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Holden202 wrote:well actually that is roughly a 25% change and yes that is pretty major, if your needing to change that much then you really should be leaving the idle AFR tables alone and adjusting the VE table!

Agree.

The ecu works like this: its measuring air pressure, and using the ve table to know at that pressure and rpm how much air is ending up in the cylinder. Then it takes in to account temperature, and looks at the AFR table, and works out how much fuel to add (simplified, but more or less thats the process). So the ecu gets its target AFR from the conditions and the AFR table, and injects the fuel. If everything is right the actual AFR should be the same as the target AFR. What your doing is moving the target AFR to drag the actual AFR to where you want it. However this throwing out the temperature corrections etc. You should be leaving the AFR tables and modifying the VE table, and in tuner pro look at the monitors page and chart target and actual AFR over the top of each other.. and when you get the VE table right the actual AFR will stay pretty close to the target AFR. Thats when your tune is good.

You might want to edit the adx a little too, and change the working for target and actual AFR to put the words target AFR and actual AFR on the sides of the monitors, as without it you'll just have two values named AFR.

Remember that when your accellerating you'll get the enrichment or decell enleanment, so actual AFR is allowed to swing further from the target AFR under those conditions.

Also do this with a warm engine so that your warmup compensation stuff is taken out of the picture while you get the VE right.

update: actual AFR is wideband AFR.

Thanks Antus. Some of the problem I was having was with the warm up compensation stuff, as it wouldn't heat up past 40°c because it was idling at 4-4.3 afr, by altering these values I was able to get the engine up to 60°- 70°c, idling & reving reasonably.

Is it necessary to alter the tune when changing altitudes eg. when racing a carburetted engine at Wellington or Gunnedah, I usually have to richen the tune up 7-10% to run at the same afr at Sydney Dragway.

A bit of update with this tune. I've converted it to a 2 bar tune for the blown motor which we started to test last weekend. I set it up pretty rich to be on the safe side. After leaning it out, it idled & revved ok, it was now time to give it a little squirt, then we noticed a large amount of smoke underneath. It has a severe oil leak from the rear main seal or sump, so it's motor out to repair. Since this is a series 1 motor with some 300,000+ kms under it's belt, he's decided to fit a low km series 2 that he has, so he is now locating a series 2 flywheel to suit, then testing will resume.

fit a new neoprene version seal into it we had no rope left when we pulled ours down.ide personally stick with the series 1 for boost ive been messing with identical turbo setups on both s1 and s2 and the s1 makes a heap more power and will take at least 4 degrees more timing

I done leak down test on the current engine & it varied from 20% to 50%, where as the s2 engine was all at 17% which isn't bad.
That could be because of the different cam timing for the s1 engine.