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Author Topic: 2008 L200 Diamond Poor MPG  (Read 2000 times)
Dmb74

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« on: 13 December, 2019, 00:43:18 AM »

Hi.

Our Mitsubishi L200 recently suffered a partial head gasket failure. We noticed a small amount of coolant ejecting from the coolant overflow bottle every couple of days. We carried out test and proved that the combustion gasses were weeping into the coolant system, but only when under load. So, the truck was taken off the road for a cylinder head overhaul before any overheating issues. During disassembly, it was found that the cam timing was one gear tooth out, and had probably been like that for some time before  we purchased the truck, The head was skimmed and crack tested, no issues found. Valves were reseated, followers adjusted and all put back together. The truck started effortlessly after the fuel system was purged and sounded a lot quieter than before (maybe as the timing was correct now).

After taking the truck for a 10 mile gentle road test, we were only getting 17mpg, it is an auto so expect it to be a little lower than my manual returning 30mpg daily, but before the head rebuild it would always return 26 to 30mpg without fail. There is no black soot from the exhaust, eliminating overfilling, the EGR has been blanked off and has been for some time, and no noticeable increase in oil level, hopefully eliminating a leaky injector bleed off pipe. I am adamant that the injectors were returned to their original cylinder so as to not confuse the ECU coding. 

Any advice on where to look would be appreciated.
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douchecalamondaes
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« Reply #1 on: 05 January, 2020, 05:32:52 AM »

injector bleed pipe check oil level, also check your coked your intake was on removal,   
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03 4work, Cummins 6BTA 5.9L engine, 40" round things, and all the accompanying hassle involved.
 
No, my rear windows dont go up either Smiley
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Dmb74

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« Reply #2 on: 09 January, 2020, 22:11:07 PM »

Thanks for the reply.

I have been checking the oil level as aware of the bleed off pipes pumping diesel into the sump, but the oil level has not moved in the last 400 miles. The inlet manifold was reasonably clean for a 190,000 mile vehicle, so no major issues. I have been in touch with a reputable Mitsubishi specialist, who said that the engine ECU and injectors need to re-learn their parameters to optimise fuel economy and lower emissions. This usually takes place once the battery is reconnected and the vehicle is taken on a long drive, but sometimes need forcing with the correct diagnostic equipment. So it’s booked in next Wednesday to see what happens.
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Dmb74

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« Reply #3 on: 23 January, 2020, 23:39:39 PM »

Update.

The L200 was taken to a Mitsubishi specialist and no faults were found with the vehicle. They suggested that I recheck the valve clearances and maybe return the cam timing back to the incorrect timing as found prior to the head removal. So the inlet manifold was removed, and before removing the rocker cover, I checked the engine compression at cranking speed. The results were as shown.....

Cylinder 1 - 24 Bar
Cylinder 2 - 25 Bar
Cylinder 3 - 25 Bar
Cylinder 4 - 26 Bar

The specifications for the engine state 31 Bar at 250 RPM, so as cranking speed is lower and it has covered 190,000 miles, I don’t see any issues with these values. I then went on to check the valve clearances (0.90mm inlet & 0.14mm exhaust), all were perfect. I then altered the cam gearing to return the cam timing back to the incorrect position, as found when removing the head. So to recap, everything has been returned back to the as found state prior to the head removal, and guess what, still only 17 MPG!!!

The MPG has been calculated by filling the tank, driving 120 miles, re-filling the tank, noting the amount of fuel needed to fill, then calculating the MPG.

Next I will be removing the injectors and have them tested (3 of the 4 were reconditioned and recoded prior buying the truck), if all are ok, I fear it will be off to Mitsubishi!!!

I have absolutely no idea what could be causing very poor fuel economy when the truck starts and drives perfectly?
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rodeast24
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« Reply #4 on: 24 January, 2020, 15:51:59 PM »

As a matter of interest, are you getting smoke while driving it normally, If you are using that amount of fuel, I would imagine the truck could not burn it all properly. Maybe do a smoke test and see the figures as in hydro carbons,CO, are correct. If the injectors are stuffed you should be getting too much smoke, If all OK, I would look at if something is binding as in the brakes/wheel bearings. 
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Warrior 2004 Silver
Fullbox, decat, egr blanked, powerchip, Mac wheels 285/60/18 coopers.Sport grill, twin headlights. 124K, New engine at 102K.
Landrover 90 and discovery td5, also 1958 series 2.. I do love my landys,
Volvo 850R, nissan 300zx twin turbo, Been ordered by a higher athority no more toys.
rodeast24
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« Reply #5 on: 24 January, 2020, 16:00:47 PM »

Also look into recalibrating the pump, with injector learn and reset on diagnostics, some ECU's need disconnection and earth the live to ground to remove current held in the ECU itself.
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Warrior 2004 Silver
Fullbox, decat, egr blanked, powerchip, Mac wheels 285/60/18 coopers.Sport grill, twin headlights. 124K, New engine at 102K.
Landrover 90 and discovery td5, also 1958 series 2.. I do love my landys,
Volvo 850R, nissan 300zx twin turbo, Been ordered by a higher athority no more toys.
Dmb74

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« Reply #6 on: 26 January, 2020, 17:43:23 PM »

Honestly the truck runs beautifully, no smoke, cold start and hot start perfect, last calculation, £50 to 130 miles!!!

I’ve lifted all four corners, and no binding brakes etc, the front prop disengages as it should when in 2wd.

As for someone syphoning diesel off overnight, very doubtful as very rural location, private drive, no issues before head removal, the trip computer is showing 16 MPG average, fuel gauge drops as driving and appears to be in the same position the following morning. None of our other vehicles have any fuel loss issues.

The Mitsubishi specialist did a re-learn on the pump but the ECU would not allow a re-learn (or I think they quoted an SQP or something) on the injectors. He said it sometimes happens if the ECU is happy with the current settings.

Our local motor factors listed a Ford specific oil, 5/30 I believe, that was what was put in last oil change some 6000 miles ago, and what was used once again,

All filters are good, last changed 6000 miles ago.

I will have the injectors tested, but have a bad feeling it’s going to be an ECU issue. I am a bit OCD when it comes to diesel fuel systems and cleanliness, they are so delicate and expensive if your not methodical.

My 5.0 V10 tdi Touareg is more economical than the L200!!!! Not as useful though!

I will update with my findings.......
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rodeast24
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« Reply #7 on: 27 January, 2020, 05:15:15 AM »

You might be looking in the right direction on the ECU then, The diagnostics will not pick up a faulty ECU,
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Warrior 2004 Silver
Fullbox, decat, egr blanked, powerchip, Mac wheels 285/60/18 coopers.Sport grill, twin headlights. 124K, New engine at 102K.
Landrover 90 and discovery td5, also 1958 series 2.. I do love my landys,
Volvo 850R, nissan 300zx twin turbo, Been ordered by a higher athority no more toys.
rodeast24
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« Reply #8 on: 27 January, 2020, 05:22:23 AM »

Have a look at the wiring to the fuel pump multiplugs
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Warrior 2004 Silver
Fullbox, decat, egr blanked, powerchip, Mac wheels 285/60/18 coopers.Sport grill, twin headlights. 124K, New engine at 102K.
Landrover 90 and discovery td5, also 1958 series 2.. I do love my landys,
Volvo 850R, nissan 300zx twin turbo, Been ordered by a higher athority no more toys.
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