AFR cycling with TPS

[angus99]

Hi all,

I have a fuel only megsuirt system installed on my 5.0l TVR Chimaera and a techedge wideband sensor. As you can see from the screen shot below, the AFR is cycling with throttle position, although I would have expected some degree of cycling with the TPS, this seems excessive. I also have a tech edge gauge which replicates the logged data and the tuner studio gauges.

I've managed to get the car running reasonably well by manually adjusting the VE table, but using auto tune or VE analyser to fine tune the MAP, seams to artificially lean out the MAP.

Any thoughts on this, I’m hoping it’s a problem with the AFR controller or wiring rather than an engine fault.

[Philip Lochner]

Every time you depress the throttle TPS moves but the the engine load (manifold pressure?) will also change as a consequence. Clearly your VE table is currently tuned to delivery leaner AFRs at higher throttle openings (engine loads). Your picture did not show AFRtarget which one would expect to be richer at higher throttle openings.

You MUST be 100% certain that MS and your WBO agree on the actual AFRs. In order for TS VEAL to tune rapidly, you must set your EGO conotrol "ignition events per step" from 1 to 4. I have used it at 1 with great success. In VEAL, under Advanced settings, "cell change resistance" must be set to easy.

Even though "Update controller" on VEAL is meant to update the VE table in MS regularly, I find that in my case it does not and I have to hit the send button frequently. (Still have to report on this)