Fuel Trim Tables

[ScottMH]

I am having a issue with a LS3 installed in a 1957 Chevy. It is using the E67 ECU out of a Trailblazer SS. The previous tuner locked the ECU so I cannot get into this one at all. The car runs rough and throws check engine lights for MAF sensor and occasionally Lean Bank 1 and Lean Bank 2. At the request of the customer we replaced the MAF (card style) with a new ACdelco one. It did not change the situation. What I am noticing on the scanner is that when you start the car the LTFT 1 & 2 is at -17 and stays in the negatives when you drive it. If i unplug the MAF and plug it back in after a few seconds while it is running the LTFT drops to 0 and the car runs better through out. I turn off the car and start it back up and the LTFT drops down to -17 and runs poorly again. If the previous tuner has the fuel system setup really rich in the tune will that make this happen? I am thinking I will need to get another ECU that isnt locked and start over but I want to cross my Ts and dot my Is.

Also, the air intake tube that was on it has a huge vacuum leak. Is it possible it was tuned for that vacuum leak and now that I have replaced the Tube it no longer has that extra air?

[schpenxel]

GM should be able to re-flash the ECM back to factory settings then you'll be able to read/write it like normal

It's really just a guessing game without more data.

[ScottMH]

Local dealership didn't want to fool with it. Customer decided to order a used ecu off eBay. Should be in at the end of the week. It's supposed to be a stock tune e67 out of a 2007 trailblazer ss. I know I will have to disable VATS is there anything else I need to disable?

[ScottMH]

Ok got the new E67, out of a 2007 TBSS, ECU in. Installed to the car, disabled VATS. Now the Car will start for 2 seconds and shut down. Seems to start nicely and idle for a second then completely shuts down. Turn the key off and start again and still the same thing happens. Hooked the old ECU back up and the car starts and idles like it did before. There has to be something in the programming that is causing this. I did read where someone had a similar problem and they had to have a different OS installed on the ECU. Attached is a copy of the file. Any ideas?

E67LS3 Start then turn off.hpt

[ScottMH]

Update: Tried to write entire on the ECM. No change.

[ScottMH]

no start log.hpl

here is a log file. the first couple of attempts on this log I tried to hold the accelerator down slightly to see if I can make it run. it did not. the rest are just cranking, starting and dying.

[schpenxel]

Your MAP sensor settings are wrong, it's showing 11psi of boost with engine off

Looks like you've tried changing the MAF tables quite a bit. Any particular reason why?

No wideband?

Fix the MAP sensor settings first

If that doesn't fix it for shits and giggles try making the open loop IVT gain vs. MAP table 1 everywhere just to see what happens

fuel-->open and closed loop, "IVT Gain Mass" is the table. At higher MAP #'s it adds a ton of fuel when intake valve temp is low, which it will be on cold starts.. I wonder if that's the issue? The falsey wrong MAP reading will put it in the higher portion of this table which adds a lot of fuel

[ScottMH]

Your MAP sensor settings are wrong, it's showing 11psi of boost with engine off

Looks like you've tried changing the MAF tables quite a bit. Any particular reason why?

No wideband?

Fix the MAP sensor settings first

If that doesn't fix it for shits and giggles try making the open loop IVT gain vs. MAP table 1 everywhere just to see what happens

fuel-->open and closed loop, "IVT Gain Mass" is the table. At higher MAP #'s it adds a ton of fuel when intake valve temp is low, which it will be on cold starts.. I wonder if that's the issue? The falsey wrong MAP reading will put it in the higher portion of this table which adds a lot of fuel

Thank you for the reply.
Ok, I will look at the MAP settings. That something I haven't touched yet.
It has a card style MAF sensor. I copied the table from a LS3 ecu to match the Hz to airflow ratios for the card style MAF.
No I don't have a wideband at this point. Will be getting one soon.

Do I need to match the IAT curve also?

Ive been going through a stock tune for a LS3 and trying to find the differences and fix that. It is a different ECU and a different Operating system so its been a bit of a challenge. Being new at this doesn't help either

[schpenxel]

Unless you're using literally the exact same intake tubing setup and air filter setup as the vehicle you pulled that MAF table from, then that MAF table won't be right. This is especially true on the card style MAF's where any difference in the size or shape of the intake tube they're in will totally change their output.

