Not sure what you mean by if they’re not varying. Should they be fluttering up and down if they are updating every second?
Yes they should. They show the amount of oxygen in the exhaust which varies with the mixture and will never stay constant. They will always flip flop from one extreme to the other as the ECU fine tunes the mixture. Static means they are either giving a fixed output, which they should never do, or they have failed and the ECU is putting out a failsafe fixed voltage which is what you are seeing.
Thanks for that. Will have another check tomorrow.
New day, new readings.
Bank A, idle. Varies between 0.05-0.78 hot or cold
Bank B, 2.5K rpm. Varies between 0.07-0.79 hot or cold
MAF readings
Hot at idle. 28
Hot at 2.5K rpm. 69
If those figures look generally okay, I wonder what the problem is, why the car is so slow?
What are the fuel trims showing on Nanocom?
If the lambdas are working its odd that your getting rich codes. It might be that its run out of fuel trim due to another issue (eg fuel pressure)
Can you try to log MAF G/s at full throttle and see what sort of range you get? I would expect around 180-190g/sec at peak power.
Funny you should mention fuel pressure. Took it to a friendly Indy who connected another code reader and he mentioned something about low fuel pressure.
Would low fuel pressure give reasonable low rev/power performance and reduced higher rev power/performance?
when i have these types of troubles i revert back to basics, air, fuel, ignition. is there a restriction in the air flow, blocked filter, rag in the system, throttle valve opening, all good, on to the next one, ignition, is it missing have dead spots, breaking down under load, running like crap, all good on to the next one, fuel. is it slow to pick up, sluggish, not revving, just will not go any faster, stalls out at 3000 rpm for instance, it's a fuel issue, first thing fuel pressure, fuel filter, fuel regulator, maf or map sensor, o2 sensors, and anything else that is associated to fuel? dose the exhaust smell bad , if any of this applies to your issues look in that direction. i think it's a fuel issue.
phazed wrote:
Would low fuel pressure give reasonable low rev/power performance and reduced higher rev power/performance?
Think about how a fuel injection system works. Depending on signals from the TPS and MAF, the ECU knows how much throttle you are giving it and how much air is flowing into the engine so that dictates how much fuel the engine needs. As the fuel pressure should be a constant that dictates how long the injectors need to open for to give the correct mixture. Lambda sensors are there to give a final check so it can fine tune the duration to keep it correct. This is the short term fuel trims. If the short term trims are constantly one way, either longer or shorter than the programmed duration, the long term trims adjust to bring the short term trims so they adjust around the default position, so sometimes going negative (shorter duration, less fuel) sometimes positive (longer duration, more fuel). What are the long term trims and, when running, what are the short term trims showing? That will tell you if it is a fuel issue or not.
With low fuel pressure, the short term trims may still be adjusting either side of zero but the long term trims will be a constant positive. As long as it isn't by a huge percentage, it is doing what it should. That is why it adjusts the trims, to account for things that aren't quite as they were when everything was new and in spec.
Thanks for that guys. I will be slowly working through the above.
Coming to an end of a Boxster project that I’ve had in the garage for the last couple of months, actually probably three months but will have room soon to get cracking on the P38.