20 replies to this topic

[pete l]

Hi all,
My MPI is nearly fixed. I have just one last problem. Here's a pic of my T4 showing the lambda readings. It stays like this, always, doesn't move at all.
Anyone any ideas ! Power is getting to the two white wires for the heater element.

 1529759161944404470650.jpg   33.06K   4 downloads

[Bat]

Hi,

Umm, not familiar with the T4 but it seems that it's not going into closed loop mode is that dude to another fault or the strange reading from the lambda sensor I can't tell from the corner of the screen?

Cheers 

[pete l]

Hi. OK, what else do you need to see ? I'll put it up.

[pete l]

It is a minispares lambda. Not an original Bosch one, that i still have, might try it out.

[Bat]

Hi,

2 volts is really rich so I think you'd be choking on the fumes if it was running like that!

It could be a faulty lambda or a broken wire, try unplugged see if you get a different voltage.

Measure the voltage on the signal wire with the lambda unplugged.

Check to see it the voltage on the T4 changes when you do this.

I presume the temp, map and TPS readings are all correct?

Cheers 

[Steve220]

2 volts is odd. Isn't closed loop between 0-1v?

[Steve220]

It should be reading around 0.6-0.7v On idle, 0.8-1.0v what.

[Bat]

Hi,

That's what I would expect Steve, like I said 2 volts is really rich!

Cheers 

[Steve220]

My point is it shouldn't even be reading that high anyway, in my opinion!

[pete l]

All other sensors are now reading correctly.
The lambda readings never change, engine running or not, lambda plugged in or not. It never changes.

[Bat]

Hi,

In that case check the wiring including the ground. After that I'd be looking at an ECU fault.

Unless the test gear is giving you rubbish information???

Cheers 

[pete l]

I've just removed the ecu and checked the wiring continuity. All is good.
I can't see the diagnostic equipment giving bad readings, its the T4 system used by all MG Rover and land rover garages.

When are the lambda readings taken in to account ? I know its not straight away. But I don't know how it works.

[Bat]

Hi,

The ECU will have a coolant temperature programmed into it when it switches to closed loop mode. It will also come out of closed loop mode depending on readings from the TPS and map sensors, which is why I asked about those as well 

Cheers 

[Bat]

Hi,

Camshaft sensor is another that may stop it going closed loop...

I can tell you of a few instances over the years where I've come across misleading dealer test equipment even the Mercedes-Benz star system, so I never rule anything out!

Rover manuals dont give any specific details it just says it controls the fuelling!

Cheers 

[pete l]

Camshaft and crankshaft sensors came up being in sync.
Do I need to test it by driving the car rather than just sitting on tickover ?