ECMlink LinkV3: BoostEst and boost gauge not equal {attached log}

[razrman8]

So either way, CombinedFT should be at 0, also deadtime and MAFComp affect CombinedFT?

What about the huge spike in my MAFComp table? It shouldn't spike as it does? Why would DSMlink suggest such a spike?

 

[Calan]

So either way, CombinedFT should be at 0, also deadtime and MAFComp affect CombinedFT?

Correct

What about the huge spike in my MAFComp table? It shouldn't spike as it does? Why would DSMlink suggest such a spike?

Because something in that area is causing a big change in airflow.

Dips and peaks are normal. Large changes and spikes usually point to something mechanical going on, like a boost leak, MAF issue, etc.

 

[razrman8]

Lol, so would you define that as a peak, large change, or a spike?

 

[Calan]

I actually haven't looked at your log yet, and am on my phone at the moment. I'll look at it when I get back to a computer.

Have you done a solid boost leak test, and able to hold 5 psi more than your max boost for at least 30 secs or more?

 

[razrman8]

Yes, I have pressurized to 21-22 psi and its slowly bleed. Boost leak test checks out. Deleted emissions not too long ago so I wanted to make sure everything was the way it should be.

From what I am understanding, BoostEst is only accurate from anywhere between 5k-6k. If my calculations are correct, I need adjust my MAFcomp between 1600-1700hz by 7%

(16+14.7)/(13.9+14.7)-1
(30.7/28.6)-1
1.0734-1
.0734

Calan, since you are on your phone, here is a picture of the MAFcomp table.

You must be logged in to view this image or video.

 

[Calan]

That 50hz spike looks pretty typical for a GM MAF, a hacked stock MAF, or a setup where the PCV breather is being vented to atmosphere (no longer connected to the turbo inlet after the MAF). This is a sign of un-metered air entering the engine, causing the ECU to fight a lean condition at low airflows.

An adjustment of 26% here means that the ECU is having to inject 26% more fuel than it calculated to get the AFR back to 14.7:1 in closed loop. So there is either more air being pulled in than the ECU expects, or the injectors aren't injecting enough fuel, possibly due to inaccurate deadtime values.

Set your injector deadtime to something close, using this page for reference, and make sure your base fuel pressure is correct at the AFPR. Use the Global fuel calculator in Link to get a good global fuel number. (List your injectors in your profile and we can help you dial these numbers in).

Next, do some non-WOT cruising around (city and highway driving) for a while, and run the "MAFComp Adjust (CombinedFT)" tool. Do this several times, collecting as much smooth driving at different speeds that you can, and reset the fuel trims each time. You should eventually get to the point where CombinedFT never varies more than +/- 3% or so. Post up some of those logs as you go.

 

[razrman8]

It is definitely on a stock MAF. Injectors are FIC 1150's.

I will get on those logs.

So after doing some MAFComp adjusting, I should be able to get CombinedFT close to zero with the appropriate suggested deadtime on my injectors, correct?

 

[Calan]

There are some pretty good known deadtime values for those particular injectors, but I can't find them at the moment. I'll see if I can get Brian to post them up for you.

 

[razrman8]

Okay. Thank you very much sir.

 

[Calan]

So after doing some MAFComp adjusting, I should be able to get CombinedFT close to zero with the appropriate suggested deadtime on my injectors, correct?

Assuming your base fuel pressure is accurate, the injector size (static flow rate) is accurate, injector deadtime at each voltage point is accurate, fuel type is correct, and O2 sensor is functioning properly...

Yep.

 

[razrman8]

Alrighty. All of those things will be correct after putting deadtime back.

 

[snowborder714]

There are some pretty good known deadtime values for those particular injectors, but I can't find them at the moment. I'll see if I can get Brian to post them up for you.

They were in your own darn thread about your injectors being stupid

http://www.dsmtuners.com/forums/tuning-engine-management/409538-ve-dip-3.html#post152908578


Once I get some time to read through this, I may post up more.

 

[razrman8]

Alrighty, got some logs after MAFComp adjustments. Using the template that DSMlink suggests is definitely bringing my CombinedFT closer to 0 with each time that I do, but with that, 0-100Hz percentage adjustment keeps going way up. Whether it should or not I am not sure but that is what I am seeing it do.


Fisrt log is a cruise after using DSMlink suggested MAFComp from a cruise. 330 deadtime.
Second log is an idle log after adjusting MAFComp for the second time.

 

[Calan]

they were in your own darn thread about your injectors being stupid

http://www.dsmtuners.com/forums/tuning-engine-management/409538-ve-dip-3.html#post152908578

DOH! I hate when that happens!

