J Chen

I have been trying to diagnos this problem for
sometime but am unable to cure it.
Change the following parts
Plugs, Cap & Rotor, Ignition Wires. Check TPS
& it's O.K. Pressure test for leaks etc.
When the car is cruising at about 80-100 kph theres
a slight stumble & when this happens, the ARM will
jump to the first blue led. Same thing happens when
I accelerate away under heavy load it will somtimes
stumble. Could a faulty KLR cause this ? BTW I have
already bypass the CV & running with a Reliaboost.
I'm also running a Huntley Stage III MAF set-up.

jimbo1111

Have you adjusted the excel on the arc2? I use to keep mine around 1 o'clock. Too rich or lean and it will stumble.

testarossa_td

I would say TPS but you tested it...how did you test it?

J Chen

Hi Jimbo yes accel is set at 1 o'clock
Testarrossa, TPS measured according to
Clarks -Garage test procedure.
Another think that I notice is that in between changing
gears during accel, the rpm will sometimes drop to about
200 rpm before recovering. This sounds like a vacuum leak
but after pressure testing, there's no leak at all. Again when
this happens, the ARM will indicate first blue led before
recovering into dither mod.

jimbo1111

Your rpms shouldn't drop that low. When the tps clicks it activates the ISV through the dme to prevent rpm drop or stall when the throttle closes rapidly. Check the ISV and/or clean it. Also check that the contacts on the tps are closing with an ohm meter. The alinement may be off. The click test is good but it well not tell you if the contacts are pitted.

jerome951

I'm unfamiliar with the Arc 2, but I had similar symptoms and found the contacts on the AFM electrical connection were getting flaky. Not hard to disconnect the AFM, clean the contacts, and re-plug as a test.