E30 Zone

Had my M30 (full BTB exhaust and Fritz's chip) on the dyno last week, mainly because a couple of people have commented that they think it is running rich whilst following the car.

Does the fuelling graph below look normal to you? The plummet into rich at around 4,500rpm worries me.

It *only* made 190 rwhp (211 calculated at the flywheel) too, so part of me is wondering how much effect that fuelling is having. I think I shall try and source an original ECU with standard chip to compare.

Martin.

21 hp drive train loss is very low. Thats around 10%. If you really have 190whp the with a 25% drive train loss (normal estimate) the you would have 253 flywheel hp. 190 whp is very good for an M30.

12:1 -12.4:1 AFR is not too excessive is it. It's a generic chip so it's never going to be perfect.

No idea on the graph but that dip does look strange

MJJ_ZX6RR wrote:It *only* made 190 rwhp (211 calculated at the flywheel)

It should be more than that, i always thought it was 18% drivetrain loss (even more with an auto) so that should put you about 230hp.

Not bad for an old slugger

Edit; must type quicker

Thanks for the input guys, it is good to know that 12:1 is not a big problem. I am still going to try and get it a little leaner than that if I can though, seems too rich to me still and petrol is too expensive to waste unnecessarily..

Regarding the drivetrain loss question, I had always thought that the dyno was able to measure this, beliveing that is why the operator dipped the clutch at the end of the power run. It definately made 190 at the wheels, so perhaps it is a fairly healthy example of the boat anchor.

Same car on Fritz's dyno (who had just sold me the chip amongst lots of other mechanical work) 6 months ago "made" 249 hp calculated. Interestingly, there was nothing on Fritz's dyno print to show wheel HP or the correction factor used. Just goes to show how much bull$h1t can be gleaned from a dyno

What kind of air intake you got ? May be starving at high revs.

zaust wrote:What kind of air intake you got ? May be starving at high revs.

Standard E32 735i airbox, and air filter. It is a bit of a squeeze in an E30 of course, so it is perhaps not getting *quite* as much air as it would in the original E32.

Martin

er... is this an N/A M30? 12:1 is pretty rich... it's going to feel sluggish with that much fuel. My M20 performs best a touch rich of stoich, around 14.3-14.5. Since this is at WOT it will need a little bit more enrichment, but I wouldn't have thought going anywhere rich of 13 was going to give you any benefit.

Seems like a lot of people like to run 'safe' rich tunes. Great at preventing detonation (is that ever going to be a problem in our climate, with euro spec fuel and the M30 C/R?), but causes bore wash, stripping the oil film off the cylinder walls. Dilutes the oil and causes uneccesary wear.

Yep, N/A M30. Standard engine, full exhaust with 6-branch, Fritz's Bits generic chip.

Is there anyway (other than tweaking/changing the chip) to lean this out a little? Is it possible for example, to amend the AFR signal so the ECU sees a little less airflow than is reality.

Possibly a dangerous move, however the fact that the car was running as rich as this under part throttle on the dyno suggests there is some safety margin here.

Martin.

if it's running a chip, chances are the tables have been modified to give you more fuel under moderate to high load to help with driveability as it's quite hard to get a car to seamlessly pull hard under accel without going lean and misfiring. That said it's not just any old ebay chip so it may have seen some dyno development and it could be pretty well mapped.

Not sure your best bet is to just get a drop in AFR all around, because you don't know what else could be affected. Although with an engine like an M30 you're unlikely to break anything. The main issue won't be low load cruise going too lean, as that isn't really an issue (low load means low in-cyl pressures so no real chance of damage). You'll probably feel it in driveability (hesitation on tip in, that sort of thing)...

Best is to work out what your AFR is like when not at WOT. Doesn't Motronic have a set of fuel tables for WOT? I don't know if this also applies to the M30 as well?