Big intercooler - problems.

[Yaro]

Guys, need advice! We fitted Subaru GDB front mount intercooler (14l instead of 6l stock one).

And we are having problems with the car. Under certain circumstances the car shuts down the turbo. I suppose the ecu sees big intercooler as a hole in piping. The problem occurs on stock ecu, flashed. Apart from intercooler the car has 76-mm downpipe / exhaust. Car is 2.0 4wd.

The question is...what is the maximum size cooler can be used on our cars ? Is anybody having similar problems ?

 

[TStaino]

Yea that’s probably it. The ECU is expecting much more pressure through the IC than you are getting because it’s more the double the size. It probably thinks there’s is a hole in the piping or a coupling is loose and letting pressure escape.

Can’t answer what the maximum size it would allow, but the only one I’ve found as a kit for the 2L is made my Maintec on Korea. I’ll see if I can find the specs on the size of that IC. I would imagine they did some R&D on the 2L IC system and figured out what the maximum size can be vs the ECUs expectation on PSI through the system.

 

[Yaro]

Yea that’s probably it. The ECU is expecting much more pressure through the IC than you are getting because it’s more the double the size. It probably thinks there’s is a hole in the piping or a coupling is loose and letting pressure escape.

Can’t answer what the maximum size it would allow, but the only one I’ve found as a kit for the 2L is made my Maintec on Korea. I’ll see if I can find the specs on the size of that IC. I would imagine they did some R&D on the 2L IC system and figured out what the maximum size can be vs the ECUs expectation on PSI through the system.

Any chance you can post a link about this cooler ?

 

[Tonkabob]

Is it catless? I would look more toward the down pipe and over boost. The 3.3 has Johny Tig FMICs which is easy x2 probably x3 the size and has no issues. Even with primary cats on people overboost on the 3.3 which shuts off the turbo until you restart the car.

 

[Sales@Tork]

any codes coming up?

 

[TStaino]

Any chance you can post a link about this cooler ?

I believe this is their direct site, but I can’t read Korean: INTERCOOLER - INTERCOOLER

Here is a link to the same cooler, but it doesn’t give the physical specs of the IC:
Kia Stinger 2.0T Maintec Performance Intercooler Kit - Kia Stinger dot com

 

[Manaz]

Yea that’s probably it. The ECU is expecting much more pressure through the IC than you are getting because it’s more the double the size. It probably thinks there’s is a hole in the piping or a coupling is loose and letting pressure escape.

Intercooler size is unlikely to have a negative impact on manifold pressure - if anything larger intercoolers tend to produce less pressure drop than smaller ones, though they can introduce a small amount of lag in pressure build-up.

As an example, the time it would take to fill the extra 8L is minimal - to produce the stock 255hp, you need about 280cfm of airflow - that's just over 4.6 cubic feet per second. The extra 8L of intercooler volume adds less than a third of a cubic foot to your intake piping, meaning it will add less than a tenth of a second to the time requires to pressurise the intake piping.

Once pressure has built up, there's no additional impact. The turbo will be operated by the ECU to maintain manifold pressure by varying it's wastegate duty cycle to suit.

Issues other than the size of the intercooler are more likely the cause of the problem here - has the Subie (noting for a GDB, it must be after-market if it's a FMIC) intercooler been tested for pressure drop (all intercoolers add resistance to flow) or even that it will hold pressure (a small pinhole or crack or split in an end-tanks could cause issues). Are you sure there isn't a cracked/split pipe or loose coupling?

Is the ECU reporting any faults?

If you go back to the stock intercooler, does the problem go away?

 

[Yaro]

Intercooler size is unlikely to have a negative impact on manifold pressure - if anything larger intercoolers tend to produce less pressure drop than smaller ones, though they can introduce a small amount of lag in pressure build-up.

As an example, the time it would take to fill the extra 8L is minimal - to produce the stock 255hp, you need about 280cfm of airflow - that's just over 4.6 cubic feet per second. The extra 8L of intercooler volume adds less than a third of a cubic foot to your intake piping, meaning it will add less than a tenth of a second to the time requires to pressurise the intake piping.

Once pressure has built up, there's no additional impact. The turbo will be operated by the ECU to maintain manifold pressure by varying it's wastegate duty cycle to suit.

Issues other than the size of the intercooler are more likely the cause of the problem here - has the Subie (noting for a GDB, it must be after-market if it's a FMIC) intercooler been tested for pressure drop (all intercoolers add resistance to flow) or even that it will hold pressure (a small pinhole or crack or split in an end-tanks could cause issues). Are you sure there isn't a cracked/split pipe or loose coupling?

