Discussion
We put the Zed on a dyno at the weekend, more for fun than anthing else as we were at a car meeting where one was there.
Ryan (my boy) had said it feels like there is a flat spot under acceleration and the print out shows this. Anyone any ideas what it may be as it is so low down in the rev range. Obviously it can be felt while driving.
1998 Z3M Roadster 42k miles, recent full service (1 month ago)
I know dyno to dyno etc can read different figures, but how does it look power wise, to those more in the know than me. Quite a long way from the quoted 321hp figures
Any comments appreciated, thanks
Ryan (my boy) had said it feels like there is a flat spot under acceleration and the print out shows this. Anyone any ideas what it may be as it is so low down in the rev range. Obviously it can be felt while driving.
1998 Z3M Roadster 42k miles, recent full service (1 month ago)
I know dyno to dyno etc can read different figures, but how does it look power wise, to those more in the know than me. Quite a long way from the quoted 321hp figures
Any comments appreciated, thanks
jonttt said:
Not uncommon to get c290BHP out of a stock S50.
The hesitation low down could be a number of things from sticky throttle cable, faulty MAF (disconnect it to see if you still get the hesitation), etc.
Have a search on Zroadster.net for possible causes and fixes ;-)
Certainly worth checking the throttle cable to see if has become slack. When the cable's loose the throttle isn't fully opened even when the pedal is flat on the floor. http://www.pistonheads.com/gassing/topic.asp?h=0&a... . Very simple to adjust yourself.The hesitation low down could be a number of things from sticky throttle cable, faulty MAF (disconnect it to see if you still get the hesitation), etc.
Have a search on Zroadster.net for possible causes and fixes ;-)
http://forums.m3cutters.co.uk/showthread.php?t=297...
Valve clearances could be out; they must optimum for the engine to give the full 321HP ( 316.6 Bhp ). MAF sensor could need cleaning.
I've run a couple of M3s with the same S50B32 engine as the Z3M uses and they were both lumpy between 1500 and 2000 when cold; I had one remapped by Evolve and it was smooth as silk from idle to redline afterwards. The notch at 2200 is the VANOS its to be expected; it looks a little more pronounced than usual though, sticking VANOS solenoid possibly ??
Edited by Crackie on Wednesday 4th July 22:33
Air leaks, dirty/faulty MAF, valve clearances, plugs, filters, cam sensors, cam timing, type of fuel, lambdas, TPS, throttle linkage, vanos, dyno etc etc...
In isolation, each might only rob you of 1 or 2bhp but add a few up and together they can easily account for the losses.
Flat spot if quite common although I'd expect to see it further towards 3k. If you are confident that all the consumables and obvious things have been addressed then maybe you need to get the Vanos examined or take it to someone like Evolve and see if they can find the missing power with a tune.
In isolation, each might only rob you of 1 or 2bhp but add a few up and together they can easily account for the losses.
Flat spot if quite common although I'd expect to see it further towards 3k. If you are confident that all the consumables and obvious things have been addressed then maybe you need to get the Vanos examined or take it to someone like Evolve and see if they can find the missing power with a tune.
Thanks guys, the only thing not done at the service was the valves so maybe we'll get them checked out. The car does pull right up to the red line with no other noticable flat spots or misses.
I checked the throtle cable and although a little slack it was still getting fully open to the stop. Will strip out and clean the MAF next.
I guess the 30 horses that are missing won't be noticable on the road anyway, will have a play and maybe get another dyno run sorted but those places are few and far between up here in the sticks.
I was reading on one of the links about putting new seals in the vanos solonoids, is this just because of oil leakage or will it affect them operating correctly
I checked the throtle cable and although a little slack it was still getting fully open to the stop. Will strip out and clean the MAF next.
I guess the 30 horses that are missing won't be noticable on the road anyway, will have a play and maybe get another dyno run sorted but those places are few and far between up here in the sticks.
I was reading on one of the links about putting new seals in the vanos solonoids, is this just because of oil leakage or will it affect them operating correctly
Be careful when trying to clean the MAF, its easy to damage and costs c£200 to replace (ask me how I know :-(
If you disconnect it the car should run fine on a default mapping so better eliminate this as a problem before trying to clean it. If your problem disappears with the MAF disconnected then you have your culprit and you can try cleaning it with nothing to lose.
If you disconnect it the car should run fine on a default mapping so better eliminate this as a problem before trying to clean it. If your problem disappears with the MAF disconnected then you have your culprit and you can try cleaning it with nothing to lose.
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