Thread: Rich when cold

There is an earth point at the rear of the LH cylinder head, for all the injectors.
Do you have gas?
If so the injectors can sometimes just stick open all the time for lack of use.
How is your economy when warm?
I would measure the resistance of your temp sensor at the ECU plug. You may have a high resistance at a connector.
It must be something to do with the cold start enrichment circuit , if the car runs well when warm. The cold start circuit adds % of time to the normal fuel injector duration depending on the resistance from the sensor.
I cannot think of any other reason than that, so persevere with testing .
On the other hand if it is rich when warm, then the injectors come into play, and the ECU itself.
Regards Philip A

It could of course just be that your injectors are drooling overnight, and then the car floods when you start.
regards Philip A

Originally Posted by rangy01

Anyone have any advice re 88 3.50 range rover running rich after starting from cold. It starts easily,then runs rich for a minute or two, then runs well until next cold start.
I have replaced the engine temp sender, tried another compuer, had fuel injectors cleaned and tested, checked fuel pump pressure and have had the airflow meter calibrated. It has also recently had new std cam, lifters, timing chain/gears fitted.
Thanks, if anyone has any further ideas.

G`day

Just to get things right .......

Is the engine temp sender your saying the one in the top of the inlet ( pass side ) or the one in the Front ( driv side ) ?

Even if the cold start injector was connected , unless you have a fault with the ignition switch/wires i won`t be at fault .

It only works will the ignition cranking and the thermotime switch only works above a set temp but still need the power from the ignition to make a circuit .

The CTS can be tested to make sure it`s working in the correct range . ( one in top of inlet )

There is a temp sensor that can be checked in the airflow meter nothing to do with calibration but would hope that was done by whoever calibrated it and if this was not right ( calibration ) could be fault .

If it were mine after checking the earths as suggested and making sure they wer all put back on after the work done ?

I`d check closely the connector and wires the run to the CTS and then test that the CTS was working in the range it should .

Also just to see i`d pull the vacuum pipe of the pressure reg and see if there was any fuel there and if there was i`d get a new reg but if at fault more likley to be rich all the time .

For cold start along with the cold start injector the ECU also signals the injectors for longer pulses ( more fuel ) one of the main places for this signal is the CTS , so if it or the related are playing up , more fuel than is need can be given as things only do as they are told from the info they have .

Cheers

edit
From you post above about line on the bench and the word sensor .........

Rover figs ..........

-10 deg C ...... 9100 to 9300 OHMS
0 ......... 5700 - 5900
20 ........ 2400 - 2600
40 ........ 1100 - 1300
60 ........ 500 - 700
80 ........ 300 - 400
100 ...... 150 - 200

Peter ?
Thanks for the above information, it is the one on the LHS on top of the inlet manifold. It does conform with the figures you quoted. I took the loom of the ecu this morning and measured the resistance from pin 13, it conformed with LR specs and matched exactly the reading taken from the engine temp sender.(therefor no extra resistance at terminals / earth etc).
Do you or does anyone know where the heavy earth wire running from the rear of the lhcylinder head should go, I found it this morning lying behind the washer bottle (after tracing it from the start point at the head). It had a 5/16 bolt and washer attached, but I cant find a suitable location for it in that area. This could be a source of this problem as it has been hidden there since I purchased the vehicle three years ago. The richness problem has been there since I purchased the vehicle. ( It takes a while to get around to these things).

Aha. That is the earth for the injectors.
It screws into the rear of the LH head. Some have studs some a bolt.
To get the position have a look at the front of the RH head, to see where the holes are as they are identical.( well in theory, unless someone has put different heads on. in any case they are in the same relative ositions , only the diameter will be different.)
I assume that you cannot see that it is actually attached to the head at the other end ie it comes from the loom.
Regards Philip A

Thanks for your quick response Philip A.
However just to complicate things even further, I found the wire you are talking about, black around 4-6mm and dissapearing into the valley cover area. That wire is attached to the head. This is a heavy flat strap enclosed in what appears to be original soft black plastic tube, it is attached to the head (next stud up from the other wire) but loose at the other end, it may even be an additional earth wire that someone has fitted at some stage.
I have just measured the air temp sender resistance at its terminal block on the air flow meter as someone suggested earlier, it matched LR specs. Don't know where to go from here!

I do not think that is original , although they probably vary model to model. AFAIR most models have engine to body earths near the starter motor. It would not hurt to connect it to the body. If it has heated washers it may be from bonnet to body, to reduce FM interference.
After your research, and you are obviously skilled, You maybe should try to find another ECU, and see if it still does it. This would isolate whether it is a sensor or the ECU. I think its looking more like the ECU now.
It still may be worth pulling the injectors, and having them tested and cleaned.
Another check may be to put a pressure gauge on the fuel inlet when cold. Maybe (long shot) the pressure regulator is sticking closed for a while. You have checked that the vacuum tube from the regulator to the manifold is connected and not perished I guess..
Regards Philip A

Just had a look at my
" Bosch Fuel injection & Engine Management"
The Rover is just a Bosch L Jetronic built under licence.

Under pulsed injection troubleshooting.
Engine stalls or idles roughly (cold or warm)
Probable cause
Engine temperature sensor faulty
Air flow meter faulty
Cold start system faulty (air bypass)
Fuel injectors faulty or clogged ( my comment maybe so old they drool)
insufficient fuel pressure or fuel delivery ( my comment unlikely cold)
Just a couple more thoughts.

Does your air bypass open? Ie does the engine idle fast when cold? If not it could flood simply because it is going too slowly. You can check this by just looking through it when cold. It is independent of anything but
the water temp.
Regards Philip A