Would anyone consider reviewing my Romraider log?

I am hoping for some insight on a overboost issue.

 

2007 LGT 5EAT, tuned professionally but looking for some answers to why I would be overboosting with fuel cut.

 

I have replaced all the vacuum lines and zip tied them. I recently had an exhaust leak repaired with Grimmspeed metal gaskets throughout each junction.

 

Other Mods: Prodrive EBCS, Crawford AOS, CNT catted DP, stock UP, SPT Cat back, Perrin Crank Pulley, Perrin TB to IC pipe.

 

If you have some skills would you mind taking a look and telling me what you see?

 

Many thanks in advance!

romraiderlog_20200502_094023.csv

Edited August 11, 2020 by VespaGTS
Typo

According to this, you're only boosting to 14-15psi, correct? If so, your tuner must have just forgotten to raise the boost cut limit. You are showing a little bit of knock between 3500-5500 rpm, but that's fine. Your timing is pretty low, and it looks like a pretty safe tune. IAM stays at 1, so if it drives well, I wouldn't worry about that. Plus, knock wouldn't trigger a fuel cut, so that's not causing it.

 

Just ask the tuner to raise the overboost limit. I'm sure it was just an oversight on his part, no biggie.

I sent him a message and he is saying since it was tuned and running well previously it must be mechanical. So now I go down the path of vacuum leaks and boost leaks. Hopefully, it’s not boost creep. If anyone has a good write up about where to start that would be helpful. I am starting with vacuum leaks, I have replaced most of the lines already via Cryotunes post but it’s possible that it’s the cause.

Vac leaks would cause your fuel trims to go crazy at idle, or it would idle rough. a boost leak would cause lower boost, not higher. You could check the vac lines that lead to your wastegate. I've see little cracks in that line cause boost spikes. But according to the log, you're only peaking at ~15psi. So I wouldn't think you're overboosting, unless you were tuned to stock boost. Are you sure it's fuel cut? (Everything is going fine through a pull and then all of a sudden a huge jerk and you let off thinking you just blew the thing up. CEL pops up P0244?). If so, that's the overboost CEL with fuel cut, as you mentioned in the OP.

 

The best way to check for vac leaks is a smoke test. Look up "Subaru smoke test" on youtube, and it should pull up a good starting point.

 

Another possibility is that the car was tuned with the exhaust leak, and now it doesn't have the leak, so it's building more boost than before. The tuner would have set the wastegate to to a certain value necessary to hit target, but now that you don't have the boost leak, you would need a lower wastegate value to hit target. You could mention the fixing of the exhaust leak to your tuner, and maybe he just needs to make a small adjustment.

You have some fine learned knock correction being applied between 3200 and 5500 RPM and you can see the boost control system disabling, your boost dropping down to wastegate pressure, waiting for FLKC to raise above -1, then slowly add boost back into your run. Strange how IAM is not being changed, maybe correction is disabled for tuning purposes and never turned back on.

Also doesnt appear that you are ever even hitting the stock boost limits OR MAF load limits, so you shouldnt be getting any overboost triggers (unless the limits were lowered, which is unlikely).

A look at the rom and a more detailed log would answer some of these questions.

Anyway, Are you getting any specific check engine lights? Please post the codes.

 

Your vaccuum seems healthy from the logs. I wouldnt suspect a vac leak.

This log has the overboost cut happening during a third gear pull. The PO244 code is thrown and it is violent like you described above. I don’t plan on doing it often as I want my car to last. It’s a scary sound. Sounds like a $7k rebuild.

 

Here is another log showing numbers that are recent. I am going to the exhaust shop next week for a smoke test. It is strange that I am not hitting target boost but throwing a code for overboosting.

romraiderlog_20200724_092612.csv

Edited August 19, 2020 by VespaGTS
Typo

Is this a new tune? How long has this tune been 'fine' for? If this is a new tune, then again, I would point to the tuner just not raising the overboost limit. In this log, you reach 16.8psi. Ok, at least that's a little more than stock and would trigger the overboost limit if it was left to the stock value. You aren't showing any knock at all, and the IAM doesn't drop from 1 at any time in the log, so the car is happy. So something needs to be adjusted in the turbo dynamics tables for you to reach your target boost, or the overboost threshold needs to be raised. However, if this tune has been on the car for a while, like over a year, then I would look at a change in hardware causing it.

 

Another thing is elevation - did you tell the tuner the elevation where you are? It's possible that the tuner raised the overboost threshold for sea level, but didn't change the value for the other elevations.

It is the most recent tune. Post exhaust leak fix. He calculated for elevation but it is possible that the limit is set incorrectly. I saw almost 19psi yesterday when driving around without a overboost trigger so now I am thinking mechanical issues. He mentioned the possibility that the coil packs might be a problem. Would that trigger a PO244?

All four coil packs would have to die at the same time, and you wouldn't get the same CEL. You would get a misfire CEL (P0300, 301,302,303,or 304) if only one coil pack died. And it wouldn't do any fuel corrections unless it was in closed loop, not WOT.

 

I wonder if there is a small crack in the vac line that feeds the MAP sensor. Or a small vac leak on the line that leads to the boost control solenoid. Do you know what the target boost is set to? Have you compared MAP reading (ECU boost reading) to your boost gauge? Basically, I wonder if the car is running fine, but the ECU is getting an incorrect boost reading and triggering the overboost protection. Or the other way around - the ECU is reading correctly, but the boost control solenoid is getting a bad reference, so it's building more boost than it should.

