Electrical, mechanical or fuel?

[ytt105]

The story so far...
Did some work on the 4.6 Thor Rangie, (fitted injected LPG)

All successful except for a terrible idle in the cold Canberra morning. Ran fine when warmed up, so drove from Canberra to Melbourne, bought a van, towed it back via Bombala, then drove to Sydney and back. At least 2000kms. Went well except chewed a far bit of fuel, LPG.

Then I discovered the air intake clamp to the throttle body was off so I obviously had a severe intake leak. Tightened the clamp and within 1 kilometre started to get solid vibration around 1500 to 2500 revs, right through the car.

So, my thought process was, air leak causes bad idle, long open road drive causes adaptive values to adjust for this air leak, when ir leak cured adaptive values are now so far rich it causes vibrations.

I just got my adaptive values deleted (thanks Paul) and it has certainly improved the vibrations but the're still there. So a new set of plugs have gone in, (maybe they were ruined by the too rich mixture), but no they look good and no change to the vibrations.

I've been concentrating on the fuel side because of the air leak, but could it be something else.

My understanding is that the flex plate issue causes vibrations above 3500 revs, so probably not it.

More facts, there are NO vibrations when revved to 3000 when in park, vibrations are engine speed dependant not road speed dependant.


So what next?

[RR P38]

Had a good look at your fan?

[Blknight.aus]

check the plug(s) and leads first.

[PeterAllen]

If there is No vibration in park at 3000 revs or in neutral wouldnt it suggest a drive train or road speed vibration rather than engine? If in all gears rules out road speed and assume your vibration is thru all gears at 1500 to 2500 . Is vibration there when egine is not under load but in gear at same revs such as driving down hill or just when engine is under load?

[ytt105]

No vibration in neutral at 3000. Yes, vibration when coasting downhill in gear. Seems to be when under some load. At 100kph on the flat, silky smooth.

Starting to think uni joints or such.

[PeterAllen]

Yes from what you have said i would be looking underneath around the driveshafts

[ytt105]

Just found a stuffed uni joint in the rear of the front driveshaft.

Will get all 4 changed tommorow.

[PeterAllen]

Hope that solves your problems

[ytt105]

Just to update on the outcome.

Yes it was the uni joint. Got all four changed and she's smooooth again.

Prices.
Got the uni's for $23 each from a bearing supplier, they had a heavy duty one for $69ea, but I doubt they would last 3 times as long as the original, 195,000k.

Was going to change them myself, but when I knocked my head with the spanner,and drew BLOOD, I then decided I'm getting too old for this under car **** so took it to a local mechanic who did it for me.

$451 for all 4 uni's replaced.

Probably not too bad, but everytime I pay someone to do work I remember why I do most stuff myself.

[PaulP38a]

For that money I'd rather pay someone to do it for me too.
When I get back from the US in about a month, I will chase you up for names and part supplier. Assume it was a local mob in Canberra?

Might get mine done as a preventative maintenance measure.

Cheers, Paul.