Is the ECU reporting any faults?

If you go back to the stock intercooler, does the problem go away?

The strange thing is that ecu doesn't throw any faults, it is shutting down the turbo. Even if you have a hole 3-4 cm diameter, it doesn't throw ecu fault, it is shutting down the turbos.

We've tested all intake pipes including intercooler with 2 bar or 29psi pressure. No leaks at all. The only difference between 2 of our cars is the intercooler. So I assumed the problem is in intercooler.

As an example in Bosch ecu's it is a common thing to rescale some tables, related to airflow / second when you install big cooler or change diameter of piping (never tuned bosch, but friend of mine does and told me this). In our sim2k ecu we cannot find those tables.

I will take down the cooler on this weekend and test the car.

 

[Manaz]

How is it shutting down the turbos?

Turbos will spin when there is engine load (at no load, exhaust volumes and velocities are generally not enough to build significant boost). Wastegates will open to prevent pressure build-up under load if the ECU wants that to happen, but there should be something in the logs, and the turbos will still spin.

 

[Yaro]

How is it shutting down the turbos?

Turbos will spin when there is engine load (at no load, exhaust volumes and velocities are generally not enough to build significant boost). Wastegates will open to prevent pressure build-up under load if the ECU wants that to happen, but there should be something in the logs, and the turbos will still spin.

Wastegate open. Desired boost 0. When the fault happen, ecu sets desired boost or something like that to 0. English isn't my first language, so sorry if I explained it incorrectly.

 

[Manaz]

And it logs no fault code or entry at all?

Does it do it every time, or only sometimes? Any consistent pre-error events or conditions?

 

[Yaro]

And it logs no fault code or entry at all?

Does it do it every time, or only sometimes? Any consistent pre-error events or conditions?

No cel code. At all. Used dealership equipment to check it.

It occurs partial throttle most of the time. 30%-50% throttle comfort / eco mode mostly.

 

[Tonkabob]

When the (3.3) over boosts it will open the wastegate/ no boost and typically no codes.

 

[xot1]

No problem with the Wagner huge ass intercooler.
I haven't heard of anyone having problems with the Maintec intercooler.

 

[Kazz]

When the (3.3) over boosts it will open the wastegate/ no boost and typically no codes.

I'd like to hear more about this. I thought I'd blown off a hose this past weekend on the Tail of the Dragon. It seemed as though the wastegate was staying open until I shut off the car. I was using a lower gear from then on and staying away from peak boost the rest of the day. But I never replicated the sound and loss of power. It's like it resets when the engine's shut off.

 

[Tonkabob]

I'd like to hear more about this. I thought I'd blown off a hose this past weekend on the Tail of the Dragon. It seemed as though the wastegate was staying open until I shut off the car. I was using a lower gear from then on and staying away from peak boost the rest of the day. But I never replicated the sound and loss of power. It's like it resets when the engine's shut off.

For me, with a beta ecu tune, if i manually shift - high gear, lower rpm which i don't normally do, you can build lots of sustained boost. You can feel a hesitation as the ecu first pulls timing to control boost, may get a little blow off as well, but if you keep banging off that boost threshold the wastegate will open until you restart the car. I'm sure if you exceed boost faster you may miss the signs and go straight to overboost especially with downpipes.

 

[Kazz]

For me, with a beta ecu tune, if i manually shift - high gear, lower rpm which i don't normally do, you can build lots of sustained boost. You can feel a hesitation as the ecu first pulls timing to control boost, may get a little blow off as well, but if you keep banging off that boost threshold the wastegate will open until you restart the car. I'm sure if you exceed boost faster you may miss the signs and go straight to overboost especially with downpipes.

Sounds a lot like what happened. I really should check all my hose connections, though. Thanks!

 

[TStaino]

No problem with the Wagner huge ass intercooler.
I haven't heard of anyone having problems with the Maintec intercooler.

Do you know anyone specifically that has the Maintec intercooler for the 2L Stinger?

 

[oddball]

That thing is much smaller than the Johnny Tig intercooler, and several of us (including me) are running it without issue.

 

[Yaro]

No problem with the Wagner huge ass intercooler.
I haven't heard of anyone having problems with the Maintec intercooler.

I've seen vagner, I suppose it'not 14l like subaru's one. Stock cooler is 6l.