Up pipe EGT use?

[kzr750r1]

I've searched and not finding a definiteve answer.

 

After replacing my up pipe with a Perrin and removing the EGT sensor there seems to be an exhaust leak. May be because I didn't drop the passenger side header or lift the motor as described in Mikes or Perrins procedure. Hoping I didn't crack a maniold... But well see.

 

With the need to drop the exaust I'm considering gutting the stock up pipe and placing the EGT back.

 

I'm not looking for a stage 2 tune at all but would like to go to a solid stage 1, post making the final HW changes. I'll likely go to Mike for an custom Etune for my setup.

 

So is the EGT a CAT health sensor or is it used for fuel map as well?

 

When I pulled the EGT during the up pipe install it was in good shape as is the CAT element. Main reason for asking is I do live in California and don't want to keep swapping up pipes to meet the visual inspection (if the tech even looks). Looking for system longevity steps moreso than a performance mod.

 

Probably need to replace the turbo as well since there is some oil making to the intake but thats another thread all together and there are plenty of discussions about that going...

[Dujo]

The uppipe egt sensor is cat protection only. It's there to read exhaust temps to make sure they don't get hot enough to melt the cat. It is not used in closed loop fueling calculations. This is why it's so easy to turn it off or put a resistor in to fool it without any further issues. If you gut your cat, you still don't need it. And you can put the sensor back in or you can plug the bung as you desire. Note that there is some small risk of the sensor end breaking off and thrashing the turbo, so there is some slight benefit to plugging it over putting it back in.

 

Have you tried thicker gaskets? The grimmspeed ones are double thick. Might be easier than gutting. Heck, used sti up for under 100 bucks is easier than gutting. Good luck!

[kzr750r1]

Thanks for the confirmation.

Understood there is a risk having it in long term.

It all depends on who inspects the car if they will nose in far enough to notice.

Seemes strange that some companies keep the EGT bung and some some dont all without elements in their up pipes.

 

Are the STI or 07+ up pipes equipped with a EGT sensor?

[Max Capacity]

A little amount of oil film in the tmic is not a bad thing. Lot's of oil is.

 

You didn't say what the mileage was in the engine ?

 

Or do you have another thread ?

[kzr750r1]

Car has 135K on it now.

 

I have not made a seperate thred about the turbo helth just yet. Since I plan on going nowhere for the 4th I may drop the DP and check the shaft play. I would like to try the stock TMIC again after I bullet proof it. See if things settle out. Theres no need for the perrin on this car right now. It's all stock except for the up pipe.

 

More I read about the VF40 the more I want to change it. Rebuild seems like a good preventitave measure but there is no assurance for how long. Thinking BNR G16 and a good blanket. With IP&T oil line kit.

 

On the UP Pipe and EGT...

Main thing is the visual during smog inspection, after talking through it with my mechanic friend last night. The car should be setup on the dyno running and pulled out running with no need to restart. Issue right now is a good tech would notice the nice shiny wrapped DP.

 

My concern is the state has the OBDII tapped while doing the test. I was thinking cold start should not settle immidiatley ay 1290 F. But since your pulling in a running car ready to roll I could get through without issue so long as I'm using the stock map and look stock.

 

Have some time...next September or so. As always trying to make my next step a good one and I'm almost 100% sure it's going to be my gutted up pipe going back in. I can tap off the bung between smogs and remove risk.

 

So for now I'm going to buy some new gaskets and pull all of it down to be sure I didn't cause the exaust leak.

 

On the grimspeed or any other extra thick gaskets... When do you decide to use them where and why???

I see them available for most gaps except for the head. Thinking it may be good to do double thick everywhere but in some cases it may not be needed.

[Dujo]

Replacing the VF40 is good preventative maintenance above 100-150K miles. You can replace it with something comparable or you can do a bit of an upgrade. A VF52 is an extremely popular turbo upgrade in these cars. BNR 16g is also a very solid choice. See BarManBean for bulletproofing measures on the stock intercooler.

 

As far as inspection, that's a little different story. It depends on your state. Is N. Central Valley in California? If so, you may need to check with the California guys. Here in Massachusetts, there is no visual inspection of the engine bay or underneath the car. They plug in to the OBDII port and if the ECU says the car is okay, then the car passes. I don't know about Cali, but I'm sure it's much more stringent than that. At any rate, the resistor mod or turning off the EGT sensor in the tune is good enough to fool the ECU, which here in Mass, is good enough to fool the test.

 

As far as gaskets and locations, there are always two ways you can go when you pull apart two flanges with a gasket between them ... you can reuse the gasket or you can use a new one. Some people recommend that you use all new gaskets anywhere you take things apart, some people just reuse them. I would say that since you have a leak, it's time to start moving into the new gasket camp. You could do 'em one at a time and try to stop the leak scientifically, or you can just replace 'em all (if you didn't loosen a connection somewhere, it probably doesn't need a new gasket, but if you took it apart at some point, a new gasket is a good idea). Grimmspeed also sells the gaskets as a set, which if I recall correctly, includes a head to exhaust manifold gasket (x2), manifold to uppipe, uppipe to turbo, and turbo to downpipe. I don't remember if there is a cross pipe gasket (x2) also, but I seem to recall that I got more gaskets than I actually used, so the set may not be the most efficient dollar choice, but it is the most comprehensive. I believe you can get any gasket that's in the set as a standalone purchase too, if you so desire.

