A little rough on idle
#1
A little rough on idle
hi
Finally got our XJ6 1986 back today. running well but is taking a little to start and running rough seems to settle after she as warmed up. fuel is more than likely stale so I give it good run once i can fill the tanks. should i run normal 89 or run 91 for a bit.
Finally got our XJ6 1986 back today. running well but is taking a little to start and running rough seems to settle after she as warmed up. fuel is more than likely stale so I give it good run once i can fill the tanks. should i run normal 89 or run 91 for a bit.
#2
Join Date: Jan 2014
Location: Delaneys Creek,Qld. Australia
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I was advised here to run 95 or 98, It does idle rougher on 91. But no real difference between 95 and 98.
I have run a few tanks of each and have settled on 95,seems to work fine.
It does idle better at 600-650rpm in drive,books suggest as low as 500-550 in drive but I find this too slow,giving a rough idle.
It may different with your car as I think it is fuel injection isn't it?
I have run a few tanks of each and have settled on 95,seems to work fine.
It does idle better at 600-650rpm in drive,books suggest as low as 500-550 in drive but I find this too slow,giving a rough idle.
It may different with your car as I think it is fuel injection isn't it?
#3
#4
#6
#7
Just got reminded by Son.
In the boot, behind the rear seat trim vertical panel, sort of to the the right of centre, in an impossible location, is the fuel ECU, and on the side of the ECU is an "idle fuel trim knob".
It can be reached by FEELING in from the left side, and the ECU will be readily felt, then wriggle the hand around and the knob will be felt. It rotates on a "Click" ratchet, and I think? 13 clicks end to end.
Once the beast is WARMED up, give it a twirl, SLOWLY, and see if that "sweet spot" can be dialed in.
His was 4 clicks out, and once dialed in, sweet as.
In the boot, behind the rear seat trim vertical panel, sort of to the the right of centre, in an impossible location, is the fuel ECU, and on the side of the ECU is an "idle fuel trim knob".
It can be reached by FEELING in from the left side, and the ECU will be readily felt, then wriggle the hand around and the knob will be felt. It rotates on a "Click" ratchet, and I think? 13 clicks end to end.
Once the beast is WARMED up, give it a twirl, SLOWLY, and see if that "sweet spot" can be dialed in.
His was 4 clicks out, and once dialed in, sweet as.
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#9
Join Date: Mar 2008
Location: Pacific Northwest USA
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Been that way up here for as long as I can remember...20 years or so at least.
what is the ethanol/gasohol or whatever other ecofreak stuff gonna do to my 83 4.2L.
From a running/driving standpoint nothing horrible will happen. You'll lose about 3% fuel economy. That's about it.
E10 can be a problem if moisture gets into the fuel tanks, so be very aware of that.
Many insist the E10 dries out rubber parts and has a corrosive effect on some metals. I'm not convinced that this is a serious or widespread issue.....real world experiences vary so greatly.... but there is tons and tons and tons of debate in the archives. Some blame E10 for everything from a drippy fuel hose to their wife getting pregnant
Cheers
DD
#10
Join Date: Mar 2008
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Very interesting!
I wonder if this is one of the differences in USA vs. ROW spec cars? I don't recall ever seeing an external ECU adjustment on our Ser III 4.2 cars. The idle mixture is tweaked at the AFM.
Or maybe I just never noticed?
The USA V12s had an external ECU adjustment, though, just like the others.
Cheers
DD
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Mad Matt (06-22-2014)
#11
#12
Doug,
I reckon you are right. Another '84 S3 6cyl stopped in today, so I clambered in the boot and dug around, NO adjuster.
Challenged the son. He was still convinced it was on his '85 S3. MORE challenge, and I reckon he is thinking of his S2 V12 D Jetronic. AT a stalemate at the moment.
Apologies for any false info I may have posted. I will attend the "naughty corner" with a fresh JD and ponder for an hour or 2.
I reckon you are right. Another '84 S3 6cyl stopped in today, so I clambered in the boot and dug around, NO adjuster.
