Hey, I’m new to the group.

I’m currently stuck trying to diagnose/ fix my car, I had the car about a month and started noticing oil behind the turbo which led to me having no boost at all, luckily I had warranty with the company I purchased it from and they replaced the faulty turbo. I received the car back and noticed it still didn’t have boost( the company who ‘replaced the turbo’ stated that it was fine and boosting as should) being a mechanic myself I knew this was not true and didn’t trust them anymore to fix the car. I started looking online at stuff it could possibly be as I’m not used to fixing fords but knew it would be the same principles as any other turbo systems. I started replacing common items like the one way valve that goes to the vacuum pump and checking for boost leaks, etc. It has been about 6 months since this happened and about a month ago I noticed that there was no nut or clip on the end of the wastegate rod (I was stupid not to check this straight away but we all make mistakes), I put a nut on the end of it and secured it and I finally had boost again. Since this happening my car has been juddering/stuttering under full throttle. I know that adjusting the penny like nut on the rod can create overboost and what not but no matter how far down the rod I adjust it to stop the over boost it still has this issue, just curious if there’s anything I’m missing or could check that would cause this.

I have upgraded induction kit including air filter, primary and secondary pro hoses and a metal cross over pipe. I also have a decat aswell, is this anything that could effect it or no. 
 

I appreciate all suggestions and help.

Forgot to mention, I have a ford fiesta 1.0 ecoboost black edition (140)

Have you measured the actual boost?  This doesn't really sound like an overboost fault to me. 

I also can't remember which way you'd have to wind the nut for less boost.  All I can say is that the wastegate is open as default, and closed by vacuum when the engine's running.

Probably the induction kit, they're not worth the paper they're written on. The airbox is the same as size on all models, 1.0 to 1.6, it doesn't matter what you do, you'll never flow as much air as a 1.6. Put the standard airbox back on with a Pipercross filter.

Probably sucking too much hot air for the map

Poor performing spark plugs can cause this issue too, if you don't know when they were changed change them

And poor fuel too

Hey thanks for the reply, when I purchased the car it already had an aftermarket air filter on it but had stock induction pipes and this worked originally, I didn’t think having silicon pipes instead of stock would cause this issue but I will put the stock ones back on and test again, and I replaced the spark plugs myself about 2 weeks ago now and they are spark plugs recommend for the car and I put normal fuel on it that I would find at any pump, would it possibly be better to put high rated fuel in or no.

Changing the boost pipes and the elbow is fine, but an open air filter is no good.

Put the standard airbox back on with a pipercross filter, not a K&N (too much oil)

27 minutes ago, Hxrv said:

would it possibly be better to put high rated fuel in or no.

Possibly, try a tank full of Tesco Super (99 RON) and see if it's any better?

Has it been like it since you had it? Have you modified it, or bought it modified?

I think I'd be taking it back and saying you haven't fixed it.

It could be wet belt issues too if it hasn't been service properly and thrashed

If you purchased it with any finance reject the car.

I bought the car with the air filter already modified and the turbo worked fine up until it blew. They replaced the turbo than told me it was working fine which it wasn’t, I than found out they left a nut off the bottom of the wastegate rod, I put a new one on and got the boost back but now it stutters when under heavy load, I think it’s down to how the wastegate is adjusted but idk how it needs to be for it to work fine again.

Might be worth dropping Pumaspeed an email to see if they'll tell you the default rod length on the 1.0 EcoBoost.