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3.5i Discovery running - rich and cold ?

Tech Talk for Rover owners.

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Posts: 11
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3.5i Discovery running - rich and cold ?

Post by slpdesign99 »

Hi guys new to the forum and to 4x4ing.

My parents recently bought a 1991 Dico with a few problem.

In the last Month had
2 airflow meters (1 was faulty)
3 diffrent grade thermostats
vac advace fixed.
temp and All other sensors check or replaced

our merchanic is running out of idea's

the car is runing extremly rich (sotting up the ouside of the exhaust)
and running realy cold (does not go above 60C :? check with a temp gun)

I read on here that the ECU in pre 93 can fail - would this cause these problems?. Is there anything else we should be looking at ???
Scott
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Post by muddydigger »

Cold start is jambed on keeping it running rich disconect the wire to it. IF need be pull the fuel hose off, jamb a bolt int he hose and clamp it back up so fuel cant get in.
The cold start the thing on the side of the plennam chamber.

Flapper ( air flow sensor) is farked. The flapper can be played with by removing the black plastic cover, there is a needle that moves ona an arc. this gives the ECU the readings it needs. If the flapper is at fault it possibel to guage it here. By widing up or relaseing the spring this will change the ECU information and change fuel mixture.

There are also two adjusting screws on the plenahm chamber to adjust idel and fuel mixture. If your not good with Rovers best not try it though!

Thermosat should be 89 degree, before it even opens.

check all vacume leads are on in particular the ones to the black ball, if they are of it will run like a hairy goat.

ALL ECU can fail, but it not likley, it more likely a sensor out.

Atke the car to Land rover mechanic, dont let any onther mechanics play with it,or it wil keep costing more and more to fix
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Post by slpdesign99 »

Thanks Muddy digger. We will get all those things looked at.

The AFM is the hotwire type and it has a new one fitted.

I will keep you posted if any of this fixes it.
Scott
(slpdesign99)
www.slipdesign.com.au
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Location: Geelong Victoria

Post by slpdesign99 »

With the cold running could this be caused by the wrong water pump having been fitted ?
Scott
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Post by muddydigger »

slpdesign99 wrote:With the cold running could this be caused by the wrong water pump having been fitted ?
Im still trying to work out how its running so cold? How did you get a wrong water pump on there!? It wont fit, I wouldnt think it has anything to do with water pumps. Is the viscos fan buggered, IE is it spinnning all the time wit the egine running, and frozen solid if the engine isnt running?. may be thats shaged as well, and not letting the car get to operating temp because it spinning all the time and shouldnt be.

get the right thermotat in there first.

Remove the viscos fan, and run the engine to see if it get a to a higher temp. if it doesnt,then who ever is doing the testing had buggered equpent.

Once thwe car is at noraml operating temp then it should be running with out the cold start, and so not as rich
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Post by muddydigger »

slpdesign99 wrote:Thanks Muddy digger. We will get all those things looked at.

The AFM is the hotwire type and it has a new one fitted.

I will keep you posted if any of this fixes it.
Of course it is, I over looked the age! :oops:
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Post by slpdesign99 »

I just went and check the Fan and I could spin it by hand !

But when I started the car (been sitting for 2 hrs) it was spinning straight away !

Think the right thermostat is installed but I will have to check with my merchanic. its just it does not read past 1/4 on gauge and the heat gun shows only 60c from 1hr of running !

that's why I mentioned waterpump as nothing we can think off will cause it to run so cold.

all this I think is causing the super rich running !
Scott
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Post by muddydigger »

running cold is definaley the issue, the temp on the guage should be half way!
If you block the radiator with a huge bit of cardboard, so the engine cant draw air will it make a diffrence?
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Post by Sprover »

I dont know if this was mentioned but you can also change your coolant temp sensor.It maybe cactus.My car was running really rich like yours and i changed that along with a few other things and it ran heaps better.
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Post by slpdesign99 »

Thanks Sprover that as been done.

new AFM
new temp senor
new termostat
Vac advance was not working - fixed.

all vac hoses checked.

It also has a problem with CO2 in the cabin but i think this has got to do with the running rich.
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Post by muddydigger »

I think the main issue is the cold running, the ECU is being tricked into thinking its still cold. So try blocking the readiator off.
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Post by slpdesign99 »

Muddydigger.

I am goin to try this tonight and go for a drive, will see what happens
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Post by amtravic1 »

If the car is running cold it must be the thermostat. That is the only thing that controls the heat other than the fan when the thermostat is fully open and the engine starts to overheat. I suggest you replace the thermostat again with a new one at 88 degrees. Its a 10 minute job.
Once the engine is operating at the correct temp and it is still rich then look for other causes of running rich.
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Post by slpdesign99 »

amtravic1 wrote:If the car is running cold it must be the thermostat. That is the only thing that controls the heat other than the fan when the thermostat is fully open and the engine starts to overheat. I suggest you replace the thermostat again with a new one at 88 degrees. Its a 10 minute job.
Once the engine is operating at the correct temp and it is still rich then look for other causes of running rich.
No the engine never overheats in fact it dose not get over 1/4 (60c) no matter how hard you drive it.

Also in 1 week we have put 3 NEW thermostats in it all different temps and no change - so the themostats are never opening ! so its NOT the thermosat something is causing it to never gt warm.

that why we are looking at the waterpump that if somehow the wrong pump was fitted could it be flowing to much waster to get the car hot ??

this way the car would always be in cold start rich mode which would be running to much fuel adding to the cooling effect.

well this is my theroy I will do sum test with my merchanic.
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Post by amtravic1 »

If the thermostat does not open then the water pump will only circulate a very small amount of water around and around the engine. It would soon overheat no matter how much the pump was flowing. I believe that the injection system allows for a very small amount of water to bypass the thermostat and circulate around the engine but it is a very small amount and should not stop the engine from warming.
Are you sure all hoses are fitted correctly and you are not bypassing the thermostat somehow?

For more info ask here. http://www.aulro.com/
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Post by muddydigger »

If you had a wrong water pump, and it was some how pumping to much water around the engine you would in fact over heat the engine!! its the same as the myth about removing the thermostats. Its ok for a tempory fix, but they werent put in for no reason!

The water flows too quickley through the radiator and doesnt have a chance to cool. As long as you have a good flow rate, the longer water has a chance to cool in the radiator the better, one of the reasons Hiluxes have issues, as they dont have big enough radiators.

Im still going to say that the viscos fan is knackered, and I agree change the thermostat for the exact right one.
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Post by DL »

Keywords here are: COLD and RICH.

I reckon the ECU in this vehicle has rediscovered cold fusion and we should preserve it and the mortal body that nurtures it and, well...........just get richer!
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Post by slpdesign99 »

Well thanks guys finally got it to the merchanics who took the viscous fan off and it looks like the problem is solved - we hope ;)

Just waiting for ther new fan to arrive to test again.

The funny thing was the fan was easy to spin by hand and it was not speeding up when you reved it so it looked Ok but alas its seemed to be stuffed.

thanks for all the help guys I hope to see you on a track somewhere
Scott
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www.slipdesign.com.au
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