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5500 RPM cut out issues - How resolved
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TOPIC: 5500 RPM cut out issues - How resolved

5500 RPM cut out issues - How resolved 12 years ago #9471

I have seen many driver come up with probelems like "car cuts out at 5500 rpm" and such. It seems to have many causes and never seems like simple issues to fix meaning guys spend weeks trying to track down the problem.

Often the fix is not that bad (unless headwork is needed), but the diagnostic time is a pain.

So can those of you have had the issue share what you did to resolve it and post that here?

I do not have that problem right now and thought new Texas 944 spec guy did, but was mistaken. Even so it would be a help for those that do get this issue.
Joe Paluch
944 Spec #94 Gina Marie Paper Designs
Arizona Regional 944 Spec Director, National Rules Coordinator
2006 Az Champion - 944 Spec Racer Since 2002
Last Edit: 12 years ago by joepaluch.

Re: 5500 RPM cut out issues - How resolved 12 years ago #9474

  • Bottoz
  • Seasoned Racer
  • Posts: 205
I recently had a cut @ 3500. The 'feelers' inside the AFM were not making good contact at that point. Cleaned it, attempted to bend it, and it worked.
C.J. Botts
1984 944 #37

2007 RM HPDE Driver of the Year
2010 RM Instructor of the Year
2013 RM 944SPEC Director

Re: 5500 RPM cut out issues - How resolved 12 years ago #9475

I know you aren't looking for only answers to that issue but I too had a high RPM stutter. I swapped AFMs and it didn't improve but low end was worse. I tried another and that one also didn't fix it. After trying everything else, I tried a "known good" AFM and it worked.

Moral of the story - I guess not all spares are created equally...and these AFMs are finicky.

Re: 5500 RPM cut out issues - How resolved 12 years ago #9476

  • rlofgren
  • Seasoned Racer
  • Posts: 222
when i first bought my '83, there was a stutter at 5500 rpm and in the end in turned out to be a broken valve spring. just my 2cents.
944-SPEC #30 Norcal 2010 Champion
944-SPEC #23 non sunroof
1990 944 S2 street
2003 Mini Cooper S
Lofgren Construction

Re: 5500 RPM cut out issues - How resolved 12 years ago #9480

  • spec28
  • Junior Racer
  • Posts: 40
known cause and solutions:

if engine pops or stutters while cutting out - replace throttle position sw.

AFM wiper arm/rail worn thru - adj wiper positon to ungrooved area of track or swap w/better unit.

if engine rpm and hp seems to level off and "float" at a specific (repeatable) rpm - head issues includeing: broken valve spring (usally inner spring), burned valve/seat issues.
Dean S.

Re: 5500 RPM cut out issues - How resolved 12 years ago #9481

I tried adjusting the arms on my bad AFMs (good instructions on Clark's Garage website) and it didn't work. Only a "good" one finally fixed it. It wasn't the throttle position switch in my case.

For another similar instance, I had a mysterious cutout/no start issue where the car would seem like it was running out of gas and then stop completely or sometimes wouldn't start at all. I checked pretty much everything until I finally found the wires to the crankshaft position sensors were brittle and would occassionally lose contact completely. Lindsey sells replacement harnesses for those and the injectors that are well worth replacing. Almost every car I've seen, the engine harness is brittle and nasty.

I've seen several cars quit or refuse to start where everything seemed to work right but they wouldn't spark. The little allen bolt that holds the distributor rotor in place had come out and the rotor was spinning freely on the cam. Relatively easy to find when you find out it isn't sparking but I've seen it drive people crazy.
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