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e34 525i - flat spot

Printed From: Bavarian-Board.co.uk - BMW Owners Discussion Forum
Category: Technical & Model Specific Forums
Forum Name: BMW 5 Series
Forum Discription: This forum will deal with any issues on the BMW 5 Series (E12, E28, E34, E39, E60 & E61)
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=10010
Printed Date: 29-May-2024 at 09:52


Topic: e34 525i - flat spot
Posted By: r6_jyh
Subject: e34 525i - flat spot
Date Posted: 20-August-2004 at 13:19
I was wondering if anyone could assist.  My car idles fine at about 700 rpm, however there is a flat spot between 700rpm and 1200rpm (very annoying when pulling away from traffic lights), also under very hard acceleration the engine pinks.   I have a crack in the cylinder head (which is being resolved), but this really shouldn't be the cause.  Over the last year it has only done short journeys, so it might need a good thrashing......Can anyone offer any advice?


Replies:
Posted By: Andrew Rolland
Date Posted: 20-August-2004 at 15:43

This fault is the reason I ended up buying a Beamer.  I had this fault on my previous car a 3.0i 24v Vx Senator.

I ended up replacing all 7 Ht leads, 6 spark plugs, cleaning the rotor arm, cleaning the dizzy cap contacts, fitting a new crank angle sensor, fitting a new lambda sensor, stripped and cleaned out the throttle body, cleaned out the idle control valve, resealed all air induction hoses and checked and cleaned numerous electrical sensor connectors.

I also ran through a tank of fuel with redex fuel injector cleaner.

None of the above cured my fault (but each time I did something the engine seemed to be more responsive and smoother but not cured) but thats not say it won't cure your fault.

I had heard that it may have been a fuel injector seal or another seal in the inlet manifold system that was leaking and causing the flat spot.  I didn't want to throw any more cash at the Sennie so I got rid of her for my E39 523i SE.

Clean and check out all what I have said and hopefully it will cure it and give it a damn good thrashing to try and burn off any coke stuck to the head and valves.

 

Andrew

 



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Posted By: r6_jyh
Date Posted: 23-August-2004 at 10:32
thanks Andrew.  changed plugs, leads, cap and rotor and increased the fuel octane - that seems to have improved the situation, I suppoe I will have to move onto the next things you suggest as well.  I am all in favour of a good thrashing - but probably not too wise with the head in its current state.....


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