Twin-turbo ls1 problems NEED HELP (bs3 logs inside)

[LTLHOMER]

I'm working on getting the logs up but I'll try to describe the problem the best I can...

At around 6700 rpm's (never fail), the engine starts decreasing revs and doing all kind of funky things going up and down between 6200 and 6700 (won't go over 6700 period) and then meanwhile the boost starts sky-rocketing even though the car is falling on its face. It then dumps a bunch of fuel in since it sees more boost and the car goes real fat and falls on its face even more and the run is over from there on. I have tried upgrading my stock LS1 coilpacks to the truck ones and the problem still exists...it happens whether I'm doing a burnout, or hammering it in 1st, 2nd, or high gear and it's always right around 6700 rpm's when the problems begin.

Here's the setup
347 inch LS1 with twin t66's
Decent sized solid roller (low 250's at 0.050 and just under .700" lift)...250 seat 730 open when put on at beginning of season with ported stock ls1 castings
a2w intercooler
th400 with chance converter

I'm running AR3910's for spark plugs.

You need the bigcomm software to view the logs found here:
http://detroitstreetcars.com/stuff/sean/BigComm.zip

And here are the logs from Alabama with the corresponding tune (.big file is tune):
http://detroitstreetcars.com/stuff/sean/w2w.big
http://detroitstreetcars.com/stuff/sean/Phenix_OnlyPass.csv
http://detroitstreetcars.com/stuff/sean/Phenix_streetpass.csv
http://detroitstreetcars.com/stuff/sean/Phenix_burnout.csv

Video of the same burnout: http://little2v.com/sean/MOL00B.wmv

And here is a few weeks later at Milan (logs + new tune as well):
http://detroitstreetcars.com/stuff/sean/w2w_new.big
http://detroitstreetcars.com/stuff/sean/Camaro_TT_Milan_Replay000.csv
http://detroitstreetcars.com/stuff/sean/Camaro_TT_Milan_Replay001.csv
http://detroitstreetcars.com/stuff/sean/Camaro_TT_Milan_Replay002.csv

Here's the main folder with everything:
http://detroitstreetcars.com/stuff/sean/

Misc videos:
http://little2v.com/sean/MOL006.wmv
http://little2v.com/sean/MOL002.wmv

Thanks for your time feel free to email me at LTLHOMER@aol.com or post on here.

I am about sick of the damn thing!

My list of things to check in order are:
1. Change to hotter plug
2. Unhook boost controller and run on the gates (check to make sure gates are functioning properly)
3. Pull a few valve springs and check pressures
4. Send bs3 box out to make sure it's a-ok
5. Check crank position sensor

Past that I'm not sure what to do...has anyone experienced a similar problem?

I posted this here and on turbomustangs so I can get as many ideas as possible and maybe run into that one person that has had this exact problem too...

Thanks in advance!

[PTE Pete]

Sounds like a cool car.I will start looking at your program & logs.Have you had any progress since you posted?

[LTLHOMER]

Checked the wastegates, bov's, upgraded coilpacks, took off the boost controller, and changed to a hotter plug. Same exact problem.

Mr. Meaney is sending me a new bs3 box to try since I had problems with mine before and it was actually dynotuned using a different one so I don't think the car ever ran right with this particular box. Hopefully that will fix the issue but if not I'll have to start pulling valvesprings and see if that could be the problem.

Thanks for taking time to check out the logs.

[LTLHOMER]

Tried the new box and no improvement...trying a new crank position sensor tomorrow had to order it from ad. auto.

[Tom McDunnah]

What are the spark plugs gapped at LT?

Almost sounds like the ignition spark is getting blown out

[Slow 69 SS]

Have you checked your valve springs for coil bind yet, or to see if the springs pressures are too low?

[LTLHOMER]

What are the spark plugs gapped at LT?

Almost sounds like the ignition spark is getting blown out

I have tried both NGK tr6's at 0.035" (same plugs the previous owner of the kit with almost identical motor ran) as well as Autolite AR3910's (edge spark so they don't really have an adjustable gap) and the problem has been the same.

