IrishLad

Hi All,
Sorry for the late (very late update).

I got the issue fixed eventually, it turned out to be the waste gate on the large turbo.
It was opening and then getting stuck, did this everytime and caused limp mode.

Eventually found it (don't recommend this) by placing a Go-Pro camera inside the engine and driving on the road until limp mode was hit, I could see the waste gate open, but not close, it's electronic so the force of the spooling shouldn't have caused this, it would close when I slowed down but not exit limp mode.

Showed this to the mapping company, and they adjusted the actuate values for the turbo and its been perfect ever since.

Hope this helps someone.

Fivethreefive

What do you mean by adjusting acute values for turbo?

Did they increase the boost ?

jaxx

The WG with stock calibration can't handle the extra IQ, simple as that.

I have tested working software solution for over-boost problem and also P4521 boost creep software fix.

Fivethreefive

So is there a fix with software or does the wastegate need enlargning

Nikola Lefterov

So anything actually works about this problem, so far I think it may be really too small WasteGate that need to be enlarged , I have exactly same issue the car just stop at high speed 210-240 sometimes when I clear the error and go w/o kickdown it goes up to 250 but eventually stops ... I throw up error 4521(strange is that in DIS it says charge-air pressure too high or low of small turbo?!?! ) which makes completly non sense the error is recoreded at 3700 rmp , and then only big turbo works , small should be bypassed ?!! And other strange thing is that after I brake to 150 and put my foot again the car accelerate just fine it dosent need to restart the engine ... So what is the problem . I change MAf sensor since I got this error too too high values , change vacuum pump with PIERBUG brand new , change all vacuum hoses , my turbos all fully rebuild,its definetly not a air pressure sensor , cause back in the time I had problem with the Big turbo sensor and when It thorw error car goes in limp mode , and need restart , now it dosent need restart means its something MECHANICAL , but what ,this is really killing me , trying to figure it out almost an year... and still cant find a solution..

MODS of my car are : ecu remap+dpf off+ egr off + decat + swirl flap removed./custom quad exhaust

thats it an acceleration w/o kick down it goes good even at 220 but it will limp sometimes at 240 or 230 or even 250 depends how hard I push the acceleration pedal , its seeems when I dont do kick down it goes to higher speed.
Also my tunner did a lot of tests of the car when he remaped it and back then it was fine even at high speed , the only thing I changed after that was my exhaust system , I replaced the stock one with some custom made quad exhaust ( I dont know what the diameter is ) , but I suspect is larger , so maybe now the exhaust goes out faster , and that spoil the turbos to spin faster and make them overboost, So right know I think there is just 3 solutions to the problem, put back stock exhaust , make Wastegate larger , or make the emergency boost limit higher so that the car will not limp at 2.5 bar , and will continue , but this will make the car 390+ hp, now its approx. 350-360.

Tiago

My guess is too much EMP. I know i guy that solve it by adding a second wastegate via egr port.

I also had that issue when my car was at 400hp level. After we increased to 440hp, that problem only occurs now at half throttle. At wot it doesn't have a issue.

Nikola Lefterov

Tiago can you tell me more about this with the second wastegate , any information , it will be helpfull. Right know im thinking of fitting bigger InterCooler and increase the limit of boost to 2.5 so the car will be 390 + hp , and the air will not be 90 degrese since I will fit twice bigger cooler then stock one? What you think is that good option , or its better to get wastegate?

Tiago

Cooling mods is always a good thing to increase reliability and consistent power levels. It won't do a thing with the poor ability of the stock wastegate to deal with excessive EMP. The second wastegate via egr port is pretty easy to do it when you already have the egr software disable. Just connect the wastegate to exhaust manifold egr port and vent it to atmoshere or into downpipe for a quieter and oem setup. To control its operation you will need a electronic or manual boost controller. You what to make it start to open a bit higher than max manifold boost to prevent energy lost before turbo.

Nikola Lefterov

Tiago thank you for your help!!! But due my lackness of understanding how the turbo system works(I should copy what you say to my mapper). I dont understand what I need to do drill a new wastegate? I really dont understand I will be more then happy if you explain me . Also do you think it will be a problem if I leave stock wastegate, and just go for bigger cooler and increase the boost limit, since now it's set to 2.3 bars and because of the small wastegate it goes to 2.5 , and problem is that the air its too hot , and car goes in limp, but if I place like 600*300*100 IC which is about twice bigger then OEM , I think the air temp at 2.5 bars will not be again 90degrese. I mean increase boost limit to 2.5 bars , so that car will not go in limp mode(since it wont detect overboost) and since cooler is bigger should not put also hot air(again no limp mode) and at the end should have about 390 hp , which is the limit I think for my stock transmission(TC is fully rebuilt) and my turbos(also fully rebuilt ,but stock). Or I really need an extra wastegate.

Tiago

Like i said above, my car is running stock wastegate without limp issues under wot. But at half throttle that issue stills occurs. IMO, increasing boost isn't the perfect solution for it but atleast allows you to make full runs under wot.

Again cooling mods is always a must when you push the engine further than stock levels. At 400hp level my car had stock turbos but wagner intercooler and full exhaust with dpf deleted. Here is where it faced limp issues under wot. Only after the hybrid turbos and boost raised it put as it stands now.