1988 XJ12 Rough idle/ running rich
#1
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Hello all so my 88 xk is having some idling problems and i'm starting to beat my head against the wall. So before winter i tuned it up, plug, cap, rotor, and fuel injector cleaning done. Drove it about 150 miles and parkrd it. Got it out late this summer, and is idling rough once it warms up. I have run two tanks of fuel through it, re checked the plugs, replaced wires, had all 12 injectors rebuilt, retimed it, new cap, found intake leak and fixed. I think i have checked everything ican think of. the rough idle feels like a miss but donest happen all the time, but is enough that i feel it sitting at a stop light. car has 25,500miles. Any help would be great.
Thanks Tim
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Also found the plugs are black from idleing. seems tobe running rich, should note found the car will not start if coolant sensor is unpluged or will die once unplugged. omhed out at 347omhs @73degrees C.
Thanks Tim
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Also found the plugs are black from idleing. seems tobe running rich, should note found the car will not start if coolant sensor is unpluged or will die once unplugged. omhed out at 347omhs @73degrees C.
#2
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Location: Pacific Northwest USA
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Normal for engine to die/not start if CTS is unplugged.
Is 73ēC as hot as your engine gets? If so, that might enter into the problem. You need to reach about 80ēC before the system stops giving "cold enrichment".
Also check:
Fuel pressure (excessive)
Vacuum and electric enrichment switches (Stuck closed)
Pressure regulators (leaking)
Post back for details if needed
Cheers
DD
Is 73ēC as hot as your engine gets? If so, that might enter into the problem. You need to reach about 80ēC before the system stops giving "cold enrichment".
Also check:
Fuel pressure (excessive)
Vacuum and electric enrichment switches (Stuck closed)
Pressure regulators (leaking)
Post back for details if needed
Cheers
DD
#3
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73C is just what it happened to be. i can wait till the electric fan turns on at full temp and still runs the same. I know that the fpr aren't leaking, by removing vacuum hoses snd turning vehicle on. Also fuel is not spraying out of them when running.
Fuel presure was good when i checked at the beginning of all this.
What vacuum and electric switches should i be looking for?
Fuel presure was good when i checked at the beginning of all this.
What vacuum and electric switches should i be looking for?
#4
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On the right side of the throttle capstain there is a micro switch that should only be closed at about 3/4 throttle. The wires from that switch go to a blue vacuum/elect switch a few inches away at the rear of the right inlet manifold. Make sure it isn't closed when it shouldn't be. It should close only under low vacuum.
As far fuel pressure goes I'm wondering if it's too high.
Cheers
DD
As far fuel pressure goes I'm wondering if it's too high.
Cheers
DD
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wigglewerks (06-03-2011)
#5
#7
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Allright now that im back from the weekend, the throttle capstain switch does not close till about 3/4 throttle.
I seem to be havinh troble finding my adapter for fuel pressure test. i'll have to keep looking.
The adjustment on the ecm hasen't been touched as i have owned the jag for a few years.
I did swap out o2 sensors from a friends 88 jag. mine runs the same but his now runs like crap with a definitely has a miss. i got some replacements on there way.
I seem to be havinh troble finding my adapter for fuel pressure test. i'll have to keep looking.
The adjustment on the ecm hasen't been touched as i have owned the jag for a few years.
I did swap out o2 sensors from a friends 88 jag. mine runs the same but his now runs like crap with a definitely has a miss. i got some replacements on there way.
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