Alrighty, got some logs after MAFComp adjustments. Using the template that DSMlink suggests is definitely bringing my CombinedFT closer to 0 with each time that I do, but with that, 0-100Hz percentage adjustment keeps going way up. Whether it should or not I am not sure but that is what I am seeing it do.

Check everything over again closely for a vac leak. Is your PCV setup still stock?

 

[razrman8]

There's only so many places for a vac leak. Pcv is still stock.

 

[Calan]

There's only so many places for a vac leak.

You'd be surprised.

 

[razrman8]

Lol. What do you mean. I don't really know an explanation as to why the adjustment is so high

 

[MY1GDSM]

Check everything over again closely for a vac leak. Is your PCV setup still stock?

THIS ^

Have you done a BLT? I only grazed over the thread real quick but a quick look at your first log and last would point to that or a Preturbo post maf leak or as said your drawing in unmeatered air somewhere... or one of the other things mentioned below if not addressed.

What's your Base fuel presure at? the reason you started the thread Imho is really not of that great concern.

Calan has some very valid points about getting things calibrated above.

You can change things in link all day But, the things he menationed before should all be adressed before doing any more changes.

Assuming your base fuel pressure is accurate, the injector size (static flow rate) is accurate, injector deadtime at each voltage point is accurate, fuel type is correct, and O2 sensor is functioning properly..

Not saying you haven't but letting everyone know exactly what you did to check these things would be a bonus... .

 

[Calan]

I don't really know an explanation as to why the adjustment is so high

A lot of that is probably due to inaccurate deadtime values, which haven't been corrected yet.

Go into the InjBatAdj DA table, and change the following and then save it (with the car off, ignition on):

7v - 3189
9v - 2443
12v - 1457
14v - 1103
16v - 831
19v - 762

Go to the fuel tab, and set:

Global deadtime: 0 usecs

...and assuming your base fuel pressure is around 43psi and you are running pure gasoline, set:

Global fuel: -61.7%

Zero out the MAFComp sliders and fuel trims, and run through the "drive a while/run the CombinedFT adjust tool" process again and see if it's closer.

 

[MY1GDSM]

I agree it should be set in DA as that is always how I've done things... And the proper way.

But, dead-time is set at 330 in that last log that I was referring to... . and with that much being added in maf comp it still shouldn't be that lean IMO... .

 

[Calan]

Yep. I still think he has a vac leak as well, or base pressure/fuel stoich values are off. But since DT is pretty far off, might as well get that closer with some good numbers that Tom measured on a similar set of injectors to start with.

 

[razrman8]

Deadtime is at 330. Which is what ECMtuning suggested

 

[razrman8]

A lot of that is probably due to inaccurate deadtime values, which haven't been corrected yet.

Go into the InjBatAdj DA table, and change the following and then save it (with the car off, ignition on):

7v - 3189
9v - 2443
12v - 1457
14v - 1103
16v - 831
19v - 762

Go to the fuel tab, and set:

Global deadtime: 0 usecs

...and assuming your base fuel pressure is around 43psi and you are running pure gasoline, set:

Global fuel: -61.7%

Zero out the MAFComp sliders and fuel trims, and run through the "drive a while/run the CombinedFT adjust tool" process again and see if it's closer.

I will follow this. Thank you.

 

[razrman8]

Fuel type is correct, pump 93. Base fuel pressure is 43, o2 works properly, has been replaced, boost leak test has been performed as stated prior.

Okay Craig, I tried what you told me to adjust and the car won't start. It sputters then dies.

I just took more time to read through this thread again. Craig, you said that the spike could be cause by PCV breather being vented. The hose is NOT connected to the intake, but rather has a breather filter on the nipple right off of the valve cover.

 

[Calan]

The hose is NOT connected to the intake, but rather has a breather filter on the nipple right off of the valve cover.

There is your vac leak.

During off-boost (idle and cruise), air is being sucked into the IM from that breather and through the VC and PCV valve. Since that air isn't coming through the MAF, more air is entering the engine than the ECU thinks there is, so it's running lean. It's most noticeable at low airflow, which is why you are having to crank up the 50hz slider so much to compensate for it.

Reset the fuel trims, bump that 50hz slider back up to around 20% (assuming they are still flat), and it should start and idle. Let it idle for 30 seconds or so, then hold the throttle so that it "idles" at about 2000 RPM for about 30 seconds. Then run the MAFComp tool again, and it should get your airflow in the ball park down low.