engine and drivetrain Tii - Stutter At ~2500 Rpm

[hegedus]

Hi,

 

I have a '72 tii (blue) with a new issue, a bit of a stutter or hesitation at about 2500 rpm.

 

The car starts well and idles at ~1000 as it starts to warm up a bit the idle will go to ~1800 for a couple of minutes and then quickly settled to ~1000 rpm.  It surges a little bit until the car is completely warm.  This is reproducible but also not the main issue.

 

In the last week, it has developed a bit of stutter or hesitation upon acceleration between 2500-2800 rpm.  The engine has good compression (~180 psi) and all the linkages have been replaced and the fuel system adjusted by A1 Motorsports in Marin ~4 weeks ago.  Right after the linkage replacement and adjustment the issue was not there.

 

Where should I start looking?

[jgerock]

Almost sounds like your car is running too lean.

 

Do you have an AFR (air fuel ratio) gauge?

Does your car backfire (even softly) when decelerating?

Have you inspected your distributor?

[ahlem]

What happens at 2500 rpm in neutral in the driveway? You can use a low cost spark checker to rule out spark issues.

[Buckeye]

I am not very familiar with tii and yor ignition, but while back I had issue with car stuttering at 40 - 70 mph. Car was starting just fine and lost of power, etc. here is link to that discussion.

http://www.bmw2002faq.com/topic/137938-advice-on-stuttering-issue/

[achman]

Believe my KFischer manual says that there is a stutter at around 2500RPM caused by the fuel being pressurized and is unavoidable...mine has a small touch of it too. But correcting a lean condition on mine fixed the surging and most of the stutter...

[jgerock]

Replacing this hard-to-find spring will sometimes help