Incredible amount of problems with tune

[cervan]

Im pulling my hair out just trying to get a decent running tune for my turbo 4.8. here is the low down on my entire build.

Stock 4.8 bottom end with 317 6.0 heads (i know low compression) ls2 cam stock everything else
aluminum ebay intake (ls1 style)
76mm on3 turbo
80# siemens deka IV injectors
tuned on 0411 pcm
4l80e transmission
SD only custom os loaded and zeroed out maf fail frequency and maf hertz.

My issue is that no matter what i do i cannot adjust my idle AFR's. it sits at 11 afr on my wideband literally no matter what i do. Ive zeroed out my base idle airflow, messed with minimum pulsewidth zero'ed out the VE table in the idle cells just about everything to get a leaner idle and nothing seems to affect it at all. It runs incredibly rich on cold start and windmills on startups for about 10 seconds sometimes seemingly at random. At idle im seeing about 19in of vac which seems low to me. And it idles extremely rough, almost like i have a miss but i cannot find a single issue with either the ignition system or fuel system. Turning the injectors off one by one shows that all cylinders are in fact hitting. Ive disabled adaptive idle, integral and proportional idle adjustments as they seem to make the idle eventually richer and richer until the engine stalls.

Here is the injector data i was given with my injectors, i cannot make anything out of it. And ive included my latest tune. Please help me lol.

[Tre-Cool]

a couple of things:
1) why no 2bar map sensor?
2) pe delay is set to 2 seconds and ramp in is very slow
3) pe throttle is way to high, a turbo car can be at full boost at half throttle


sounds like your injectors are just way to big and have trouble firing, i had a similar problem with a car with some 60lb's. could idle fine at stoich but as soon as it went it to low vacuum it would richen up.

[turbo 6l]

Capture.PNG

[turbo 6l]

2 bar map sensor hth

[turbo 6l]

Capture.PNG your ve table should read 215 kpa for 2 bar or 310 for 3 bar or something close to that not 105 kpa fyi hth

[turbo 6l]

you should also see this screen Capture.PNG

[cervan]

Thanks for the input and ill check out the settings that you guys highlighted. I found that in my front cam sensor conversion with the ls2 cam i needed to change the input voltage to the sensor from 12v to 5v and that was throwing off the injection timing. It still idles rich but atleast its stable now. I have a 2 bar map sensor on the way it should be here tomorrow to put on the car, i was simply trying to get the lower end of the ve tables tuned before the map sensor came in.

The reason alot of the map is wierd, is because it was idling so rich it would die constantly, so i copied over the stock map and slowly adjusted from there to the point im at now. Ill update this thread when i have a log file of the new map sensor and cam sensor wiring.

One thing i do find strange is that my injector pulsewidth never deviates from 1.5 when im logging at idle. Even though im lower than that on my min pulsewidth? Here is a log file from cold start from the old tune. And i forgive me i havent figured out how to add the wideband to the scanner in version 3.0, but all of my AFR's on the wideband were in the 11.8 - 11 range from start to end of the log. And thankyou again for the help

[redmonaro]

Ive read about people always having trouble with siemens injectors, partically at idle,
You thought about getting ID injectors?

[Montecarlodrag]

You would have much better idle fueling using Siemens 60's, they have low enough PW for small engines like yours.
Try lowering rail pressure to 40 lbs to see if the AFR can be improved.

[cervan]

i think you guys are right, there seems to be a hard limit to the lowest possible m/s injection time of 1.5 ms. I had my injection adder, and pw min set at 300 and it still sits steady at 1.5ms injection pw. So it seems that no matter what i do i will never get a clean idle with these 80lb injectors. This also explains why my startup is so rough as well, as the minimum quantity of fuel is still extremely rich.

If anyone has an information on how to lower the pulsewidth below 1.5ms i would be grateful before i go out and spend another 400$ on injectors.

[Russ K]

0 the Min Fuel Milligrams field.

Russ Kemp

[cervan]

0 the Min Fuel Milligrams field.

Russ Kemp

i will try that tomorrow. Im also getting a cam position sensor low error. I read online that the ls2 front pickup cam sensor is supposed to see 5v and i was getting a P0341- cam position sensor circuit A high, so i found a 5v reference from the fuel tank pressure sensor output on the pcm and wired it to the input on the cam position sensor. Now im getting the opposite, P0342 cam position sensor circuit A low. Am i missing something, or is this sensor supposed to get 8 volts, or something between 5 and 12?

[Tre-Cool]

you need to swap the outer wires when running an ls2 cam sensor on ls1 wiring and it uses 12v.

either swap outer wires on the pcm end or plug end.

[cervan]

Swapping the outer wires worked perfectly, no more codes! im getting perfect cam counts now.

Zeroing out the min injector pw tables allowed me to get a leaner idle but now im fighting a surging issues, so im guessing i need to start from zero and work my way up to my minimum pulsewidth to find what i want for my idle AFR's and leave it there right? Should i want to add any wiggle room so the ecu could lean out the PW past what it would idle at?

