250RS Dan

I read the thread re carbon build up in the plenum and runners etc about 18 months ago. I attempted the 'clean out procedure' ages ago but didn't get far. I don't really have the right tools for it. The Nissan dealers were going to charge me upwards of $700 for the job so i passed on it. Wouldn't mind trying it again I also tried the Subaru cleaner with the same result as you. My car has 148,000km on it now. I've only done about 21000km in the last 2.5 years (i live 5km from work) and haven't noticed the economy change at all in that time. It has always been quite thirsty for a hi-tech 2.5lt engine in my opinion...but i'm used to it now. I get about 9-10km per litre for mainly around town and the occasional longer trip around Auckland. On a return trip to Wellington i got about 11km/lt...not much better really, but that was running 95 octane. Perhaps 98 would give me better performance and economy. Cheers.

My M35 is n/a. Yeah, i searched and read as much as i could on these forums about the Gull fuel to see what the consensus was but i'm still not sure from what others here have reported. I think i'll stick to 98 but not necessarily the Gull Force 10. May have to look for a BP or Mobil that sells it locally.

The rough idle problem seems to have sorted itself out. Took about 155km of the new fuel and it is idling ok now. Compared to when i was running Shell 95 it feels much more powerful. It always felt sluggish on hills and i just figured it was underpowered but now it barely loses any speed on hilly/undulating roads so i'm pretty happy with that. I think i'll stick to 98 fuel despite it being more expensive. The trip computer seems to be reading quite optimistically with regard to fuel economy though. Maybe it needs to recalibrate...anybody seen similar results when changing fuel?

I filled up my M35 Stagea with Gull Force 10 the other day and it has a very rough idle now. Seems to run ok under load, but when there is little load on the motor or idling it's rough to the point of nearly stalling. Anybody experienced anything similar? I plan on changing the fuel filter in case the new fuel has cleaned out some rubbish from the tank or lines and it's possibly clogging the filter in low fuel flow situations. I've only done about 100km on the fuel and it was filled from nearly empty...75lt went in when i filled it. The trip computer is indicating significantly better fuel economy too, not sure if this is the ECU adjusting to the new fuel or if it's actually that much better. The car has done about 147000km, i've done about 20000km over the last 2.5 years and not changed the fuel filter since i owned it. I normally use Shell 95 octane petrol.

'$35 air powered 1/2" ratchet '...that sounds like something i see on the F1l!! I assume you need a source of compressed air to use this tool? I know what you mean about the oil change, considerably more effort than the Primera i used to have. Thanks for the advice...i'm determined to give it a go again at a later date. Will have to wait for a nice weekend.

I attempted this engine cleaning procedure back in January but didn't get far. I dropped my 10mm socket onto the back of the motor as i was attempting to undo the EGR bolts. When i couldn't find it i lost my enthusiasm and put the throttle body back on. I had taken that off and given it a good clean but had hoped to clean out all the intake tract. Disappointed in my lack of mechanical skills and the fact that i lost my 10mm socket...i think it's still stuck somewhere behind the engine block on top of the transmission. I may give this another go at some point as i'd purchased the cleaning gear to do the job. Will get myself a good set of ring spanners...i think they may help a bit. Any advice in addition to what is already in the thread would be appreciated.

I did 1000km around Northland in NZ back in January with four adults and luggage. Took 5 days and covered mainly non-highway roads ie hilly and twisty. Average fuel consumption was 10l/100km. That was what the trip computer read and was confirmed at the pump. Was reasonably happy with that given the roads and stop/start nature of the driving as we were touring around and stopping at all the touristy spots. Was also warm and wet due to the tail end of that cyclone hitting Northland over that weekend so had the aircon most of the time.

Hi, hopefully some of the earlier contributors are still monitoring this thread as i'm interested to hear about any updates re the intake cleaning and results. I read the thread with great interest as i bought a 2004 M35 250RS 12 months ago. I've been quite happy with it but noticed the occasional light surging when under a trialing throttle or going up a steep hill. I changed the spark plugs around Xmas 09 and was horrified at the state of the old plugs. They may well be the original plugs...the car's done 134000 now. Anyway, i expected to see a marked improvement in performance and economy given the state of the old plugs but i can't honestly say it drives any better. The fuel economy hasn't improved at all which really surprised me. I did notice at the time the build up of soot on the inside of the butterfly valve. This thread goes a long way to explaining why it's there. So last week i bought some Subaru upper cylinder cleaner and followed the procedure expecting to see massive clouds of smoke billowing from the exhaust...i even warned the neighbours! To my surprise and mild disappointment there was no noticable increase in exhaust smoke from the normal exhaust smoke. Next step is to pull the intake apart and give it a good clean as described previously. Thanks for all the input and information above, has been an interesting thread.