Cold Start Issue - V12 '82
#1
Cold Start Issue - V12 '82
Purchased a v12 XJS a little while ago - had a few issues which I've worked through
Next on the list is 'cold starting' - bit of a process to get it started from cold which usually involves 3-4 attempts and lots of 'feathering' of the throttle
Car runs fine once its warmed up - although a slight idle issue when its hot which may (or may not be related)
Any thoughts on where to start with the cold start issue?
Thanks
Next on the list is 'cold starting' - bit of a process to get it started from cold which usually involves 3-4 attempts and lots of 'feathering' of the throttle
Car runs fine once its warmed up - although a slight idle issue when its hot which may (or may not be related)
Any thoughts on where to start with the cold start issue?
Thanks
#4
#5
IIRC pre HE had the cold start injector. If yours does not (which I'm going off the assumption it does not) then turn the key to "run" and push down the gas pedal twice then attempt to start. Pushing the pedal with the key in run will "pulse/spray" the injectors. Make sure your throttle plates are set correctly also .002" If they are full closed this will also make for harder starting. V12 JAGUAR THROTTLE LINKAGE ADJUSTMENT / AJ6 Engineering
The following 2 users liked this post by JTsmks:
Doug (01-17-2017),
Grant Francis (01-17-2017)
#6
The early HEs had the cold start injectors as well but were problematic and discontinued. Many, I think, have been disconnected for years.
The coolant temp sensor certainly plays the big role in cold fueling.
Here's the resistance specs on the CTS
Testing the Coolant Temp Sensor
This ^^^ is actually for the Series III XJ6 sensor but the specs are virtually identical.
Cheers
DD
The coolant temp sensor certainly plays the big role in cold fueling.
Here's the resistance specs on the CTS
Testing the Coolant Temp Sensor
This ^^^ is actually for the Series III XJ6 sensor but the specs are virtually identical.
Cheers
DD
The following users liked this post:
Grant Francis (01-17-2017)
#7
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#8
Cold start injectors won't be working unless very cold. Probably sub zero temperatures.
Can you check fuel pressure to see what's happening?
Might be worth checking throttle potentiometer setting and seeing that it's sweeping correctly.
Run a few bottles of injector cleaner through it.
We used to add the cleaner and drive the car get it nice and hot. Then leave the car to stand for a few hours.
Would improve idle. Lower hydrocarbons and increase Co. Due to poor injector spray pattern.
It's always hard. Lots of little thing to do to keep these v12's running properly. The throttle plate setting is good advice. Check and set mixture. Set idle speed correctly.
Can you check fuel pressure to see what's happening?
Might be worth checking throttle potentiometer setting and seeing that it's sweeping correctly.
Run a few bottles of injector cleaner through it.
We used to add the cleaner and drive the car get it nice and hot. Then leave the car to stand for a few hours.
Would improve idle. Lower hydrocarbons and increase Co. Due to poor injector spray pattern.
It's always hard. Lots of little thing to do to keep these v12's running properly. The throttle plate setting is good advice. Check and set mixture. Set idle speed correctly.
Last edited by melhookv12; 01-18-2017 at 02:50 PM.
#9
have checked the coolant temperature sensor - can't seem to get any reading at all from it. I might be doing something wrong - but i'll just replace it anyway to be sure as they are cheap enough
Interestingly - I started reading the manual last night and noted it referenced a cold start relay in the engine bay which sits under a protective cover alongside the fuel pump relay.
When - I took the cover off, the relay wasn't there! For some bizarre reason - the relay has been removed and not replaced. obviously - i'll replace this also.
Question - this looks like a generic relay setup, can this be sourced from a local parts store (not Jaguar)? If so - what should I be asking for?
Interestingly - I started reading the manual last night and noted it referenced a cold start relay in the engine bay which sits under a protective cover alongside the fuel pump relay.
When - I took the cover off, the relay wasn't there! For some bizarre reason - the relay has been removed and not replaced. obviously - i'll replace this also.
Question - this looks like a generic relay setup, can this be sourced from a local parts store (not Jaguar)? If so - what should I be asking for?
#10
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Grant Francis (01-21-2017)
#11
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Grant Francis (01-21-2017)
#12
ok - I've got myself into a bit of pickle here, so please bear with me while I explain
Still sorting the cold start issue - and was following the links provided.
