Car is running rough/stumbling while idling and under load during open loop. Can raise RPMs while still in open loop not under load with no problems. Once warmed up it runs and idles fine. Ran data master and I have a code 33. I tested the MAP sensor and had 4.7v losing about 1v for every 5lbs vacuum.

Would this code be the cause of the rough idle during open loop? Since the MAP sensor is reading fine should I replace the orange seal? What are other possibilities to throw a code 33 that I should check?

Thanks

 

That code sets when the MAP sensor reads >80kPa, with the throttle less the 3% open. With the CC306, you will have high MAP (but not 80kPa), and with a seal leak, you could be seeing 80kPa. What does your DataMaster log show for MAP at idle?

Also check the harness connector. They tend to dry out and crack, resulting in intermittent connections to the sensor.

 

Just ran data master again. MAP KPa during rough idle bounced around 85 as it smoothed out it was around 68-70.

 

Bouncing MAP would indicate misfires or sticky/misadjusted valves. Think of MAP as (sort of) the opposite of vacuum (barometer minus MAP = vacuum).

 

I'll try replacing the plugs tomorrow. Since it smooths out after its warm and the MAP sensor stays steady does that seem like it would decrease the chances of it being sticky valves? Is there a way I would test for sticky valves?

 

Problem solved! Ended up replacing the spark plugs which got rid of the occasional miss under load. But I also noticed on the datamaster that my IAC counts were a constant 160. I dont know when or how my set screw got turned to the point of useless, but I adjusted that and the TPS to get my counts back down. Night and day difference.