Mot Fail

[messi]

Maybe you guys can help me with my question, infact there's is no maybe about it, i think you guys will help me. Took my car in for mot yesterday, and it failed on emissions, not by much though. Now he did say to me It can't be fuel related as I always use v power shell and the fuel lines are fine, but I do feel a slight mis fire sometimes, now when I got the car in october last year, I just gave an oil and filter change of course using parts from lexus dealers, the guy at the mot station did say to me 1 I need to give the car a good blast on motorway, as I always do start/stop driving and 2 changing the sparkplugs should fix the problem as he noticed a slight misfire. I have bought sparkplugs from the dealers yesterday, they are denso ones, do you guys think this might be a fix? I have sneaky suspicion that the sparkplugs in the car now are not denso, I don't know why, but I just have a suspicion.

It's a mk3 gs300

[Maduggo]

Mine had an mot fail on emissions, it was slightly over on hydrocarbons which equates to unburnt fuel, i did change the 8 plugs for NGK and took the car back the same day and she passed with flying colours, the emissions changed from just over to being well inside the legal requirement.

If they say it can't be unburnt fuel because you use shell then tell him thats rubbish, the type of fuel you use has nothing to do with it, read the emissions document you got, if it shows hydrocarbons ( HC fail ) it is unburnt fuel no more no less. How does he know the fuel lines are fine, what did he do to say that.

The current HC pass mark is less than 200 ppm, mine with old plugs was 259ppm and after new NGK went to 7 ppm.

Denso or NGK plugs are as good as each other and don't ever buy them from the dealer, get them from your local motor discount shop and pay much less than dealer prices, i got IFR6T11 - 8x NGK Laser iridium Spark Plug for £45 including delivery next day.

Other things that could be making the issue worse is an old filter, worn piston rings, dodgy HT cables and ignition coil pack.

Check the plugs as you change them and look at the business end for anything other than a brownish greyish tan on the electrode.

After the plug change, warm the car and go for a run and clear any cobwebs so to speak.

[ls400lpg]

Use seafoam. Put half in a bootle in fuel and the other half in brake booster.

[messi]

thanks for the advice guys, I do find the ls400 owners more helpful than gs300 owners, for some reason they don't like giving advice to me, anyway I bought some oem sparkplugs, took the car for a good run, and it passed the emissions, so big thanks to you guys

[cruisermark]

messi just recently saw your old 400 fr sale which just about passed its mot due to rear suspension wear

[messi]

Where did you see it for sale? I miss that car, it was lovely car

[cruisermark]

it was on eBay for many weeks X89 MBE (or similar) - chap from corby

[messi]

Oh yeah that was chap in sold it to. I've just remembered, I've got the spare wheel for that car sitting in the shed, all refurbished too

[robdave22]

It's me!

Still got it - lovely car just needed something more practical so have an RX now as well.

It passed its mot, to be fair the garage said it could keep on passing for a good few years yet :)

Rob