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Tech Forum : Pre-ignition

- BMW E21 Community
   - Tech Forum
      - Pre-ignition
sepehr   Posted Saturday, Mar 26th 1:09am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 11

Canada
320i
My car (US spec 320i) has had some pinging at 2500 to 3100 rpm since I first bought it. I misdiagnosed it to be incorrect valve clearance, but after repeated readjustments, I had to admit that wasn't the cause.
I've tried richening the mixture, and retarding the timing. Still get a little ping with supreme gas.

Should I just give up? The car isn't worth fixing with my financial situation(student).

What I DID notice is that the ping disappears with new spark plugs.It returns within a week. Inspection of the plugs shows carbon on the electrodes. The car also burns oil, about a litre every two months. Is it the oil thats causing the plugs to foul? Compression is at 130 across all cylinders.

What do you guys think? Excessive carbon build-up in the combustion chambers?

RDAvena   Posted Saturday, Mar 26th 2:26am [Edit] [Quote] [IMS] [View car]
Staff
Post nr. 1172
   
SELECT * FROM users WHERE clue > 0
1981 323i, 1988 545is, 1997 528i
might want to search on this site for 'steam cleaning' the compression chamber. It will get rid of the carbon that is accumulating on your combustion chamber.

Some have stated that 'spirited driving' will help clean the chambers as well but if that is not possible then use the steam method.

sepehr   Posted Saturday, Mar 26th 3:01am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 13

Canada
320i
I read that post a while ago.

I was just wondering though... How would steam clean off deposits formed under all that pressure and heat in the combustion chamber? Its not a concentrated jet thats in the chamber in this method, just some water vapor under pressure. The piston moving down in the cylinder will pull in a fixed amount of gases from the intake manifold. What would the effect of trading air/fuel for water be?

RDAvena   Posted Saturday, Mar 26th 8:52am [Edit] [Quote] [IMS] [View car]
Staff
Post nr. 1173
   
SELECT * FROM users WHERE clue > 0
1981 323i, 1988 545is, 1997 528i
I would like to post some well thought out Newtonian answer but in reality I do not know why it works, it has been proven to do so. I have read this fix, have seen it done, and have done it and in all cases nothing but positive outcomes.

To give you a slight case of associated reality that some others might recognize, have you ever taken apart an engine that has blown its headgasket? Have you ever noticed how shiny the combustion chambers that the water was leaking into were after the fact? The only slight bit of associated proof I can provide.

But don't take my word for it. Try it out. What have you got to lose, water?

sepehr   Posted Sunday, Mar 27th 7:43am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 14

Canada
320i
I will definately try it. Just curious... The nerd in me won't shut up.

Thanks for the quick answer

g323   Posted Sunday, Dec 17th 7:15am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 48
   
California
323i 1982
How do i steam clean the compression chamber? What does the process involve, did this work for you man? I have the same symptoms as your first post.

ArnZ   Posted Sunday, Dec 17th 2:14pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 38
   
Qld, Australia
BMW 323i
i giv my 323i a lil spirited drive every once in a while. it gets rid of alot of carbon build up for me


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