Hesitation killing my will to live (SOLVED)

[ExiledWeegie]

the ones in there are NGK Platinums PRF6Q,, its got to be running a bit rich with the black plugs, the unburnt fuel burbling in the exhaust when off throttle and the LTFT having to lean out the mixture a bit, I know obviously its still within tolerance but it could be a bit lower than -6.2% thats its now sitting at.

 

[nd-photo.nl]

Found this Beru document I had on my laptop

 

[ExiledWeegie]

according to that document its Cold/Carbon Fouling, when I run my finger round the plug its comes off as black soot.

got the new BKR7E plugs, still waiting on injectors and a feeler gauge, cant find the one I had and I dont trust the little round gap tool I have.

 

[ExiledWeegie]

got the BKR7E plugs, gapped to 0.028 and put them in, the misfires on full boost are gone and no codes so thats a win, still hesitation though sometimes before boost comes in and then sometimes when boost is in, injectors should come tomorrow and i bought an inlet manifold gasket so going to do both together, if that doesnt cure this I seriously dont know where else to go with it.

 

[nd-photo.nl]

Fingers crossed for you

 

[ExiledWeegie]

Fingers crossed for you

well thats the inlet manifold gasket done and 4 Bosch injectors in it, reset the ecu with battery off for 30 mins and took it for a 5 mile run, seems to be running good, didnt really give it any beans yet, time will tell now, im taking it for 15 mile run tonight so that should show more. cross your toes as well please, i need all the luck i can get with this thing

 

[nd-photo.nl]

Toes crossed en buttcheeks clamped with 100Nm force, check

 

[ExiledWeegie]

that was 20 miles done tonight, maybe a bit more, plus the 5 earlier today, car seems to be running good, I couldnt really open it up as the wife and son were with me but I monitored the fuel trims from setting off, got home and the LTFT is -0.8% so massive difference, those cheapo injectors mustve been pissing fuel through. tomorrow I'll open it up a bit and see if all the hesitation is gone but first impressions seem good.

 

[nd-photo.nl]

Good preliminary results, lets hope it solved for good now Seems like 100Nm buttcheek clamping force is the sweet spot

 

[nd-photo.nl]

Any update ?

 

[ExiledWeegie]

yeah not great, car deffo drives better with everything thats been done, the fuel trim is creaping up again though to -4.6% which im not too worried about right now, still a bit of hesitation though, sometimes on part throttle and on full throttle, like it misfires around 2000-2500rpm, the misfire count is disabled when driving though and theres no misfires at idle so I cant be sure what it is.

ive ordered a new bosch maf sensor to see if it makes a difference, ive no clue if it will though, really getting down to having tried everything except the coil harness or the turbo or some internal fault, although compression was really good when i tested it.

 

[nd-photo.nl]

Hmm annoying...Might be worth going to a specialist if you can reproduce the behaviour easily. But first try the MAF. Did you also try disconnecting the MAF and trying to reproduce?

 

[ExiledWeegie]

today the fuel trims are at -7.0%, thats the highest ive saw them, hopefully maf comes soon and i can see if it makes a difference

also noticed that on the obd monitors the catalyst is not completing, it used to complete fine, only thing that didnt was the SAI as ive got that blanked and code deleted. could the secondary O2 sensor be causing fueling problems? i know that some folk say that it doesnt do anything other than monitor cat but ive also saw others say it has an effect on fueling too, i have no codes for it showing.

edit: found this...

A faulty secondary (downstream) O2 sensor on a 1.8T engine can lead to fueling problems because it signals the engine control unit (ECU) that the catalytic converter isn't working efficiently, potentially causing the ECU to over-fuel the engine in an attempt to compensate, resulting in decreased fuel economy and potential performance issues.

so with this in mind, i have a 200 cell sports cat and ive got a 90degree angled spacer on the post cat sensor, and the cat not completing the readiness test, it could be something to do with post cat sensor?

edit 2:

just had a look under the car and the plastic coating is all burst on the wire to the secondary o2, can see it dangling down a bit, hope its really as simple as just changing this sensor, ordered one, lets see lol this bloody car will be brand new by the time ive sorted this.

 

[nd-photo.nl]

Hmm, split wiring is not good. I was under the assumption that the secondary O2 was only a control O2 sensor.

Please note that O2 sensors have an replacement interval, that almost nobody respects (replace only when broken). Usually they should be replaced around 175-250k kilometers.

 

[ExiledWeegie]

yeah so was I until I read that earlier, the majority of people say it doesnt affect fueling, but then you find info that says it does, hard to tell but I will replace it anyway after seeing the rubber coating all torn.

also my car is at 146000 miles which is roughly 235000km so right within that time to change, the front wide band is already new, only a month old.

 

[nd-photo.nl]

Let the clenching begin (again)

 

[ExiledWeegie]

god damn this car!!!!

just found 2 of these bolts finger tight, like so loose i could just unbolt them with my fingers all the way, I had just put on the new maf sensor and while i was there thought id try tighten up the manifold to cat bolts see if there was any of them just not tight enough, while I was there I checked these bolts and 1 was fairly tight, still managed to get a turn or two on it but 2 were crazy loose.

why would that be? just vibration working them out or have they been off at some point and not re-torqued up? is there any locktite supposed to be on them? (although would that even work with them getting so hot)

I'm now wondering if this is the problem all along, a big leak before the wide band o2 sensor causing overfueling and the hesitation, if it is then Ive spent some amount of money and put in some amount of time for something as stupid as a couple of loose bolts Im now letting the ECU reset with battery off for a while to reset fuel trims and whatever else so over next couple of days I'll see if this had cured it or not.

 

[nd-photo.nl]

Yes, they are known to come loose due to vibration, especially with aftermarket headers. If I remember correctly, the original bolts have something to prevent them from coming loose (like a ribbed collar or something)

 

[ExiledWeegie]

still getting a slight bit of hesitation, noticing it more in 2nd and 3rd at part throttle, I had the TIP off today (fun job) to check for any splits but none found, looks in good condition. also noticed fuel trims are now showing -7.8% after a 110 mile run last night, fuel economy is really good though, getting 20-25mpg around town and on the long run I got 42mpg so very happy with that.

contacted the guy who mapped it about the running rich and he said because its an older car and all the mods Ive got its basically set up for stage 2 but as Ive got a stage 1 it could just be seeing lots of air and adjusting fuel to match, hes going to do a carbon clean on it and we will talk more about it then.

I'm thinking this hesitation is gonna end up being the coil pack harness and throwing the odd small misfire, I dont see any at idle and when driving the misfire count is disabled in vcds so cant tell if it is or not.

 

[nd-photo.nl]

Carbon clean is not necessary, as its a port injected car

How did it work out with the turbo manifold?