HELP! My ongoing Weird ST issue...

[Grombil]

2015 Fiesta ST. Stage 2, downpipe, Milltec catback, R-Sport intake, Bigger IC, Quaife diff, New Clutch and flywheel, Big break kit, OZ rally wheels with Nankang NS-2R 205/40/17.

I "raced" a Golf GTI and at 6000rpm or so i let off and get a puff of smoke behind me (ECU protecting the engine i assume). After this the car starts bogging down as soon as i get boost. It bangs in the exhaust like im about to go on the 2 step.

I have changed spark plugs just prior to this but it ran fine for a few trips before this happen. I also pulled them and they look fine. Plugs was from Pumaspeed and pre gapped. After this i changed MAF and MAP sensors, new coils, comp tested all sylinders and they are fine. Also bought new sensor with the turbo with 3 small rubber hoses... Now the fault may happen at higher rpm... We tested fuel pressure and it dosent drop on full wot even when it starts to bungle. A mechanic felt it was like water in the fuel or condensation so i added some treatment, ran the tank empty and added full tank of 98octane...But it still the same...

Culd this be injectors? Any other suggestions to what to do next?

 

[Mega ST]

Is it generating boost? Can you monitor? Could be a charge pipe blew off.

 

[TyphoonFiST]

Is it generating boost? Can you monitor? Could be a charge pipe blew off.

Could've crapped the exhaust turbine i there is No Boost* Gotta take the DP off though for INspection though.

 

[Grombil]

Yes there is boost... It still rips but uneven

 

[Grombil]

Could've crapped the exhaust turbine i there is No Boost* Gotta take the DP off though for INspection though.

I have healthy boost as far as i know. I shuld take a video to show. It goes if wot but it has small "dipps" like if ignition was on/off... So im thinking if an injector is having troubble it wount give a code would it?

 

[LucasHigh]

If it was misfiring it would normally throw a code, I would also try to watch AFR to make sure those stay consistent

 

[TyphoonFiST]

If it was misfiring it would normally throw a code, I would also try to watch AFR to make sure those stay consistent

Not unless it hits the Misfire threshold. every manufacturer is different. Every car misfires some. But not alot. I think its fuel related

 

[fiestar]

Have you noticed any difference in fuel consumption since this started happening? Could give a clue about what's going on.

 

[LucasHigh]

Not unless it hits the Misfire threshold. every manufacturer is different. Every car misfires some. But not alot. I think its fuel related

thats what I was thinking as well

 

[Grombil]

Have you noticed any difference in fuel consumption since this started happening? Could give a clue about what's going on.

First of all THANKS for helping me out! All of you...!!!

Not realy... It might be higher but if so only slight. AFR seem to be ok even at wot- Also checked fuel pressure and its consistant.

Im thinking something happen that time i raced the GTI... The puff of smoke most likely was the ecu protecting the engine. Question is what can give this reaction...? Would a bad injector result in this? Would a blown headgasket result like this? There is no mix of oil and coolant either in engine or in the coolant. No smoke while driving either blue or white... It runs fine until å push it... False air cant give these symptoms? I looked over everything and its fine... I will do a comp test and leak test again. Just to eliminate it!

Since the stuttering is not regular and wount hinder me to reach full rpm i agree that it could be a gas issue but i did put some stuff to mix if there is condensation and also i drove it to 0km in range and filled it with 98octane with no ethanol...But its still the same.

Could a bad injector give these symptoms?

 

[LucasHigh]

come to think f it when i had an injector go bad the car stuttered nonstop under throttle but idles fine, might be worth checking your injectors, I know also that the high pressure fuel sensors have a tendency to go bad but i feel like that would throw a code.

 

[Grombil]

How wold you go about testing Injectors on these? Since idle is fine, even up higher as well...Sometimes it stutters just by getting at boost and other times only at harder acceleration. Maby time to get bigger injectors and a turbo...

 

[LucasHigh]

as far as I know to test injectors you have to put them on a test bench, if you plan on pushing your car really hard I definitely recommend the double sealed injectors I know @Woods247 is trying to sell a set