M20b20 holding back on revs and back fire, running ruff.

Post Sun Dec 13, 2015 9:32 pm

M20b20 preface hold back on revs at 3000, then when running holding back at 5000 ish, slight back fire, running lumpy.

Checked spark plugs, rotor arm, distributor cap... Afm looks clean and good on track... No air leaks.

Could it be timing?

Some help would be great.

Thanks.

Post Sun Dec 13, 2015 9:59 pm

Does this have the distributor on the side of the engine block?

Post Sun Dec 13, 2015 10:11 pm

Yea it dose.... Checked the arm and has new cap... Not sure what's going on

Post Sun Dec 13, 2015 11:32 pm

Cam belt been changed recently?

Post Sun Dec 13, 2015 11:47 pm

About 1 and half years ago but always been holding back around 5000 ish on and off...

You think the timing is out? Is the only way to sorting that is to have cambelt off?

Post Mon Dec 14, 2015 12:14 am

I was thinking if mine is a preface, which it is I can adjust and distributor

Post Thu Dec 17, 2015 7:04 pm

What you thinking brian?

Post Thu Dec 17, 2015 10:06 pm

When changing the cambelt on most E30s, the only timing marks you have to line up are on the crankshaft pulley and the cam pulley, but on the older one's, with the block mounted distributor, the auxiliary shaft has to be timed up as well. There have been a few cases over the years on here where a DIY (or possibly professional) cambelt changer has failed to appreciate this, and has ended up with the ignition timing out, even though the timing marks on the distributor line up.
This can be corrected by rotating the distributor body, but the marks will no longer line up as they should, so you'll need an old school timing light to do so.

Post Fri Dec 18, 2015 12:27 am

Thanks for your help man! Really appreciate it.