 

As far as oem or grimmspeed, that's up to you. I would say with a known leak somewhere that the thicker grimmspeed ones are the way to go. As far as STI ups, I believe that all Subaru uppipes are interchangeable in terms of fitment. I also think that an 04+ sti uppipe should fit and is completely catless (and therefore EGT bung free, I think there's a heatshield though). In addition, I'm pretty sure that the 07+ LGT and OBXT uppipes are also catless and perfect oem fit (again, no bung though, though they do all have heatshields and still look pretty oem). Basically, they only put that stupid uppipe cat in the 05-06 LGTs and OBXTs and that's it. Double check all that info before you spend money based on it, since I'm not 100% sure though.

[kzr750r1]

Thanks Dujo... Already spent some money and will consider this. They get into the engine bay here. Even look at the dipstick seal integrety bla bla and yada yada...

 

Not 100% sure if there is a check list of emissions items to ID based on year...

May all depend on how sharp the tech is on seeing mods.

 

I'll read up on the VF52 but gleening what I have seen it's a more than my goals need. My goals would be for a long term solid stage one tune.

[Dujo]

Left: 05 LGT oem uppipe with cat and egt and heatshield

Right: 08 LGT oem up with heatshield, no cat, no egt ... I think that an sti up is almost exactly like this.

 

They both have "Subaru" stamped on 'em.

[Dujo]

If all else fails, send a pm to Infamous or to LALGT. They're in California and should know more about the local ordinances and testing.

[kzr750r1]

I may call Mike later. Want to read more on the turbo options today before I do. Pretty much ready to have him map the ECU once I get the parts list settled. No sence in getting the VF40 map rolling if I'm gong to settle on a VF52. Thenks for posting the pictures. Probably have seen comparisons before and didn't recall of the EGT was on the other stock pipes or not. If I keep the resistor mod in play I'll be potting the resistor into the connector to make it look clean as possible.

[rob-2]

I will be running the EGT stage 2 with an EGT gauge to watch for ultra lean conditions.

[BigTDogg MA]

EGT in the OEM position is pointless, IMHO. needs to be closer to the head. I did the resistor mod and didn't look back.

 

I replaced my turbo at 145k-ish miles as preventative maintenance. The turbo was actually fine; zero shaft play axially or longitudinally. YMMV

[rob-2]

EGT in the OEM position is pointless, IMHO. needs to be closer to the head. I did the resistor mod and didn't look back.

 

I replaced my turbo at 145k-ish miles as preventative maintenance. The turbo was actually fine; zero shaft play axially or longitudinally. YMMV

 

Got no shaft play at 98K. None at all.

[kzr750r1]

How would the EGT give you a lean condition flag?

Are you talking about using a wide band air fuel guage?

[BigTDogg MA]

When you get stupid lean your EGTs skyrocket.

[JmP6889928]

Lean=Heat. Heat=problems. Problems=$$$$$

[kzr750r1]

Ok so how high would you consider a red flag?

[JmP6889928]

With the EGT the ECM will tell you by putting the car into limp mode or even making it completely stop (ask me how I know-bad front 02 long time ago and ran it hard even with the CEL and it simply shut down because the 02 wasn't reading and letting the ECM compensate for AFR). I, as BigDogg said, did an UP and the resistor mod and have never had another problem since.

 

To put it in an analogy, if you've ever used an acetylene torch, you can make the flame MUCH hotter just by applying moar oxygen in very tiny increments. The louder the hiss, the hotter it is. If you've not ever used one, find someone that you know that has one and ask them to demo it to you. Have them make a good flame that does not hiss but has a nice blue color and apply it to some scrap steel about 2" away and time how long it takes to get red. Then have him really turn the oxygen up and do the same test and see how much faster it gets red-less than 1/2 the time if he really turns it up.

 

Same thing in the engine-lean (lean on fuel compared to oxygen) means too much oxygen for the amount of fuel which in turn drastically increases the heat which in turn makes aluminum parts (pistons, heads, blocks) and fairly delicate steel parts (valves, valve springs, piston rings) suffer. Rich, on the other hand, (rich on fuel compared to oxygen-too much fuel) can also cause problems by creating too sooty an exhaust because of all of the fuel not being burned and then being pumped out of the exhaust valves into your catalytic converters, and can cause them to clog. It also will make driveability issues, stumbling, stinky exhaust, not to mention using more gas than it should.

 

Lean is FAST but only for a short time. Drag racers try to get right on that razor's edge of lean enough/not too lean because it produces horsepower by completely burning every spec of the fuel. When you see a drag engine blow apart, it generally is because they didn't hit that edge but went past it.

[rob-2]

Ok so how high would you consider a red flag?

 

You're looking for a spike. IE under heavy boost your EGT spikes, you need to back off and check out what went wrong.