19 replies to this topic

[The Dodge]

Hi Everyone,

I have found plenty of great info on the spi system from this forum but i'm hoping someone might be able to help with my specific problem, fingers crossed. . . .

The car is a a 96 mayfair, its my girlfiends daily car with low miles at 11,000.

The fault i have is a misfire around the 2000 rpm mark. Previously the car has been o.k. The car now seems to run perfecty, and i do mean not even a hiccup, for 15 mins or so then the missfire kicks in.

It won't rev past about 2000 with any real acceleration load. its possible to very very gently build up speed and higher rpms but i can only just touch the throttle or it cuts in and out violently, like a rev limiter with a hard cut.

Since i have had the car, what i did think was annoying speaker feedback, i have now realised is the fuel pump in the tank. (all my previous minis were carbed so this is new to me).

The pump does seem loud, is this normal? its kind of a high pitched tone.

The missfire is definately being caused by the pump cutting in and out, i can here it click out and then spin up again during the fault.

Will a knackered pump do this but be o.k. at lesser throttle openings? Does the pump have anyway of shutting itself down, i.e from sensing over pressure?

I am wondering if the fuel filter may be silted up as the car only did roughly 1000 miles over a 5 year period at one stage so surface rust may have formed in the tank

Does anyone have experience with the crank position sensor failing? do they just die or can they become intermittant in operation?

One strange thing is the rev needle drops as well during the cut which is normally a sign of the coil not discharging, its definatly the pump as well tho. . .

So confusing. . .

I have checked the inertia switch, o.k. pump fuse, o.k. fuse block isn't melted, the pump connector is sound. The plugs, leads, dizzy cap, rotor arm and coil are all about 5 months old.

What if anything will kill the ignition and the pump simultanously, but still leave the car partially drivable?

Am thinking ecu but before i spend alot of money on diagnostics maybe someone has an idea

Sorry if i'm raking past ground, just the other posts aren't quite the same as this problem.


Any help would be great,

Thanks,
Roger

[The Dodge]

Hi Everyone,

I have found plenty of great info on the spi system from this forum but i'm hoping someone might be able to help with my specific problem, fingers crossed. . . .

The car is a a 96 mayfair, its my girlfiends daily car with low miles at 11,000.

The fault i have is a misfire around the 2000 rpm mark. Previously the car has been o.k. The car now seems to run perfecty, and i do mean not even a hiccup, for 15 mins or so then the missfire kicks in.

It won't rev past about 2000 with any real acceleration load. its possible to very very gently build up speed and higher rpms but i can only just touch the throttle or it cuts in and out violently, like a rev limiter with a hard cut.

Since i have had the car, what i did think was annoying speaker feedback, i have now realised is the fuel pump in the tank. (all my previous minis were carbed so this is new to me).

The pump does seem loud, is this normal? its kind of a high pitched tone.

The missfire is definately being caused by the pump cutting in and out, i can here it click out and then spin up again during the fault.

Will a knackered pump do this but be o.k. at lesser throttle openings? Does the pump have anyway of shutting itself down, i.e from sensing over pressure?

I am wondering if the fuel filter may be silted up as the car only did roughly 1000 miles over a 5 year period at one stage so surface rust may have formed in the tank

Does anyone have experience with the crank position sensor failing? do they just die or can they become intermittant in operation?

One strange thing is the rev needle drops as well during the cut which is normally a sign of the coil not discharging, its definatly the pump as well tho. . .

So confusing. . .

I have checked the inertia switch, o.k. pump fuse, o.k. fuse block isn't melted, the pump connector is sound. The plugs, leads, dizzy cap, rotor arm and coil are all about 5 months old.

What if anything will kill the ignition and the pump simultanously, but still leave the car partially drivable?

Am thinking ecu but before i spend alot of money on diagnostics maybe someone has an idea

Sorry if i'm raking past ground, just the other posts aren't quite the same as this problem.


Any help would be great,

Thanks,
Roger

Sorry, i should have put this in injection specific. Newbe error

[Sprocket]

Moved to the correct section

[Sprocket]

Not being funny, but i will reply to this some time in the evening, its late now and ive just spent an hour typing up some posts on another forum for my VEMS ECU, and it was real heavy and my head is mashed, LOL, oh and its rather late as well.

[The Dodge]

Not being funny, but i will reply to this some time in the evening, its late now and ive just spent an hour typing up some posts on another forum for my VEMS ECU, and it was real heavy and my head is mashed, LOL, oh and its rather late as well.

