I was wondering if I had to replace my ECU/ECM. I know you can order a secound hand one and give them your VIN and they program it. I have an aftermarket cam...Elgin E-1840-P Cam. Does the ECU need to be specially programmed different for this cam, or just a regular programing.

I'm having an issue where the check engine and the stored info for errors is not storing or not being able to recall from a bluedriver OBD2 earlier I had a million mis fires and when reving up the engine the check engine light would flash. Long story short no codes for faults found no solid check engine light.

Only way to find the misfires was to get an XM reader and watch in real time.. im wondering if i replace ny ECU the codes will be stored ? Hard to chase problems when i cant find any codes.

2006 H2 Hummer
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That probably just means the misfire isn't serious enough yet to throw a code. The flashing lights to tell you there's a misfire going on. I would start by checking your ignition system. Coils, plug wires and plugs. Is it a random misfire, or specific to one or two cylinders? A good scanner will be able to show you live data with a misfire counter per cylinder. If it's just on one or two cylinders, you can swap the coil, plug wire and plug over to another cylinder and see if it follows.

Other potential issues are fuel pressure related, evap solenoid not operating correctly, vacuum leaks, loose or corroded ground connections, and wiring harness issues.

 

Based on your "Flashing Check Engine Light" thread your truck has been tuned for the cam, this will require either you have someone with custom software pull a copy of the current tune and then install it in the new ECU, OEM programing will not support your cam. You can have the replacement ECU programed with the OEM tune then have the custom tune loaded into that ECU but you need to get the custom tune downloaded prior to pulling it out of the truck, or you can have another tuner do a full tune after getting the replacement ECU with the OEM programing.

Has the truck ever ran without the flashing light since you've owned it?
Your cam will cause this issue if not tuned correctly, also if your crank sensor or cam sensor calibration drifts slightly it will do this and as Robert has mentioned a crank relearn could possibly fix the issue.

The flashing CEL doesn't always set a code, the ECU looks at all the sensors and determines that the mixture may be rich enough to damage the CAT's, if it does set a code its usually a P0300, random misfires.

Your best option is to have a "Crank Relearn" performed and then if that doesn't fix the issue have a tuner like Black Bear do some tuning on it and see if they can work it out, they can do it over the internet.

With your blue driver look at the O2 sensor readings and see what they are doing while driving when the CEL starts flashing,

Neal

 

clogged catalytic converters or backed up exhaust can also cause the CEL to blink.

 

We had the hummer for about a year and no flashing CEL ( check engine Light). Then it started showing up when driving constantly, I could park and rev to 1500 2000 rpm and the CEL would flash, picked up a XTOOL of Amazon and I could see like 500 to 800 misfires in a minute on cylinder 1 and some in 3, after swapping coils...no change finally I pulled the 1 plug and looked bad. So i changed them all and problem solved for about 6 or 8 months.. but now on a 1/2 hour highway drive might get about a few minutes of flashing CEL and a shaking vibration. Returned the XTOOL after fixing the plugs and it wouldn't do the crank relearn. But that was the $300 A30 model they have a $600 D75 model not sure if anyone has tired a relearn with it? The seller will justvsay yes it works

But i would have thought that having 800 misfires in a minutev would throw a code for solid CEL, but nope, i think maybe once i had a CEL code for misfires. Before i could just sit in the drieway and watch realtine, but with the random CEL flashing you almost need the gear hooked up and have someone else driving while you try to check out.

hard to track a problem when no codes are popping up. I had O2 sensor codes and fixed that other codes for silly stuff like radio data commincation lost etc. Just not the important stuff like misfires.

 

do you hear any rattling or knocking when under load and accelerating? i had an issue that if i was on the highway doing 60 at about 4000 rpm up hill the CEL light would flash. it wound up being the cats where a bit clogged mostly the drivers side cat.cylinders 1,3,5,7 live there.