turbo LQ4 help

[Frank_Castle]

Hey everyone.
Im trying to get my turbo LQ4 build back on the road. It was my in DD in NA form for the past 28k miles. I have watched several of chopperdocs video's on youtube and looked at several threads on here but Im at the point that I need some help. I have the car where it will idle pretty decently when warmed up, but it hesitates terribly bad and throws codes putting it into limp mode before it will even get into boost. My AFR graph is showing pretty drastic values that im unsure are correct. My AEM wide band seems to ---- out when the ratio is to far off. Ive made so many changes recently (2 BAR os, injector data, MAP linear and offset, high and low octane spark, etc) that I am unsure what is not correct and what needs to be addressed first. Any help, advice would be appreciated.

P59 ecm ( with shitty 2 bar resolution OS)
tick performance 3 bar map sensor (bought before I found out my ecm couldnt do 3 bar)
SEP 1500 injectors with injector data
sloppy stage 2 cam (elgin 1840p)
stock internal LQ4 with 317 head, pac 1218 springs
VS 7875 next gen 1.25ar
4 inch turbo back
t56
greddy profec boost controller (would like to run 7psi off, 10psi low boost, 14psi high boost)
snow perforance water meth stage 2 (progressive)
50mm vs wastegate with 7lb spring

[5FDP]

Turn off the transmission abuse mode and set the brake torque mngt under the system options to zero to stop those from getting in the way.

Large injectors like those will want the minimum fuel milligrams table lowered some to stop a rich idle as well. Probably can go down to .014 instead of .028.

What code does it throw when it goes into REP?

You will likely need to increase the P1514/0068 table in the engine diag tab way up to stop that from happening and going into REP.

Remove the 1 bar map from your logs, replace it with the 2 bar channel.

[Frank_Castle]

Thanks 5FDP,
I have made all the changes that you've suggested except the P1514/0068 table. Should multiplying it by 1.5 be enough or should I increase it by more? Also will I need to "write entire" after zeroing the brake torque management?
I am not sure what codes were being thrown to put it in REP, I cleared them just to make it back home. I plan on trying again tomorrow evening after work with the new setting and will try to get better logs of what is going on.

[5FDP]

Most people just max the table out or raise it near the max so it doesn't do it anymore. No write entire required, a normal write for the brake tq mngt is just fine.

[Frank_Castle]

Okay thanks! I’ll make the changes and see what happens

[Frank_Castle]

I made the changes and no more REP!!, but the fueling is still way off. It wont idle until its at least 130deg and still seems to be all over the place. Smells flooded when running. I logged the warm up which required me throttle it to keep it running and then a short drive up the road. I had multiple backfires and tons of hesitation and surging. The log isnt much better but there are a couple slow pulls around the 8:20 mark... but even the map looks off. I order a 2 bar map sensor that is supposed to be in Wednesday maybe that will help?

[Carlfromkerikeri]

I think a 3 bar map sensor will give wrong values for the 2 bar os tune

[Frank_Castle]

My 2 bar MAP sensor (GM 12615136) is supposed to be in tomorrow, hopefully that helps. I don?t see the point of trying to scale the injector flow until I change that.

[Frank_Castle]

I installed the new 2 bar map sensor, flashed 200 and 8 for linear and offset. Started the car and still had similar issues? had to throttle to keep it running. Check my injector data once more, input the newest injector data that I requested from the seller, dropped the minimum plus width to 0.35 and rewrote the tune. Bam, started, idled and drove with much better throttle response. My Wideband was actually able to read and not ?? out. However it was idling in the 12s. My question would be, should I add 4-5% to my flow vs Kpa table to see if that will get my idling AFR closer to stoich or should I just leave the injector data alone and start VE tuning to adjust the fueling?

[Carlfromkerikeri]

Don’t have my laptop to look over the tube at present, Check that your EQC ratio verses etc table is commanding 14.68 (1) at the temperature that you saw it running 12afr first, it’s under the open loop tab of fueling tables, my p59 ecu was targeting a rich afr on cold etc, then was switching lean to presumably heat up the cats to operation temps quickly before commanding 14.68 afr at normal operating temperature

[5FDP]

Never adjust the injector data after you change it once.

The VE table is what is controlling all your fueling. If fuel needs to be removed, you remove fuel from the VE.

[Frank_Castle]

Oh ok thanks, I had the understanding that NA areas of my previous VE table should be the same with the new injectors as long as the data was calibrated correctly. I went ahead and started tuning the VE table as you suggested and it seems to bs going well.