[matty b]

Start over, shit in>shit out. Start with RAF tuning if you get surge and go back and forth in the VE table to clean up your idle AFR. After that, typical VE tuning is done.

[cervan]

So ive been doing alot of research and im trying to get this thing figured out.

is the wideband input through either the egr/ac input read at all times just like the stock narrow band o2 sensors while the laptop is not connected while your in closed loop to get your long term/short term trims or is this specifically for tuning and not read afterwards?

Im also getting alot of conflicting information, do i need to scale my injector IFR table on my gen 3 0411 ecm under the 62lb limit of the gen 4 ecms? i tried searching for this did not come up with anything pertaining to gen 3 only gen 4.

Im also having alot of issues with getting a stable idle under 1.4ms-1.5 pw. This is obviously due to my injectors having a rated cutoff at around 1.8ms perhaps this is another way around this issue that i do not know about? under 1.3ms the injectors turn off and do not open. I also attempted to lower my fuel pressure at idle to help remedy this issue. I found that quickly was not the answer as it only started to change the AFR at idle under 10psi.

Im going to try relearning my IAC valve and opening the TB as much as possible, as right now im getting counts in the 120+ range at 600rpm while commanding 1000 rpm.

[Montecarlodrag]

is the wideband input through either the egr/ac input read at all times just like the stock narrow band o2 sensors while the laptop is not connected while your in closed loop to get your long term/short term trims or is this specifically for tuning and not read afterwards?

They are always reading but the PCM doesn't use them for anything, for fueling it only uses O2 in closed loop. Those inputs are used only for tuning.

Im also getting alot of conflicting information, do i need to scale my injector IFR table on my gen 3 0411 ecm under the 62lb limit of the gen 4 ecms? i tried searching for this did not come up with anything pertaining to gen 3 only gen 4.

No, Gen3 PCMs allow much larger injector values, no need to scale injector size. You may want to scale for airflow limits but that's another thing.

Im also having alot of issues with getting a stable idle under 1.4ms-1.5 pw. This is obviously due to my injectors having a rated cutoff at around 1.8ms perhaps this is another way around this issue that i do not know about? under 1.3ms the injectors turn off and do not open. I also attempted to lower my fuel pressure at idle to help remedy this issue. I found that quickly was not the answer as it only started to change the AFR at idle under 10psi.

Even if the injectors are a little big for the 4.8 it should idle pretty good at around 13 AFR. I have never used them on a 4.8 but I have a turbo 5.3 with same injectors and they work very good. I'm using 45 psi base pressure with vacuum/boost reference regulator.
You should be able to lower PW to around 1 ms or lower, spec minimum PW is 0.599 according to datasheet. Even at 11 AFR the idle can be stable, I think you have incorrect airflow and idle tables and that makes the idle unstable. Return them to stock and start over.

Im going to try relearning my IAC valve and opening the TB as much as possible, as right now im getting counts in the 120+ range at 600rpm while commanding 1000 rpm.

[cervan]

well thats kind of shitty, so i still have to emulate a narrowband just to get readings in closed loop when im not tuning it? Should i put the narrowband output to both banks, or just one?

One thing im not understanding is the idle ve table and primary ve table. Should i just zero out the idle table and use just the primary ve table with adaptive idle disabled?

And for idle airflow, does that change fueling at idle, or is that primarily for the IAC. i cant really understand what they are talking about when they say to get RAF tuned first, i have no way to effectively tune the RAF because i have no maf sensor. What exactly am i logging to get my base idle airflow values?

[Montecarlodrag]

You need to read a lot.
You don't need narrowbands, for turbo engines I just delete them and run open loop. You can install narrowband oxygen sensors and run closed loop in a turbo engine. I don't see the need.

Don't zero any VE table, adjust them to match what the vehicle needs.

More air = more fuel. IAC is used to control idle speed and it has an airflow table which tell the PCM how much air is letting in. The PCM will adjust fueling based on all airflow adders.
RAF can be adjusted without MAF, there are several PIDs lo datalog.

There are several tutorials here for each problem you are having, you just need to read them and start tuning. I strongly suggest you to not go into boost until you have a good grasp on the tuning basics, boosted engines can be destroyed very easy.

[Montecarlodrag]

I started tuning my own turbo 5.3L. Just installed wideband and AFR is 11.9 at idle and doesn't respond to VE changes. Pulsewidth is stuck at 1.9 msec
I played with injector settings and VE table but engine started surging when PW approaches 1.5 msec. Goes very lean and dies eventually. Lowered fuel pressure from 45 to 30 and AFR stabilized at 14 but that's not a fix for me since this is a turbo car and it'll need all the fuel up top.
I think this is the same issue you are having.

I'm 100% sure there is a fix, I have done in the past I just need to remember. Gonna check old files to remember what I did.