Explaination of BE (Boost Enrichment)

[smithers]

Hi all,

Spent a few hours looking through threads on this, perhaps someone can clarify.
BE. (using a 2bar OS)

A few threads mention that there are some issues with this. Spiking, transition from (PE EQ vs RPM) to BE tables? can someone clarify this scenario? when does this occur?

what is the PROPER method of using all these items in the Power enrichment tab when using a centrifugal.

Do you eliminate the PE Enable TPS % and go solely with MAP enable (ie. 85kpa)?

Do you just throw 1.27 in the PE EQ vs RPM table (11.5:1 for example) and the same in the BE table? or do you use the BE table at all?
Or same values in and slowly go richer in the BE?



Thanks in Advance.

[Chris@HPTuners]

the issue is it does not activate as fast as PE does, there is a longer delay due to the processing loop the code is in.

For any kind of engine driven supercharger just use PE.

BE was intended for use as a safety mechanism on turbocharged vehicles when the turbo could spool for some reason below the PE threshold and run lean. This generally happens if the turbocharger is not sized correctly for the engine (too big or too small). When i had twin turbo's on my car i used PE only and had BE set to enable at the same enrichment as PE when boost exceeded 110kPa. Usually if the turbo is unexpectedly spooling it is not at a high load situation anyway (your TPS is below PE threshold).

Some tuners will also use BE as a safety mechanism to protect the engine if the customer changes the wastegate settings manually or if an electronic wastegate controller is fitted (E-boost). They set BE at the max boost limit and then really richen up the fuel above that. In the newer PCMs we added an overboost fuel cut to provide even better protection for this case.

Hope that helps,

Chris...

[smithers]

Chris,
Thank you for the clarification.
Good explanation of the intent and use of BE as well as the underlying issues.

So I will lower the TPS % enable to a low value and utilize using the MAP (Map PE Enable) as a PE trigger at 85kpa (approx) ...
And have the target 11.5:1 AFR for example in the PE (EQ ratio vs RPM) table (1.27 right across)
and as you mentioned, will have BE (EQ table) set the same (1.27) and slightly richer with higher boost. Either have the BE Enable map at 105kap or I could just increase the BE Enable Map to a value near max desired boost.

[DWC]

Bump

[DWC]

Under Boost enrichment vs. MAP,do theses settings need to be the same across or is it ok to stagger them? Looking at lower numbers in the 100kpa to help spool and higher numbers starting at 180 kpa to help with knock.

Regards
DWC

[erics_02_z06]

I like how when you are buying, this is what is said: "- New MAP referenced "Boost Enrich" table".

While true, the code is so slow to respond sometimes it isn't useful as a tuning tool, or really even as a safety. I can set it to turn on at 100KPA and it can be as delayed as 140KPA before it kicks on.

My issue with using PE is, I am in the 11's for 85-100KPA. Not a big deal I suppose. when I have some time, I plan on setting the PE eq to 1, the throttle % low, and using the MAP enable set at 85 to go into PE. When in PE mode, it should look at the OLFA and use the richer of the 2 values. I'm hoping to set my OLFA to 12.8 for 80-95, and then 11.6 for 100KPA. I then will set my BE to be 11.4 and enable at 100KPA. I'm hoping I'll be 12.8 for 80-95, 11.6 for 100KPA to 1??KPA (BE delay is usually around 30KPA for me), then 11.4 till redline. I'm guessing this works...feel free to give it a shot if you have time first

[smokeshow]

Bumping this.. I've been aware of the BE delay for a while now, but it has never proved itself an issue on my personal vehicle. Coding delays notwithstanding, I've used BE as the primary enrichment for quite some time now and have never had any concern as to whether the delay would cause lean problems on a boost transition. I have a ball bearing twin turbo setup on my 6.0 and the MAP graph on the scanner is just about vertical after mashing the throttle, so its not like its a laggy setup giving BE time to react.

So, what kind of delay are we talking here? 0.1 seconds, milliseconds? And is the delay in the commanded EQ ratio following a transition to boost enrichment, or is the delay in the actual delivered fuel following the commanded EQ?

[DSteck]

Yea, I have no idea what delay people are seeing. I've never had an issue with it.

[5_Liter_Eater]

It's not an issue on the 4th gen PCM's but on the 3rd gens I've seen/heard of it taking seconds.

[DSteck]

I do a lot of boosted third gens, and still never have an issue.

[LSxpwrdZ]

I have a few logs from turbo cars that are on the wastegate and still at 1.13 commanded EQ from the PE table because the BE table hasn't enabled. Some cars are worse than others due to features the PCM processor has to process.

[PICNIC_GEORGE]

I have a few logs from turbo cars that are on the wastegate and still at 1.13 commanded EQ from the PE table because the BE table hasn't enabled. Some cars are worse than others due to features the PCM processor has to process.

How much is it delayed? Enough to be dangerous? Obviously if you're running 175kpa and 1.13EQR there is a problem lol

[LSxpwrdZ]

How much is it delayed? Enough to be dangerous? Obviously if you're running 175kpa and 1.13EQR there is a problem lol

You can set it up to where the worst lag still doesn't hurt it. I ended up setting it up so that lower rpm PE is commanding what I would want on a NA engine and then ramp the BE in as boost increases. The trick is setting the enable point sooner on the BE so that it isn't as laggy. Normally I'll go down to 100kPa or 105kPa as the enable point. As a safety precaution I'll go in the upper RPM region of the PE table and command the same amount of fuel that I would at full boost just to make sure fuel is there in case BE has a brain fart.

[MikeOD]

I've never had an issue with a delay on a commanded EQ ratio in boost using BE on the Red/Blue or Green/Blue enhanced OS's. I've always set the enable KPA to 105 KPA, and then set the 105 KPA cell to match the number I'd run in normal PE on an NA engine...after that I ramp fuel in with the rest of the BE table, and the commanded EQ always follows.

The only delays I've seen (on the P59's), are due to the "Enable Torque" setting in the PE section. Seems to not matter on most files that start from cars, but does seem to matter on trucks. If I leave that number at 100%, it will cause some calibrations to not enable BE or PE for a delayed amount of time, and that delayed time seems to be inconsistent, depending on when the driver smashes the pedal down. On those applications, I set desired torque to 0%, and PE/BE enrichment kicks in instantaneously when my other conditions (TPS/MAP) dictate that it should.

[LSxpwrdZ]

http://www.hptuners.com/forum/showth...-and-BE-issues

From 4yrs ago....

[Stuffs]

the issue is it does not activate as fast as PE does, there is a longer delay due to the processing loop the code is in.

For any kind of engine driven supercharger just use PE.

BE was intended for use as a safety mechanism on turbocharged vehicles when the turbo could spool for some reason below the PE threshold and run lean. This generally happens if the turbocharger is not sized correctly for the engine (too big or too small). When i had twin turbo's on my car i used PE only and had BE set to enable at the same enrichment as PE when boost exceeded 110kPa. Usually if the turbo is unexpectedly spooling it is not at a high load situation anyway (your TPS is below PE threshold).

Some tuners will also use BE as a safety mechanism to protect the engine if the customer changes the wastegate settings manually or if an electronic wastegate controller is fitted (E-boost). They set BE at the max boost limit and then really richen up the fuel above that. In the newer PCMs we added an overboost fuel cut to provide even better protection for this case.

Hope that helps,

Chris...

can someone please post an example or tune i can take a look on how to use PE on a centrifugal SC?

I have use 2bar OS and always use the PE for N/A area ,and set BE to the boost area (105kpa an up)