RPM spike and fuel cut

[johnp]

Hi,

Got my Audi 80 Quattro running with a 2.0 16v engine and t3/t4 0.63ar turbo, haven't had a change to tune it peacefully because it randomly misfires. In Estonia our current outside temp. is -1 c. It Cold starts just fine but the rpm spikes which make it misfire are coming in like every second or two, as it warms up, spikes get rarer and it usually doesnt misfire with steady cruising or a warm idle, but when accelerating, it spikes again.
Got high impedance 600cc injectors, v2.2 board with 029y4a code, 36-1 trigger with hall sensor(shielded wire), wasted spark with GB14C40L transistors(sprk A R25, Sprk B R28), sensors are grounded at megasquirt and controller itself is grounded to engine, everything is done as the manual states. Plug wires or any high voltage source is atleast 10inches away from sensors wiring, only injector wires are closer but that shouldn't matter. What have people done when having rpm noise issues?

Other thing is that when i made datalog with 1,2 and third gear WOT and it misfired a tought it was rpm noise again, but datalog is showing that dudy cycle is cut to 0 in some point. I cant figure out why fuel is cut.

Datalog and msq:

https://www.dropbox.com/sh/8ebjhvxhss11 ... M2Q7a?dl=0

Thanks!

[Matt Cramer]

Can you get a tooth log from the Diagnostic menu of the RPM spike?

[johnp]

Here it is, fully warmed up, accelerating with third gear and it misfired few times.

I tried different ground points and extra ground from battery to engine, disconnected afr controller and tach output from power, moved the coil and spark plug wires totally away from any sensor wires but it just seems to get worse

[johnp]

well it seems i got my rpm spike problem solved. I changed plug wires and right now it runs great with no spikes. But one random question more - what can i do to get map reading smoother, in datalog it is quite rough, i tried different point on manifold but it didn't change anything.

[mazdaspeed]

Fit a inline crimp terminal inline with map hose crimp it up slowly untill your map readings become stable then u could put in the hose. Thats ehat i did with a camed engine to filter the reading

[Matt Cramer]

Another option can be to try a different location on the plenum. Some spots can have a standing wave that gives a weird signal.

[johnp]

thanks, i will try them out.