1990 ZR-1 Issues

[Paul Workman]

Originally Posted by frantinoro

Any idea what to test next? I hooked up my scanner and the left bank is running lean (BLM iand int Anmrr at around 150)

IF the right side is running LEAN, the scan of O2 sensors would be of interest next.

-the cross counts and the sensor voltage would be go to k ow.

But, the proof can be accomplished too by swapping the O2s right to left & left to right and see if the lean condition follows the respective O2.

Note of concern: high KNOCK counts and burned valves can result from a lean condition. You wouldn't want to be driving it in that condition (lean on one side).

[frantinoro]

I will swap the O2 sensors and see if anything changes. I will also get the cross counts, but afaik I have not noticed any knocks being registered

[frantinoro]

if anyone else has the snap on mt2500 scanner, I'd love to hear if your scanner registers a value for vacuum(kpa) at idle. let me know!

[frantinoro]

So I pulled the plenum, double checked the secondaries and manually fired the injectors, and they're all spraying fine. If I swap the O2 sensors wouldn't that not make a difference when cold? It runs off when cold or warm so I'm stumped. What do I check next?

[grahambehan]

Do you still have the air injection on the car, if so look at the check valves on the manifolds, air leaking there can cause the symptoms you decribe

[frantinoro]

How do I test these check valves?

[frantinoro]

So I swapped O2 sensors, left side still lean. I noticed in open loop the right o2(which was on the left) cycles, while the left does not.

[grahambehan]

So, the sensor , now on rhs is stuck around 450 mg and the sensor on the legs is cycling above and below that value, but still addind fuel to the long term trim.

[frantinoro]

Hi Graham,
Let me clarify. I swapped the sensors with no effect, but In open loop, the left injector doesn't cycle. In closed loop it cycles normally.

[grahambehan]

Ok my # is 260 701 8860, if you wish to discuss