Is there a way I can tighten up the gap on the edge spark autolites?

Here's a pic of a plug similar to the ar 3910's:
http://www.sparkplugs.com/glossaryImages/42.jpg

[LTLHOMER]

Have you checked your valve springs for coil bind yet, or to see if the springs pressures are too low?

I had the springs setup when the motor was built and they were all tested and what not to make sure they were up to par. I guess they could have gone bad in the meantime so if the other couple ignition things don't fix it, I'll have to start looking at the valvesprings.

I am putting a new crank position sensor in the car today since I've seen a few people with similar problems w/ the ls1 stuff and it seemed to be the fix for most.

I'll report back later today.

Thanks for all the help and suggestions guys.

[Six_Shooter]

Wow your starter is really getting a work out.

I haven't seen any mention of the electrical in your car, besides the fact that you have a BS3 box, which I don't have the software to view your logs. Anyway, to my point, where are you referncing ground? Is the PCM ground to the engine? Is there an engine ground strap? I've seen many cars act the same as yours with poor electrical connections, or that one connection that when the car is staic will lose contact when you get to a certain RPM or speed, or twisting the car in a certain way.

Also one thing that comes to mind is valve float, or more the intake tract gets backed up so much, with the boost pressure you're creating and at a certain RPM (range) you can stuff no more air into the engine and causes the boost to spike, which causes all the symptoms you describe.

Also do you have pics of the installation? the tubing, the routing of everything, there might be somthing else causing this, in that realm.

[Six_Shooter]

This is your car, correct?

http://detroitstreetcars.com/images/zoom/XUNHMW/viewsize/ltlhomermotor.jpg

BTW, looks nice from what I can see, the layout looks good.

[Tom McDunnah]

LT

That picture you posted looks like a power tip plug,I wouldn't run that type of spark plug,instead I'd be putting the "AR" series plugs back in the engine and gap the plugs to around .028 to .030
You may see some improvements by just tightening up the gap some.

I guess I am not too farmiliar with a LS1 igintion,,will that ign. hold up under cylinder pressure like a MSD ignition?? Do they even make an aftermarket ignition for that style engine??
I know if it were me and trying to run a twin turbo set up,I'd certainly have a MSD ignition.
Some times "stock" ignitions won't handle the cylinder pressure and cause problems like you are seeing. Cylinder spark blow out at certain RPM's and limitations as you are seeing.

I have a question,LT, What type of boost numbers are you seeing when this problem arrives?

Cylinder pressure does some funny things to ignitions

On another note,a torque converter will some times limit and engines RPM to if there is issues with the sprag being broke.
Just some options to consider,,I may be all wrong,,but I am trying to help

Tom

[Tom McDunnah]

Six Shooter
You have some very valid points to consider,
The grounds,seen this many times the grounds doing funny things,like back feeding etc.

On some aftermarket ign. nitrous and other electrical components,I have run separate grounds directly to the battery
Also I have kept my ignition grounds separate from other components

Tom

[Slow 69 SS]

MSD Does make an ignition kit for the LS1.

http://www.msdignition.com/2006/06-6.htm

[LTLHOMER]

That is just the coilpacks...the same coilpacks I'm using are used are cars making almost 2000 hp. I upgraded from the stock ones and the problem still persisted without any change.

The cam, compression, intake, cubic inch, turbo kit, etc is the exact same as the previous owner that had success with it, so I don't think it's some kinda cam issue where the cam is just not going to work with the engine or anything like that.

The boost can be anywhere between 6 and 15 when the problems happens, and it starts going up as a result of whatever the problem is, instead of it being the problem itself.

I am running the AR series plugs, but that's what they look like is all I was trying to say. AR3910's is the p/n. They are like 5 steps colder than stock and seemed to work fine on the dyno up to 7k a few times but hasn't worked since.

BS3 grounds are right to the battery. I have the coilpacks ground right to the cylinder heads as I was told, and then I have a ground strap running from the heads back to the chassis as well (it's a motorplate car so it probably grounds through that anyways but better to be safe than sorry.

And yes that is a picture of my car.

It's raining now so I can't test out the new crank position sensor, but I don't know what else to test as far as electrical goes?

Oh and if you want to view the logs, you can download the software free off of http://www.bigstuff3.com Go to downloads and you'll see the bigcomm software. Then all you have to do is open the software, load any tune file, and then go to view log from file and check it out.

I will report back if it dries up and I can try the new cps.

[Monty Mikho]

LT, a few questions. I am not familiar with the Big Stuff 3 stuff and have used FAST for my nitrous motors. Anyway.. A few things I have questions about..

#1 is the trigger set up so the sensor is lined up with the magnet at 50*'s?
#2 have you ever taken baseline passes in closed loop to see what the motor is doing?
#3 are you running an IAC on the throttle body?
#4 Im assuming you are using 80 lb/hr injectors? I tried converting the 900 cc/min and I came up with 79.4 lbs/hr.. which could be wrong with my conversion
#5 In the Operation Configuration: What is injector flowrate A and Injector flowrate B? Is this deactivated? I could not find it..
#6 In the Hardware Configurations: Is says "Second bank injector switch point" and it is set to 50%? Is this trying to go to the second set of injectors "Injector Flowrate B" which is setup for 65535 cc/min which would mean you have a 5808.69 lbs/hr injector?
#7 is that surly a GM style TPS in your throttle body..

Again excuse the ignorance.. Im trying to learn myself..

[LTLHOMER]

LT, a few questions. I am not familiar with the Big Stuff 3 stuff and have used FAST for my nitrous motors. Anyway.. A few things I have questions about..

#1 is the trigger set up so the sensor is lined up with the magnet at 50*'s?
#2 have you ever taken baseline passes in closed loop to see what the motor is doing?
#3 are you running an IAC on the throttle body?
#4 Im assuming you are using 80 lb/hr injectors? I tried converting the 900 cc/min and I came up with 79.4 lbs/hr.. which could be wrong with my conversion
#5 In the Operation Configuration: What is injector flowrate A and Injector flowrate B? Is this deactivated? I could not find it..
#6 In the Hardware Configurations: Is says "Second bank injector switch point" and it is set to 50%? Is this trying to go to the second set of injectors "Injector Flowrate B" which is setup for 65535 cc/min which would mean you have a 5808.69 lbs/hr injector?
#7 is that surly a GM style TPS in your throttle body..

Again excuse the ignorance.. Im trying to learn myself..

1. Stock cam/crank sensors. bs3 is setup to use the stock ls1 stuff which are located in the block itself (swapping the crank sensor tonight)
2. no baseline passes in closed loop...not sure even what that means? Care to elaborate I'm new with this stuff myself.
3. Yep running an IAC. Ford style accufab tb with Ford to GM iac adapter plate and GM IAC motor.
4. 96 lbers. Not sure why they programmed them for 900 cc especially since I'm running them at a higher than rated pressure (55 base plus 1/1 with boost), but all that was done by w2w and since it's a constant, it can just be programmed out when you're doing the fuel maps and what not.
5. Injector flowrate A would be for the ones I'm using...B would be if I had a box that supported 16 injectors (2 sets in other words). Dont' have that so any commands by that are just ignored.
6. It might do that if I had the drivers and what not for a second set, but it doesn't have an effect on the main set...the a/f and injector pulsewidths seem to be on par for what the engine is doing...
7. yeh it's definitly GM style...the tps seems to be right and for the logs, it was mostly at 100% so I don't think it was dropping out or anything like that and messing things up.

No questions are bad questions...I'm as stumped as the next guy and I am thinking about stuff all day...

[Monty Mikho]

#1 The crank angle shows 50*'s.. This means the maganet is picking up at 50* BTDC to give the computer enough time to calculate the real output timing.

#2 Closed loops uses the O2 sensor to correct with. It will use your target A/F ratios setup in your A/F table and correct for the target. On the FAST units it showed the amount of correction so you could correct it on your base fuel map. You can set Max and Min parameters on how much it is allowed to correct... Then after the correction factor is less than .2-.3 the target A/F ratio you can put the computer back into open loop (which doesn't use the O2 to correct with0

#3 Just wanted to make sure since the map was set up for one

#4 You may want to talk to someone about this. My calculations (which could be wrong) came out with 80# injectors with .699 weight fuel.. I ran 86# injectors with 88 PSI of fuel and set the parameter to let the FAST unit think it had 114# injectors in there..

#5 .. OK cool

#6 Cool I didn't know that

#7 Perfect..

[Jim Monson]

When/if you try closed loop operation I would suggest turning down the amount of fuel you let the computer remove. Right now yor negative correction is at about -10%. If you loose a cylider (leave a plug wire off, etc.) you'll have unburnt fuel in the exhaust. The O2 sensor will see a rich contition and pull fuel out of the motor. Leaning the motor out by -10% scares me.

[LTLHOMER]

When/if you try closed loop operation I would suggest turning down the amount of fuel you let the computer remove. Right now yor negative correction is at about -10%. If you loose a cylider (leave a plug wire off, etc.) you'll have unburnt fuel in the exhaust. The O2 sensor will see a rich contition and pull fuel out of the motor. Leaning the motor out by -10% scares me.

How do I even make it so the car will run in closed loop? Just set the closed loop parameters so that it's no longer out of the 'closed loop' range and would therefore simply try to meet the target a/f? And then make sure it can't correctly negatively more than say, 5%?

[LTLHOMER]

#1 The crank angle shows 50*'s.. This means the maganet is picking up at 50* BTDC to give the computer enough time to calculate the real output timing.

Crank trigger parts are not used with the LS1 box...it uses the box just to the right of that, labeled COP. I had that setup when it was getting tuned, which is a simple procedure that is similar to if I was running a regular crank trigger setup.

[Jim Monson]

I'm making this stuff up as I go along so bear with me. Your BS3 file is the first time I have ever seen the stuff.

Looks like you want to go to:

1) Configuration
2) Hardware Configuration
3) Change Control Feedback to Closed Loop

Then go to:

1)Air fuel ratio
2) Negative O2 Correction %
3) Change those numbers to -5%

Then go to:

1) Air Fuel Ratio
2) AFR Parameters
3) Make sure the on rpm is above your launch rpm. You don't want the O2 trying to correct while you're on the rev limiter at launch.
4) Looks like you want the off rpm about 100rpm below the on rpm

If it blows up, blame it on Monty!

[LTLHOMER]

I'm making this stuff up as I go along so bear with me. Your BS3 file is the first time I have ever seen the stuff.

Looks like you want to go to:

1) Configuration
2) Hardware Configuration
3) Change Control Feedback to Closed Loop

Then go to:

1)Air fuel ratio
2) Negative O2 Correction %
3) Change those numbers to -5%

Then go to:

1) Air Fuel Ratio
2) AFR Parameters
3) Make sure the on rpm is above your launch rpm. You don't want the O2 trying to correct while you're on the rev limiter at launch.
4) Looks like you want the off rpm about 100rpm below the on rpm

If it blows up, blame it on Monty!

lol sounds like a plan! The blaming on monty part that is.

I just swapped the crank sensor so I'll try it out tomorrow morning and if it's still fugged up, I'll try the closed loop stuff. My neighbors love my car! lol!

[Monty Mikho]

LT, before you go out make sure to read the help manual that came with the BS3. I was reading it last night and I believe you will see you have a few errors. It talks about the LS1 crank angle and closed loop. It recommends you take your baselines on closed loop if you are using an O2 sensor..

[LTLHOMER]

LT, before you go out make sure to read the help manual that came with the BS3. I was reading it last night and I believe you will see you have a few errors. It talks about the LS1 crank angle and closed loop. It recommends you take your baselines on closed loop if you are using an O2 sensor..

I verified the TDC mark last night so I'm going to check the timing at 5k rpm's and 30 deg of timing (as per john meaney's suggestion) and see if I'm actually getting the timing I'm calling for in the program. That should tell me if the sensors are reading right and what not.

The tune itself I think is pretty close which was done up at w2w powertrain.

[Monty Mikho]

I verified the TDC mark last night so I'm going to check the timing at 5k rpm's and 30 deg of timing (as per john meaney's suggestion) and see if I'm actually getting the timing I'm calling for in the program. That should tell me if the sensors are reading right and what not.

The tune itself I think is pretty close which was done up at w2w powertrain.

Cool let us know what you find.. That way I can save the headaches on my car.. If the guy I sold it to ever sells it back :-D

[LTLHOMER]

Cool let us know what you find.. That way I can save the headaches on my car.. If the guy I sold it to ever sells it back :-D

Should know something by Friday night...no time lately with finals coming up for LTU, work, and my own small business thing to work on the car except on weekends...

[LTLHOMER]

Looks like valvesprings because at 6700 it starts firing through the intake and actually made the turbos push air out...going to swap some new ones on and report back.

[LTLHOMER]

Looks like valvesprings because at 6700 it starts firing through the intake and actually made the turbos push air out...going to swap some new ones on and report back.

Pulled 2 intake and 2 exhaust springs and they are spot on...260-270 closed and 725-730 open for all four. If all 16 springs check out, what am I supposed to do next???

[redvictor]

Pulled 2 intake and 2 exhaust springs and they are spot on...260-270 closed and 725-730 open for all four. If all 16 springs check out, what am I supposed to do next???
Have you checked how much turbo back pressure you have?

[LTLHOMER]

Have you checked how much turbo back pressure you have?

Can't say I have...but the problem persisted even when we ran it n/a.

[Monty Mikho]

Pulled 2 intake and 2 exhaust springs and they are spot on...260-270 closed and 725-730 open for all four. If all 16 springs check out, what am I supposed to do next???

Put the car in closed loop and see what it tells ya...:cool: Make sure to data log the run.. or do you have any past datalogs?

[LTLHOMER]

Put the car in closed loop and see what it tells ya...:cool: Make sure to data log the run.. or do you have any past datalogs?

I've never run the car in closed loop...but once I get the springs back on it, I'll try it out, log it, and post it up here. Just seems more like a mechanical/electrical problem moreso than a tuneup problem but what do I know I can't fix it either...

Thanks for popping out ideas...every little bit helps narrow it down.

[Jim Monson]

Might be a lean pop?

[LTLHOMER]

Might be a lean pop?

Yeh if the springs don't work out, I'm going to try moving the wideband to the opposite bank and seeing if that reads in line with the other side...and if not, I have a set of 160 lbers I can swap in if I think one of my current 96's is clogged or leaking or something along those lines.

Pulled another 6 springs today and will get them checked tomorrow. What a PITA changing them with the motor in the car...would have got the other ones but my tool broke. :(

[Jim Monson]

What does the O2 read when it pops?

[LTLHOMER]

11.5 - 11.7 for about a second after it happens, and then the boost starts going up so it adds fuel and makes it go down to mid to low 10's.

[Jim Monson]

That's not lean enough to do the fire cracker/popcorn fart pop.

[LTLHOMER]

That's not lean enough to do the fire cracker/popcorn fart pop.

It's so weird I will get it on video next time and post...it will rev perfectly fine until it gets to that rpm, and then make a loud boom and send a ball of fire out the intake (if turbos aren't hooked up) and then I lift off the gas and it immediately goes down to like 200-300 rpm's and then just slowly dies down within 4=5 seconds or so.

[LTLHOMER]

Want to thank John Meaney for taking time to diagnose the car and figure out what needs to be done...he is the man!

Can't wait to get this thing out there and start pounding on it!!! Thanks John!!!