During club track events boost is fine for several sessions. 1.2 bar is set point by software and stays there fine. By the afternoon session all the sudden it is max of .8 bar. This is not progressively lower like heat soak, it just wont hold more that .8 bar max in the afternoon sessions. Let it cool off for about hour and half, drive it home, still not more that .7-.8 even after relaxed cruise at 60-70 to make sure it is cool.

Next morning it is fine. This has happened twice, two weeks apart. Both same situation, fine all morning and by the afternoon session same thing. Smoke tested no boost leaks. No engine codes. Seems too much of a coincidence that the max boost goes to .7 or .8 bar, or default wastegate pressure. But no code from factory boost control solenoid ( no aftermarket boost controller)

Rest of configuration is EPL tune, gt28 hybrids, diverter valves, and water/meth which is wired to boost solenoid as failsafe, but seems to be functioning fine, meth/water is still spraying when boost problem is occuring, so there is not a signal to cut boost. Then as mentioned before it is fine the next morning.

It does not do it on the street just running around, full boost always works, has only done it at the track.

Just odd, any suggestions?

 

Ideas anyone?

 

Have you pressure tested the system for boost leaks, not just smoke test.

 

Yes the smoke tester pressurizes the system slightly 1psi, and no smoke leaked anywhere until a hose clamp was unscrewed. So no, not a high pressure test like 15psi. However remember it is fine the next morning and holds boost, so it does not seem like a leak.

 

Try reading the codes...perhaps n75 heats up...Do you use boost controller?also a wastegate might heat up and not operate proper...

 

Log durametric runs when it does this... log some when it is fine, then once it starts doing it grab a few.

I'd feel like I was blind with your mods and no way to datalog....

A

 

There are no codes, and I will log it for sure next time. I was at the track and did not have my laptop with me with the durametric on it. I am not able to replicate the problem on the street. Next time it does it I will log boost set point etc. For now I am going to try changing the factory boost control solenoid since it a cheap part. I am guessing that it can fail by sticking and not give a code.

skandalis447 - not using ebc, just ecu boost control

 

The wastegates may be hanging open after getting too hot. wastegate linkage may be binding when hot.

Maybe you are running a little lean or with a restrictive muffler?

The factory boost solenoid will give you a soft code if it's not working. if it was then you would get whatever boost that your wastegate spring is. The boost wouldn't go up and down like it is.

 

I have upgraded wastegates that came with the gt28s, so my default pressure is .8-.9 bar which is about what I am seeing when this happens. So the boost isnt really going up and down it is either 1.2 as normal or .8-.9.

Cant imagine its a little lean or restrictive Muffler. The muffler is full 3in with 200 cell cats, and either one wouldnt explain why it is fine the next morning.

Tony at EPL has suggested replacing the stock solenoid as it is simple and cheap. Also there is boost solenoid cut built into the meth control unit that activates under several circumstances. One is low fluid, one is low flow, and the last is loss of electrial power to the meth control unit. All three could trigger the boost cut. All three however are working and OK. However, according to Tony, even though the meth is still spraying and working fine, the limit settings on the control box that send a signal to go to default waste gate pressure in the event of a meth malfuntion could still be cutting boost. I need for it to happen again to test this. By turning the sensitivity adjustments on the control box to wide open I can disable the boost cut feature to see if that make a difference. Sounds to me like a pretty good candidate for this problem.

 

Have you determined what the issue is? I had the same problem when only on the track. My setup is oem except for BMC Air filter and epl tune.
I was going to swap my maf. Seems strange that this happens under isolated conditions. In your case you seem to have changed just about everything... good luck....

 

Not yet, I will keep you posted. I am replacing the factory boost control solenoid today to start. Doubt it is wastegate mechanical related. Seems electronic in nature. I have one more thing to try related to the Meth injection control, however I have only had this problem on the track after a morning of sessions so I have not been able to replicate on the street. Next track weekend is November at Barber.

I have had some slight boost holding issues where my boost has crept down from 1.3 solid to 1.2 and sometimes 1.1, but could be more related to summer heat. However, it should hold boost solid regardless. Some dedrigation of boost control is a sign of a failing boost control solenoid so I am trying that first.

 

Hello I have the same problem but at the street, I changed the selenoid, but the problem persist, I turn on the car, then I push hard, first, second and third gear, and the boost is ok (1.0), but after a few minutes pushing hard the boos pressure goin down (0.5 - 0.6).

I will try to check the wastgates.

I tryed when the boost is going down I turn off the car and inmediatly turn on the car and push hard in the 1,2,3 gear and the boost worked ok. buet after a few minutes using the car the boos pressure going down.

What anyting else i can try?

Thanks

My car have a EPL Re-mapping

 

First hit up Tony. Change the maf.

 

Tim941 may be on to something.... I have been following this thread for months and that may be the issue. I have followed a number of cars that
have changed just about everything with no change to their problem Including leak checks.... smoke checks.... My car is stock with just epl tune and bmc filter.... with the same problem.. all hose connectons are good and car still goes to 1.1 bar. But .6 on the track. Seems like the Maf is next to try. This issue is not easy to find... good luck

 

all you can do is just already written..only what you can do is find a route what you check step by step...easy things first...

durametric fault codes and datalog analysis
clean maf
check wastegate adjust (left and right)
check n75 valve (do a pressure test in the wastegates opening line...you can see if the ecu regulate down ore it is a mechanical failure)
check DV

and after above written checks you must do a boost leak test and what i have learned is this last check in most cases give the answer....imho