2.0MPi losing power head scratcher

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Jacopo

New Member
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9
New the forum after lurking for a couple of years and learning about Defenders

I have a ‘97 D90 Carabinieri 2.0MPi

It runs really rich and recently it has been losing power when I hit the gas. To be more specific, in 2nd or 3rd gear, when pushing down accelerator, all power leaves and it feels as if the engine is getting flooded (I used to ride dirtbikes and this is as close to the feeling as I can describe). When I take my foot off of the gas, or lift the pedal to a sweet spot, the engine regains power, but I am unable to press the gas past that point or the issue happens again.

A couple other items. I keep losing coolant, but see no puddle under the vehicle in the garage. I took it to a mechanic and he noticed a coolant leak at a hose, but this was small.

The power issue was not a problem if I added Lucas Fuel Injector cleaner and lubricant in the gas tank. However, this no longer fixed the issue.

As the problem got worse, I was recently stranded and unable to get the engine to turn over after I ran an errand. I drove for 20 mins to my appt with no issue (2cans of Lucas). After my 1hr appt I was unable to get the engine to turn over. Sat for an hr and tried intermittently, then finally it started and I limped home with the power issue

My fear is that it is a head gasket leaking coolant into the engine and the lucas detergent was getting rid of the collant, allowing for a better mixture to run normally. This leak has gotten worse and now I need to replace the head gasket, which I have struggled to find the parts/kits. Atlantic British said that they do not have the kit for the engine. Others too.

I noticed a sizable 2.0mpi community here (at least 3 owners here and 1 guy did a full engine refurb) and thiught that this would be my best bet before throwing in the towel on the engine
 
Parts are available.
Also remember they were mainly used in the rover car so rover/mg people will more likely have bits too.



Before you go through all that, have you actually had it checked for head gasket failure or just guessing?

J
 
Just guessing on ny limited mechanical knowledge - and preparing for the worst

Thanks for the links!
 
Could be a misfire under load, so plugs and leads first stop. Worth watching the engine tickover when its really dark outside, you can sometimes spot a stray bit of HT leaking
 
Update after all of your helpful suggestions - takes a while to get the parts in US

Replaced plugs and leads - no improvement Replaced 1 coolant sensor
Unplugged the other from the mems and def runs smoother, just when it gets hot the power loss/flooding feeling comes back, leading me to believe it is the other engine coolant sensor.

When replacing the other sensor - they look different but the sensor plug going to mems fits the new sensor

Is the sensor i am replacing look like engine coolant sensor?

If different shapes - will this impact performance?

Appreciate the feedback and for heloing me on this odyssey
 

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There are 2 coolant sensors (if I remember) 1 is for the gauge and the other goes to the “brain” to control the fan and I would expect other things like fuelling.

Can you post a pic of where it is on the engine, the 2 are close together.

J
 
The red circle is the sensor i am trying to replace no

The yellow circle shows the most recent sensor replaced, which is also shown in the second pic

I am thinking that the sensor i am trying to replace now (the red circle and pics of the sensor in my previous post) is a knock sensor

If the knock sensor is bad, would this cause the loss of power issues I described?
 

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I will need to check my files, but it could be a knock sensor and it could restrict power.
In your second pic there are 2 sensors, 1 is gauge 1 is fan and brain. If you disconnect them you should see the gauge react and the fan should come on. can’t remember which is which but I did measure mine and post on here for another member.
You say it feels like “flooding” have you looked at your plugs?

J
 
I changed all the plugs due to someone suggesting this in prior post

I just recreated the issue w the hood up. Fan does not kick on when it gets hot, so i will replace the other sensor that is next to the first one changed

Also saw some smoke from wire harness on top of this apparatus - whatever this is

I unplugged a few other sensors when the issue was happening and nothing made it better, so process of elim continues

Will post back when i get the other sensor

Going to owe you some whiskey when this gets fixed
 

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I can confirm that other sensor is a knock sensor (ADU 8229).

I find it hard to get it up to temp enough to run the fan on the drive. I have never heard it run but I know it does as if you disconnect it it will run the fans.

Have a read through these threads 1 of the threads has a link that has the wiring dia for the 2.0mpi with connector pics to I think. Its for s Disco but the engine and wiring of should be the same.


That looks like the heater box.

When you took the old plugs out what colour where they? did it indicate a rich mixture?

j
 
Thank

The plugs were black. Clearly running a rich mixture because the garage has black soot everywhere

Can also smell the gas

I pulled the lead to the coolant sensor i replaced and the fan turned on. Then Pulled the other lead and tried to recreate the issue and it happen - so hoping it is due to that sensor. Trying to find what that sensor is so i can order replacement.

Will run through these threads.

About this close to just biting the bullet and doing an engine swap with something that is easier to find parts

Will keep you updated

Thanks again
 
Just to add I am pretty sure the MEMs only looks at the temp sensor you changed not the other 1 on the top.

Went through what I have (its not much ;)) but here's some reading that may help explain what its supposed to do.

Its from a D1 manual as I have so far not been able to find defender MPI info;) But it should be relevant.

Where are you in the world?

J
 

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I am in the States in the East Coast

thanks for sending the disco manual - helpful in understanding what is read by mems

Really appreciate the help
 
Update:

Replaced the knock sensor, the collant temp sensor, checked for exhaust leaks (none that showed via soap and water test)

The coolant fan turns on when the collant temp sensor is unplugged and engine rpms pick up - but runs smooth. When the sensor is lugged in, the fan does not kick on even when running hot

I also see some smoke coming from the engine throttle body when coolant temp sensor is plugged in, none when unplugged and fan running.

I have videos of all of this but can’t upload to forum for some reason.

Appreciate any thoughts
 
To post videos put them on Utube or insta (others available )then link here is what most peeps do.

So you keep saying its getting hot, have you confirmed that it really is getting hot? What does the gauge on the dash show?
Have you checked the thermostat is opening, try leaving it out maybe.

You say smoke, Is it smoke or steam? do you still have the coolant leaks. It maybe happening when the fans are running its just you cant see it as the fans are blowing air around. Maybe try unplugging the fans so they wont run when the sensor is unplugged.

I guess a compression test maybe a good thing to check.

Just a thought, There is a small pipe that runs from the manifold to the ECU is that secure and leak free, there are a few others cant remember what/where they go do but they are all worth checking as it could affect the others. The MAP is inside the ECU and uses the vacuum from the manifold, it also uses it for spark timing, which could affect power.
Sure I took a pic and marked up where they all went too/from in 1 of the threads.

J
 
Thanks J

I will check the pipes into ECU

Is the MAP easy to change?

Here are 2 videos of what I am talking about with the idling and with the steam/smoke coming from the throttle body.

I also ordered a temp gun to see how hot the engine gets. I dont have a thermostat in the dash. Will report back in Sept

Really appreciate your responses and help



 
The MAP is inside the ECU is it easy to change, I have no idea. But at a guess without looking, no. then you would have to find another.

I was talking about leaving out the engine thermostat, to see if there is any change in engine behavior.

You second video is hard to see what you see. But as that's a coolant/heater hose which looks like to have given a puff out. Of course when you disconnect the sensor the fans come on and the air movement will not let you see them again.
That circuit could easily be bypassed for testing/nice weather.

J
 
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