GTI Exhaust Overheat High RPM

[isbop]

Got a 2012 GTI 155. The check engine light would come on when pinging very high rpm’s in sport mode. If I slow down for about a minute it goes away. Took the code to get read and the guy told me to replace the exhaust temperature sensor. Thats th sensor that sits between the resonator and the muffler. I did that and took the ski out again and same thing. Sport mode actived, high rpm, check engine light.

I’ve checked all the connections around the exhaust and resonator and nothing is melted and everything looks normal.

My assumption is there is debris somewhere in the ski maybe cause the sensor to trigger. But I’m not sure where to look. Any ideas would be great!

 

[Milehighguy303]

Check all your cooling hose clamps and connections - specifically at the jet pump inside the hull. Make sure your hose from the jet pump to the exhaust is on tight. If it isn’t on tight, you would likely be getting excess water in the hull, which doesn’t seem to be an issue. But you need to start with that hose from the jet pump, and trace it to the exhaust and make sure it is free and clear. You could even disconnect the hose at the exhaust and make sure there is water flowing from the jet pump to the exhaust when riding at faster speed.

Something is definitely preventing a high volume of water flowing to the exhaust to cool sufficiently at the higher speed and temperatures.

 

[isbop]

Check all your cooling hose clamps and connections - specifically at the jet pump inside the hull. Make sure your hose from the jet pump to the exhaust is on tight. If it isn’t on tight, you would likely be getting excess water in the hull, which doesn’t seem to be an issue. But you need to start with that hose from the jet pump, and trace it to the exhaust and make sure it is free and clear. You could even disconnect the hose at the exhaust and make sure there is water flowing from the jet pump to the exhaust when riding at faster speed.

Something is definitely preventing a high volume of water flowing to the exhaust to cool sufficiently at the higher speed and temperatures.

Thanks for the reply. If I was to disconnect the jet pump to the exhaust how would I test that exactly ? Keep it on the trailer and just back in the ski so the intake is under water? Also would that not flood my hull? Sorry kind of new to diagnosing something like this

 

[Milehighguy303]

Thanks for the reply. If I was to disconnect the jet pump to the exhaust how would I test that exactly ? Keep it on the trailer and just back in the ski so the intake is under water? Also would that not flood my hull? Sorry kind of new to diagnosing something like this

I think I would take off the seat and ride it around the ramp and dock area with the jet pump cooling hose disconnected from the exhaust, so you can see the flow at idle and when accelerating. I don’t know that you can measure anything, but the flow at idle will be a small flow and a strong, significant flow when accelerating. Zip tie the hose where you can see the water flow. Yes, it will pump water into the hull if the jet pump is working as it should, but you are just testing for a few minutes and can drain the hull when you pull it out of the water.

 

[isbop]

I think I would take off the seat and ride it around the ramp and dock area with the jet pump cooling hose disconnected from the exhaust, so you can see the flow at idle and when accelerating. I don’t know that you can measure anything, but the flow at idle will be a small flow and a strong, significant flow when accelerating. Zip tie the hose where you can see the water flow. Yes, it will pump water into the hull if the jet pump is working as it should, but you are just testing for a few minutes and can drain the hull when you pull it out of the water.

Someone on facebook mentioned this "I'm wondering if the 4 pinhole injection ports on the exhaust manifold may be blocked which is restricting how much water is making it into the waterbox. The exhaust overheat triggers at 230 degrees so if its only happening at high rpm that lines up with partially blogged injection ports"

I also am wondering if it could be an oil pressure sensor switch

 

[Milehighguy303]

I don’t know what an oil pressure switch would have to do with exhaust cooling. That could be a smokescreen taking you down a rabbit hole.

I am not very familiar with the pinhole ports themselves, but it is a good recommendation to investigate as part of the water flowing thru the exhaust system. I think you are getting set up well to follow the water flow from inside the hull at the jet pump, all the way into the exhaust system. It seems you gave a restriction somewhere that is preventing adequate cooling when at higher or full throttle RPMs.

 

[skiasylum]

The pinholes aspirate the open loop water to cool the exhaust gases cooling the muffler and exhaust piping, the temperature sensor is mounted on the muffler. The faster you go the more open water pressure to the pin holes. If they are clogged at all it means less cooling higher temps probably triggering the warning light. They are located before the muffler, take the exhaust apart and clean the holes with CLR.

 

[isbop]

I don’t know what an oil pressure switch would have to do with exhaust cooling. That could be a smokescreen taking you down a rabbit hole.

I am not very familiar with the pinhole ports themselves, but it is a good recommendation to investigate as part of the water flowing thru the exhaust system. I think you are getting set up well to follow the water flow from inside the hull at the jet pump, all the way into the exhaust system. It seems you gave a restriction somewhere that is preventing adequate cooling when at higher or full throttle RPMs.

Appreciate the feedback. I’ll update you after the test this weekend

 

[isbop]

The pinholes aspirate the open loop water to cool the exhaust gases cooling the muffler and exhaust piping, the temperature sensor is mounted on the muffler. The faster you go the more open water pressure to the pin holes. If they are clogged at all it means less cooling higher temps probably triggering the warning light. They are located before the muffler, take the exhaust apart and clean the holes with CLR.

Thanks for the input! I’m trying to figure out how exactly to take this muffle apart. There aren’t really any good YouTube vids out there so trying to read the shop manual. Once I figure that out I’ll give it a good attempt