Hesitation when accelerating

[Dronan]

Hi guys first time posting here.i have a issue with my fiesta st and it’s driving me insane.It has a intermittent problem when accelerating between 2500 rpm to 3000rpm it sort of hesitates and stop boosting for a split second.Theres no codes stored or lights on the dash and my local mechanic isn’t sure what it is.Other than going to ford and getting ripped off I’m at a loss to what could be causing this issue.Could any of you guys help me out ?

[slybunda]

Turbo lag.

[Saleen836]

Which model Fiesta ST?

[Dronan]

Mk7 pal

[p4cks]

My suggestion to you is don't just assume that because one mechanic can't fix it you need to go to a main dealer. Find another mechanic who can have a look at it and see what they say.

Normally it's duff spark plugs or coil packs but then again I'd expect to see an EML illuminated on the dash

[Belle427]

Air flow meters can give this kind of problem which are hard to pin down and don’t usually flag the eml.

[Lotobear]

....I was going to suggest the MAF sensor too, at least worth a check and (careful) clean

[cornflakes2]

Hmm could be something similar to me. I have a VW Scirocco R (2.0 petrol, TFSI) which is I believe a very similar platform and build, only the exterior is different.

I have been experiencing some weird issues with turbo boost gauge reading....it seems to read very high boost (10-15 psi or 1 bar) but I'm not even going that fast and a lack of power and acceleration has always seemed a little hesitant.

I ordered VCDS Hex Key so it's about to arrive in a few days. Hopefully I will find out what might be the issue.

When I went to a VAG garage couple weeks back, they only found a fault code about the Emissions system and changed out my Charcoal Canister. That didn't seem to solve anything other than get rid of that code. The other things it could be is as some people mentioned, dirty/faulty MAF, incorrect airflow readings, possibly even something to do with replacing the purge regulator valve (N80).

I'm trying to deduce what the source of the problem is.

[E-bmw]

cornflakes2 said:

I have a VW Scirocco R (2.0 petrol, TFSI) which is I believe a very similar platform and build, only the exterior is different.

Whoever told you that you need to completely ignore on any car related matter ever again.

Different car, different engine, different gearbox, different manufacturer and I would imagine the only common parts between them are the light bulbs.

[cornflakes2]

E-bmw said:

Whoever told you that you need to completely ignore on any car related matter ever again.

Different car, different engine, different gearbox, different manufacturer and I would imagine the only common parts between them are the light bulbs.

Ok, first you need to relax.
My mistake. I saw him post Mk7 and thought it was a VW Golf Mk7. Simple mistake.
I'm going back and forth with this forum and vwvortex as the only two sources for car help and discussions and I must've just assumed every car in this thread was about VW lol.

Edited by cornflakes2 on Wednesday 18th September 15:28

[GreenV8S]

cornflakes2 said:

he never stated what car he had in the original post.

The first sentence of the first post says Fiesta, and it's mentioned again in several later posts. It is quite obvious that the question is about a Ford Fiesta. Nobody mentioned VW or Golf at any point, so it's a huge leap to assume that 'MK7' refers to whatever other brand/model you were thinking of.

[Dronan]

Ok guys cheers for the input il have a look at the maf and give it a clean

[cornflakes2]

GreenV8S said:

The first sentence of the first post says Fiesta, and it's mentioned again in several later posts. It is quite obvious that the question is about a Ford Fiesta. Nobody mentioned VW or Golf at any point, so it's a huge leap to assume that 'MK7' refers to whatever other brand/model you were thinking of.

Yes, I totally missed that. I don't know why people need to be so critical when I was just offering my advice, even if it was for a different car. Who doesn't have different cars on this forum? Are we only allowed to comment about cars we actually own? I didn't think it was a big deal (not at you Green, about e-bmw). Anyways, NP. My mistake.

[cornflakes2]

BTW, I used to own a Ford Focus for a few years. That was my first car. I've always wanted to get the Focus ST back then. Later when I heard about the Fiesta ST and saw reviews about such a little car having 200 hp sounded great! Very peppy and it was fun watching the youtubers review the car because the grins on their faces were always ear to ear! Something about that car gave them smiles. Where I live now, there are hardly any Fords here. Never saw a Focus or Fiesta here. I would have bought a Ford if they had the Fiesta ST or Focus ST.

[Dronan]

I love my st it’s a lot of fun,but this gremlin is ruining my fun,it just seems to be missing some power and this hesitation problem I can’t find the solution to is annoying

[Saleen836]

Dronan said:

I love my st it’s a lot of fun,but this gremlin is ruining my fun,it just seems to be missing some power and this hesitation problem I can’t find the solution to is annoying

Have you googled the symptoms?

I had a quick google and it looks like a common problem

[Dronan]

Yea iv looked everywhere just seems like I’m goin have to start with the cheapest thing and work my way through it until I fix the fault.

[Dronan]

Iv been under the car this morning and found two clamps are loose and will only tighten so far before they slacken off.maybe this could be the problem.would this cause a boost leak even though the hoses are still connected?

[GreenV8S]

Dronan said:

will only tighten so far before they slacken off.

That sounds as if you may be describing a stripped thread on the clamp. If so the clamp would need to be replaced. That could potentially lead to a boost leak which could cause the erratic symptoms you describe.

[Dronan]

HI guys I never got to the bottom of the problem,but on the way home tonight the car is struggling to boost.Its started juddering and is struggling to accelerate.it feels like it wants to stall when accelerating.Its also vibrating strangely on idle.Yet again there’s no engine management lights on any ideas guys?