Piston slap sounds like spark knock .............. (archive)

..."popcorn popping" sound. The dreaded timing chain noise is louder and more constant, more like marbles in a coffee can. I had that one too, occasionally, until I did the complete timing chain job. The piston slap noise goes away after 1 1/2 to 2 minutes of driving. The timing chain noise was too loud and scary to drive the car. It always went away quicker than the slap (30 seconds or less, unless I had just taken the tensioner out).
John
88 ///M3 Cinnabar

Hi Guys!
My engine has developed a cold engine piston slap. I was planning to rebuild it this summer, but have a chance to get an EVO 2 engine. Problem is that that engine is non catalytic and that is a no -no here in Germany.
Included are the intake & airbox as well as the nice header, but no electronics or afm.
Could I use my harnes, afm, ecu, etc. ??
How involved would that be? Anyone any experience with that ?
I�d love to have those 220 hp !!
What is you guys opinion ??
Mike (Germany)
89 M3
95 525 TDS Touring
68 GT500
What do you mean by cold engine piston slap? I just bought my second M3 which has a 2.5 TMS kit with only 32k miles and around 3k miles since installation and it makes something like a timing chain noise at start up but smoothens out when warmed up. I am planning to replace tensioner soon but with only 32k on it, its hard to believe its the chain or even tensioner. Do you think that noise is normal because on my other m3 with 93k miles there is very minimal start up noise? But love the power of the 2.5:)

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