Henrik

Here's the weird thing, injector pulse widths are not substantially different in the regions you've highlit as compared to outside yet the AFR's are 2 whole points or more lean. So either the engine is misfiring leaving more O2 in the exhaust stream along with unburnt fuel (recall that O2 sensors only detect presence of O2; ie a 12.0 AFR mixture that didn't burn would read very lean) or un-metered air is getting into the intake or fuel pressure is suddenly down.

Unplugging the O2 sensor should have made it run richer during light throttle.

What kinda shape are the plugs/wires in?

-Henrik

The Wankler

iTrader: (14)

I myself have new plugs and wires. Also a Crane hi-6 with lx92 coils. I do believe I have "crosstalk" I guess you could call it? Prior to runing new injector wires and a new 02, I saw interference on these hot wires. One side of the ohm connected to the engine ground, the other to the proper pins on the ecu, inj, 02, pressure sensor. I noticed a reading of .245ohm's. THis was with the harness removed from the ecu and engine ground removed from block.

HAILERS

*******Unplugging the O2 sensor should have made it run richer during light throttle.**************************************

That all depends. IF the user has removed a lot of fuel at a given rpm, then if the 02 sensor is disconnected he might read 17-18 afr's at steady speed at that particular rpm. BUT if he reconnects the 02 sensor, and the ECU goes into closed loop at that particular rpm, then the ECU will drive the afr to the 14.7 range. It will not show the previous 17-18 afr's experienced when the 02 sensor was not connected.

A ECU that is stock will read in the 13afr at a steady speed, but if the 02 sensor is reconnected it will now read in the 14.7 in closed loop.

I'm saying, whether the afr is rich or real lean, once in closed loop the ECU will drive the afr to the 14.7afr.

By the way, I just tried this out on a series four n/a 1986 car by removing fuel at a given rpm and having the 02 sensor connected/disconnected. I know of what I speak. I learned this lesson using a SAFC in a prior life.

So my question is: has there been any removal of fuel in the rpm range that your experiencing this hesitation?

HAILERS

And by the way, when I removed that fuel as described in the above post, and then reconnected the 02 sensor and went for a steady speed ride, there is indeed a *hesitation* when in closed loop as the ECU tries to pull the Lean fuel mixure down to the 14.7 afr again and again.

Another question might be: has anybody been messing with the internals of your afm?