So is this the issue with my 88' or just a red herring?
#21
08-10-2017, 06:36 AM
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A vacuum leak will not cause incorrect fueling or mixture. When more air comes in, via a leak or the throttles, the ECU adjusts fueling to keep the mixture correct. So, a vacuum leak shouldn't cause incorrect fueling or incorrect mixture.
Cheers
DD
#22
08-10-2017, 06:48 AM
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#23
08-10-2017, 06:58 AM
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It's the 'model year' versus build year thing again.
Brad is in Illinois so we're talking about a USA-spec car. For the USA market Marelli ignition came along part way through the 1989 model year...which might indeed include some cars built in 1988 calendar year.
The earliest USA 1988 model year XJSs were built in Feb 1987. I know, because I had one !
Cheers
DD
#24
08-10-2017, 10:03 AM
Right.
Think of the Aux Air Valve. It increases idle speed on a cold engine by letting more air in. It might be called an intentional, controlled vacuum leak. Or, if you leave the air cleaner housing bolts out the idle speed will be very high...because you're letting more air in. Meanwhile, the ECU adjusts fueling to match....because it doesn't know or care if the air is coming in through the throttles or via some other source.
In a case like this diagnosis is more about 'process of elimination' than anything else, IMO. Choose a stepping-off point (fuel pressure is as good as any, IMO) and go from there. If that checks out, move on.
Cheers
DD
Think of the Aux Air Valve. It increases idle speed on a cold engine by letting more air in. It might be called an intentional, controlled vacuum leak. Or, if you leave the air cleaner housing bolts out the idle speed will be very high...because you're letting more air in. Meanwhile, the ECU adjusts fueling to match....because it doesn't know or care if the air is coming in through the throttles or via some other source.
In a case like this diagnosis is more about 'process of elimination' than anything else, IMO. Choose a stepping-off point (fuel pressure is as good as any, IMO) and go from there. If that checks out, move on.
Cheers
DD
Thanks for the help on the xjs vacuuming it's starting to make some sense.
#25
08-10-2017, 12:49 PM
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I thought the right side rail at the regulator had a spot for a pressure gauge? Maybe I'm remembering incorrectly...
I would still try some fluid to look around for a leak, only takes a few minutes. Since you mentioned re-doing the injectors I would be suspicious of you forgetting to connect something or bumping into something and cracking a line while you were in there.
I would still try some fluid to look around for a leak, only takes a few minutes. Since you mentioned re-doing the injectors I would be suspicious of you forgetting to connect something or bumping into something and cracking a line while you were in there.
#26
08-10-2017, 03:53 PM
I thought the right side rail at the regulator had a spot for a pressure gauge? Maybe I'm remembering incorrectly...
I would still try some fluid to look around for a leak, only takes a few minutes. Since you mentioned re-doing the injectors I would be suspicious of you forgetting to connect something or bumping into something and cracking a line while you were in there.
I would still try some fluid to look around for a leak, only takes a few minutes. Since you mentioned re-doing the injectors I would be suspicious of you forgetting to connect something or bumping into something and cracking a line while you were in there.
Well I'll not only did I redo the injectors I redid the harness... wish I had my old one to try just in case I screwed up but I dissected it. There's a junkyard car an hour away from me that I'm tempted to go see if it still has its harness.
#28
08-10-2017, 07:55 PM
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#30
08-11-2017, 02:02 AM
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#31
08-11-2017, 01:55 PM