No Worries, any help when you can would be great. . . . anytime. I have read alot of your posts on the spi and you definately know your stuff

I just can't piece together my fault, or i have ran out of brain power, plus things to try without parts.... and sunlight.

Cheers,
Roger

[Sprocket]

I recon this sounds like the MAP sensor has fuel in it.

Pull the ecu out, get some cotton wool, and twist it thin enough to ease it into the MAP connection port. Leave the ecu on a warm rad or airing cupboard over night. Blow through all the vac lines ensuring they are clear, and also check they are free of nicks and cuts. Check the elbows at the ends are not split. Becareful not to push the elbows too far onto the connection ports which might cause a blockage. Check the fuel trap is also free of fuel and blockages. Put it all back together ( firstly removing the cotton wool, LOL) and let us know how you get on.

Oh the only other thing that might cause this is a faulty throttle position sensor, though as of yet i have not seen the symptoms of this to be sure.

It may be wise to have a diagnostic done to see if any faults have been logged. Dont expect the guy doing the diagnostic to know what hes doing, most these days dont seem to anyway. Just get as much information as you can, with the engine idling and up to temperature, note all the sensor values, air temp, coolant temp, Oxygen senser volts ( Min and Max ), Throttle position volts (Min and Max), MAP value, ignition advance ( an avarage)

Edited by Mini Sprocket, 03 April 2007 - 11:01 PM.

[The Dodge]

I recon this sounds like the MAP sensor has fuel in it.

Pull the ecu out, get some cotton wool, and twist it thin enough to ease it into the MAP connection port. Leave the ecu on a warm rad or airing cupboard over night. Blow through all the vac lines ensuring they are clear, and also check they are free of nicks and cuts. Check the elbows at the ends are not split. Becareful not to push the elbows too far onto the connection ports which might cause a blockage. Check the fuel trap is also free of fuel and blockages. Put it all back together ( firstly removing the cotton wool, LOL) and let us know how you get on.

Oh the only other thing that might cause this is a faulty throttle position sensor, though as of yet i have not seen the symptoms of this to be sure.

It may be wise to have a diagnostic done to see if any faults have been logged. Dont expect the guy doing the diagnostic to know what hes doing, most these days dont seem to anyway. Just get as much information as you can, with the engine idling and up to temperature, note all the sensor values, air temp, coolant temp, Oxygen senser volts ( Min and Max ), Throttle position volts (Min and Max), MAP value, ignition advance ( an avarage)

Thanks, i will try what you describe with the ecu first, first chance i get to work on it will be tomorrow afternoon as i'm away with work tonight.

So the diagnostics aspect isn't as easy as plug in, get code, compare code to fault list, replace part. . Hopefully it won't come to that then. I guess i'll have to be with the mechanic to record all the values rather than trust them to get it all right.

In your experience would a rover garage be any better equiped than a standard place offering diagnostics? Be it actual equipment or knowledge?

Will let you know how i get on tomorrow,

Cheers,
Roger

[Sprocket]

A Rover garage 'should' have the full gear for carying out complex diagnostics tests, more so that any of the scanners such as the Snapon, Sykes and Crypton hand sets. The Rover diagnostics (Test Book) is deffo a better tool, specific for the job. Ive got my eye out all the time for one on ebay, but even now they are not cheap, not one bit.

Still dont expect the Rover guys to know whats going on with it though

[The Dodge]

Cheers Sprocket,

The ecu has now been removed, there was indeed petrol at the map sensor fitting. Not enough to run out over the floor but definately wet with fuel.

I have taken off the fuel trap and the trap to ecu air line, flushed them through with warm water and set to dry with the ecu.

The trap and the line seem to be less restrictive now, as tested by the highly scientific 'blow down it before and after' method

I'm away again until sunday so they have plenty of drying time. . . .

Will keep you posted, fingers crossed.

Thanks,
Roger

[The Dodge]

Well, no luck i'm afraid. . . . .

she ran fine for a while but the missfire still occurs

I have bought a fuel filter as the pump does sound loud to me, like its working hard, but i'm not convinced its this problem alone.

Changing the filter can't hurt tho. . . .

I managed to open up the relay module and all looks perfect inside, all the connectors are also good. it has been carefully resealed with rubber cement.

I'm just going to clean up the ecu earth point now. . .

Someone at work suggested perhaps an immobiliser fault, i have located the lucas 5AS unit under the dash, i don't want to pull the whole facia off but i have enough space to just unhook the connector. can i just unplug it for test purposes or will the car not run at all, alarm or possibly become permanently immobilised? I don't want to make things any worse!?!

