i have 89 daimler which is having an idle issue after warmed up . starting up the engine no issue at all .. its just that after few minutes of driving , on idle ... the timing will go up and down... from 850 to 500rpm... and black smoke comes out shows that its running rich , it might stall once in a while ... and it will go back normal and comes back in a while . what could be the issue here ?

i have :
cleaned the throttle body and MAF , replaced air filter , checked for loose connections and so on

havent replaced any parts yet .

i was trying to check the oxygen/lambda sensor but i couldnt find it , the 89 model dont have it ? or the previous owner removed it ???

all tips are appreciated , have attached pictures of the engine and ecu

 

Just a suggestion - does temp gauge come up to "N" after warm-up?

One cause of rich running is a failing temp sensor or stuck thermostat. Worth checking out, not too expensive to swap.

Larry

 

Hi . Yes the temp is at N ... thermostat is fine . Coolant sensor i tried removing the wire ...still the same .....

 

If still the same I'd say it isn't working, get a new one!

It tells the ECU what the temperature is, so if not working properly the ECU will keep sending a long fuel signal through the injectors. You can get the info to check it electrically if you search the archives for coolant temperature sensor.

Larry

 

oh and BTW, the CTS has a 2-wire plug, the single wire is the sender for the gauge.

 

Hi larry . Thanks and yes im aware on which is the cts .

btw . Does this 89 model 3.4 have a o2 sensor ?

 

Not sure but I think all the cars do? it's located in the exhaust pipe just past where the manifold pipe goes into one pipe from two.

You can check your model/location parts list here

https://www.jaguarclassicparts.com/u...xj6-xj12-parts

Larry

 

After searching ...i cant find the o2 sensor on my 89 jag.. checked from the manifold up to the split section tail pipe all the way back ... but i noticed a new stainless steel pipe on the centre.... can anyone send me a photo on exactly where it is ? Mine is 3.4cc . 6 cylinder. 89 model..

 

Hi ka14,

Welcome to the Jaguar Forums.

As far as I know, a 1989 model year XJ40 would have either a 3.6L or 2.9L engine. Later model years were equipped with 4.0L or 3.2L engines, or the 6.0L V12. I don't recall ever hearing of a 3.4 Litre engine in an XJ40.

In some countries the exhaust systems were not fitted with catalytic converters, so it is possible they were also not fitted with oxygen sensors. If you live in Selangor, Malaysia, you may have to do some research to learn how your Jaguar was originally equipped.

BTW, I believe the ECU in your photo is the Transmission Control Module (TCM), not the Engine Control Module (ECM).

Regarding your rich running, the CTS is a definite suspect since the ECM applies cold-start fuel enrichment when the coolant is cold, but transitions to normal fueling as the engine heats up. If the CTS is stuck at the cold reading, the ECM continues to incorrectly apply fuel enrichment even after the engine reaches operating temperature.

One thing you can do that may help is to check the Vehicle Condition Monitor for any stored diagnostic trouble codes (DTCs). To check, turn the key to position II (ON) but do not start the engine. Press and release the VCM button on the trip computer beside the steering wheel, and watch for a message to appear in the small display window below the speedometer. A code will be in the form of "Fuel Fail" or "FF" and a numeral, as in FF8. Please write down any message you receive and post it here exactly as it appears.

Also, please visit the https://www.jaguarforums.com/forum/n...-intro-must-5/ and post a required introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Cheers,

Don