OliverLS

Hello everyone, I have a simple question, this maybe connected to another thread that I have posted but I don't want to make that thread too long.

¿Should I use an octane booster on my 2004 LS430?

I have a really bad misfire, and I know that the car has many other problems and I'm sure the root of the problem probably isn't the fuel I use, but, my LS430 like other LS430 should use 91 octane fuel or 96 RON.

In my country the gas stations only go up to 95 RON, I can't get 96 RON fuel, however, I can buy an octane booster for the car, I would use like half a bottle on this one and half a bottle on my 2008 ES350 (this car runs perfect, no problems) since it's supposed to use also 96 RON.

Is the 1 RON rating difference bad? Or is there no problem? I don't have knocking issues, but maybe using an octane booster will make the car run a bit better?

kos

iTrader: (1)

Most octane boosters are just snake oil, so any "gain" will just be a placebo effect of using it.

If you have a misfire, I would try to sort that out first, before using anything as a bandaid to try and mitigate it.

jharris400

Is your check engine light on? Misfires likely won't be solved by octane boosters and I doubt your octane is low enough to cause a problem. People here in the US use 87 octane which is the lowest available and get away with it.

Striker223

It can use down to 85 via the knock sensors if needed but will have less power, you need to fix the misfire you have been chasing the last month already. Replace all vacuum lines and reseal the TB and intake and I'm still convinced it's a VVT problem

You can literally remove the O2s and the engine should default to base map and still not miss, same if you remove the MAF. If you however have a cam/crank sensor issue or VVT issue it will miss. However you should still start with making damn sure you don't have any air leaks

OliverLS

Thanks for the info! I'll look into the VVT system, which parts should be checked? Oil control valve only? I haven't got a code for that part yet (I'm not sure if there's even a code for that) or maybe the part is failing but not enough for it to throw a code. I'll keep you updated, thank you.

Aus430

I use 91. It works fine. Have tried 95 and 88 and have noticed any difference. I don't use ethanol fuel.

Replace those spark plugs, get the o2 sensors working.

There could be a vvt problem but as you say it runs smooth after computer reset. So I don't think vvt solenoids yet.

if the problem is still there then there is a vvt test in techstream to see if it is the vvt solenoid. But let's get some basics plugs o2's fixed first.

Striker223

It very much can and usually does only fail enough to throw missfire codes for one bank only. If you run the self test and check the swing response time you can see if it's slow or not

OliverLS

I haven't tried that test yet, I'm not sure how to perform it, I'll check on techstream, I did measure the resistance on the VVT solenoid, on both banks was around 9.4 ohms at maybe 95 °F (is this within spec?)

Striker223

Resistance doesn't matter as much as the motor actually moving fast and accurately

Aus430

No missfire after reset = unlikely to be vvt.
When my vvt solenoids were broken, the missfire was very much there after reset along with vvt code.
B1o2 broken matches the side with the missfires
Fix the o2 circuit.

When that circuit/data works properly and IF the missfires on one bank come back then lets look to the vvt solenoid problem.