It's probably more in the ballpark than the old stock one, but it will need to be adjusted once the engine is running

Yeah you should use the IAT table from a vehicle that used that MAF, however, I really don't think that's the problem. They're pretty much all close enough to work just to get something started so I wouldn't really worry about that for now.

[ScottMH]

I went in a changed the MAP linear and offset to match the numbers on the LS3 tune I have on file. Still has the same problem but the map reading has decreased. Here is the data
no start log 2.hpl

I then went into the IVT Gains and changed all the numbers to 1s. Same problem slightly different. The idle doesn't go up as high and dies a lot faster. Here is the data
no start log 3.hpl

As far as the tune I am basing all this off of it is a Stock GMPP tune for a GM connect and cruise package 430HP. The intake tubes are in fact almost identical. On the tune I am basing this off of the car has never had any starting or driving problems. But it was also never "tuned" for the intake. We followed GMs guidelines for the tube construction and made it.

One of the issues I am facing is the scaling on the charts from the GM LS3 tune to the E67 Tune are not the same. Ive copied and pasted some of the data from one table to another but in the case of the MAF sensor the frequency range on the E67 is not as high as the GM LS3 ecu. Also, the frequencvy on the E67 is split into two charts while the LS3 ecu is one chart. I am trying to be as careful as possible.

Here is a copy of my current Tune
Ricky Carter LS3 Trailblazer SS stock tune + disable VATS 9.hpt
Here is a copy of the stock tune for the E67
Ricky Carter LS3 Trailblazer SS stock tune.hpt
Here is a copy of the LS3 Tune I am basing this all off of
John Minter 1968 Camaro LS3 Stock Tune + 750 idle + more idle air.hpt

[schpenxel]

Really weird. Commanded AFR just makes a huge sharp change for some reason then it dies.. I'll look over it some more but I'm not sure what is going on. I don't know if something else is killing the engine and the change in commanded AFR is just a side effect or if it's actually the problem.

Hopefully someone else has seen this before.

[ScottMH]

Really weird. Commanded AFR just makes a huge sharp change for some reason then it dies.. I'll look over it some more but I'm not sure what is going on. I don't know if something else is killing the engine and the change in commanded AFR is just a side effect or if it's actually the problem.

Hopefully someone else has seen this before.

Thank you for everything. What drives me crazy is if I plug in the old ECU that was on the car it will start, idle and drive. However, its rough and throws codes. To make matters worse, its locked so I cant see what was changed to get it to that point.

[ScottMH]

One more piece of information. I just switched the connectors back to the original ECU and fired up the car with the data logger on. Started and idled. Here is the data

carter old ecu log.hpl

only off thing I see comparing this data log to the dying log is the timing is shoots up when it dies while the timing stays in the negative on the running log. Could it be trying to compensate for too much fuel by adding timing

[schpenxel]

Add injector PW to your list of channels, I'm curious whether they're cutting off or not when it starts to die

[ScottMH]

with pulse width
no start log 4.hpl

So weird its like its turning the key off.

I almost wonder if the VATS isn't still on somewhere and is going into anti theft?

[schpenxel]

Also log MAF airflow, VE airflow and dynamic airflow. Sorry, should have listed those earlier

Also, mass air flow [frequency]

[schpenxel]

Wait.

If "Ricky Carter LS3 Trailblazer SS stock tune + disable VATS 9.hpt" is the actual file you're using then that is a (and likely the) problem

The VE tables are all 0'd out. Can't do that

The MAF high table is also all 0's but shouldn't be an issue at startup, but obviously will be later

[ScottMH]

Wait.

If "Ricky Carter LS3 Trailblazer SS stock tune + disable VATS 9.hpt" is the actual file you're using then that is a (and likely the) problem

The VE tables are all 0'd out. Can't do that

The MAF high table is also all 0's but shouldn't be an issue at startup, but obviously will be later

Yes that is the current tune file
The VE tables i havent touched. Is the LS3 stock tune a good place to start?
The MAF high table i have no excuse for. I edited them and did not hit save after, maybe.

[schpenxel]

Try this for "Normal IMRC Closed" and "normal IMRC Open" tables and see what happens

MAF high sounds like you can fill in later, or maybe fill in something real quick just to be sure it has something in there

ScottMH.xls

[ScottMH]

RECTune Idle.hpl
We have liftoff!
Should I be concerned that the LTFT worked its way down to -18.8?