In reply to a message from Win sent Thu 1 Nov 2012:
I’m backing Win’s theory on this one.
When was the last time you cleaned the EGR port in the TB?
I would do that first.
My AJ6 4.0L Engine Management System/OBD1 Diagnostic Guide
manual says that DTC 39 is an EGR temperature sensor circuit.
Under Possible faults the first two possible faults contain
Blockage in EGR transfer pipe between valve and intake manifold
Blockage in intake manifold EGR adapter
The other Possible Faults
Disconnected leaking or blocked vacuum hose to EGR solenoid
vacuum valve or EGR valve
Defective EGR solenoid valve
Defective EGR temperature sensor
Open or short circuit wiring
I did have that little blue EGR solenoid go bad but I think
it is a rare instance.
Are you sure the vacuum line from the solenoid is connected
on both ends and the hose is not leaking?
Most often the problem is like Win mentions, a blockage at
the EGR port.
Although the metal to metal thing is open for discussion. I
had my Jag dealer look up my VIN ans said that my VIN did
require a gasket. Indeed my parts seller (not Jag dealer)
had the gaskets. Gasket installed I honestly found no
difference in the operation than having no gasket.
If you remove the TB having a small ratchet set and some
extensions and maybe a swivel head. I have a few different
methods now to remove the TB.
I’ll e-mail you more about the DTC 39 subject–
The original message included these comments:
Odds are on the EGR port being so clogged you’re not getting
enough exhaust gasses through it to get the temperature rise.
Time to pop off the throttle body and clean out that port.
Probably a good time to clean the throttle body as well.
Throttle body is a metal to metal facing on the intake
manifold, no gaskets or sealant is required.
John 90 XJ40
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