Last Modified Nov 04

As previously stated I felt that the engine wasn't running full boost even after changing the fuel to Optimax. Howwever if you have forgotten or just come straight to this page then the suspicion's were raised by the following.

I floored the throttle and the turbo came on alright but the drive was stuttered and hesitant and generally not quick. Afterwards John, in his 8v Golf GTi, admitted he thought I had been in 5th not 3rd. Ah pants thought I. What is wrong now, on the first drive of ownership. Now the dad had put a full tank of fuel in the car and my thoughts were that he had put in some 95 Octane Unleaded. More use of heavy throttle and the engine was definitely holding back especially in the lower gears where the acceleration should have been explosive. S'ok, I do loads of miles so I burn that off in a day and hey presto load up on 98 Octane Optimax. A couple of tankfuls later, yeah the cars quick but not that quick.

I knew from looking through the forums that the Mk2 MR2's have clever ECU's that retard the ignition and boost if the engine is run on crap fuel ie 95 Octane. This is mainly on the turbo versions but the n/a's can also show this tendency albeit on a smaller scale. Generally its the knock sensor that complains about low Octane fuel so it tells the ECU which then starts cutting the ignition advance and then cuts back on the boost level. This is generally on rev3+ as they have a different ECU and VSV setup. I have no experience of the Rev1/2 but it should be similar if not the same.

So I pulled the fuses as marked and left them out for a couple of minutes then replaced them. I then nailed the throttle and yup it was quicker for sure. Great thought I. Its running as it should. As is the way however its not that simple. A run in with an Audi turbo diesel made me think that all was not well. Now the turbo gauge on the dash was moving upto the +mark but since these gauges are as accurate as an egg timer and have no PSI markings I still had no idea about actual boost. More searching and yet another ECU fuse was mentioned. Right, the buggers getting it now. I pulled all three fuses, ECU in front fuse box and ECU and EFI fuses in engine bay. Twiddle my thumbs for 5 minutes and put them all back in again. Nail the throttle and OH MY GOD did it pull. Unbelievable power, 2nd gear over in a blur and third had acceleration like I haven't felt before and the boost gauge was off the clock. Now that's horsepower with a healthy dose of midrange torque thrown in. Quite something, let me tell you.