Incredible FUEL Dilution on my Montana

[JAG]

Something you replaced is likely the cause. Search for the problem by starting with the easy to check things and moving on to more difficult.
1. Spark plug brand/model correct?
2. Spark Plug Gaps correct? Also check condition (color/deposits) since it can indicate if just one cylinder is cause for the fuel dilution or all of them. If that checks out then...
3. Then I'd move on to suspect the ignition coil or one or more of the spark plug wires are faulty. Not sure how to check that but that's what I'd look into next.
I doubt any of the other things above would cause fuel dilution.

 

[21Rouge]

But there was an oil change analysis well after the above work was done

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002919#000000

The dilution should have shown up then but it didnt.

 

[JAG]

Oops, I missed that. That rules out the idea that one of the parts you installed was faulty from day 1. So something just went bad after some time. I'd still go thru the same procedure I wrote above. If you have a check engine light on, you could have someone scan for the error codes as well.

 

[21Rouge]

quote:

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If you have a check engine light on, you could have someone scan for the error codes as well.

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Agreed! But no CEL at all. And the likely culprits causing such excessive dilution should trigger a CEL should it/they?

[ January 20, 2006, 01:43 PM: Message edited by: Boxgrover ]

 

[The Critic]

Injector leak??? Doesn't always trigger CEL.

 

[JAG]

"And the likely culprits causing such excessive dilution should trigger a CEL should it/they?"

I'd like to think so but your engine has proved that it isn't always so. It could be that right amount of fuel is getting injected but the spark in that cylinder (or multiple cylinders) is too weak to fully burn the mixture. Or it could be that too much fuel is getting injected and the spark is good. Each scenario has multiple potential culprits. As said above, a leaky injector is one way to get too much fuel and the ECU wouldn't count that fuel being leaked...hence, no CEL. Reading your plugs is definately the best first step to see what's going on. Good luck.

 

[IslaVistaMan]

I agree with JAG. Go back to the basics, and start with the plugs. If they're all the same color, then you know you have a different problem than a single leaky injector.

What did the "injector service" you had done involve, btw? Fuel rail cleaning and...what?

 

[sebring01]

I had a ton of fuel dilution too on my 95 Sidekick, which only goes 2 miles to work, 2 miles home daily. Short trips appear to do this.

 

[21Rouge]

Thanks for the feedback.

quote:

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Injector leak???

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What is involved in diagnosing and repairing an injector leak? Can a small independent do such a job?

 

[21Rouge]

Just got back the next report on my 2000 Pontiac Montana:

Immediate prior report can be found at

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002919#000000 :


OCI: 4 months (September to January) and 1200 miles. (This car's weekday routine is generally 2 trips per day, 3 miles each way. Additional trips are short...almost no hwy miles)


Miles on Car: 65 000
OIL German Castrol (green)

ALUMINUM 3
CHROMIUM 1
IRON 17
COPPER 12
LEAD 4
TIN 4
MOLYBDENUM 11
NICKEL 0
MANGANESE 11
SILVER 0
TITANIUM 0
POTASSIUM 3
BORON 21
SILICON 9
SODIUM 5
CALCIUM 3420
MAGNESIUM 88
PHOSPHORUS 749
ZINC 944
BARIUM 0

Flashpoint 250
SUS Viscosity 57
Fuel% 6.8
Antifreeze 0.0
Water 0.0
Insolubles 0.4

And if you check the previous OCI with M1 5W-30 there is no evidence of fuel dilution.

Additionally the following service was done last April and less than 5000 miles ago (prompted by a CEL):

replaced EGR valve and gasket
replaced fuel filter
injector service
replaced fuel filter
replaced spark plugs and spark plug wires
replaced ignition coil
clean throttle body

ALL this was done less 9 months ago and less than 5000 miles has elapsed.

Terry of course red flagged me asap but not exactly sure what can be done given this background. I need your input.

Btw, before gettign the report I replaced the GC with XD 0W-30.

 

[Hirev]

Short trips and almost no highway miles is a very good recipe for fuel dilution and sludge motors.

Something does not sound right here. Are you sure the information ("no evidence of fuel dilution") you received was accurate on Mobil 1. Because no evidence of fuel dilution on such short trips of 3 miles and almost no highway miles seems very unlikely.

One thing I would do is replace the PCV valve with a high quality one. Because lots of very short trips will kill them very early.

 

[21Rouge]

quote:

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Something does not sound right here. Are you sure the information ("no evidence of fuel dilution") you received was accurate on Mobil 1. Because no evidence of fuel dilution on such short trips of 3 miles and almost no highway miles seems very unlikely.

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As I recall the miles put on this vehicle, tested in the previous ssample were summer miles and there was more hwy mileage than it experienced from September to January.

 

[21Rouge]

quote:

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Short trips and almost no highway miles is a very good recipe for fuel dilution and sludge motors.

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And so for the past 4 changes I have used only quality synthetic ie M1 GC and XD

 

[T-Keith]

I'm curious about the "injector service" as well. I have seen them cause problems on some vehicles. High fuel doesn't suprise me a bit with that driving in winter. Would it hurt to take it out on the freeway once and a while?

 

[Ramblin Fever]

I think the biggest issue is the only 3 miles each way; that's not even enough to bring the engine up to half-way temp.

Get that engine good and hot at least twice a month.

 

[21Rouge]

quote:

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I think the biggest issue is the only 3 miles each way; that's not even enough to bring the engine up to half-way temp.

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That's what I wonder ie is the dilution due to driving patterns or is it a mechanical problem.

Btw, had it on the hwy for a 3 hour drive last night....oh there was a reason for me to drive it so much yesterday...didnt just drive it to work on the dilution problem

 

[Hirev]

The fuel dilution is due to driving patterns would be my best guess.

My dad had a truck he bought new, used it mainly for going back and fourth to work about 2 miles each way. He changed the oil on this truck every 2800 to 3000 miles. When it was about 10 years old with only 35,000 miles on it he had me change the valve cover gaskets because of a oil leak. I could not believe all the sludge that was inside this motor.

Later on I worked a engine remanufacturing shop for a couple years. I seen the same pattern on customers engines. In that customers who mainly used vehicle for short trips back and fourth to work always had motors that accumulated a lot of sludge and varnish.

If it were mine i would try to get it on the highway at least 2 or 3 times a month.

 

[21Rouge]

quote:

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The fuel dilution is due to driving patterns would be my best guess.

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PCV valve showed clean. Car starts on first turnover everytime. Car drives smoothly when driven as it did last night on its hwy run of 150 miles. And no CEL.

And lost of basic maintenance was done last April ie plugs, fuel filter,.. (see above).

Unless more develops all I am going to do for now is give it more extended miles.

It has had synthetic oil for the past 4 changes...and currently there is the Esso XD 0W-30. That should help keep the sludge at bay.

 

[JAG]

You looked at your PCV valve but not your spark plugs? Doh!

 

[21Rouge]

quote:

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You looked at your PCV valve but not your spark plugs? Doh!

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Fair enough Jag. Okay so I went to a mechanic I have used before. He had only enough time to check the front three plugs. I did not tell him when I had them last changed as he removed them. All three looked equally very worn. They were to be gapped at .06 he observed from the info on the bottom side of the hood but these three were much closer to .08. He said they looked about 5 years old. It was than I told him they were replaced April 2005, 5k miles ago. He couldnt believe this was so. I then showed him the dealer invoice/receipt. Any suggestions as a next step?