We have posted about your cold start several times..please see quote below in BOLD. The cold start has nothing to do with fuel trims and 99% chance it wont go away once fuel trims are fixed since cold start isnt using the o2 sensors.

 

Hey guys I had a victory last night with the fuel trims.

Sure enough the O2 sensors were plugged in to each others bank, so as bank 1 was reading rich it was telling the computer to lean out bank 2, and as bank 2 was reading lean it was trying to make bank 1 richer and the snowballing effect began. (I might have that backwards but you get the idea)

Let me tell you the white stripes on the O2 sensor wires are real hard to see with my eyes.

Long Term Fuel Trims are now -3.91 on each bank but the problem starting still exists. Starting the engine from cold is difficult and stalling after being revved still occurs. A light rev and it will come back to idle but too quick of a snap on the throttle and it will stall.

The cold start was still difficult, I had to feather the throttle butterfly while I was cranking the engine, then when it would fire up it would rev to about 2000 rpm for a few seconds then start to slowly come down to around 900 RPM (see log attached) So open loop is still an issue. I feel like it has something to do with the TB butterfly idle screw. I did take the screw out and turn it upside down for easier access to adjust.

One thing that has been on my mind is my test stand wiring. I have a main disconnect on the battery which kills all power at the battery box. Then there is an ignition switch on the operator panel that when turned on powers up the PCM, sensors (orange and pink wires) and activates the fuel pump.


My question is should the orange wires (PCM power) be hooked to the side of the battery disconnect that stays hot all the time, even after the battery is disconnected?

I wonder if killing the computer when the ignition switch is turned off is killing its memory and causing problems?

 

I did a IAC and TPS re-lean last night and the engine fired up right away. It still revs too high for the first few seconds but then settles down and idles very nicely.

The problem is if I try to open the throttle by hand the engine will stall. Sometimes I can open it a little then slowly feather it closed. As the throttle closes all the way, revs drop right down and it will stall or on a couple of occasions will catch and come back up to idle, but rarely.

New data log attached below.

You can see on line # 104 the engine was restarted and revs at 1800 RPM for a few seconds then down to the 900's.

As the engine warms you can see the idle revs coming down into the high 700's but every time after a restart, the revs jump up to around 2000 for a few seconds.

Doesn't seem to make any difference if the engine is in open or closed loop.

As you can see in the data log, in closed loop my LTFT's are -3.91 on both banks which indicates to me I don't have any mechanical issues.

Is my next step to place a call to LSX Power Tuning and see what they can advise? I am running out of options here and wish I could get a bit more feedback from this forum.

Thanks to you guys who have offered me some advice though.

 

Without the ability to actually tune it, it's pretty hard to solve a tuning problem with mechanical adjustments, and vise versa. It's 100% in the tune. There is really only so much you can do for the mechanical side, in this case it's really just the blade you can play with. Say like if your IAC is closing too quick, or the spark is dropping out too fast, yes, it will cause it to stall. These things are in the tune. Stall saver, idle airflow, and idle RPM setting, all that plays a part. This also includes the throttle follower, fueling, and everything else. I will also add, fuel and spark both have a MASSIVE difference in idle behavior, MUCH more so than air.

I'm sorry you're not getting a lot of responses, but from where we are, there isn't much we can do here. If I was near you, I would come over and help you tune it, but that's just not the case. You can try mail order tuning, with various vendors on this site even, including LSX, but this is not guaranteed to satisfy since there are many variables. Also, when you have it in the car, the addition or the transmission, and extra weight of a TC could also be a factor, and whatever airflow setup you have on that in car will have to be adjusted for as well.

EFI isn't like the old days. The good old "screws" on the carb are now accessed with a keyboard. The tune essentially controls everything you can think of on your engine, especially idle.

 

He has been told multiple times what he needs to first diagnose the cold start issue. The IAC steps need to be logged and the throttle blade set accordingly to get around 30-50 counts on a hot idle.

Yes the tune may need to be adjusted but regardless setting the IAC counts is the first thing.

 

Thanks Mate, I appreciate your explanation and confirmation that I need to be looking at the tune rather than anything mechanical or spark / fuel / air related. I had pretty much figured it was down to the tune at this point.


OK, if you had read my thread you would see the cold start issue is fixed, starts first go every time, it just revs high and stalls after being revved (hot or cold).
I will be calling you guys in the next day or two to discuss what can be done with my tune. I sent the PCM to you guys for the mail order tune it currently has, that doesn't work. I do not have access to HP Tuners, so I cant read IAC counts. I can't even get anyone from here locally to respond to my request to possibly come and help (other than Chopper) and I offered to pay for it.

It sounds like you think I am not taking your advice or listening to you but there is only so much I can do with what I have, which is why I paid you guys $250 for the mail order tune. I am doing my best but the LS platform is new to me and I have zero programming experience. Sorry but I am learning as I go.

 

We have posted in here numerous times with advice with no reply from you or contact from you. We have said from the beginning the tune may need to be adjusted and recommended that vs buying parts. People are trying to help you including us.

There is no possible way to get every mail order tune perfect especially on engine swaps, aftermarket cam, custom fuel system, exhaust etc. no matter who does the tune. Its physically impossible. Thats why we tell people they have to get it checked in person and it may need adjusting. From your post it appears the idle and startup may need adjusting some BUT to make adjustments we would need some data.

 

I understand I am never going to get a perfect mail order tune but I would expect to be able to rev the engine without it dying.
I will give you guys a call tomorrow to discuss my options.

 

The best option is to get it done in person, really. I should of re-read your original post, as I now realize that you already have the mail order tune. As LSX said, there is just no way to get it perfect without data. No adjustments in the tune are made without using data of somekind. There is some guessing occasionally with some of the tables, but these are not random. We still observe the data and what the changes did. A good example of that would be something like the cylinder charge temp bias table. No way to really log it, but can be pushed if needed one direction or the other.

The rest of the “normal” tables we use error percents, and literally pull the adjustments right off the scanner to plug into the tune. With idle though, this has some of the most “best guess” tables as every engine behaves differently, and goals vary. There isn’t a specific layout that works across the board is what that means. Generally, reducing the adaptive air a bit to control the range, and then using spark to maintain rpm works pretty well, so long as fueling is spot on.

From own a cold start this becomes increasingly difficult.

Moral of of the story is, sounds like it runs pretty well, has a few hiccups and needs some adjustments. Pretty normal really. It can take days to get cold starts right. And that’s in person, obviously, using data.

 

No problem just give us a call, we are open M-F 9-6 central time. It could be the tune or the throttle body could need adjusting, without any data everyone including us is just guessing. Even though we have done 5k plus tunes its still impossible to get every combination right on a single tune (base tune or mail order tune), there isnt any shop or tuner that can get every tune right in a single try especially idle and WOT. I dont think your understanding the limits of a mail order tune, it sounds like a mail order tune may not be the right option for you in your situation. No matter who does the mail order tune it will need to be fine tuned and data logged in person.

 

I would hate to have a customer as hard headed as this one lol. Complaining about the engine dying on an engine stand after revving it lol.. be happy it turns on with a mail order tune.

 

Hard headed... maybe. I would consider myself persistent and a bit of a perfectionist. But thanks for your input, it was invaluable.

 

hard headed and classy to boot.

nice.

 

So I just spoke with Lawrence, a super helpful guy at LSX Power Tuning.

My options are to leave things where they are until the engine is in the car and hooked up to a transmission before I bother to fix the tune, as changing the exhaust manifold and fuel pump will possibly necessitate a change in the tune anyway.

As I need to data log things like IAC counts before any changes to the tune can be made, I can buy HP Tuners, data log the parameters needed, then email the data log to LSX PT and they will email me back an updated base map which I can load into the PCM.

Buying HP Tuners would probably cost much the same as having a tuner come out and do the same thing (if I can even find one), but this way I have the program for continual updates and mods down the road. I would like to learn more about the tuning aspect of this engine anyway so I think that's the way to go.

I would have called LSX PT sooner but I wanted to make sure I had all mechanical aspects in order before I bothered anyone there.