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Old 24th November 2019, 14:26   #51
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Also fuel pressure. What should the normal value be?
3.5 bar or 50ish psi

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Old 24th November 2019, 15:44   #52
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Hooked up my scanner and the following values looked interesting to me:

Intake manifold pressure: steady at 40kpa/12inhg which seems a little low to me, I read that it normally should be about 16-20inhg. When revving on idle it goes to 90kpa then drops to 20kpa when letting go of the pedal and then stabilizes at 40 again.

Air mass meter 65mg/stroke at idle

Also, the value for indication rich mixture bank 1/2 constantly switches to on-off-on-off and so on for both banks

Also, another thing I noticed now, when starting the car from cold it idles at about 1500rpm and as the engine warms up it slowly goes down, but it takes a few minutes..

If anyone has some ideas or can compare these values please let me know.
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Old 24th November 2019, 17:18   #53
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The fuel pressure as measured at the Schrader valve should be around 3.5Bar (50psi area).


The gross fuel contamination of the sump oil in such a short period as you've described is worrying. Like other contributers, I'd also recommend a standard compression test to confirm all the valves and piston rings are functioning normally.


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Old 25th November 2019, 12:27   #54
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Read something pointing out that the idle control valve could cause the fast idle when cold, but would it be able to also cause misfires? Also what about the map sensor? Should that be a place to look?

One more thing, I bought 6 spark plugs from Champion, platinum ones and they have a 0.8mm electrode gap. Is that fine for a KV6? Haynes says 1mm but I've read some shortened the gap to 0.5mm and it supposedly cured their slight misfiring issues, and not only for one of them, read a lot of cases, what do you guys think?
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Old 25th November 2019, 13:28   #55
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Many K-series owners find a spark gap less than the specified 1mm does reduce some minor firing issues. I have 0.7mm on my 1.8T but others do indeed go down further. It can't do anyharm I guess.

Rather than spend more money on parts that don't appear to be solving the problem, a simple comression test will be very informative.


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Old 25th November 2019, 17:43   #56
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Of course. That will do my mechanic tomorrow since the last time when I thought that the issue was cured I canceled the appointment. In the meantime, would someone know what are the "normal" compression values on both dry and wet tests?
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Old 25th November 2019, 18:07   #57
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I bought 6 spark plugs from Champion, platinum ones and they have a 0.8mm electrode gap. Is that fine for a KV6? Haynes says 1mm but I've read some shortened the gap to 0.5mm and it supposedly cured their slight misfiring issues, and not only for one of them, read a lot of cases, what do you guys think?
1.0 mm is the correct gap for the KV6. Reducing it has been done on the 4 cylinder engine but not, to my knowledge, on the KV6. After all, it's not an easy job extracting the plugs from the RH bank. I have never had any trouble with sparking plug gaps in fifteen years of ownership.

As for it doing no harm, I recently had trouble starting my SD1 V8 from cold with terrible misfiring. I found the cause to be an incorrect plug gap on no.8. It was too small! Once enlarged to the specified size the engine started beautifully. So on that basis I'd say that your plug gaps definitely need to be 1.0 mm and no smaller.

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Old 25th November 2019, 18:31   #58
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would someone know what are the "normal" compression values on both dry and wet tests?
I think 140-150psi will be near the optimum for well lubricated pistons.

EDIT: Haynes (which I guess means RAVE) indicate 10bar (about 150psi) minimum with a variation not exceeding 1.5bar (22psi) between any two cylinders.

Note that all values will vary depending on the teperature of the engine. Most people will do compression tests when the engine is cold.

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Old 25th November 2019, 22:34   #59
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Unestimated value you are providing here! Never thought it was possible for an engine to misfire if the gap is smaller, thought it could only misfire if the gap is larger since smaller gap allows for the spark to get ignited better. I think the logical explanation for this is that the ECU also calculates the exact time of the spark taking into consideration the normal spark gap and if the gap is smaller, the spark happens just a bit too early to create misfires, of course I am only speculating.

Will try tomorrow to increase the gap to 1mm, do you guys know a way to do this with stuff I can find at home or in my garage without damaging the plugs?
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Old 25th November 2019, 23:02   #60
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I think the logical explanation for this is that the ECU also calculates the exact time of the spark taking into consideration the normal spark gap and if the gap is smaller, the spark happens just a bit too early to create misfires, of course I am only speculating.
Yes, you're speculating. For all practical purposes, the spark occurs at the same instant irrespective of the size of spark gap.

Quote:
do you guys know a way to do this with stuff I can find at home or in my garage without damaging the plugs?
Maybe click here? https://www.google.co.uk/search?sxsr...4dUDCAU&uact=5

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