Jaguar V12 Sensors, Cold Start and Cold Idle

I am working through minor recommissioning issues with my 1976 Jaguar XJ 5.3 Coupe 7P29464. I have a little cold start difficulty- it fires on the second attempt but smells rich and has a low cold idle. I have replaced the AAV which was pretty seized and, with a reconditioned MAP sensor now fitted all is well when the engine is at operating temp. I wanted to try replacing the air and engine temp sensors C42167 (0280130006)and C42166 (0280130014) but nowhere stocks them under any of the Jaguar, Lucas or Bosch codes. Does anyone know these can be substituted with alternative sensors from the Bosch range, that might be available please? I have also looked for the cold start valve C42161 (0280170033) and thermo time switch C42159/1 (0280130212), which again I cannot find anywhere under any code. Thanks

Hi Gareth,

why do you want to blindly swap all parts. COld start is effected by following parts if warm engine runs well:

• Cold start valve - disconnect electrically or better from fuel line. Engine should still start
• Check leaking injectors - take them out of manifold but still connected to fuel line. Build up fuel pressure and check for leaking injectors
• Measure resistance of air and engine temp sensors on ECU - I should have those sensors here
• AAV will not make rich fuel mixture - that only is a foot on gas pedal increasing air flow

Hi Garret <your first name???>,
you should at first verify your components, you find the values in the  D-Jetronic-compendium here.
The temp-sensors of the water-cooled D-Jet-cars do have all the same electrical values at the air- and the water sensors.
In many cases you can find alternatives in the Bosch program that are fully compatible.

A replacement for the thermo-time-switch is the 0280130214. (to be found mostly used only).
An electronic newer version is available at Bosch Classic: www.bosch-classic.com/de/de/produkte/fah...6T03100#produktsuche
You have to replace the connector by a L-Jetronic-version for both switches, but that's all.

The air temp sensor 0280130006 should be available, maybe used.
Same with the motor temp sensor 0280130014.
Both were used in other cars, too and should be available in used condition..

I think replacements for the CSV could be 0280170039 and 0280170040. They both have identical volume and angle with the Jaguar device. I don't know they are available - used in US-cars only.

Don't replace the injectors with the Chinese ones with the three-hole-head and the Bosch-# without the Bosch-logo. They are sold as being compatible, but aren't.

Regards
Norbert

Thank you for your reply. The cold start valves and injectors were tested and replaced as required shortly before I bought the car. As I am a complete novice with no facilities or comfort in undertaking the first two suggestions, I therefore prefer, for the timebeing, to assume the problem lies elsewhere, which leads me to your third suggestion and hence my post. Annoyingly the engine sensor connector casings completely disintegrated when I removed the connectors to inspect, so will need replacing. Rightly or wrongly, I have been replacing items where possible as I have gone along, for peace of mind as much as anything, which may have proved unnecessary, or not. The AAV held no vacuum at all, but thank you for confirming this is irrelevant to my stated issue here. Best wishes. Gareth

Thank you Norbert. I clearly need to do some more investigating. And thank you for the warning about Chinese injectors.
Best wishes
Gareth
btw had you intended to add a link to the d jetronic compendium when you wrote 'here', or were you simply referring to jetronic.org site? Thanks again.

Yes, information about the sensors to be found here: jetronic.org/en/d-jetronic/troubleshooting

Regards
Norbert