Firstly - the throttle pentameter was reading 1.3 - and should have read 0.32 at closed throttle according to the AJ6 information at closed throttle so I adjusted the pentameter accordingly
Also - the throttle plates were fully closed with no gap - so I adjusted (and rechecked) the gaps at 0.002"
Feeling very pleased with myself - I restarted the engine and still had the cold start issue, but more worrying was the idle had jumped to 1300rpm and I can't seem to adjust it down using the AAV idle bolt
I also seem to have introduced a slight miss on A bank - which I don't think was there before. Anyway - seem to have gone backwards at a rapid pace
Any help would be much appreciated
Still sorting the cold start issue - and was following the links provided.
Firstly - the throttle pentameter was reading 1.3 - and should have read 0.32 at closed throttle according to the AJ6 information at closed throttle so I adjusted the pentameter accordingly
Also - the throttle plates were fully closed with no gap - so I adjusted (and rechecked) the gaps at 0.002"
Feeling very pleased with myself - I restarted the engine and still had the cold start issue, but more worrying was the idle had jumped to 1300rpm and I can't seem to adjust it down using the AAV idle bolt
I also seem to have introduced a slight miss on A bank - which I don't think was there before. Anyway - seem to have gone backwards at a rapid pace
Any help would be much appreciated
#13
Also - the throttle plates were fully closed with no gap - so I adjusted (and rechecked) the gaps at 0.002"
Feeling very pleased with myself - I restarted the engine and still had the cold start issue, but more worrying was the idle had jumped to 1300rpm and I can't seem to adjust it down using the AAV idle bolt
Feeling very pleased with myself - I restarted the engine and still had the cold start issue, but more worrying was the idle had jumped to 1300rpm and I can't seem to adjust it down using the AAV idle bolt
You have extra air coming in from 'somewhere'....most likely a stuck AAV. But it could be a hose, loose intake manifold bolts.....any number of things.
The fact that throttles were set to zero clearance suggests someone has been in there ahead of you trying to mask the problem.
But.....
Did you have the air filter housings completely removed? If so, make sure all the bolts are tight. The bolt holes are open to the manifold so an air leak past the bolts is effectively just the same as a partially open throttle
Cheers
DD
The following 2 users liked this post by Doug:
Grant Francis (01-21-2017),
Greg in France (01-22-2017)
#14
only removed the airfilters - not the housings, so that shouldn't be an issue
The thought of an airleak occurred to be me as well - but have triple checked and can't find any loose pipes or missing connections
Next step presumably will be to remove and check the AAV as per your response Doug?
The thought of an airleak occurred to be me as well - but have triple checked and can't find any loose pipes or missing connections
Next step presumably will be to remove and check the AAV as per your response Doug?
#15
Doug has answered my thiughts also.
ALSO, that idle adjust bolt is ONLY for when the engine at operating temperature, and the COLD idle speed is controlled by precut slots in the AAV piston.
Have a read below.
AAV rebuild procedure.doc
Adjusting the HE TPS.doc
HE Tune up.doc
ALSO, that idle adjust bolt is ONLY for when the engine at operating temperature, and the COLD idle speed is controlled by precut slots in the AAV piston.
Have a read below.
AAV rebuild procedure.doc
Adjusting the HE TPS.doc
HE Tune up.doc
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#16
The following 2 users liked this post by mobileman:
Grant Francis (01-22-2017),
Greg in France (01-22-2017)
#17
#19
quick update to the many of you who have helped in this search for a solution to my cold start issue
Have rechecked the setting on the pentometer - that checks out ok.
The AAV failed miserably on the suction test however - so have just removed and clearly its badly seized.
Looks like the next job is an AAV rebuild as per the instructions provided - then i'll also probably undertake a full tune including the spark plugs, timing etc
I thnk i'm making progress - thanks again for the help
Have rechecked the setting on the pentometer - that checks out ok.
The AAV failed miserably on the suction test however - so have just removed and clearly its badly seized.
Looks like the next job is an AAV rebuild as per the instructions provided - then i'll also probably undertake a full tune including the spark plugs, timing etc
I thnk i'm making progress - thanks again for the help
The following 2 users liked this post by mobileman:
Greg in France (01-29-2017),
orangeblossom (01-29-2017)