14 replies to this topic

[minisilverbullet]

So i have been having a nightmare with high emissions, and not being able to access a suitable or working code reader/rover test book, its been a bit of guess work to say the least.

New lambda and new coolant temp sensor made no difference.

The car had staling problems last summer and, while at minisport they removed the fuel tarp and ran the vacuum pipe straight from the manifold to the map sensor in the ECU.

I have since replaced all the vacuum pipes and replaced the fuel trap.

Anyway the car went for its 3rd mot today. Before it went the garage who have the car did a gas analyzer test and the CO at 2500 rpm was up around 5% (10 times the limit). The mechanic, suspected the MEMS so pulled the vacuum pipe at the MAP sensor off. allowing the emissions to drop to a suitable level.

Now this isnt sustainable either -
driving with this vacuum pipe disconnected
or reconnecting it and over fueling = €€€€

So we now reckon that the
- he thinks its the MEMs unit which may need an overhaul
- I think it is the MAP sensor due to driving without the fuel trap for 8 months.

What are the solutions?

Would removing the ECU and plugging the MAP sensor hole with cotton wool work in this
situation?

Or is it likely that the ECU needs looked at?

[Pitcrew6464]

Hi, take a read of this.... http://www.gaima.co....r/RoverMEMS.pdf see if this helps

[jamesmpi]

Surely that's worth pinning. Very useful document!

[minisilverbullet]

Any way to test the map sensor?

Also I have taken the ECU of. I am going to try and stuff the map sensor with cotton wool. But for the fear of asking a stupid question do i need to remover the nipple? or stuff it down the nipple!

[greg.harvey]

Just posting to remind myself to come back and get that PDF!

[minisilverbullet]

Well, Went for a drive today with the vacuum pipe connected to the map sensor! Car ran fine, but was stalling at junctions under breaking. Now this used to happen before. Minisport in Padiham removed the fuel trap and just ran the vacuum pipe direct to the MAP sensor. Which stopped the stalling.

So removed the vacuum pipe for the journey home and ran the same but didn't stall.

Could the ECU gone into limp mode and, meaning that the MAP sensor is actually playing little part in how the car is running?

[xrocketengineer]

Hi,
It sounds to me that you still have a vacuum leak/obstruction between the intake manifold and the MAP sensor or the MAP sensor itself is leaking. Is the vacuum pipe in perfect condition?
When I bought my Cooper, it had a very high idle speed 1200-1300 RPM. Usually that is caused by a leak. I found the little elbow that connects the Thermac valve red pipe broken at the manifold connection. After I replaced it, the idle speed came down but once the engine warmed up it would stall when trying to idle. Then I found out that an aftermarket hose had been used to replace the pipe from the manifold to the fuel trap. The hose had collapsed/melted/dissolved turning into something like chewing gum right where it connected to the manifold preventing a proper vacuum signal from reaching the MAP sensor. Replacing that solved the problem.
As far as the limp mode goes, my understanding is when some of the sensors are not receiving valid data, the ECU will ignore their values and rely on other data to operate in limp mode. I am not positive that if the MAP sensor is disconnected reading atmospheric pressure mean that automatically the ECU will compensate and go into the limp mode. However, I had a Chevy truck that if the MAP sensor was electrically disconnected, the ECU would go into the limp mode (Check Engine light on) and the engine ran fine.

Hope that helps,
Ivan

[minisilverbullet]

Thanks Ivan
I think i can be certain that it isnt the vacuum pipes.
All three vacuum (manifold - fuel trap, fuel trap - MAP, and the red one) pipes are new from their packs, as is the fuel trap.

With the fuel trap to MAP disconnected the car runs fine thats why i have thought it my have/ be in limp mode.

Should i be able to feel a vacuum (sucking) on the fuel trap to MAP pipe?

[xrocketengineer]

Yes, you should feel a vacuum (sucking) on the fuel trap to MAP pipe. Otherwise there is a leak somewhere.

[minisilverbullet]

I might have cracked it!

There was no vacuum (sucking) on the fuel trap to MAP pipe. So i removed it for the fuel trap end and felt the sucking there.

The two elbows on the vacuum pipe are different one slightly fatter. I think that they were the wrong way round. At the fuel trap end the vacuum pipe was essentially pushed on to tight totally sealing the vacuum. I swapped it around and now felt sucking on the pipe. All connected back up.

SO fingers crossed it was as easy as that!

[xrocketengineer]

Well is this sorted?

Ivan

[minisilverbullet]

Well is this sorted?

Ivan

Well the car idles perfect (it bounced a bit on start up before), seems a bit more efficient on petrol, doesn't drop revs under heavy braking as it did before.

The proof is in the pudding though, i will take it for a gas analysis test next week! Fingers crossed!

I have got to say though i have almost had it with the SPI engine.

Thanks for the help (again).

[greg.harvey]

I have got to say though i have almost had it with the SPI engine.

Honda conversion?

[CarsOrBikes]

The trap should be left in place, it is to stop oil collecting in the vac pipe and finding its way to the ecu. It was developed to stop the stalling off throttle, or some kangarooing on acceleration

If you have oil in there, from the trap being removed for a while, take off the ecu, insert some thick cotton into the sensor, and turn back the correct way, then leave on a warm radiator for up to 24 hrs, the oil gets drawn out and restores function, this was done prior to fitting the trap as a Rover fix, before they became a standard fitment.

[minisilverbullet]

The trap should be left in place, it is to stop oil collecting in the vac pipe and finding its way to the ecu. It was developed to stop the stalling off throttle, or some kangarooing on acceleration

If you have oil in there, from the trap being removed for a while, take off the ecu, insert some thick cotton into the sensor, and turn back the correct way, then leave on a warm radiator for up to 24 hrs, the oil gets drawn out and restores function, this was done prior to fitting the trap as a Rover fix, before they became a standard fitment.

I did this just last week! The cotton was fairly oily when finished, great tip!