AEM ECU flooding engine

[LtPyro]

Ok so you can't get all the info from the title.  But here is the short version:

My father and I are both running Honda 3.5 engines and recently added turbos.  We both bought AEM ECUs.  I have installed the same tune on both cars, essentially the stock tune modified just a little (lower rev limit, lower MAP sensor BAR pressure...).  My car runs perfectly fine on the AEM with no issues.  My fathers car however floods itself.  On the stock ECU he has no issues.  After installing the AEM and turning the ignition on (but not starting the engine) one or two cylinders (guessing on the number) flood themselves as if the injectors are being held open.

I took his AEM and installed it into my car and it runs perfectly fine, no issues.  Just doing this leads me to believe the issue is with his wiring or engine.

I'll be heading out to Havasu this weekend to help him troubleshoot it.

Any ideas of what might be the issue or things to check would be helpful.

 

[Rockwood]

Swapped back to stock ECU yet?  AEM series 2?

 

[John@Outfront]

first double check the pressure regulator, if the diaphragm is broken it will dump fuel through the small vacuum hose right into a "few" cylinders

if that is not it, I'm voting ecus are fine and it could then only be  stuck injectors (e85 by chance?) but really think the wire harness is bad

 

[LtPyro]

Swapped back to stock ECU yet?  AEM series 2?

Yes swapped back to the stock ECU and it runs like it did before adding the AEM s2.  Only floods when the AEM s2 is installed.

 

[LtPyro]

first double check the pressure regulator, if the diaphragm is broken it will dump fuel through the small vacuum hose right into a "few" cylinders

if that is not it, I'm voting ecus are fine and it could then only be  stuck injectors (e85 by chance?) but really think the wire harness is bad

The car is running pump gas.  We don't think an injector is stuck because you can go back and forth between the AEM and stock ECU and it will run fine on the stock ECU but floods on the AEM.

I will check the fuel pressure regulator.  Its not a stock unit, he changed it out for an AEM or Aeromotive (can't remember which).  But like i said before it works with the stock ECU.

 

[Rockwood]

Both are stock injectors as well? Odd….

 

[Kraut_n_Rice]

If you pull the upper plenum you should be able to see which cylinders are causing your issue.  Then, see if the harness is grounding those injector plugs.

eta..why would you lower the rev limit?

 

[LtPyro]

Both are stock injectors as well? Odd….

Another thing we got as a suggestion last night was it may be possible that the injectors are not responding well to the voltage from the AEM ECU and therefore not working properly.  I have some spare injectors I'll be taking with me tonight to see if that's the problem.

 

[LtPyro]

If you pull the upper plenum you should be able to see which cylinders are causing your issue.  Then, see if the harness is grounding those injector plugs.

eta..why would you lower the rev limit?

I lowered the rev limit from the AEM canned tune which had it set over 8k back down to 7200 which I believe is the stock rev limit?

 

[Kraut_n_Rice]

I lowered the rev limit from the AEM canned tune which had it set over 8k back down to 7200 which I believe is the stock rev limit?

Stock rev limit is around 6500, but most people do up it from there when using an aftermarket ECU.

 

[LtPyro]

Stock rev limit is around 6500, but most people do up it from there when using an aftermarket ECU.

Well that’s why over 8k snapped a rod in my engine lol. I’ll double check what I set it too, maybe I went less than 7200.

 

[Kraut_n_Rice]

Well that’s why over 8k snapped a rod in my engine lol. I’ll double check what I set it too, maybe I went less than 7200.

Not likely. You threw a bunch of boost at stock rods.

 

[LtPyro]

Not likely. You threw a bunch of boost at stock rods.

Off topic but two years, two cars setup the same way and the only break was when I held it over 8k rpm.

 

[ChasingSand]

Have you tried calling AEM directly? I wonder if they could remote login to see what’s going on. 

 

[John@Outfront]

You could simply have a bad MAP sensor or coolant sensor. If so they could go full rich. Even an air temp can do ghat. Or theMAP sensor hose bad (if you have one)

 

[richard h]

Didn't you prove it was not the AEM by switching them between cars?

 

[LtPyro]

Have you tried calling AEM directly? I wonder if they could remote login to see what’s going on. 

No, but i think its safe to say the AEM itself is not the issue.  

You could simply have a bad MAP sensor or coolant sensor. If so they could go full rich. Even an air temp can do ghat. Or theMAP sensor hose bad (if you have one)

We swapped out the MAP sensor.  If it was a bad sensor I would expect it to behave the same with either ECU installed.

Didn't you prove it was not the AEM by switching them between cars?

I would say yes, I mean the unit itself isn't the problem, the parameters on the tune might still be an issue that needs to be fixed.

 

[LtPyro]

Well short story, we didn't get it fixed this weekend.  We had to work on the boat as first priority this weekend and only got a little time to work on the sand car.  But my father did pick up a test kit for checking the wires to the injectors and he'll do that hopefully today or tomorrow.  I also gave him a second set of injectors I had sitting around, maybe he just has a couple injectors that don't like the AEM.

I'll post some more when we figure it out.

 

[richard h]

I would say yes, I mean the unit itself isn't the problem, the parameters on the tune might still be an issue that needs to be fixed.

Agree, I think there is some other issue and do not believe the aem is causing it imo.