LTLHOMER

iTrader: (10)

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)...260 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/s...x_OnlyPass.csv
http://detroitstreetcars.com/stuff/s...streetpass.csv
http://detroitstreetcars.com/stuff/s...ix_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/s..._Replay000.csv
http://detroitstreetcars.com/stuff/s..._Replay001.csv
http://detroitstreetcars.com/stuff/s..._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!

So far I have checked, replaced or whatever:
1. coilpacks
2. cam position sensor
3. crank position sensor
4. plugs (different kinds and different gaps, etc)
5. tried new bs3 box

We put an ossicoscope (sp?) on all the major sensors and had Mr. Meaney on the phone and everything seemed to check out fine. Cam and crank signals were good but the car still did the same thing. We tried sticking another calibration in there just in case mine was somehow corrupted and that was no luck either. We even ran the car naturally aspirated and it still did the same thing right at 6700 rpm and backfired through the intake.

Then we thought it had to be valvesprings...well I pulled four off last night and had them checked by my engine builder and they were all right on spec where they should be. I am going to check the rest but I am thinking they are all fine as well.

Any ideas???

GoldRust

iTrader: (2)

Trust me when I say this because I went through this on Wormboys car Through the coil pacs in the dumpster and put a distributer on it and run a msd 7 series ingnition box. That is exactly what his car was doing but it was blowing head gaskets when it would break up.

LTLHOMER

iTrader: (10)

I'm assuming you are running a front drive distributor then?

How come a lot of other people have run the stock-style ignition setup without much trouble? I don't really want to just throw parts at it, but instead try to understand what's going on and fix whatever needs to be fixed.

Can you elaborate?

Phate

iTrader: (2)

That's pretty strange. I would assume that if it was a spark problem then it wouldn't have reared its head when the car was N/A.

What plugs were in the car when you were running it N/A, still the AR plugs?

I have seen something similar to this (I haven't looked at the logs) before with another TT car. The problem there happened to be a poorly designed intake that caused reversion back into the turbos...but again, you wouldn't have seen this N/A.

Also, there are two types of truck coils...ones with the heat sinks and the ones without. You want the ones without them, are those the ones that you have? Also, have you adjusted the dwell on the coils or just swapped them out? Kurt or Rich Gala should be able to guide you through it.

LTLHOMER

iTrader: (10)

I've had a guy familiar with the coils play with the dwell time and that had no effect...

I am running the mitsubishi truck coilpacks, which are the ones people said were the better ones.

Hoping to get the rest of the springs checked this week and then either reinstall them and try a few other things or swap them to something different.

Phate

iTrader: (2)

PSJ had a problem that was something like that where the reluctor wheel on the crank was wobbling and causing an intermitent loss of signal. I believe that it was RPM relates as well. I would assume that you would have seen this in logs or when you were looking at the wave forms though.

Maybe PM PSJ about how they discovered the problem...

Pro Stock John

iTrader: (34)

...But my engine would shut off because the crank sensor would no longer 'see' the reluctor. Suddenly there were no teeth for it to reference.

So can you shift the car at 6500 and make a clean pass? What springs are you running? What is the car running?

MIGHTYMOUSE

iTrader: (59)

ill check the logs see if i can have an opinion

Pro Stock John

iTrader: (34)

Sean should at least let folks know if the car performs up to 6500 since that helps eliminate some possible culprits.

LTLHOMER

iTrader: (10)

Runs great up to 6500 or so...have even made street passes shifting at 6500 and it ran pretty good...obviously not optimum since that's just getting into the powerband but she moved out pretty well. See the 'streetpass.csv' for reference. It's from the Alabama trip logs.

Dunno what the springs are but they are 1.550" OD, double spring with dampener, and are 260 seat and 730 open at 1.880" install height. Got at least 0.100" before coil bind as well.

InconFormula

iTrader: (7)

Throwing the coil packs out for a distributor is nuts, we have 2 cars in the 8's with truck coils and bs3 and have absolutley no issues. You have another issue somewhere unfortunatley I can't think of what it might be..

MIGHTYMOUSE

iTrader: (59)

did you verify your timing (crank offset) my number was 364 and yours is 14 degrees lower. that is a big timing difference when you are only talking 20* total advance

also if the car is going way rich on you why dont you switchto closed loop and let the computer pull fuel for you? at least temporarily

LTLHOMER

iTrader: (10)

The car doesn't go rich until the boost starts going up (perhaps reading pressure from the exhaust being in the intake manifold or something?)

Well, we checked the timing with the value set at 350 as it came from w2w, and we set all the timing values to 30 degrees as per Meaney's suggestion. We checked it at 2k, 3k, 4k, and 5k with a light and it was off a steady 6 degrees (I recently replaced the crank/cam sensors so that probably has some to do with the difference). So we changed the value to 344 and the timing was dead nuts on all the way up. I will double-check that once I get the valve springs back on it just to be certain it's where it should be but I am pretty confident that much is right now after checking it at a bunch of different rpm's with the timing light.

What procedure did you use to find the 364 number? I tried doing it like the bs3 manual says but when the cam sensor went to 0 volts, the crank sensor was not at 12 volts like it should have been according to the directions. And I called John and he said to skip that and just check it with a light since the overall point of the whole thing is to get the called timing in the ecu the same as the actual timing in the motor. Or am I missing something?

lcvette

iTrader: (3)

what cam timing set are you using? I once installed a cam heads up late at night with poor lighting and missed by a tooth.. I lost about 6-700 rpm.. the hole shot was phenominal but it fell off up top like hitting a brick wall.. I know it is one of those things you hate thinking about checking, but it is possible if your using an aftermarket timing set that it is installed a tooth advanced or retarded.. or the crank sprocket if it has various timing keyways could be installed one way or the other. this is just something to throw out after first glance at this post so don't bash me... I will rack my brain a little and see if I can conjure up any other ideas.. these things are generally simple smack yourself in the side of the head resolutions by the way... its just determining what they are that is such a pain in the ***.

do you have an egt sensor/gauge to see whats going on in the primaries.. that could help diagnose whats happening during the comnbustion event..

Chris

LTLHOMER

iTrader: (10)

I have EGT's in each primary but don't have a gauge to hook them up to...but I think I can get a simple one that reads one at a time for a few hundred...do you know of any that can read 8 at a time all K-type thermocouples. I thought I saw one for around 800 before...might be worth it at this point.

About the cam...I'm not sure what timing set I'm running because that was done by the engine builder, but I will check my build sheet when I get home. I doubt that is the case because he's super meticulous but you never know. Now if I put the cam in myself, that'd be one of the first things I would look at lol cuz I will be the first to admit that I would be one to do something like you described.

lcvette

iTrader: (3)

I agree... most engine builders when assembling an engine of this caliber will degree in the camshaft.. I would see what his notes were on this and then scrutinize your cam card to see what advance was ground into the camshaft.. it may lead nowhere, but at least you will have crossed another item of your check list.. cam timing can be a fickle thing.. and even if he was meticulous.. the cam manufacturer may have not ground the cam to spec.. I have received a few cams from cam motion that were off a little when checked on a cam doctor from my cam card.. it was a simple mistake in shipping I suppose.. but ya never know.

as for an 8 at once egt setup.... never had one of those myself, but if you have plugs and can switch it out.. it will certainly identify if something is going wrong in one or two cylinders.

what is your valve lash supposed to be? I see you are running a solid roller.. with an engine like that I would probably run a little looser lash setting due to more heat carrying through the valve.. it could be chewing up your lash setting in the upper revs from excessive heat in the chamber and hanging the valves just ever so slightly causing some reversion perhaps.. just something else to check. they may clack a little bit more while cold, but if they need the extra space when at peak engine output....... let em have it. on a solid roller it would not be quite as drastically noticeable as with a hydraulic pumping up.. you have enough spring pressure and at that rev range, things are happening VERY fast.. add in pressure in the intake tract combatting some minor reversion and it could possibly appear as a significant power drop with little other symptom. just something else to check that wouldn't require emptying you savings.. these little things are what I go for first to be sure all is right before I start replacing the money parts.. may take some wrench time, and I know for alot of us that comes as a premium, but I would still take the time to check it since you have the springs coming off anyways. trying it a little loose can't hut anything.. maybe a few thousands to see if it makes a difference.. if it does but not cures it correctly 100%.. you have a direction to play with..

Chris

LTLHOMER

iTrader: (10)

We tried running it a little looser than what Harlan ran it when he had it, and still had the same results. They ran it at 0.020 hot, we set it to the cam motion spec of 0.025 hot and we could definitly hear the valvetrain more but it still did the same thing. If all the springs check out, I will try a few thou looser maybe 0.027-0.028 and see if that makes a difference.

lcvette

iTrader: (3)

good... well at least you gave it a go.. and have that crossed off.. can you get a degree wheel on the front of the motor... you could check the crank reference angle to the valve events to be sure all is where it needs to be fairly easily with a dial indicator especially with a solid cam which should read accurately with no hydraulic lifter slop.. I know it seems like I am stuck on the cam thing, but if all else is going well with the tune in BS3, (I use DFI Gen 7, so I can't check your logs to see what you posted) which from your write up it sounded like all was well until it tried to fix an existing engine high rpm problem.. I would try and systematically go through the mechanics... and rpm and camshafts go hand in hand so until I had that completely eliminated I wouldn't go anywhere else on it. does BS3 count misfires? I know it is the best on the market but am not familiar with its functionality or benefits.. maybe see if you can determine a misfire uptop? I also am not terribly familiar with the LSx platform but is there an airgap for the cam/crank pickup to reluctor wheel?

Chris

LTLHOMER

iTrader: (10)

You can download the bigcomm software right off bs3's website which is http://www.bigstuff3.com Go to downloads and it's right there just a simple program. Then download all the tune files and log files that I posted and when you open the bigcomm software, it will ask you to load a tune file which you can choose based on which logs you want to view, and then go to the logging menu and select 'view log from file' and pick whichever ones you want to see. It's pretty neat looking at all the different parameters and it allows you to toggle on and off any of them to make it look less messy.

Or just click here to download the software:
http://www.bigstuff3.com/BigComm.zip

I will try the new springs and if it stays the same, I'll probably just pull the motor and go over everything with a fine-tooth comb. Keep the ideas coming though they are definitly helpful and let me know if you need help figuring out how to view the big stuff files.

LTLHOMER

iTrader: (10)

bs3 uses the stock cam and crank sensors so the air gap is fixed...I can't modify that at all.