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stevebfl · #8 05-29-2008, 07:45 AM

So did you determine for sure whether the CTP correction was positive or negative. This is critical to the evaluation.

While a loaded adaptation of 1.22 is well within the accepted range, it is not established at idle. This is sometimes called long term adaptation. The point is that it is adapting slowly constantly, but does have certain criteria.

I think the new systems can take some input at all load rpm cells, but the early cars give a good feel for how this should be interpreted. The early LH 119 cars that would set the code 19 trim code. Coul be evaluated over and over by reseting and then making changes and then relearning. If one waited for the matural process it could take weeks, but on a dyno I could do it in minutes. There was a screen in SDS that allowed such and it waited till closed loop warm motor and then brought up a screen that showed rpm and load (based in the kg/hr flow rate). The car had to be at a certain rpm range (lower partial ) of say 1600 -2200rpms and then a certain load was required something like 40kg/hr to 70kg/hr (not exact it been a long time). Once these two conditions existed the screen would state that the process was beginning. It would take about 20 seconds within that band to finish the adaptation. The point is that on the road it was almost impossible to do as that load range will accelerate the vehicle unless climbing a steep hill. If one accelerated one broke out of the rpm load cell criteria.

Anyway, the issue that is to be reviewed from data is the degree to which the adaptation is skewed to the level of rpm and load. The easiest way is to look at the relationship of the CTP and lower partial figures. If its negative at idle then the loaded adaptation which is an average taken over time of all the normal driving on later cars would need to be negative (less than 100) to be a linear sitaution. If it is 1.22 and negative at idle it is obviously very skewed to air flow. If it is positive at idle and 1.22 at load it is much harder to judge. If the first case is the issue then it is logical to conclude that at higher than average airflow (such as a 80mph drive or an acceleration up a hill ) if done long enough to adapt the number would be momentarily out of range. While an actual adaptation takes some time the results of running out of range bring instantaneous results: low power, hesitations, misfires. It can feel above 4000 rpms much like a blocked cat. I've experienced it scores of times with a instant repair by AMM replacement.