 

Or maybe the MAP sensor is going bad. I've never seen that before, but I guess it's possible. I would compare the MAP versus your boost gauge to confirm that the ECU is getting the correct boost reading.

Thanks I will check with the tuner and also check the vac lines again. I saw 19psi today without overboost error. It’s frickin weird.

i was wondering if it wasn't a bad MAP sensor? I know I got the same code when I bumped against the upper end of the MAP sensor range with a 21 psi tune.

Reaching the limits of the stock MAP sensor wouldn't do it. I'm running 25psi on the stock MAP sensor on my other car, and it just stops reading at 23-24. It doesn't throw a code unless the MAP reading passes the threshold of the overboost table.

interesting, I was just reading about this in another thread which is where I was getting the info I passed on. Think this was the one https://legacygt.com/forums/showthread.php/map-sensor-max-psi-bad-map-sensori-175423.html

Yeah, that's all about trying to get an accurate reading from the stock sensor. On my other car (25psi), I'm using an MBC and bypassing the turbo dynamics tables altogether. That's how I know about what the max is, and what it does when it reaches it. In the case of that car, it just flatlines at 23-24psi in all the logs, but my MBC is set to 25, and I read boost with my boost gauge. The key there is that I don't use the stock boost control, and don't use the turbo dynamics tables, so the ECU doesn't need to know what the max boost actually is. But it's speed density, so it uses it for everything else. And it works fine for all part throttle stuff, just not the difference between 23 and 25 psi as my max load/boost table.

 

On my OBXT, I have the car set to 20-21psi max boost and I am running a MAF tune with all turbo dynamics tables active. The stock MAP sensor on my car has no problem reading/adjusting at those levels.

 

According to the thread you referenced some people have a problem and some don't. I guess it would be worth checking to see if the stock MAP sensor on an 08 OBXT is a different part number than on an 07 LGT. The difference is that in that thread, people are attempting to get it to read accurately. Only mention of an overboost CEL is that he didn't trigger it. Which is as expected - when it tops out, it just flatlines at a certain number (either 18.5 or 23.5psi). As long as that number is below the threshold, it shouldn't trigger the overboost protection.

Update:

Did a professional smoke test and nothing was leaking. They see overboost in my log but its not the tune. They are thinking mechanical issues at this point. Also it happens in all SI driving modes.

 

Potential causes being looked:

Waste gate to EBCS hose diameter?

Porting waste gate?

New turbo? Currently VF46.

 

Basically they don't know whats happening and we are looking for the mechanical cause of the problem.

 

I don't want to bury myself in diagnostic expenses and searching for issues if I can help it.

 

Any ideas?

Edited August 27, 2020 by VespaGTS
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If you’re using a turbo heat shield or blanket have you removed it to confirm its not impeding the wastegate rod?

If you’re using a turbo heat shield or blanket have you removed it to confirm its not impeding the wastegate rod?

 

Great point. It’s not impeding movement.

I vaguely recall that one of the "divorced wastegate" downpipes had a divider that impedes the wastegate from opening fully. I don't remember which brand downpipe. Has that downpipe been on the car before the tune?

 

Otherwise, as mentioned, I would check to make sure the wastegate rod isn't making contact with anything.

 

If the wastegate opens and closes freely, maybe try swapping the stock boost controller back in and see if you still overboost. If you're tuned for the Prodrive unit, the the stock hardware would boost less and kind of be all over the place. But it wouldn't overboost so if you're still overboosting, then it's not the boost controller.

 

Oh, also, have you changed the restrictor pill in the wastegate vac line? If you haven't changed it, I wouldn't worry about it, but it's possible that the wrong restrictor pill could cause overboosting.

Update

Mechanic says:

MAP Sensor good.

All exhaust gaskets replaced with Grimmspeed metal no leaks.

Turbo waste gate not cracked.

Catted downtube not problem.

No vacuum, boost or exhaust leaks.

Compression leak down test was 1-4 : 125, 121, 127, 120psi

Waste gate is actuating normally.

Didn’t swap out EBCS due to him not having one in hand.

The restrictor pill is out due to 3 port Prodrive EBCS.

 

They are blaming the tuner.

Edited September 2, 2020 by VespaGTS
Typo

Huh, well that's frustrating - everybody pointing fingers at someone else.

 

The restrictor pill removed: was that at the request of the tuner? Has it been that way for a while, as in: you didn't change boost controllers right before you started having problems or right before the new tune?

 

You could do a test of connecting the vac hose from the wastegate directly to the nipple on the turbo. That would bypass the boost controller and just run wastegate boost, which should be in the neighborhood of 7-9psi on a vf.

 

If you bypass the boost controller and boost 7-9psi, then you know that the problem is related to the boost controller. Either the unit, or the plumbing to/from it, or the programming of it is off.

 

If you still overboost, then you know it's a hardware issue (though I doubt that since it sounds like your mechanic did a pretty comprehensive look of the hardware.)

The restrictor pill was removed when we install the three port EBCS As it is no longer needed. It has been out for years. I’m seriously considering buying a Grimsby and EBCS for $120 bucks and testing it out.

 

All tubing has been done recently and the tuner does not think it’s the tune. So I am wondering what to do next? I might try your suggestion. I just need to hook it up which sounds easy.