Rich after Flash

[90zcrex]

Is it normal for Gen 4 Ecus to run rich for 10 minutes after a flash even in open loop? I started a Maf tune on my car yesterday, set up to only use MAF and set all the afr correction tables to all 1's. Seems as if everytime I flash a new tune it runs about two points rich for 10-15 minutes and it slowly leans itself out to where it should be.
Am I missing something or is this normal? I'll post my tune file for reference. (DUSTIN)-maftune1b.hptThanks.

[90zcrex]

Nevermind I found the answer in another thread. For Future reference it looks as if the newer Gen IV ecu's have an evap routine that makes them run rich for the first 10-15 minutes after a reflash, you can shorten this time by driving the car hard.

[MikeOD]

Nevermind I found the answer in another thread. For Future reference it looks as if the newer Gen IV ecu's have an evap routine that makes them run rich for the first 10-15 minutes after a reflash, you can shorten this time by driving the car hard.

It's a giant pain in the ass, because whatever is going on is not effecting the commanded EQ ratio...but it is effecting the measured AFR. I really wish there was a way to disable it. Seems like if you're only tuning full throttle, and you only use data from full throttle, it's ok...but if you're working on the VE or low frequency MAF stuff, you'll never get the tune right until you know to wait it out.

[openwheel25]

Do you guys think this evap problem would make the afr swing larger with big injectors? I have the same problem but the swing between rich and lean is huge. The car can be 8% lean and I can make a small .5% change and after a flash it will be 12% rich. I have ID 1000 injectors.

Thanks,

[Mike@G-Force]

Its common... A way to disable would be nice!

[rynez06]

dear god do i agree

[MikeOD]

Do you guys think this evap problem would make the afr swing larger with big injectors? I have the same problem but the swing between rich and lean is huge. The car can be 8% lean and I can make a small .5% change and after a flash it will be 12% rich. I have ID 1000 injectors.

Thanks,

I see the same 10-12% rich after a reflash with stock LS3 injectors...

[Mike@G-Force]

I see the same 10-12% rich after a reflash with stock LS3 injectors...

So HP Tuners Support.... Can you disable the EVAP test?

[xrelapse13]

monstrous pain in the ass when doing driveability stuff

[HartRod]

So HP Tuners Support.... Can you disable the EVAP test?

+1, 2 and 3....

[LSxpwrdZ]

I don't think EVAP has anything to do with it... unplug and block off the EVAP physically and the engine still runs rich after a re-flash on the stuff I've done.

[MikeOD]

I think it's part of a diagnostic test...that still tries to test without things plugged in.

[griffincox]

Just thinking out loud, but this seems like it could also be caused by calculated temps like the IVT (intake valve temp). At normal operating temp I see IVT of 280-300° F. After a flash it's basically reset and recaulated. It doesn't have a way to better estimate the IVT than to use ECT and run time and whatever else is used. I see after a flash And hot restart, the IVT start at 200° or less and then warm back up to 280-300°. Could this and other calculated variables cause this situation. If the ECM thinks that the IVT is lower than actual it will add more fuel than needed and that fuel will vaporize more quickly and completely than expected by the ECM, etc.

Am I way off?

[LSxpwrdZ]

^^ If that were the case the resultant commanded EQ ratio would reflect that as the IVT table is a modifier to current commanded EQ only in OL. Beyond that I always delete that table and fill it with 1.0 so it doesn't screw with me commanding 1.0 Lambda. Also take note of the pulse width of the injector... if it were something like that calculated it would show with a pulse increase however in all the cases I've looked at the pulsewidth reports the same value. This makes me think it's something in the pulse modifier section on a restart or reset that causes it to command more fuel. I really need to hook an oscilloscope up to an injector and measure the total pulsewidth after a reflash and compare that to the pulsewidth after the rich condition goes away. The reported pulsewidth in HPTuners is injection pulsewidth and not a total time pulsewidth. So the reported pulsewidth + voltage offset + short pulse etc would be the total pulse.

I do find it funny that alot of trucks don't do this. I did a 2007 6.2 truck yesterday that didn't go rich after a re-flash. So that tells me that there is definitely something that causes it on the cars that "should" be able to be turned off.

[Michael_D]

Why it is that this phenomena is not mentioned in any of the "how to books" or videos I have, and why it's just now getting attention on this site? I have not ever heard anyone mention this till about two weeks ago. Now it's being talked about as if it's a well known irritation.

I'd be interested to hear from some professional tuners who have been tweaking cars with this ECM for several years if they've seen the same thing?

[10_SS]

I have not ever heard anyone mention this till about two weeks ago. Now it's being talked about as if it's a well known irritation.

That's because people don't like to admit they really didn't know, so they say Oh yea, I knew that.. LOL. It's not in the books because they didn't know either.

[griffincox]

To be honest, with my 2008 E67/LS2 combo I haven't really noticed this. Just an interesting topic I've been reading about.

[MikeOD]

Why it is that this phenomena is not mentioned in any of the "how to books" or videos I have, and why it's just now getting attention on this site? I have not ever heard anyone mention this till about two weeks ago. Now it's being talked about as if it's a well known irritation.

I'd be interested to hear from some professional tuners who have been tweaking cars with this ECM for several years if they've seen the same thing?

I've been fighting with it since I bought my car in 2011...4 summers of not knowing how to avoid/disable it.

[Michael_D]

So have you ever tried to cycle the engine after a flash? Flash > Start > Off > Start

It looks like the weather may cooperate this weekend. I plan to start over again with VE cal today. Is there anything in particular that I should log or look for to indicate the ECM is done screwing with fueling and I can start logging data?

[Michael_D]

Wow, what a downright PITA….

Now that I aware of this glitch (or whatever it is), it is abundantly obvious to see. It appears to have more of an effect after a MAF re-cal than VE, but both are definitely effected. I probably spent 10 hours logging and flashing my car this past weekend. There is no set pattern that I can see, and no particular length in time either. I can flash a new cal that only moved table cells 2% to hit the target, then see STFT’s in the 25% range. Sometimes they settle back down in five minutes, sometimes twenty, sometimes there is no apparent effect at all. Sometimes the trims will not settle down, and I have to shut the car down, re-start and see if the trims have settled down. Very bizarre. I don’t understand what could be causing this, as the commanded AFR does not change.