Does computer automatically compensate for injector degradation?

[FE 065]

If the injectors degrade in their performance, does the computer automatically sense it and compensate for it by extending injector duration?

To include WOT (open loop)?

 

[1TONY1]

I would say closed loop, yes. Open loop, no.

 

[Jack B]

Tony is right, with the scan tool you will see adaptives are not active in wot. Some cars will carry the adaptives over in open loop/WOT, not the viper.

 

[RedGTS]

Excuse me for asking what is probably an engine management 101 question, but if the adaptives are not active at WOT, how does even a stock car compensate for wide variations in temperature, air density, etc.? And if the answer is the IAT sensor and other onboard monitoring devices are still active at WOT and aren't the same thing as the adaptives built into the computer, then why do you need adaptives at all?

 

[Tom F&L GoR]

Detail - if one injector degrades (or gets plugged with deposits) the best the ECU can do is enrichen all injectors (or all on that bank.) The result is that 4 run rich (got more fuel than needed) and the fouled injector still runs lean, but on average (as best the O2 sensor can tell) it's OK. Sort of.

 

[FE 065]

Excuse me for asking what is probably an engine management 101 question, but if the adaptives are not active at WOT, how does even a stock car compensate for wide variations in temperature, air density, etc.? And if the answer is the IAT sensor and other onboard monitoring devices are still active at WOT and aren't the same thing as the adaptives built into the computer, then why do you need adaptives at all?

Good question

 

[Dyno Dave]

Excuse me for asking what is probably an engine management 101 question, but if the adaptives are not active at WOT, how does even a stock car compensate for wide variations in temperature, air density, etc.? And if the answer is the IAT sensor and other onboard monitoring devices are still active at WOT and aren't the same thing as the adaptives built into the computer, then why do you need adaptives at all?

The US06 portion of the EPA/CARB tests require the engine to run stoichiometric air/fuel ratios (closed-loop) at all times with the exception of those areas of the engine map where engine component/catalyst temperatures exceed their operating limits (open-loop) and then no richer then LBT +6% (Lean Best Torque).

The adaptives allow all of the stackup variances in the components and the crazy variety of gasolines that are required in different parts of the country to be accounted for and allow true stoichiometric operation every time the engine starts. Otherwise, the air/fuel ratios would potentially be out of the stoichiometric area and the pcm would have to relearn after each startup.

 

[FE 065]

Excuse me for asking what is probably an engine management 101 question, but if the adaptives are not active at WOT, how does even a stock car compensate for wide variations in temperature, air density, etc.? And if the answer is the IAT sensor and other onboard monitoring devices are still active at WOT and aren't the same thing as the adaptives built into the computer, then why do you need adaptives at all?

The US06 portion of the EPA/CARB tests require the engine to run stoichiometric air/fuel ratios (closed-loop) at all times with the exception of those areas of the engine map where engine component/catalyst temperatures exceed their operating limits (open-loop) and then no richer then LBT +6% (Lean Best Torque).

The adaptives allow all of the stackup variances in the components and the crazy variety of gasolines that are required in different parts of the country to be accounted for and allow true stoichiometric operation every time the engine starts. Otherwise, the air/fuel ratios would potentially be out of the stoichiometric area and the pcm would have to relearn after each startup.

Thanks Dave. I'm asking because in the event I should make my plenums larger one way or the other.....would the computer adapt to the changes in plenum volume/runner flow (hopefully increased) at high rpm/WOT by itself?



I'm wondering if it'd be safe to drive without things being all haywire-especially if I had plenum volume increase at like 4500rpm... rather than a fixed increase in volume. Or otherwise went outside the bounds of what's currently on the engine. Might it be as simple as maybe putting some miles on it and giving the computer time to re-learn things, or might the plenum volume change be outside the max/min parameters engineered into the computer...


Should initial tests be done on a dyno rather than the open road for safety's sake?

 

[Dyno Dave]

The pcm will adapt those areas of the map that operate in closed-loop only. The open loop areas will not. If the shape of the volumetric efficiency curve changes due to hardware modifications there will be some areas that are rich and some that are lean. This will occur even within the closed loop area. Ignition timing may also be ******** or advanced (with respect to what would be the optimum). There is no way the end user can correct this with the stock pcm.

The reason this occurs is because the software interpolates spark and fuel along a straight line from map/rpm breakpoint to map/rpm breakpoint. The breakpoints are clustered around the inflection points of the VE curve to make a smooth as possible curve. If the inflection points are now different due to engine modifications, the interpolation will not occur along the new VE curve and spark and fuel delivery error with respect to the new VE curve occur.