I have a Jim C Chip and had q's about fuel

[nealf]

Had it in my car for years. I remember directions saying only run premium fuel. Saw a post on that 'other' board saying 535is because of their lower compression actually do run better on 87. Will this screw up my driveability with a non-stock chip if I run 87 or 89? Thanks.

nf
'90 535iA

[angrypancake]

if the directions say run premium, then by all means run it. m30's stock chips are tuned for 87. but once you replace the chip, its premium all the way.

[Bill R.]

regular with the lower compression(ie because it contains more energy per pound) you cannot run regular with a chip. The m30 does not have a knock sensor and will not adjust its timing depending on what fuel you have. Newer engines will so the fuel usage is a little more flexible. One of the biggest gains you get from a chip is advanced engine spark timing. By advancing the timing on an m30 it then requires higher octane to prevent pinging or preignition

Had it in my car for years. I remember directions saying only run premium fuel. Saw a post on that 'other' board saying 535is because of their lower compression actually do run better on 87. Will this screw up my driveability with a non-stock chip if I run 87 or 89? Thanks.

nf
'90 535iA