EGT/Wideband question

[ricehunter]

So I was looking at my DSMLink logs (not tuning just getting a feel for how the program works) I noticed there's an A/F ratio. So I was wondering if I need a wideband or EGT gauge.

[cotsi95]

Wideband for a/f ratios, egt gives you Exhaust Gas Temps

[thiazole]

The default A/F mixture is just an estimation based on the air count and injector duty cycles. It isn't super accurate, but can be used to determine a change in A/F mixture from one tune to the next (ie, if it says you are running 10:1 with one tune and 11:1 with the next tune, while the actual A/F ratios may be different, the second tune is about 10% leaner than the first as the numbers would suggest). If you get a wideband and wire it in you can log the measured A/F mixture which is very accurate.

[ricehunter]

I will go ahead and buy one and wire it in, because I'm not entirely trusting the equations. the Log stated Max boost put as 10.3PSI, i did find the link on how to adjust it... looks like tomorrow's project. I may just schedule some time at RP after I get the injectors in to do a couple pulls and tune for them.

[prophecymiller]

What do you mean max boost is 10.3psi? Do you have a boost sensor you are logging? Is actual boost the same at 5500 rpm as boost est? Why don't you post a pull from 1500 rpm to redline in 3rd.

How are your fuel trims doing? Have you gotten those in check?

[prophecymiller]

Also for your estimated a/f ratio, as long as your air metering and fuel pressure are accurate, and you don't have boost leaks, it should be close to the actual ratio.

[burnett03]

So I was looking at my DSMLink logs (not tuning just getting a feel for how the program works) I noticed there's an A/F ratio. So I was wondering if I need a wideband or EGT gauge.

EGT's are a waste, unless however you are driving a diesel.

[ricehunter]

Well I'm trying to find a place to do a good 3rd gear pull, but there's that whole 100MPH on the streets. Unless someone knows of a good place to do one (pm).

Well I know there are people that tuned before Widebands were available.

[burnett03]

Ya you can tune without a wideband.. It's called tuning for knock.. And who says you need to do 100mph to do a tune? I never do. Set the logger, and hit it on the on-ramp to the highway.. 2nd gear all the way through will tell you a lot.

[burnett03]

Ya you can tune without a wideband.. It's called tuning for knock.. And who says you need to do 100mph to do a tune? I never do. Set the logger, and hit it on the on-ramp to the highway.. 2nd gear all the way through will tell you a lot.

[matthewdesigns]

Well I'm trying to find a place to do a good 3rd gear pull, but there's that whole 100MPH on the streets. Unless someone knows of a good place to do one (pm).

Well I know there are people that tuned before Widebands were available.

PM sent.

[ricehunter]

Ok, I was trying 3rd gear pulls to 75-80 on the on ramps yesterday. I might try that today to see if I can adjust my boost properly (it was showing 10.3 at about 17)

[prophecymiller]

What do you mean adjusting the boost? Are you talking for the wastegate or in dsmlink? Do you mean boost est is showing 10.3 while actual is 17 at 5500rpm?

[ricehunter]

Yes, DSMLink shows the boost as 10.3PSI when my boost gauge shows 17PSI (both are peak) I think at 5500 I'm about 14-15 PSI actual but DSMLink shows 8.5PSI. I'm going to try to get a pull today and keep track of my boost/RPM and use the adjustment that I found in the DSMLink forums for dajusting a GMAF

[ricehunter]

I've been looking at the zeitronix setup or the AEM uego, just not sure which one to get.

[thiazole]

The boostEst feature in DSMLink seems to underestimate the boost on smaller turbos - especially at this elevation. All it is doing is saying your air flow/rpm is X and at whatever volumetric efficiency your engine is at, you must be running a certain amount of boost to make that kind of airflow (ie, if your engine is at 100% volumetric effeciency at 5000rpm, and you are flowing 50% more airflow than would be calculated possible without boost that you must be running 50% of 14.7psi or about 7.35 psi boost - but up here you would need to run 10psi or more to flow that much air). The problem is that it assumes that atmospheric pressure is 14.7psi (you can adjust for that) and that your turbo has some predetermined efficiency that smaller turbos don't seem to have. People on the DSMLink forum often say that all turbos should be accurately represented by the BoostEst feature, but it seems that everyone making that claim is using a 50 trim or bigger turbo. It seems like whenever someone with a 16g or smaller turbo posts a tune that was adjusted for BoostEst, he gets flamed for it (even though the same people say it should always be dead accurate).

[ricehunter]

Well I need to calibrate for the atmosphere, which I believe is 11.8 and follow the instructions here: http://www.jeffgst.com/gmafcalibration1.html

[prophecymiller]

If I remember right, yyou need to put your elevation in the boost est properties, and ideally follow the instructions on the link for each airflow slider- meaning you adjust your wastegate to run whatever psi you need to in order to be running a corresponding airflow to each slider. I'm pretty sure this would make the maf calibrated at all airflows respectively.

[prophecymiller]

If you already have your elevation properties set, your boost est would indicate your air metering isn't accurate. If boost est was higher than actual boost, I would think you have boost leaks. You don't have ignore baro selected or anything like that do you? Meaning is it still at all defaults?

[ricehunter]

The only thing that's changed is I set all the fuel timing and global to 0 and turned off CAS inversion because it came for a 97+ with 660s. I went into the boost properties and changed the altitude to 6000 and it seemed to help out. Says about 16PSI @ 4300RPM and dropping to 13PSI @ 5500 (which seems to be about 1PSI off) or I might just be seeing my boost gauge wrong.