325i down 10bhp on dyno run

[MrOtter]

Hi guys,

I had the chance to get a free power run done the other day whilst doing some uni work at a dyno, so of course I said yes. Was a little disappointed to find that 10 horses have vanished from my engine over the years. Now I'm not really that bothered to be honest, the car runs really nice and is still plenty fast enough for me at the moment.

However, just out of curiosity, is there anything obvious any of you experienced guys could tell me is wrong from the print out below? I know it could probably be any number of factors that are causing the power loss, but worth a shot... the torque curve looks awful wobbly, is that normal?

20141116_001859 by svenicusminimus, on Flickr

The car is a manual 89' Touring, the engine is standard apart from a 'mild' chip on the ECU, and has done about 110,000 miles. The only slightly 'off' thing it does is idle low at about 600rpm when warm, but apart from that it runs and drives beautifully.

Cheers

[Speedtouch]

Is it a later low compression (25 6K) engine? Some of those did only give around 160bhp.

[MrOtter]

Honestly, I haven't the foggiest. Is that 25 6K referring to the engine number?

I wasn't aware there was a low compression version, I just had it in my mind that I should have 170bhp + a little bit extra with your chip if I was lucky . For now I'll assume I've got the low compression engine to make myself happy.

[Brianmoooore]

, and has done about 110,000 miles. The only slightly 'off' thing it does is idle low at about 600rpm when warm, but apart from that it runs and drives beautifully.

Cheers

If it's fuelling from 110,000 mile old injectors, then that's likely to be where at least some of the ponies have gone.
Also, it's nor running 'beautifully' if it doesn't idle correctly. This needs sorting, starting with checking out the throttle position switch.

[Speedtouch]

Honestly, I haven't the foggiest. Is that 25 6K referring to the engine number?

Yes, if you look, there's a machined flat to the right of the inlet side engine mount, just above the block:sump interface. It should have either 25 6E = High compression or 25 6K = Low compression stamped into it. Below that is the engine number.

You may need to use a wire brush/Jenolite rust remover and a strong torch to be able to see it though.