Quote:
Originally Posted by jtj
Another quick test you can do with many cars (although I have never tried it with a Lotus) is a cylinder balance test with a graphing multimeter, scope or a scan tool that will show a pid graph for a component and freeze frame it.. I use this on jags to verify injector faults/repairs, but its prtetty generalized for any car that can be forced into open loop with a wide band o2. put the car into open loop, usually pulling the number 1 injector plug while it is running will do this on nippondenso based systems. while the dtc is set, the ecu will ignore 02 input for fuel map/injection and use a preset base line. the 02 will still read the ratio however because it doesnt know its being ignored. dfepending on the tool used you can get an actual reading or a voltage in the case of a scope backprobed into the sensors harness . then, while running the o2 voltage graph over enough time to see all cylinders on that bank in one screen shot, pull one injector plug at a time long enough to see a viewable waveform then plug it back in long enough to return to the engine baseline ratio before unplugging the next one. then you can compare exactly how much fuel each injector is dumping in relation to the others on that bank (especially easy when a "picture" of them all is laid side by side to compare.) wide bands are extremely accurate and this will show something like a dirty injector nozzle that otherwise might not show in other tests and without dissasembling the injector rail etc. it can also verify faulty 02 sensors if you have one thats possibly stuck/dead/lazy and want to see an actual value change at the sensor, although a scope is better for that due to refresh rates etc.
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i actually had a chance to try this out on a lotus the other day, and unless there is another way to force it into open loop for the duration of that key cycle then this will only work on a scope that can show a time display of 5 minutes or so if your a slow mover/no assistant.you could do it one frame at a time and print the waveform/pattern for each cylinder and compare later if your using a lower end scope/meter, but i would prefer them to be on the same screenshot for better comparison. unplugging an injector will take about 20 to 30 secs to put car in open loop, plugging it back in takes less than 10secs for ecu to return to closed loop (based on lotus scan data anyway, although its prob more instant and the tools refresh rate is slowing it down).its doable but not really as easy or practical as it is on other cars. just thought i would let you all know...