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I've been having issues with my 56 plate Fiat Idea for a while now. It seems to drive normally up to about 2500-3000 rpm where the car lurches a little, as though i shifted down a gear, the MIL light comes on and the car becomes incredibly sluggish. Not quite limp mode but sluggish.

My basic knowledge is telling me it could be a blocked EGR valve, and my code reader is reading two error codes relating to turbo intake, which could be indicative of an EGR fault I suppose?

I have ordered some EGR cleaner that you spray into the intake as the valve is located next to the gearbox linkage so there's no way to easily access it without having 5ft long arms made of elastic; otherwise I would attempt to clean the valve properly.

What's weird is that after a few restarts, the MIL light goes off and the engine functions fine, until I hit around 2500rpm again, where it goes into this near limp mode. And you can push the revs to the limiter in neutral without a problem.

What are your diagnoses on this problem? Am I wasting my time with the EGR? Also, what is the likelihood of it passing it's MOT in a couple of weeks time? The light is not currently on and if I can avoid going above 60mph, I can make it stay off until the MOT. But will their tests cause it to come on? And does the EGR effect emissions enough to cause it to fail?

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Welcome to the site. Could you post the exact codes you're seeing?. Thank for a great question. – Zaid Jan 11 at 10:13
2  
@Zaid I'm sorry but i don't have the codes at hand. If the MIL light returns i'll check the codes again and edit them into my question. – Ctrl-alt-dlt Jan 11 at 10:16
    
Sounds great, thanks – Zaid Jan 11 at 10:17

One possibility is that the turbo is sometimes over-boosting, which is being detected by the engine MAP sensor. The way that the engine ECU can control this over-boost to avoid engine damage is by limiting the amount of fuel injected into the engine, which would of course cause a sudden drop in power. The over-boost could be being caused by a seized turbo waste gate. If you are able to, check that the waste gate mechanism on the turbo is not seized.

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