I'm looking for a good way to test GDI injectors in the car. I have a 4 channel Pico that I've used on traditional injectors many times. Looking for guidance.
Vehicle is a 2018 Honda CR-V with a dead hole misfire cylinder 1 for about 30 seconds immediately after starting. Goes away once ECT exceeds about 85 degrees F.
You can measure injector control signals on both the voltage supply and the ground control wire. Next test is current ramping the injector.(s). Tapping into the fuel rail pressure sensor signal wire while ac- coupled will allow you to identify pressure changes (or lack of them) in the rail due to injector opening. If you do this with a sync signal from one specific injector you can also identifu each individual injector.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
My personal go-to is still secondary ignition testing. A lean GDI injector will still cause a lean secondary waveform, same as port injectors.
I've also started experimenting with doing impromptu 'balance' testing when the scan tool allows it. You monitor the upstream air/fuel sensor while disabling individual injectors. The relative flow rate of each injector will be proportional to the impact that injector had on the air/fuel ratio.
Built-in injector balance tests are hit and miss. :silly: The Ford test is pretty decent, the GM one is not.
In the case of your Honda, I thought there's a specific PID related to individual cylinder air/fuel ratios? :huh: Fuel factor study, or something along those lines. Since your misfire mostly takes place on a cold engine, I'd also be suspicious of intake valve carbon buildup.
Possibly intake leak? To much air getting in causing variables to go out of spec. Surprisingly there was something with why they added the secondary low Pressure injectors. Can't recall what the reason was such as burning off the carbon buildup, cold engine starting, open loop something makes me think about those as it was discussed in a gdi class with John Thornton or Jerry G Truglia just can't recall which person it was though.
You could make sure it's not a intake leak with a little shot around the intake of some choke cleaner, won't take much. Other option with summer coming up is soon it'll be 85 when some people wake up and they can wait till that time of day? JK .... Lol....
Thanks all. The issue is simply a misfire briefly during warmup. I put a pressure tester on the cooling system overnight and checked the cylinder for coolant. None found. It's possible the head gasket only leaks after running for a few seconds but not very likely.
I'm going to play with this vehicle again tomorrow so we'll see what we find. Secondary ignition was checked and compared with a non misfiring cylinder and found to be roughly the same. Both during idle and snap. It's strange because it's a dead hole misfire. Anyway, I will report back tomorrow.
