: Question on type of gas for 98 catera



SgtDriggs
04-18-06, 09:55 AM
When I first bought my catera 1 year ago, I noticed a low engine knock. The Lexus dealership that I bought it from said it was from bad gas. Then used some cleaner stuff and ran it at high rpm's (smoke and crap came out of the exhaust). Anyway, I have been using mid-grade and noticed a knock when pressing on the gas for excelleration from first to second and second to third. It only happens when I tap the gas. Any suggestions or does anyone know of the type of gas my car is supposed to have?

Elo
04-18-06, 01:38 PM
Try running high-test and see if it helps...

-Elo

wamanning
04-18-06, 02:32 PM
the catera has a (relatively) high-compression engine and is intended to run high-octane exclusively - read your owner's manual.

however, i believe the ECU is capable of adjusting timing to accommodate lower-octane gas...to a point. in the 2 cateras i've owned i used 87 exclusively with no knocking problems whatsoever. both were relateively low miles (1st one turned in @ 24k miles, current one @ 48k miles and still going strong).

lately i've been running 92 just to see if there is any noticeable increase in power (there isnt) or any measureable increase in mileage (there isnt).


Try running high-test and see if it helps...

-Elo

Resilient
04-18-06, 03:48 PM
Same here... standard 89 octane... I use two different stations only: one with usual 89 octoane, the other has an ethanol blend at 92 octane... same price as regular 89....

guardian
04-18-06, 04:05 PM
You need to tell us how many miles are on the car.

Assuming the heads have never been off and the engine has not been decarbonized:

As the miles go up you can get carbon deposits in the combustion chambers. The presence of this carbon raises the compression ratio and can force need for higher octane gas if your computer is unable to compensate.

If your miles are high this could be becoming a factor. If your miles are still low, it is not.

SgtDriggs
04-19-06, 03:28 PM
You need to tell us how many miles are on the car.

Assuming the heads have never been off and the engine has not been decarbonized:

As the miles go up you can get carbon deposits in the combustion chambers. The presence of this carbon raises the compression ratio and can force need for higher octane gas if your computer is unable to compensate.

If your miles are high this could be becoming a factor. If your miles are still low, it is not.

70 thousand and when I took it to Lexus they did decarbonize it. The mechanic had me pretty scared when he said there is a low engine knock. I will try the premium and let you guys know if it helped. Also, when the power steering reservoir was changed the stupid mechanic cracked the head on the drivers side so they replaced that.:thepan: