CutLS

iTrader: (6)

I have a 1972 Cutlass (CutLS) that I swapped in a LS1/4L60E from a 2000 Corvette. I had a company unlock and "base" tune the PCM so I could start the vehicle. I was having issues with the vehicle stalling at stop lights and I was getting a P1518 because the vehicle cranks so long. I brought it to a place to get dyno tuned. The vehicle ran well and would start up after a few cranks, just like a normal car. A few years later while coming home from Powercruise in Minnesota, My alternator went out and I realized I might not make it home the extra hour drive. My brother brought me a charged marine battery my dad had so I could make it home. This was the first time I disconnected my battery in a year or two. I replaced the alternator and put in a new battery. Ever since then, it seems like my vehicle wants to crank 6 or 7 times before starting, if it wants to start without setting a P1518. If the code sets, my vehicle will not run. I did the diagnostics for the DTC and thought I might have a bad PCM because of one of my meter readings, so I went to a junk yard and got a PCM with the same part number. My readings were the same so I figured that wasn't it. All wiring circuits end to end are good. I found one block to chassis ground loose but no change. I bought HP Tuners to start learning on how to tune and maybe figure out if it was a tune issue. I have a wideband gauge and realized my normal driving and idleing, the vehicle was lean. I did one tune change with the MAF so far to richen it up, but it still has an extended crank. I feel like something changed in my tune. Any Tips on what parameters I should watch (i.e timing, fuel, starting/cranking afr) or things I should double check?

mstansbury0704

Is it a stock or near stock engine? Since it’s a swap and all that other mess, my advice might not be good. But I’d try A crank relearn if it’s never been done. You can do this through the vcm scanner special functions tab. Also try an iac&tps reset. Basically key off and pop the hood and unplug them, turn key on and then back off. Plug em back in and turn key back on. Unsure if vettes were drive by wire in 2000

Ive had the slow start happen once when I disconnected my pcm on my 2000 Ls1. Did the crank relearn and tps/iac reset and I was starting within half a second of turning the starter. Did both at pretty much the same time so unsure what cured my issue
If it’s not a stock engine or has a healthy cam I would also double check my IAC counts at warm idle. (Again unsure if vetts had iac in 2000)

CutLS

iTrader: (6)

Its basically a cam swap, and springs. Otherwise stock. Ill give that a shot and see.

mstansbury0704

How large of a cam are we talking? If you’ve never adjusted the opening on the throttle body blade there’s a good chance that could be a part of it. It’s been forever since I’ve tinkered with my raf and iac area but until someone that’s better than me can get involved I can try and help you along

CutLS

iTrader: (6)

Its an SLP cam SLP51016. ADV DUR 273/278,, DUR @ .050 224/228, VALVE LIFT 592/600. LSA113

mstansbury0704

That’s a fairly small cam and shouldn’t require too much of anything to get to idle.
Have you tried any of the things I mentioned?

Again, unsure what type of setup or anything because of the swap, however I do suggest checking your iac position at warm though. You’d want to turn off A/C and everything else and then command fans to OFF using the vcm scanner controls and let your vehicle come up to 210 degrees then check your iac position(Be sure not to walk off and forget about it, it will overheat eventually).
If it’s all the way at 120+ counts that may be some of your stalling out at stoplights etc issue as at that point your basically idling off of the iac alone. the iac can’t give it anymore air.. To log this you’d have to find the appropriate channel for idle air control position or something along those lines in your scanner. For a cam that size probably 30-40 counts at warm idle would set you right. You lower the counts by opening the throttle blade and vice versa for raising them.
If you adjust the throttle blade you have to reset the iac/tps sensors in the method I talked about earlier or your TPS % will not be correct.

I personally like to log and record my TPS voltage as well in the scanner. If it goes even worse you can set it back to where you had it if you know the voltage of the sensor before adjustment.

It’s odd to me as it ran fine forever until dead battery.
There is an IAC position relearn procedure that you can google and try to do..but before that I’d try to verify it’s not something mechanical that the car overtime simply adjusted around and now has forgot.

CutLS

iTrader: (6)

I don't have issues anymore with stalling out once I had gotten it done tuned. I did try unplugging my IAC And TB and cycling the ignition. Maybe got 1 less crank but still long cranks like a turbo racecar. I went to do the crank relearn but it didn't say if it passed or not. I'm used to the factory scanners of it saying when to do it and if it passed. I won't be able to try anything for a few days because I started leaking brake fluid from a fitting on a car cruise on Saturday, so I'll have to get that fixed.

79LS1FOX

iTrader: (11)

I had the same issue(long crank before start) after I put an LSA on mine and changed from E38 to E67 the tune in the E67 had a 2 sec. fuel pump prime, I upped it to 6 sec. and now it starts almost immediately, I think it had something with fuel pressure, because it never reached 58 lbs. on the first key on. Maybe hook a gauge to the fuel rail and see what kind of pressure you get before cranking. Don't know it stopped after a battery change, but we all know how flakey computers are LOL.

mstansbury0704

I haven’t had to do the crank relearn in a long time(over a year) but if you floored it and it only revved to 4K and then you let back off then it should say it passed. I thought it prompted you and displayed the instructions but I don’t remember.
Since the tps and IAC reset seemed to have an effect I HIGHLY suggest you open up the vcm scanner and log your “Idle Air Control Position” and then do as I instructed on forcing the cooling fans to OFF and observing your iac count at idle at 210 degrees.
also, just for a test, maybe you can try to start your car while holding the pedal open a bit. And see if it starts up quicker. If it does then hey hey you’ve found the issue and where to focus. Also, if you think it’s a priming issue, you can force the fuel pump to ON in the vcm special controls and wait a few seconds and then try to crank it up.

if you can, post your tune file and I’ll take a look at some tables and compare them to a stock file to see what they’ve done to your airflow tables if anything. I’d expect to see a little tinkering in the running airflow and iac effective tables. But still, Losing batt power won’t change your tune, but it will reset all of your STIT and LTIT adaptives that may have been what your car was relying on to stay breathing.
At this point without a tune file or a log it’s kind of a shot in the dark what’s going on.

AGAIN I can’t stress enough I am more of a “tooner” but seems Ls1tech is dead in this section so I will try to help you if I can and can send you some tables to try and write to see if that helps.

CutLS

iTrader: (6)

Here is my tune that I saved as I found it.

mstansbury0704

I did have a chance to check it out vs a stock f body file, I’ll have to get a stock vette file off the repository to really see what they’ve done or if a lot of the stuff is just a difference between platforms, I was tinkering with some stuff in it but my laptop battery died lol. What kind of maf setup do you have? I was seeing some crazy high values in the maf curve table. Also, what’s with the huge hole in your VE table? Looks like your idle/cruise is commanding way less fuel than a deep decel, then while pulling a lot of fuel from the main VE tables, they turn around and add it back in at initial startup(if what I’m reading is right and I’m not missing a table), they have it set to startup commanding super rich 13.0 using an open loop factor table. For what it’s worth, I have a much bigger cam, and I idle a little higher but my car STRUGGLES to idle at 13.0 AFR with way more idle timing than you . In fact, I idle best at 15.5ish @ 22 degrees. I think some of your issues may be tune related. I know you’ve been having issues of it stalling at stoplights, etc. there are a few tables I noticed they have set to 0 for your idle state(I think it was in airflow dynamic tab). Bad news is, most ls1s I’ve ever scanned don’t read 0%TPS. They always settle in at around .04%. Even the stock pcm files have this set higher than absolute 0% because of this. I really think you need to check your IAC counts at warm idle. I had to readjust mine even when I had a comp 275hr (222/224 cam I think)
I made a few changes to some tables. When I get my laptop charged back up I’ll try and send you something to try, it probably won’t be right for your car but if it starts up any quicker or slower then might be worth looking into retuning it.
still, you need to do the iac count portion of it and readjust your throttle blade opening to get your iac counts around 40-50 at idle

brownrd

Since this is swapped from a Corvette I assume the TB remained electronic (i.e. not cable). If yes IAC is not relevant. First thing I would check is fuel pressure at the fuel rail when cranking. Long crank is often caused by no prime or a faulty fuel check valve. If you want to spend the time and money to get a wideband there are some improvements that can be made to the tune (overall it looks ok), but if you were happy with it before you may not want to bother.

CutLS

iTrader: (6)

I haven't had issues with stalling until I got it dyno tuned. That only happened when I got the "mail order" tune (brought my PCM to get it initially VATS tuned out at an aftermarket tuning shop). I have an AFR gauge and I do know at cruise I have been running 15-17.5. At times a little higher. Idle it does go up to 15ish. I don't have my AFR gauge right to battery so it turns off and restarts when I start it, so I don't know the right away start up AFR. I'm going to check the fuel pressure to make sure that its good, this weekend. I know a few times a few years ago when I was getting the swap done and having starting issues, I thought I cycled the key a couple times to get to start faster (not sure if fuel related or wake up related)

mstansbury0704

I’m glad someone else chimed in, I wasn’t sure if the vettes were always drive by wire or not. And OP said he did iac learn so I just assumed they must have switched mid production to electric TB or he didn’t want the hassle and used a cable setup
Id Assume all the basic fuel, spark mechanical things were checked. But you know what they say about assuming lol

OP i have had a fuel pump in my old lt1 that would pressure test GOOD at key on and idle and then psi drop off after running for 10 minutes. Lmao THAT got me a on a goose chase for a few days until I just ran the gauge and taped it onto my windshield and went for a drive. Anywho, If you suspect it’s a weak pump or check valve, cycle the pump a few times with the key or force it to “ON” with the vcm controls and then try to start it, essentially priming the rails. If it sings up I’d suspect a mechanical issue more than tuning related.

Just at glance I could tell you were probably lean at cruise.My car does the same thing, if I set it up to idle nice where I want it in the VE tables on open loop it will hit those same load cells on a drive and go stupid lean. I prefer to cruise at 14.7 and my idle is whatever, I’d rather be rich at idle than lean cruise. ..I run closed loop and full exhaust so I go rich as hell anyway at idle so I don’t worry about it much..

most people tend to use a open/close loop hybrid and use the PE table to remove fuel from idle to achieve a good idle and then not lean out when driving in those low load cells
Also, on startup AFR I’m talking about the OPEN LOOP/ Base tab they are commanding pretty rich, my table is set to 1.0 across the board. I found it would flood my car out when warm started and it would stumble until it switched to closed loop and decayed out so I just eliminated it entirely. I’m sure there is a proper way to tune this but for me, I just eliminated that extra fuel adder and no issues at all
also, you said the stalling was eliminated after the dyno tune? That’s good. I was going to suggest building a stall saver into the spark advance table to combat this. Before I got all those throttle follower tables nailed down I had to have this, if my car drops to 600rpm it throws 30 degrees back at it and picks itself up

CutLS

iTrader: (6)

With the Open/Closed loop, normally on a regular vehicle those are going to monitor the O2 sensors after awhile. Now since I have long tube headers and no Converters installed, how effective are those going to be? They should be ok since they are just monitoring the front O2 sensors, right? I've always wondered that since its Cat-less.
Yeah the stalling and the extended crank was resolved after that dyno tune 6 years ago. I called them the other day to see if they still have the tune saved on their computer, but the tuner was out. My fuel pump is not a quiet one so I can definitely hear it running. I just don't know if its not priming enough. I do know I did change my Corvette regulator style fuel filter a few years back but I think the issue was still happening before that, so I can't say for certain that I'm not bleeding pressure back from that.

mstansbury0704

Because of the swap and idk how you’ve wired you’re fuel pump idk if this will apply. But I’d try hooking up the laptop and key on, start your log up and go into the special controls and under fuel system command fuel pump to ON and let it sit for about 10 seconds, then try to start it.
Also, the way I was describing, it’s popular that people would edit their PE tables in the 8-1200 tab to be in power enrichment at 0% throttle and then just command something like .95 or whatever to COMMAND a 15.X ratio. That way when idling at 0% throttle it’s commanding to be a little extra lean and ignore the 02 sensors. Then once out of 1200rpm all is back to normal. it was dubbed close loop hybrid and most people with lots of overlap cams went this route. Between the overlap inefficiency of the cam combined with the tendency of longtube headers reporting false lean at idle the car would be maxing out STFT regardless of the huge hole you’d try to put in your VE table and the idle would burn your eyes to tears. In power enrichment it would just idle at whatever AFR you’d want and it would ignore the O2 sensor and disable the fuel trimmings.
to your question, yes your longtubes will effect your accuracy of the narrowbands at idle

brownrd

Start is always in open loop, then depending on ECT closed loop is enabled from as little as 20s. Front O2 sensors control STFT, rear O2's prove that at CAT is in place but do not impact fueling. So your front O2's installed on LT's do work - however, they are typically further from the engine than the stock location which impacts their behavior, especially at low flow (i.e. idle). This can be managed through the Idle Proportional Fueling (increase fueling change to initiate O2 oscillation, decrease gain to manage surging) and Integral Delay (add 25% from stock to represent the extra distance) tables but is a bit tricky to get perfect, so the hack is to go PE at Idle and ignore the O2's. Post back your findings re: fuel pressure when cranking.

CutLS

iTrader: (6)

I haven't hook-uped my scanner yet but I threw my digital fuel pressure gauge I'm borrowing from work. It doesn't hold fuel pressure. The fuel pressure goes to about 30 on key up and then drops don't to nothing. Once running it stays around 49-50psi. I timed my fuel pump prime and it's just over 2 seconds long. If I key it on, and let it prime and stop and then try and start, it will crank as the fuel pressure rises until it gets enough to start. I'll go in and try to change the fuel prime timer and see if that fixes some. I know you guys have said looking at my tune, there is work that needs to be done and I don't doubt it now that I've got more sensors monitoring it.

brownrd

Progress! Goal is solid 58 psi running. Sounds like new check valve and pump are in your future.

CutLS

iTrader: (6)

https://www.dropbox.com/s/ny9tujp6yn...75420.mp4?dl=0 here's the video of my fuel pressure.