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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Tweaks For Better Economy?Views : 1183 Replies : 28Users Viewing This Thread : |
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May 10th, 2021, 21:33 | #11 | ||
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Also some time before doing the oil/filter change, add 0.5L of Carlube ATF-U to the engine oil. When you do the oil change (leave it a minimum of a few days driving), after the old oil has drained and you've refitted the sump plug and new filter, add 0.5L of ATF-U to the engine then top up with your choice of 10W40 semi-synthetic oil to the right level. I do this on both my beasts for many reasons, on the non-Volvo in addition to everything it does on my Volvo, it helps keep the hydraulic tappets working as they should. On all engines though it helps free sticky piston rings, valves, revives oil seals (won't cure major leaks but can remove minor ones) and generally cleans the engine gently. There are a couple more things it helps with (such as improving emissions) as well. Also when you clean the PCV system out, make sure the inlet manifold stub is clean on the inside (carb cleaner) and clean the inside of the throttle body and AICV with carb cleaner too. On no account EVER touch the throttle stop screw on the throttle butterfly. We've had a few on here lately that have decided to play with this to solve an idle problem and caused themselves even more headaches! Remove fuse ~1 after doing the service for 30seconds and refit. Also, where does the temperature guage sit after about 5 minutes of normal driving from cold? If it's not halfway, invest in a new thermostat. Also if the mileage is 100k or more and there are no signs the Lambda sensor has ever been changed, consider changing it in the near future. They only have a service life of ~100k miles/10 years anyway and a weak/failing one can cost you precious mpg and maybe an MoT fail. A dose of injector cleaner when you pick it up will help on the journey home (try and get a sustained high speed drive like a motorway to help get the cat hot and burn off excess carbon on the way) to clean the injectors : https://www.halfords.com/motoring/en...te-247886.html Other than that and all the usual stuff such as wheel alignment, tyre pressures, making sure brakes aren't binding etc and you should be fine - i can easily get 32mpg on a decent run out of mine and that's a 2.8 V6 auto!
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Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........ Last edited by Laird Scooby; May 10th, 2021 at 21:40. Reason: Typo |
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May 10th, 2021, 21:37 | #12 |
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I have a 940HPT.
Stage one to ensure the car is running right. Most engine mods, at least to start, concentrate on upping boost so won't improve economy. My ranges between 40mpg on a long 60mph motorway run to 18mpg on short trips round my (hilly) town. Decent super unleaded makes a difference. Not really done a lot of testing of that but I am sure it makes a few more mpg, more than 10% difference I reckon.
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May 10th, 2021, 22:09 | #13 |
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Interesting to run a 940 on 98 unleaded. Always run my B230FK on 95.
Will have to try 98. My Lambda sensor is old. 5 years with me when bought car and swapped it out from old exhaust and refitted to new exhaust 5 years ago. What is a good genuine one? James. |
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May 10th, 2021, 22:49 | #14 | |
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Usually when they are removed, they let go with a bang and this makes a shockwave through them that damages the zirconium rendering it useless or at least causes premature failure! Keep an eye on your economy, if it starts dipping, time to get the multimeter out and see what the Lambda output is doing!
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May 11th, 2021, 07:50 | #15 | |
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What readings would you expect from the Lambda/how to test? |
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May 11th, 2021, 07:53 | #16 | |
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I'd also recommend playing around with the tyre pressures. I've found increasing mine by about 3PSI all round has given me another MPG. I do mostly long runs in mine, rarely exceed 70 (but sitting at 70 where possible) and mine has averaged just over 45MPG for the last 30k+ miles. It is the 6 cylinder diesel though, but most people struggle to top 40mpg with the diesels I also found retrofitting cruise control gave me at least 1MPG |
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May 11th, 2021, 10:50 | #17 | |
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It's easier to see with an oscilloscope but any reduced output voltage puts the Lambda in question.
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May 11th, 2021, 11:32 | #18 | |
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And... Definitely not going to try touching the throttle stop screw then! |
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May 11th, 2021, 11:51 | #19 | |
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With my 760, the only fuel it runs right on is BP Ultimate, all supermarket brands are now "emergency use only" after Sainsburys changed from having BP as their sole supplier and my economy dropped through the floor. Normally all my running is short runs so i generally get 25-26mpg although that was compromised by a handbrake fault following an MoT - long story! Using Sainsburys (while i hadn't realied they were no longer supplied by BP) super unleaded i was down to 14mpg. Changed to BP Ultimate and immediately went back up to ~22mpg (this was with the handbrake fault) and now the fault has errrrrrr.......... "cleared itself" it's back up to where it should be. Coincidence? No. My other beast was down to 18-20mpg on Sainsburys fuel as well, switched that to BP Ultimate and back up to 28-30mpg for normal runs, haven't had the chance to do a long run as yet for various reasons. Yes, BP Ultimate is ~10% dearer than the supermarket equivalent but it returns 50% better economy - no brainer in my book! For the record, i know the problem with the handbrake and have new disc/drums, shoes, pads, flexi hoses etc to fit. I can finally get onto that sometime soon, now i have my other beast back!
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May 11th, 2021, 12:03 | #20 |
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Remove nearside wing mirror.
Tape up gaps around headlights, cover half the grille. Run 4 space saver tyres. Lightweight battery. Put panels underneath chassis so it's flat. Remove the seats, radio, heating system, sunroof, glass, carpets, trim. Drink some Carlube ATF-U. Splash some meths behind your ears. Carry nothing in the car, not even yourself. Convert it to remote control and drive it by following it in a diesel. Should get over 30mpg.
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