[Frank_Castle]

So I've been driving, logging and VE tuning and have been running into some problems. I feel like there has to be some ECT fueling adder table that is turned on somewhere that I am missing. all of my logs keep telling me to pull as much as 15-20% out of the bottom left of my VE table but after doing that multiple times I am still getting an 11-12AFR at warm idle. However it is extremely lean on cold start... doesn't want to start and surges back and forth between 10.0-20.0 AFR until it gets above 130ish degrees than settles down at 11-12AFR. My car is a 6MT car but I was previously told to keep the automatic trans setting. Im not sure if there is something with the PN/Drive enrichment section that could be causing this. Im not sure how it works with my 6 speed so Ive left it alone. Any help would be appreciated.

This is a screen shot showing how my VE tuning is working how it should in the area circled in blue but the lower load and KPA areas of the chart continue to require fuel to be taken out even though Im down as low as 4,5,6% in those areas in the VE table.


240sx drive log 11-22-21 screen capture.PNG

[Frank_Castle]

My car has been on the lift waiting for a new transmission mount so I haven’t been able to make any changes to the tune. I compared some similar files to see if anything was drastically different but wasn’t able to come to any definitive conclusions. Could this be a transient fuel problem? Should I lower the minimum fuel milligrams table more or is there a way to calculate what it should be rather than guess work? At this point I’m thinking about adding more fuel back in the bottom of the ve table so it’s not so lean because the rich warm idle was about the same before taking it out.

[eXo3901]

What type of fuel system do you have and what is your fuel pressure set to?

The SEP website rates those injectors at 43psi. You'll have to adjust the data if you are not running 43psi. Also, they are rated at 142lb/hr at that pressure. Your flow rate table starts at 138lb/hr. I would think that the flow rate should start at 142lb/hr. I could be wrong as I do not have the most recent version of SEP data, only what I could find on here and it looks to be dated from January 2020.
https://forum.hptuners.com/showthrea...ontrol-of-AFR)

So, verify your fuel system details and then, assuming the post above is the correct data for your injectors, you will need to update your flow rate table, offset vs. volts table, short pulse adder table, and short pulse limit table. If you received different data from SEP then just double check those tables match the data you received.

[Frank_Castle]

I have a walbro 450 pump, corvette return filter regulator, 3/8 lines, factory LS1 rails. I checked the fuel pressure as suggested and its reading 75psi at idle!!! I check the return line for kinks and it was fine.. I guess the corvette regulator isn't strong enough for the 450 pump? So obviously that's going to cause problems, I never even thought to check it. last time I did it was 58-60. Anyone know of a good and affordable return style adjustable regulator and 10 micron filter I could slap in place of the corvette filter?

Also this is the injector data that I was sent three weeks ago from SEP, which I assume is the most up to date.SEP_1500Long.xlsx

[blindsquirrel]

https://forum.hptuners.com/showthrea...e-running-Rich

You don't NEED the regulator to be referenced, unless you just want to. Injector data has to be changed if you want it referenced - if you have enough injector headroom at the boost you plan to run I wouldn't bother. You can mount a regulator in the same spot you now have the filterthing and use it non-referenced, solely as a bleed-off to keep pressure capped at 58psi.

[Frank_Castle]

Thanks, this is great info! I just ordered a return regulator and filter and will mount it in place like this dude did his. Hopefully that will take care of a lot of my fueling issues and let me start accurately tuning this thing.

[kingtal0n]

I recommend referencing the regulator for a couple reasons.

1. Lowering fuel pressure when it isn't needed such as during vacuum situations, will prolong the life of the fuel pump and preserve fuel system components.
Always run pressure systems as low pressure as possible, to protect system components, whether blood pressure, oil, fuel, coolant, etc... lowest pressure can prevent leaks and blowout. The vacuum reference is a free (no cost) way to enable this feature so it is always recommended.

2. Boost pressure in the intake manifold lowers the pressure differential at the fuel injector. So for example if you have 30psi of fuel pressure, and 30psi of boost pressure, no fuel can exit the fuel injector. Likewise if your injectors are rated flow at 43psi and you have 43psi in the fuel system and 20psi of boost, now you only have 23psi of fuel pressure at the injector rated flow. In other words 20psi of boost cuts your injector flow rate in half because there is no reference.

All factory turbo vehicle are using regulators with reference because of #2.
#1 is just common sense from fluid mechanics engineering perspective.

[blindsquirrel]

Yes of course boost with a non-referenced regulator will reduce injector flow rate. 1500cc injectors have plenty of overhead at 58psi to deal with any feasible amount of boost from this combo. It's not ever going to make 40 lbs of boost, come on. Get your head out of the damn engineering textbooks and go play in the real world for a while.

Mark this down as an example of how 'common sense' ain't all that common.