Here is what I have come up this morning on my 99 RS on MSnS (controlling fuel only, not ignition) with original motor, injectors @ 130K miles. Been out in the field mon-fri the past 3 weeks and only have been driving it on the weekends. Last weekend I noticed a drop in economy and sputtering at idle and more noticeably between 2500-5000 RPM. Screamin demon pack and MSD wires are a month and a half old. Put new plugs in this morning. Old ones had normal signs of wear and were worn to about .060. Gapped new ones to OEM spec. Pulling each wire boot off confirms each cylinder is getting spark. Pulling the boot off Cyl #1 does not affect the already crappy idle. Then I proceeded to pulling the injector harness off #1 and it did not affect the idle or driveability. I attached a jumper to the harness side and it killed the motor, so their is a signal.

EGTs normally were around 12-14 at cruising speeds, now at 900.

Using a screwdriver, placing the blade against the base of each injector and putting my ear to the handle I can listen to the clicking of the injector opening and closing at idle on all four, leading me to believe that at the least, the PWM signal is reaching the injector however the injector is clogged and not flowing fuel. Mechanical fuel pressure gauge confirms 52 PSI @idle and throughout RPM band.

MegaTune and LC-1 wideband indicate a 16.5:1 lean condition. Is it reasonable to think that one cylinder is just pumping air in and out without any fuel being burned?

All of this leads me to think that Injector #1 has failed. I attempted to wrap on the injector as rough as I dare to but it did nothing to dislodge any potential dirt or debris. Autozone wants 275 for a special order injector. HAH. I called up ModernPerformance and have a 30lb set of Accels enroute via FedEx.

You smart ones out there agree with me on this? My stock injectors have seen their share of miles, but I know others have had stock injectors last much longer. I know there is spark. Without question. So it has to be fuel. Right?

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2012 2500HD LML

I have spent the past half hour messing around with a brand new MSQ file as I realized that with new injectors comes a completely new VE table. So I started entering constants, target AFRs etc. For the most part as soon as I bang the new injectors in, I have to do a firmware update to the board (they are up to 29y2 now it seems) and flash the ECU. I will keep you posted.

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2012 2500HD LML

with a balence test on cylinder one showing no change in rpm, its very safe to say cylinder 1 injector has gone south for the season!