Thread: 3.5 ecu running 3.9?

Hi guys new to forum,
Just a question about my ecu, i have an 88 rrc that i bought with a 3.9 in it, out of disco in think and its still running the 3.5 ecu, will this effect the car over long periods of running, i have driven it over short distances and seems fine, but not sure over longer distances. Its on gas so no biggie but as it has duel 40 ltr sill tanks, well could extend driving range.
Thank in advance.
Rick

My '87 now has a 3.9 fitted, running all the original injection gear with no problems over the last 2 years.