Ok guys,

Last night I started my G for the first time in 6 weeks. I have been fabricating a custom turbo setup with an HKS twin turbo setup kit (GTRS aka GT2871R) and JWT intercoolers. I am running a CJM stage 0 fuel return, DW 600cc injectors, and a UTEC. The MAF is custom mounted in a 3" (2.88" ID) pipe, which is just a hair larger in diameter than the stock MAF housing. I also have a AEM UEGO wideband which I will be connecting to via UTI software so I can logmap it along with the UTEC readings.

The first thing I did was load the Turbo XS map and parameters for the APS TT with 550cc injectors. I figured it would be close enough to get the car running, and it was. When I looked at the parameters, I noticed that the MAP crossover point for open loop was set to 3 psi, and the minimum and maximum MAP values for mapping were 3psi and 20psi respectively.

This brings me to my first question: Since I am only going to run about 6-7 psi, wouldn't it be better to set my maximum MAP value for mapping at like 10 psi? Correct me if I am wrong, but wouldn’t that give me higher resolution since each load site will represent a narrower band of pressure? Or will it just make tuning harder because now I will be hitting twice as many load sites? And if I did change it, then all of my fuel values will be shifted (spread out) and I will have to manually space out the columns and interpolate the missing values between them correct? I don't think I would ever run more than 8 psi or so on the UTEC, so I don't see the point in mapping up to 20 psi. I was going to set the overboost cut at about 9 psi. If I ever build the motor for more boost, I will ditch the UTEC andyway.

My second question is, why does TXS have it set to crossover to open loop at 3 psi of boost? Shouldn't the crossover be 0 psi, so that as soon as the car goes into boost it goes into open loop? Or are they doing it for driveability reasons, to smooth out the transition (if I recall, the stock MAF should be able to handle 3psi of boost no problem). I was thinking of making my open loop from 0-10 psi, so that each of the 10 load sites would represent 1 psi of pressure. That way, if I run 6 psi I will be hitting 6 load sites.

Ok so moving on I started the car and it ran really rough. I checked my fuel pressure and it was only like 20 psi, so I turned it up to 50-52 psi and the car started running a lot better but still rough. Watching my wideband gauge I saw that it was reading off the scale lean, so I started messing with the 0% column. The map I was using had -17 in the 0% column so I went to -10 I think and it the A/F finally leveled out for a moment, then it went super rich. I continued to mess with the numbers in the 0% column, going from 0 all the way to -25 and honestly it didn't seem to have any correlation to the A/F reading on the gauge. Sometimes it would get leaner with numbers like -5, and then the next minute it would be super rich at a -15. There were even times when it was idling ok around 14.5 A/F and then all of a sudden the engine would bog for a second and the gauge would read full lean, then it would gradually come back to the 14s without me touching a darn thing! This brings me to two more questions:

When I am editing my fuel map, do the changes take place in real time, or do they only take effect after I use ctrl-s to save the map? Also, is the stock ECU fighting me when I am trying to make adjustments to the idle A/F ratio? Is that why it's so damn hard to dial in?

Could my idle issues be caused by injector latency? I found latency specs for Denso injectors (the DW's are Denso's IIRC) and they are supposively .640 ms. I'm not sure but I think the UTEC only allows 1 ms adjustments (from 0-3). Either way, I should be better off with 1 ms latency correction than 0 ms right?

Lastly, I figure it's probably a good idea to perform the ECU reset and the idle air re-learn procedure, just to make sure the ECU is not remembeing anyting from before it was turbo. Do you think that will help with my issues?

Sorry for the long post but as you can see I have a lot of questions and the UTEC manual doesn't help much. Thanks in advance!

 

You can set your min to 1 and max to 10. This will give you a better resolution with 1 psi increment. 10 psi max will also give you that head room just in case you spike or overboost.


Base map crossover was set to 3 because your Min Map value was set to 3. What is the point of switching to 0 if your map is tune at 3psi. Once you have set your map min to 1psi then you can set your map crossover to 0psi... I have to go and I'll try to answer the rest later..

 

Thanks for the help. Yes I intended to change the crossover point and the min map value both to 0. I am not sure why you are saying to set my min map value to 1 though...if that were the case then it would crossover at 0 psi but wouldnt start mapping until 1? If I do 0-10psi the load sites will look like this:

10% = 0-1 psi
20% = 1-2 psi
30% = 2-3 psi
40% = 3-4 psi
50% = 4-5 psi
60% = 5-6 psi
70% = 6-7 psi
80% = 7-8 psi
90% = 8-9 psi
100% = 9-10 psi

 

its not real time tuning. only changes after you save and are under 1500 rpms

600cc injectors at ~45 psi fuel pressure should idle perfectly with about -10 in the 0%. The UTEC doesnt deal with idle scaling very well, but 600cc injectors are small enough it should be perfect. If you cant get it just right, its not the tune.

 

Well that helps! That's why my changes seemed to make little difference - I only saved a couple of times. Every time I saved the engine would die, so I didn't want to save too often. I will try lowering the pressure to 45 and going to -10 in the 0% column, saving, then I will see where I am at.

What about the injector delay? Uprev seems to make a big deal out of it when they talk about idling big injectors, yet I never hear UTEC guys talk about it.

 

there is a little bit of a delay so you may want to set your map crossover point 1 psi sooner.

For ex. I have my map min. value for mapping set to 1 and my max to 10psi. I'm only running 8psi so I dont see load 90 or 100 unless I spike.

It look more like this..

10% = 0-1 psi
20% = 2 psi
30% = 3 psi
40% = 4 psi
50% = 5 psi
60% = 6 psi
70% = 7 psi
80% = 8 psi
90% = 9 psi
100%= 10 psi

When you look at the logs you'll see that once you hit 2psi you will be on load 20, and at 3 psi you will be on load 30....etc.

I know it is weird but that is what I see when I log. There is a delay on the log so wont see an exact psi value all the time but Turboxs said it does it in the background.

Here are one of my log when I was tuning for the Winter Season. My A/F is still out of wack lol