Quote:
Originally Posted by codymac
Wow... you just changed my opinion that most modern tech.s are merely parts replacers.
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Unfortunately many of them are. Its sad the number of people who claim to be techs that can only pull a code and guess at a part with no further diag involved, and actually make a living doing it that way. I stay busy with cars from other shops that still arent fixed. The common one is lean codes and kwik car did a injector flush, put an air filter, oxygen sensors and a mass air flow meter on it then sent them to the dealer because the code still returned (and they got enough of the customers money I guess). Each one you can hear the vacum leak with the hood shut while standing beside the car! Every time I go to factory training for Jag, I am amazed at the backyard bumkin who is there (every class has at least one) that thinks an obd2 code is all you need to fix a car. that and the fact he actually convinced a dealership to let him touch $100k cars is pretty amazing too...
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.