I have had this problem ever since owning the car.( '87 xj-s) When cold the
car starts up fine then, as it starts to gain rpm it suddenly drops back to
around 300 rpm and struggles to keep running. If I give it gas it “bogs out”
and dies.
I have attempted various cures:-
Re-set throttle butterflies and linkage.
Remove and test aav.
Remove and test coolant sensor.
Remove and discard 45 sec. vacuum delay system (replumb dist. vac. hose to
top of RH manifold.) Retained sol. air valve.
Also added external sol. valve to give even more air at startup.
Clean Dist. mech. advance.
When engine is warm no problems are evident .Car runs fast and strong.
I feel I am missing a sensor or a signal is going astray. Any clues would
be appreciated.–
Cheers, Les
'87 XJ-S
'79 Harley Davidson (93 ci)
I own an 87 XJS, but I don’t know a whole lot about cars. I just
think the car is sweet so I bought it and have been putting money
into it. Most of my problems are fixed accept for the cold start.
If the car has been sitting for more than 12 hours, when I start it
up it seems to start fine, but if I push on the gas to go soon
after it seems as though the engine chokes on the gas and sputters.
I can push the pedal to the floor but it creeps at 5 mph until it
gets higher in 1st gear. After the car has warmed up for at least
15 minutes, I do not have this problem. Is it simple to fix like an
O2 sensor or am I looking at a serious problem. Also the
acceleration became worse after I had a tune up a couple of weeks
ago.–
Jeff Matteson
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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Jeff, there are a few things to check: verify that the mechanical advance
inside the distributor is not frozen (rotor should rotate about 11 degrees
and “snap back” to rest position when you release it quickly); verify that
the vacuum advance works (disconnect the hose to the capsule and apply
vacuum - the distributor rotor should move) and then verify that all the vac
hoses are connected and that the hose ends are not cracked; check the timing
(18 degress BTDC at 3000 RPM with the vac advance hose disconnected and
plugged); and check the TPS to ensure that there are no worn tracks at the
idle position (measure 0.32v across the red and yellow wires at idle
position and check for a smooth, unbroken transition to 4+v as you rotate
the throttle capstan by hand, engine off, key in the “run” position).
Jim Johnson - NCJOC
'88 XJ-S, V12, Lucas (CEI), TH400 (w/B&M), Dana 2.87
Annapolis, Maryland
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