This is the last try before i give in to diagnostics. . .

At least i know a damn site more about the car than i did two weeks ago tho

[Sprocket]

It could indeed be the fuel filter starving the injector of fuel, but you would normaly notice this under hard acceleration.

Its an odd one, id have to have a look at it my self to try and pin point whats wrong.

Id be looking at a loose conection or corrossion on the connections, causing a miss fire. Check the fusebox and inline fuses as well for corossion. You say the coil has been replaced, it is the right one? and the plugs are NGK BPR6E?

One other thing to check is the colour of the spark plugs after a run out. if they are clean with white electrodes then its running lean and chances are its a lean missfire. if they are black then its rich and its a rich missfire. if they are niether clean nor black then its probibly fueling right.

It could be a faulty sensor causing the ECU to fuel it wrong.

to be honest having a diagnotic done could narrow down any problems, as you can read the figures that the sensors are telling ECU and compare them to what you can measure with calibrated instruments.

[The Dodge]

Well changing the filter didn't accomplish anything. . . other than soaking my arm in petrol

I think the problem may be something heat related, thats why it takes time to happen and when left overnight its fine for a bit.

Either an electrical component or joint getting hot and losing continuity, or maybe something like the lambda sensor starting to die when the exhaust gets fully warm.

I think the coil is the right type, i gave all the model details when i got it. Its not getting hot anyway. Its made by inter motor, god knows if they are any good?

Plugs are Bosch Supers but i can't see what code, again they were supplied for this particular year and model.

I'll take it to the auto electrician by my workplace tomorrow for diagnostics, hopefully the visit will yield some helpful info.

Can't wait for when i'm finally able to name the culprit part! Fingers crossed

Cheers,
Roger

[AlexM]

It might be an idea to swap for the NGK ones just to eliminate this as a possibility. Coil should be the unipart item, i had problems with a poor quality coil, make sure connections to coil are good and clean. Change the leads too. Actually got some from rover for like £7.

Definately check the connections to the fuse holders. I had pump problems (cutting out and in randomly) caused by a poor connection to the fuse holder.

Is the air filter clogged?

Replace distributor cap and rotor arm as a precaution...

Can't think of much else......

Edited by summergnu, 11 April 2007 - 02:04 PM.

[Sprocket]

What does the dizzy cap contacts look like, if they are burning out it might be that the dizzy is not in the correct position so as the revs rise so does the advance, the rotor arm will be further away from he plug lead contact causing a missfire.

Adjusting the dizzy on the SPI will do nothing, it needs to be set in the right place to allow the ECU to control the spark within a 45 degree angle without burning out the cap

[The Dodge]

Right. . . . there has been a bit of a delay while the car was getting diagnostics.

The first place didn't have the right computer to talk to the ecu, the second place (rover specialist independent) read no ecu fault codes.

They did adjust the idle parametre for when the throttle is released and the engine slows down. they said it dropped too far initially so it now goes to 1000rpms then after a timed peroid to correct idle.

The fault still remains, i opened the relay module again and drove the car enough to create the missfire.

When it is cutting both the FUEL PUMP RELAY and the MANIFOLD PTC HEATER RELAY are opening and closing rapidly . They do it at precisely the same time.

The heater relay coil is powered by the BROWN/PURPLE wire which also finds its way to the positive side of the coil. . . . i'm pretty sure i am losing the coil during the cut as the rev needle drops and bounces around like the coil failing to discharge.

I have tried to make some sense of it by studying the haynes wiring diagram for the module and other ancillaries but i keep going round in circles, it seems practically everything in the system is linked through the module and the ecu but i can't pin point a given part for taking both the relays out. . . .

Is it possible for the ecu to be faultly yet display no fault code? i.e. does it diagnose itself as well as monitor the sensory feedback of the rest of the system for values out of tolerance.

I have a new module on order for thursday, faulty or not i'm not happy with it now its been apart a few times. Its know its the correct one because they wasted half my day with the wrong one to begin with

By the way for anyone using the haynes manaul the module diagram is correct for pin positions and wire colours but the relays on the picture are shown in the wrong places physically. As you look at the page the module connnectors would be pointing down. They show the RHS top relay as PTC HEATER and the RHS lower relay as STARTER. They are the otherway round in real life on the pcb. . . . .

Any Uber-sparks out there that can interpret the diagram. . . . . Sprocket