the extra expense to use a genuine Rover head gasket of the latest spec. Over the years the spec of the gaskets has changed many times in an effort to eliminate the common oil leak from the area aound number 4 plug and that corner of the engine. I have yet to find a non Rover head gasket which is any different to the gaskets used on the 1985/86 models!! The Turbo gasket is a reinforced one and has been used on naturally aspirated engines before (the old Maestro Challenge Cars for instance) but the newer Rover gaskets are as good and cheaper.
Costs will depend on what you have done, ie whether you do the labour intensive shimming yourself, or buy a complete head ready to fit. So that between £350 and £450 will be a good base line figure to assume.
I am biased but Peter Burgess heads do work, with the worst engine giving only 12 bhp extra at the wheels, and the best giving 20bhp more. This is with the standard valves. More power can be extracted by using larger inlets, but the knock on effects for the power gained made it non viable. Remember that these power figures needed the exhaust change as well. No other changes are needed as the engine management self compensates at this level of modification.
Gearboxes
The Turbo box uses larger and additional internal bearings to provide extra torque capacity, along with a 3.65 to 1 ratio diff, compared to the 3.9 to 1 of the EFi. All Turbo engines really need the Turbo spec box if the turbo torque is used!! EFi's fitted with Turbo boxes lose acceleration and some top speed. Turbo's with EFi gearing become a pain due to the too short gearing married to the narrower power band of the turbo engine. Not to mention the fuel bills and what can be a much shorter life!
The early and late gearboxes are interchangeable, as are those from the newer Rover models. The Turbo boxes will have codes K7AR for the earlier Honda built versions (gold coloured identity label), and K7AO for the later. (White paper label with a bar code) Note that the EFi identity codes have only the number different to the Turbo with K6 instead of K7! If you are really fortunate you can use a box from a late Rover Turbo model with few changes.
Very early Efi gearboxes had a very slightly lower final drive ratio, which affects the overall gearing so little as to have no consequence. Read the 5th gear MPH per 1000 rpm as 22 to 23 for the Efi with the Turbo at 25. As the internal gear cluster is the same for both the intermediate ratios will have the same variations as is applicable for 5th gear.
K6AO is the gearbox fitted to MG and Si Montego's with the 2.0i designations. The K6 indicates it is the close ratio with 3.9 final drive, and the AO indicates that it is the Longbridge built version.
They were introduced from 1987, but as a quick referece always refer to the rear badging which was changed to 2.0i from EFi at the same time. Incidentally the MG Maestro of the same period used the same gearbox and the 2.0i badging ident also applies.
If you just want a replacement gearbox, the K6AR (earlier Honda built version) offers the same internal ratios (except for some which had a very slightly higher 3.89 final drive) It is directly interchangeable with the later boxes, excepting that the clutch release arms have different cable ends. Even that is a simple two minute change with just one 10mm bolt to remove. The Honda built versions do seem to have longer lasting internals which may be due to the bearing cages being steel, rather than the later nylon.
Gearbox filler plug…….Looking from the nearside of the car, at the same level as the driveshaft and to it's right. Has a 19mm(3/4") hex headed bolt with, if you look carefully, a sealing washer. This is the combined filler/level plug for all the 2.0 litre type gearboxes.
Gear ratios and LSDs
The MGF uses a version of the standard Rover PG1 series gearbox first seen the Montego 2.0 litre cars, then to many others. The same box is also fitted to the other 1800 K engined Rovers (218Si and Vi).
The history is as follows:-
1984 Montego launch the gearbox is a Honda built unit of what was the series 1 type. These have a 4 letter/digit prefix followed by a 6 figure number starting with 1. These were standard on all the 2.0 litre O series engines (and M16) up to 1987, when the 2 series versions appeared. These incorporated some changes, but essentially the difference was that they were now built by Rover at Longbridge on a new gearbox assembly facility. The simple identity check between these two series are the identity labels on the clutch housing face, which faces the front of a FWD car. The Honda built unit is a plasticised gold, whilst the Longbridge version is white paper and carries a bar code in addition to the gearbox ID code and number.
The codes for the MG Maestro and Montego EFi boxes are G6AR and K6AR, with K7AR for the Turbo. Both 'K' versions use almost the same internal ratio's with just the final drive ratio changing the overall gearing, 3.9 for the EFi and 3.6 for the Turbo. The G6 box used a different set of internal ratios with a 3.8 final drive. Internal ratios were from 5th down to 1st : G6. 0.85 to 1, 1.04 to 1, 1.33 to 1, 1.89 to 1, 3.25 to 1. K6. 0.77 to 1, 0.94 to 1, 1.24 to 1, 1.75 to 1, 2.92 to 1. K7. 0.76 to 1, 0.94 to 1. 1.22 to 1, 1.75 to 1, 2.92 to 1. When the 2 series boxes arrived the MG's used boxes with codes K6AO and K7AO with ratios within 0.01 or 0.02 for the top two ratios. Most of the parts were carried over as the parts slides show the same individual part numbers.
During this time the old square shaped Rover 216 (Honda Ballade) was using the S series engine mated to another version of the PG 1 series gearbox. This use was expanded when in 1989 all 1600 Montegos went over to this gearbox too. Also the Rover 820 range used it's own versions of exactly the same gearbox, excepting that here the cable clutch operation was replaced by a hydraulic version. No casting differences, just a different bracket, so swaps between cable and hydraulic versions is simple. Clutch release is also identical. (as are most clutches!)
The normal 'cooking saloons' used a 'long set' of ratios with the 3.9 final drive. There are some variations and I haven't got full details, but suffice to say that overall ratios will be very close for them all. The non MG based Montego 2.0 litre cars used a box with L6AR codes with internal ratios as follows: 0.65 to 1, 0.85 to 1, 1.14 to 1, 1.75 to 1, 2.92 to 1. Just the upper three ratios being different.
The Montego/Maestro Diesel variants also used another version of the same box.
When the Rover 220/420 range arrived they used versions of the same box and I believe that final drives and internal ratios are similar to the Montego. The extended range of Rover 2 litre cars now added some subtle extras. The Turbo T16 engines in the 2, 4, 6, and 8 series cars all have a Torsen LSD as standard. Some other non turbo versions could have the same LSD as an option. Gearbox codes are similar with 2/400 models using K4BS for standard non turbo versions, K4BX for the same with the Torsen diff, and K7BX for the Turbo cars. The X being the significant ident code. This coding has varied and I'm not sure of current codes. I am aware that the Torsen diff (Part number TBB 100550) bolts straight into any series 2 or later gearbox in place of the original, and quite probably earlier boxes too.
All these FWD applications are virtually the same now as they were 10 years ago. For the MGF and other 1800 K series engines, the PG1 gearbox was used for the greater torque capacity over the original Peugeot based gearbox used from the start of K series cars. The case is different to match the K series, but internal parts are the same as other versions. I haven't done a full comparison, just a selected number of parts and these were all the same, so I have presumed the rest would follow. I do know that the 1.8i MGF uses the 3.9 final drive, whilst the VVC uses a lower 4.1 final drive.
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