Challenged the son. He was still convinced it was on his '85 S3. MORE challenge, and I reckon he is thinking of his S2 V12 D Jetronic. AT a stalemate at the moment.
Apologies for any false info I may have posted. I will attend the "naughty corner" with a fresh JD and ponder for an hour or 2.
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autotec40 (11-10-2014)
#13
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Grant Francis (06-24-2014)
#14
Join Date: Jul 2012
Location: Walnut Creek, California
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Points:
1. I read the other day that E85 is sold at some locations here in the USA. What I did not realize before is that it is not 15% Ethanol, but 85% Durn near all alky!! And that some very late cars handle it well or at least somewhat.
2. E10 is the fuel of the day around here. No options that I am aware of. My cars do OK with it. My 2 cycle lawn engines and generator not so much. The 4 cycle Honda powered lawn mower does Ok with it as does the Honda knock off predator powering my chipper/shredder.
3. Fresh, clean fuel is the key. Octane to match engine needs. At about 9 to one engines do fine on 87. More #'s and higher is needed.
4. Some engines are octane happy and others not so much.
5. Way back when,. I rebuilt the engine in my 69 FJ40 Toyota land cruiser. I used parts of the 69 engine and parts of a 74. Result, flat op pistons and a small volumn head. Lottsa #'s, but needed 98 to be "happy".
Same with my Edelbrock headed flat head Ford V8. Not happy with less than 98!!
I wonder what my WWII vintage Tecumseh powered generator will think of E10!!
Carl
Carl
1. I read the other day that E85 is sold at some locations here in the USA. What I did not realize before is that it is not 15% Ethanol, but 85% Durn near all alky!! And that some very late cars handle it well or at least somewhat.
2. E10 is the fuel of the day around here. No options that I am aware of. My cars do OK with it. My 2 cycle lawn engines and generator not so much. The 4 cycle Honda powered lawn mower does Ok with it as does the Honda knock off predator powering my chipper/shredder.
3. Fresh, clean fuel is the key. Octane to match engine needs. At about 9 to one engines do fine on 87. More #'s and higher is needed.
4. Some engines are octane happy and others not so much.
5. Way back when,. I rebuilt the engine in my 69 FJ40 Toyota land cruiser. I used parts of the 69 engine and parts of a 74. Result, flat op pistons and a small volumn head. Lottsa #'s, but needed 98 to be "happy".
Same with my Edelbrock headed flat head Ford V8. Not happy with less than 98!!
I wonder what my WWII vintage Tecumseh powered generator will think of E10!!
Carl
Carl
#15
Getting slowly to the problem. Heading to my mechanic tomorrow, we going to run a fuel pressure test, indication is could fuel regulator problems. Getting it up to speed and she runs like dream. Go to turn around and shift gears and it stall starting produces black smoke and struggles to start.
What is every thoughts on the fuel cooler on the aircon. We have had the whole aircon replaced and found out today that they did not add back the cooler.
What is every thoughts on the fuel cooler on the aircon. We have had the whole aircon replaced and found out today that they did not add back the cooler.
#16
#17
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Getting slowly to the problem. Heading to my mechanic tomorrow, we going to run a fuel pressure test, indication is could fuel regulator problems. Getting it up to speed and she runs like dream. Go to turn around and shift gears and it stall starting produces black smoke and struggles to start.
XJ6 Series - EFI Rich Mixture
If the black smoke/rich mixture seems to occur only when the engine is cold, consider the 'cap mod'...
XJ 6 Series III 4.2 - Cold Start EFI Overfuelling
What is every thoughts on the fuel cooler on the aircon. We have had the whole aircon replaced and found out today that they did not add back the cooler.
Cheers
DD
#18
Found the problem just by accident, checking all the sensors. And found that the two wires leading in to the temp sensor where just pushed into the plug. Grab the plug from the spare and temp hooked the wires up. Problem solved. Whoop whoop, on to the next thing. Thanks guys for all your input. As for the cooler I won't stress now if others have had no issues.
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