Ronin-951

Not the Coil, full Boost is it's worst enemy. I'd guess the Wiper Track for the AFM too. Check clarksgarage.com for the test.

86 951 Driver

Something that my car has always had is a not running 100% smooth on part throttle. WOT it runs and pulls just fine, spools great, etc. When I am say 50% throttle or part throttle and in the boost abit(2-5 psi) my car doesn't seem to run smooth like it does on WOT. It almost pulsates. Its not really that bad like a true misfire where you would be bucking, just not smooth.

Could this be caused by a weak coil? My 924S never did this, but it was turbocharged either. My coil is original. The other compenents of the ignition system(wires, cap &rotor, plugs) have been replaced.

Is this normal behavior or something I really need to look into?

carlege

AFM?

86 951 Driver

Hmmm. I have been wanting to get a MAF lately. Maybe this is the icing on the cake.

divil

I have a spare AFM you can swap out to test it. PM me if you're interested.

Lex_GTX

I've been through the part throttle hesitation and have swapped every electronic component under the hood and DME and KLR.

2 things fixed it:

1. Deal with all vacuum leaks
2. The big one - the O2 sensor. Unplug your O2 and see if it smooths out.

86 951 Driver

I replaced every vacuum line when I bought the car 2 years ago.

txhokie4life

Put a vacuum gauge on the lines, something could have come loose.

mike

DannyLaQc

A good thing for Vaccum leak is to make your own pressure tester.
Mine is a blood pressure pump with a 0-30psi gauge.
Pressure test line by line from the manifold banjo bolt to components.
A tiny leak is acceptable depending what it supply.

For myself I found that my Fuel purge valve was leaking.
Leak from banjo bolt components can lead to bad fuel rail pressure and all leaks lead to AFM false reading.