LS400 fuel system/injector clean

Razor61 · February 21, 2020

Ever since I bought my 1996 LS400 last year, my first one, I've felt that the performance should be better than it is/was. It seemed like I had to press the throttle pedal further down than expected to get anywhere and it seemed to be sluggish. I didn't know how the performance should be as it's my first LS400. I purchased a service kit with a set of plugs with the intention of replacing the plugs to see if it made any difference and planned to run some fuel system/injector cleaner for the same reason. I haven't checked/replaced the plugs yet or used any fuel system/injector cleaner, all I've done is remove the bits needed to do the job and fitted them again as a sort of 'dry run' in preparation. Last weekend before I went on a 60 mile journey I decided to fill the tank with Shell V Power which cost a fair bit....I've always used it on high performance cars, M3's etc.

I'd say after using 1/4 to 1/2 of the tankful of V Power I noticed the car performing better and continued to get better and better, I don't have to press the throttle pedal any where near as much as before, car is more responsive, zippier and is better to drive because of it. Performance is very good now and fuel economy seems better as well, how much better I haven't figured out yet.

Granted, V Power is higher octane fuel and I'd expect an improvement in performance but nothing like the improvement I experienced, it really was a big difference. I've read about the additives etc that help performance and help clean/keep clean the intake/fuel system in general. I suspect it's the cleaning bit that has made the biggest difference as it was a gradual improvement, I didn't notice anything straightaway, or maybe the UCU is adjusting to a better fuel. Regardless of the reason, I'm pleasantly surprised what a difference it's made and will try another tank of V Power then a few 'normal' fill ups and see what happens.

Farqui · February 21, 2020

Hi Paul, running a premium fuel through is an easy option if it's helped your issue 🙂

Hmmm, I thought Shell V Power contained more additives vs regular fuel options but that it didn't boost the octane.

Whereas BP Ultimate does boost the octane.

References; https://www.shell.co.uk/motorist/shell-fuels/shell-v-power/shell-v-power-unleaded.html

https://www.bp.com/content/dam/bp-country/en_au/media/fuel-news/fuel-octane-power.pdf

Premium fuel threads can become quite heated and I hope this thread doesn't fall into a long winded snake oil rant.

If it worked for you and your seat of the pants dyno, then that's all that matters.

Just out of interest, how many miles has your LS clocked?

I also wonder how well maintained it was before you took ownership?

Cheers, Lee

cruisermark · February 21, 2020

Hi

Glad you are enjoying your LS

I was a bit disappointed with your post - I was expecting a full dismantle, clean and rebuild of the throttle body 😀 - I expect that is going to happen very soon

Just for info The mark 4 LS has electronic throttle control, The Mark 3 has not - for the is reason the Mark 4 throttle is very responsive and the car feels very light.

I remember this particularly well when I upgraded from Mark 3 to 4

Malc · February 21, 2020

if you drive it permanently in the effective Sport mode " PWR " you will find it perkier and usually more fuel efficient too

mine's in permanent PWR mode

Malc

Razor61 · February 21, 2020

56 minutes ago, Farqui said:

Hmmm, I thought Shell V Power contained more additives vs regular fuel options but that it didn't boost the octane.

Maybe it doesn’t boost the octane but I remember the old version of V Power did, at least I think it did!! Without causing a ‘heated debate’, all I can is it made a difference and it was a marked difference. I didn’t need to be an engine performance, F1, or performance car expert etc to notice either.

It’s done 72,000 now and it might have been run all it’s life on, dare I say it, lesser quality/cheaper fuel as I have been doing most of the time since I bought it. I honestly did not expect much, if any difference, using V Power. I just thought I’d stick some in the car and see what happens that’s all.

Razor61 · February 21, 2020

51 minutes ago, cruisermark said:

I was a bit disappointed with your post - I was expecting a full dismantle, clean and rebuild of the throttle body 😀 - I expect that is going to happen very soon

Ha ha, you are spot on🤣 I’m picking up a throttle body gasket tomorrow and planned at some point to do exactly that!

Razor61 · February 21, 2020

13 minutes ago, Malc said:

if you drive it permanently in the effective Sport mode " PWR " you will find it perkier and usually more fuel efficient too

mine's in permanent PWR mode

Malc

Interesting, I’ll try that as well😉

Razor61 · February 21, 2020

Shell V Power octane rating............see link below.

https://support.shell.com/hc/en-gb/articles/115002792532-What-is-Octane-

rich1068 · February 21, 2020

V Power is definitely a drop of the good stuff. I try to run it whenever I can and at roughly £6 or £7 more per fill up I can live with that.

Not sure about the '96 LS but might be worth disconnecting the Battery for a little while too.

Razor61 · February 21, 2020

33 minutes ago, rich1068 said:

Not sure about the '96 LS

Well I am sure about my ‘96 LS, it’s made a difference. I’ll keep anything like this to myself in future I think......

February 21, 2020

These cars deserve the best fuel you can give them. I always run all my vehicles on the higher Octane stuff, the highest rated is from Tesco at 99 Ron and the other companies equivalent including Shell is 97 Ron. Like the post above they apparently have advanced cleaning properties over and above the standard stuff. Also a load of drivers get better MPG out of the better fuel, so a cleaner running car with a bit more kick when required and similar costs, not bad.

ColinBarber · February 21, 2020

40 minutes ago, Wisemonkey said:

and the other companies equivalent including Shell is 97 Ron.

Shell is 99 RON.

February 21, 2020

Thanks for the update appreciate it on the Ron front.

rich1068 · February 22, 2020

3 hours ago, Razor61 said:

Well I am sure about my ‘96 LS, it’s made a difference. I’ll keep anything like this to myself in future I think......

Touchy much?

I was referring to disconnecting the Battery. Later cars have adaptive ECUs that can benefit from a reset occasionally. Disconnecting the Battery does this but I'm not sure if the '96 LS has such an ECU. Hence my uncertainty.

I'd already mentioned my preference for V Power.

Razor61 · February 22, 2020

5 hours ago, rich1068 said:

Touchy much?

I was referring to disconnecting the battery. Later cars have adaptive ECUs that can benefit from a reset occasionally. Disconnecting the battery does this but I'm not sure if the '96 LS has such an ECU. Hence my uncertainty.

I'd already mentioned my preference for V Power.

I owe you an apology then😬 so I apologise and yes it was a bit of a strop! I did have the battery disconnected for a few weeks when I did the suspension work last year, it was unintentional ( I left the boot open somehow) and that didn’t make any difference.

royoftherovers · February 22, 2020

17 hours ago, Wisemonkey said:

Thanks for the update appreciate it on the Ron front.

RON is not a Member, it stands for "Research Octane Number"

Malc · February 22, 2020

and I've been successfully using standard 95 octane for as long as I can remember ( and that's almost since the modern ( 1960's ) motor car was invented ) using unleaded fuel and no harm has knowingly come to me or my cars by using it in this lifetime ...................... over several hundred thousand miles maybe :yes:

Thank you RON

Malc

rich1068 · February 22, 2020

10 hours ago, Razor61 said:

I owe you an apology then😬 so I apologise and yes it was a bit of a strop! I did have the battery disconnected for a few weeks when I did the suspension work last year, it was unintentional ( I left the boot open somehow) and that didn’t make any difference.

Not a problem :thumbsup: