MEAN GTO

iTrader: (1)

Hi everyone! I haven't been active on the forums much over the past couple of years due to blowing the motor in my turbo GTO for the second time (back to back) after going the turbo route.

I used to have a Magnacharger, and made 508 RWHP with many passes at the track. The car was tuned by professional tuner and was running 10.9's consistantly at the drag strip. I wanted more power and had a custom twin turbo setup fabricated, had the car retuned by the same tuner, and started having problems. Immediately after getting the car back, my new, built 4L60E transmission wouldn't upshift at WOT. The tuner couldn't figure it out, and this was not an issue with the previous tune. Several weeks after the tune I was trying to narrow down why the transmission wasn't upshifting, and blew the motor during a WOT run. I tored the engine down and it was found that all 4 pistons on bank 1 had broken ring lands.

I put very low-mileage stock pistons and rings back in the engine, and before I started driving it hard at all I had someone else look at my tune. We discovered that the tranmission upshift RPM was set to 6500, and the RPM limit was also set to 6500. We lowered the upshift RPM several hundred increments and this resolved the issue.

I then took the car to the drag strip on a hot day and it performed very poorly. It had dyno'd at 639 RWHP with the new tune on the same dyno as it was previously tuned on with the Mangacharger. So 639 RWHP with the twin turbo setup, compared to the 508 RWHP it previously made when it had a Magnacharger on it, on the same dyno. With 130 more RWHP the car wouldn't budge out of 11.2's in the 1/4 mile. It just didn't have the power in that weather for some reason to overcome the ET's that I was doing with my old supercharger setup in cooler weather.

A week after the ugly day at the drag strip then engine blew during another WOT highway run. After speaking with other people familiar with tuning, I think we have pin-pointed the problem, but without pointing the issue out I would to see if you guys wouldn't mind looking at my tune file and dyno chart to see if you see what may have caused this engine to blow both times.

Please provide any feedback you can, whether you're a beginner, amateur, or pro.... I would really appreciate your input so I can have a "case" to present to the tuner if in-fact he should be responsible for the bad parameters that were created in the tuning process.

The car is a LS2 with a custom blower cam, twin 62mm turbos, and upgraded valvetrain. It does not have catalytic converters, in case that question comes up. Thank you very much in advance!

HPT file: http://www.tinyuploads.com/download/file/u82Y9t

(I couldn't simply attached the HPT file because mine is 1.42MB and the maximum upload size on here is 1.24MB).

NicD

iTrader: (7)

The last thing I would be asking for online would be any feedback from beginners and amateurs and arm chair tuners that like to just read the internet.

So engine details? Boost level? Octane gas?

salemetro

iTrader: (5)

Running fat most of the way through the pull....then 6200rpms hits BAD times. Look at your afrs....

Tuner probably killed your knock retard as well....

MEAN GTO

iTrader: (1)

Thanks for the response! And good point Nic, but yeah I was assuming if amateurs will catch what has been pointed out to my by a few other people. Just looking for everyone's opinions, though I think it's safe to say that the issue has already been determined. I just need to hear several more people point at the same thing before I present the issue to the tuner.

Boost level was just 8 PSI, on 93 Octane gas from Shell. Custom blower cam on an otherwise stock LS2 block. Looking forward to getting some input from you Nic, thanks again.

MEAN GTO

iTrader: (1)

Thank you for the response salemetro. As far as the AFR at 6200 RPM, the tuner had originally pointed that out to me and "claimed" that the reason for the lean condition right there was because that's where he backed out of the throttle on that dyno run. What do you think?

NicD

iTrader: (7)

He clearly let out at that point, look at the reported power from the dyno.
His knock sensors are turned down but not off.


So what did people point out? Just because you have three people that point something out doesn't mean it's a fact.

However 22 degrees of timing at 8 psi with a stock LS2 long block on 93 octane sounds way high. I would expect it to be more around the mid teens area if that up top but this is all just speculation from my chair posting on the internet. Hell down in the lower RPM range timing would have to be lower still.

edcmat-l1

iTrader: (10)

MAF table is bone stock. That's scary.

Too much timing for a boosted LS2.

PE is too lean until way up top, and is still a little lean up there.

Knock sensor sensitivity is left stock, but the max knock retard has been cut in half, so if it DOES knock, it will only pull 4 degrees,instead of up to 8 degrees.

Knock retard recovery is too high.

MEAN GTO

iTrader: (1)

Hey again Nic! I don't want to point out yet just yet what the other people have noticed-- I'm hoping to see multiple people on here to point out what the several other people not on this forum already have.

So from what you noticed, do you think that the 22 degrees of timing could have/would have blown the motor? Do you think that much timing is also maybe what caused the poor performance at the track on the hot day that I tried running it? Thanks again!

MEAN GTO

iTrader: (1)

Thank you for your input edcmat! Sorry for the ignorance, but what is "PE"? Would that, and/or the knock retard issue(s) that you mentioned cause the motor to blow (blown ring lands) at WOT like in my situation?

I'm honestly ignorant when it comes to tuning, so like I said, I am just trying to gather information to determine if the tune is at fault for the engine blowing twice in a row.

By the way, the engine only had 22k miles the first time it blew, and 23k miles then second time it blew. Never had ANY issues whatsoever with the engine (nor transmission) prior to the twin turbos and re-tune, but again, the transmission tune problem has been resolved since the first time the engine blew. It was a very strong engine and burned less than half of a quart of oil every 5k miles (oil was changed with Mobil 1 every 3,000 miles).

outkast6991

iTrader: (34)

PE is power enrichment aka your fueling at heavy or WOT. the saying is "lean is mean" and if your lean while in boost that can't be good. i'd be looking to have a GOOD tuner tune your next build

salemetro

iTrader: (5)

PE is short for Power Enrichment. It is the commanded AFR when entering WOT. With regards to timing; generally-speaking, mid-teens are the norm on FI LS1s....even lower on LS2s, so it could easily be argued that timing might be too high and would contribute to detonation. Combine that with the max retard only being 4 degrees TOTAL, and there seems to be evidence that timing is at least partially to blame here. As NicD has stated earlier, this is all just presumptions. What kind of fuel are you using? What do the data logs have to say? They would tell a lot. Without that, you're just left to "educated speculation". But I think that you already have a good idea what is going on here...and don't discount in the slightest what Edcmatl1 has stated here.

Edit...DFCO is also enabled, and so is rev limiter fuel cut. Not good. I also see part of what Ed was saying about the MAF curve...it is only scaled to 12khz...there is a 15k patch available. I didn't check the cell values against a stock tune, but it's more than safe to say that ED knows what the hell he's talking about. It's fairly likely that you're maxing out the maf. When looking at commanded PE....just like Ed stated....it's WAY lean in the tune....which means that your tuner is likely fudging the fueling in either the MAF g/sec. or the VE table. Obviously YOU are using HPTuners....what is your "tuner" using to tune the car?

MEAN GTO

iTrader: (1)

Thank you outkast. I am definitely aware of the "lean is mean" status, and absolutely need a better tuner next time around. This guy and his business had a really good reputation, and I didn't have noticeable problems with my previous tune he did when the car was supercharged, but who knows what that tune even looked like. Thanks again!

MEAN GTO

iTrader: (1)

Thank you for the detailed info! I am running Shell 93 octane fuel, but have not done any data logging. This is probably a horrible question, but since the car still technically runs, is it too late to do datalogging right now? It feels as if this time maybe only roughly 2 of the pistons are shot as opposed to 4 last time (guessing by my butt dyno). Like I said, the engine still runs, and the car still drives... you just hear some noise from the engine like the first time it blew only it runs a lot better than it did when I lost 4 cylinders the first time. I absolutely won't discount anything that Ed has stated, sounds like good info. I won't discount anything at this point, I'm open to anything anyone can find in the tune that may be responsible for this issue.

Another point you brought up was about the MAF-- I was talking to the tuner about doing a speed density tune before I finished having the fabrication done and before I obviously brought him the car. He talked me into leaving the MAF in there, saying something along the lines of "tricking" the MAF or something so it doesn't max out. He said he did the same thing with other high-horsepower GTO's without issue, so I left the MAF in the car and let him do his thing when I brought him the car for the tuning. Does this paragraph/explanation give you any further information about the possible situation with the MAF?

The tuner was using EFI Live to do the tuning, we just used HP Tuners to pull the tune file and have it examined.

Thanks again salemetro, and to everyone else who is helping me out with trying to determine the cause of the problem here.

NicD

iTrader: (7)

Regardless if the MAF table was left stock and regardless of what the PE multipliers say it was actually fairly rich throughout and just starting to look right up in the higher RPMs according to the dyno data screenshot. Besides, with 60 lb injectors the injector flow rate isn't going to be "correct" because of the flow rate limitation on these ECUs so just throw those out the window. The fueling was not a problem, but the timing looks to be just too high.

DFCO has no bearing on anything so I'm not sure why that was mentioned and same with the fuel cut. The factory PCMs cut fuel entirely to the cylinder, they don't do it in the middle of spraying the injector as that would be a major problem regardless if it was bone stock or boosted. The only time that matters is with a secondary fuel source like meth or a wet shot. The 15khz patch just prevents it from going back to 0 when it exceeds ~11khz and has nothing to do with changing the scale of the MAF table. It was a bug in the factory operating system and that's it. I know I touched on this above but whatever it says in the tune is irrelevant for fueling because of the injectors exceeding the allowable flow rate in the ECU, what matters is what is coming out of the tailpipe as shown in the dyno screenshot and it was actually a bit rich. Stop giving "advice" on things you know nothing about.

Slowhawk

iTrader: (12)

The timing blew the motor. It won't show up much on a dyno but it's too high for long pulls like going down the highway.

LSxPwrDZ

iTrader: (4)

Timing for sure.... Needs race gas and Methanol to get by with that much timing and even then would be pushing it.

vmapper

iTrader: (8)

Completely agree.
Every vehicle is different, 17° past peak tq (top rpm) is the most ive pushed a stock on pump fuel at 8# (centri setups), would definitely not be at 17° through the most cyl pressure range, maybe 14 tops.

salemetro

iTrader: (5)

Obviously the car was running rich...but it was not obeying what was commanded....and what was commanded was not good. That's why it was mentioned.

So fuel cut to control over-revving under boost is a good thing as opposed to pulling loads of timing?? DFCO was simply mentioned because on most boosted vehicles that I've seen, it's disabled to keep the exhaust from "popping" under decel.

Yep.....and it's possible that he could be having other issues previously not mentioned with "maxing" the MAF. It's reasonably fair to say that on a twin-fed LS2, this issue should/would have been addressed. That is why it was mentioned.


I'm aware of the flow rate "limit", but if the commanded PE target was set up correctly to begin with...and the injectors "scaled" and tweaked through other "adders", then commanded PE displayed in the tune would equal ACTUAL PE....which it's not. I know that some will get to the same "result" differently, but this just shows laziness, IMHO.

I'm not claiming to know it all by any means, but let's not start a "I know best, you know nothing" pissing match here... as we're all just trying to help the OP out.

MEAN GTO

iTrader: (1)

Thanks again for all of the replies everyone. So, cat is out of the bag-- what I was previously told before coming on to the forum with this thread is that the timing is believed to be the issue.

Now, with my experience with this tuner, I know him to be very stubborn on other peoples' and tuners' opinions. He believes that anyone on the Internet immediately does not know what they are talking about (ie: the tuners that know what they're doing apparently do not post tuning comments regarding tuning on the Internet). So I'm in a tough spot with needing to prove to him that the timing is likely what caused my engine to blow.

How can I prove that timing did this??? Can I still run datalogs with the engine in the condition that its in (still runs and drives) to somehow show that the timing is doing damage????? Sorry for this ignorant question, but I just know absolutely nothing about logging, let alone logging an already-blown (not to be confused with "boosted", but rather "damaged") motor.

Thanks again,
Andrew

minytrker

iTrader: (13)

I would find a new tuner, to much timing done cost you two motors. You shouldnt have to convince your tuner why he is wrong. For whatever reason most unexperienced tuners always want to run way to much timing and run them way to rich.