i bought a 97 es300, i read that the fuel requirement is premium fuel. (91-92 octane where i am)

WIth the company I work for I don't have to pay for fuel, but it's only 87 octane. Is this ok to run? or is there compression/detination problems?

 

I'll hit the highlights, because if you search, you'll find it answered so many times your eyes will bleed. We wouldn't want anyone to get hurt.

Will run regular, best engine performance on premium
May be light pinging
Particular engine family is bad to have over-sensitive knock sensors - lowering performance regardless of fuel, but obviously anyone suffering will get even worse performance on lower octane






Why don't you reset the ecu (Pull the EFI fuse a second & replace), put in a tank of their 87 octane & drive around. When you get past the first 1/8 tank, the fuel trims should be sorted out. If you experience surging power, or sluggishness above say 4500rpm, or you get a light pinging, you have your answer.









FYI Welcome to the family!

 

Can you explain to me why you do this? I use try to use premium, but the wife is always putting regular unleaded into the vehicle, no matter how much I explain the long term effects.

She's just CHEAP! CHEAP! CHEAP

We don't seem to have any problem switching between the two grades and have never experienced any problems, but I do notice a performance difference.!

 

Long term shouldn't hurt it if it's just a light pinging. It takes so long now a days for it to ad dup to anything signifigant, you've allready done hundreds of thousands of miles on the engine. It's probably toast anyway.
Now if it's bad pre-detonation... You're going to have problems cropping up.



You reset the ECU to reset the long term fuel trims. Otherwise, you spend the first gallon-few gallons having the ECU transfer big short term fule trims into stored long-term fuel trims.

 

So, resetting the fuse is not a huge issue and the system does modify itself on it's own?

When I refered to "Long-Term," I'm referring to general wear and tear on the fuel system and longevity of the engine, emissions, and exhuast, along with performance issues.

 

OBD-II has short term & long term fuel trims.
If a short term change has been around long enough, the ECU will go ahead and store some portion of that change in long term fuel trim.
Stft is on the fly.
Ltft is what the computer stores.

It adjusts on it's own constantly (Tho Ltft changes take a lot longer). It'll just save the computer a lot of time if you're doing some major gas swapping.

 

Wouldn't this process (fuel trim) also change for every fill-up or partial, because one may use different stations? How about the quality of fuel (at a single station) changing due to temperature, humidity, fuel delivery, etc.?

 

Short term changes all the time. Long term changes anytime it meets the criteria to.

What I'm telling you, is that if you're going to be swapping gas around, testing any measure of performance, or economy. It's faster & more consistant if you reset the ECU first.