Thoughts on petrol injector cleaning
Submitted: Sunday, Nov 11, 2007 at 00:32
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Scubaroo
Have a 2000 3.5L V6 Pajero that's just clocked 100,000km. Fuel economy has been slowly decreasing the past 12 months, and I've decided that I'll replace the O2 sensor to see if there's any improvement.
I've been running the vehicle on Shell 98 octane (V-Power, previously called Optimax) for the past 35,000km, as I found that gives the best economy (both litres and dollars per 100km). Given that this is meant to be a good fuel for keeping injectors clean, should I consider getting the fuel injectors ultrasonically cleaned as a good maintenance practice now that the vehicle has hit 100,000km? Haven't checked the handbook to see if/when Mitsubishi recommend it, and I'm not sure if it could introduce problems or not, or be worth the expense.
What are your thoughts? Leave them alone, or spend the money and hopefully get a worthwhile improvement in economy? To be honest I've no idea how much injector cleaning costs for a V6 petrol engine - I would want them ultrasonically cleaned, not with one of those processes where they pump cleaning fluid through them while the engine runs etc.
Reply By: Member - Phillip S (WA) - Sunday, Nov 11, 2007 at 00:57
Sunday, Nov 11, 2007 at 00:57
Hi Scub....when I had the commadore I seem to remember that part of the service schedule was for the fuel system and injectors having a thorough clean out by hooking it up to a machine for an hour or so...for around $2-300...they had some samples of what comes out of it in little bottles....yukky poos....might pay you to check it out....Phil
AnswerID:
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Reply By: Member - Kiwi Kia - Sunday, Nov 11, 2007 at 06:52
Sunday, Nov 11, 2007 at 06:52
Hi Scubaroo, My understanding of O2 sensors is that they either work or don't work, ie there is no. So if the engine is running smoothly then I would not be spending the money on a new sensor.
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Reply By: Member - Kiwi Kia - Sunday, Nov 11, 2007 at 06:52
Sunday, Nov 11, 2007 at 06:52
Hi Scubaroo, My understanding of O2 sensors is that they either work or don't work, ie there is no. So if the engine is running smoothly then I would not be spending the money on a new sensor.
AnswerID:
271175
Follow Up By: Member - Kiwi Kia - Sunday, Nov 11, 2007 at 09:23
Sunday, Nov 11, 2007 at 09:23
The above should read; ....they either work or do not work ie there is no inbetween state.
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Follow Up By: Scubaroo - Sunday, Nov 11, 2007 at 12:48
Sunday, Nov 11, 2007 at 12:48
My understanding is that they can degrade with carbon buildup etc... but if it's electrical failure then yeah, they would just be "broken".
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Follow Up By: pop2jocem - Sunday, Nov 11, 2007 at 16:37
Sunday, Nov 11, 2007 at 16:37
just a question not an opinion. if an O2 sensor was faulty would that show up as a fault in the diagnostics of the engine management module?
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534199
Follow Up By: Member - Kiwi Kia - Sunday, Nov 11, 2007 at 16:57
Sunday, Nov 11, 2007 at 16:57
Yes it should show up as a sensor fault but be aware that a faulty plug or a manifold leak may also indicate an O2 sensor fault.
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534204
Follow Up By: Member - Kiwi Kia - Sunday, Nov 11, 2007 at 17:05
Sunday, Nov 11, 2007 at 17:05
Found this on O2 sensors:
A lambda sensor's normal life span is 30,000 to 50,000
miles. But the sensor may fail prematurely if it becomes clogged with carbon, or is contaminated by lead from leaded petrol or silicone from an antifreeze leak or from silicone sealer.
As the sensor ages, it becomes sluggish. Eventually it produces an unchanging signal or no signal at all. When this happens, the Check Engine Light may come on, and the engine may experience drivability problems caused by an overly rich fuel condition. Poor fuel economy, elevated CO and HC emissions, poor idle, and/or hesitation during acceleration are typical complaints.
In my experience rough running was a key indicator to look at intake manifold leak or O2 sensor. Also note that if you want to clean your O2 sensor you need to use a special cleaner.
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534205
Reply By: nowimnumberone - Sunday, Nov 11, 2007 at 10:53
Sunday, Nov 11, 2007 at 10:53
if its just klicked over 100000ks and your getting a mechanic to do the timing belt plugs ect the injectors are just about off.
cleaning them of the car should only be about $25 each we pay $20 trade.and maybe half an hour more labour
cheers
AnswerID:
271197
Reply By: Gerhardp1 - Sunday, Nov 11, 2007 at 13:59
Sunday, Nov 11, 2007 at 13:59
After a
tank full of crappy fuel on the cape last year, I had the injectors flushed at Ultratune in
Cairns. There was crud that had got through the main fuel filter and into the rails.
After driving back to
Melbourne I removed and cleaned the fuel
tank & installed a new pump which had also been degraded by the crappy fuel. After re-installation I still had a tiny miss, almost imperceptible, so went to Ultratune and had the injectors removed and the rail cleaned again.
The key point of all of this is that the injector spray patterns were not affected by all the crap that had gone through/past the nozzles, even driving with dirty fuel from
Bamaga to
Melbourne.
So I think with yours it could be a waste of money taking them out - a normal flush should do the trick. This job also cleans out all the insides of the throttle body and manifolds - dirt in here (at 100,000 you will have some) can affect perfoprmance.
AnswerID:
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Reply By: wrexed03 - Sunday, Nov 11, 2007 at 14:27
Sunday, Nov 11, 2007 at 14:27
Leave them alone
mine has 140K and runs sweet as. To do the injectors you need to remove the top half of the manifold. 100k do timming belt plugs (manifold off) and any other bits and pieces. Careful with the timming belt make sure the fellow knows what he is doing.
Mine was done before i purchased it and had a shake on idle very slight but enough to bleep you off. After swapping everything with a donor vehicle problem was still there. Asked mechanic to rip the front of the motor apart and found timming belt was out by one tooth on one of the cam gears. All good now :)
Mine is duel fuel and still runs sweet on petrol when i run it once every couple of months. Re 02 sensor they can get lazy. If your economy has diminished do this first you can get a universal that will do the job for 60 bucks. Thats what i did.
Regards
AnswerID:
271219
Follow Up By: Scubaroo - Sunday, Nov 11, 2007 at 17:48
Sunday, Nov 11, 2007 at 17:48
Thanks - already had the timing belt replaced at 90k, as
well as the plugs (even though they weren't due to 105k).
Might just replace the sensor for now and track the difference. Apparently in the Pajero a bad sensor won't trigger the check engine light, but will show up on the ECU if hooked up.
Looking at getting a set of Wildcat headers fitted anyway andI believe the O2 sensor fitting is on the headers, so I'll just put a new sensor in with the headers.
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