Hesitation killing my will to live

[ExiledWeegie]

hi guys this might turn out a long post but I need some help badly and I'll write every bit of info I can...

I am getting a bit of hesitation on boost from when the turbo kicks in and at higher boost, it happens at part throttle and at full throttle. so far heres what Ive done to try cure the problem....

New Bosch Maf sensor
New Febi Coolant temp sensor and Thermostat
New Alpha Competition blue coil packs
New NGK plugs gapped to 0.030 (any lower and I get misfires at idle, any higher and I get misfires at high boost)
New Febi MAP sensor
New Febi rocker cover gasket
New PRV valve and PCV valve with motorcraft silicone hose to simplify the PCV system
New alternator and battery
New coil pack connectors
New wide band O2 sensor
New fuel injectors
New Lucas throttlebody
New Lucas intake temp sensor
New Febi timing belt and waterpump kit (2000 miles ago)
New Lucas crank sensor
New Lucas Cam sensor

now onto the mods....

Stage 1 remapped (had this taken off and it still hesitates so had it put back on also had the sai incorrect flow fault code mapped out)
Toyosport front mount
TA Techniks 200 cell sports cat
TA Techniks Straight through cat back
Ramair Cone air filter
Forge 007p DV
N249 Bypass
SAI blanked
All useless one way valves and vac hoses deleted and ends plugged where applicable. (except the charcoal cannister thats still attached)

Ive tried smoke testing the system and all is air tight, the idle is stable at 740-760rpm and vac is -25 inHG on my boost gauge and doesnt move, also the oil cap is under slight vac and when taking it off or the dipstick out you can here the car idle change so I think the whole vac side is working well. Ive completely sealed exhaust system and there is no leaks at all from it. Ive also replaced the 2 coolant elbows, one from the block and one further forward and flushed the coolant system when doing it. its been serviced with new oil and bosch oil filter last month. I also tried a compression test and the numbers were great for a 21 year old car.

I reset the ECU earlier today and went for a short run and fuel trims look good at 0.8 idle and 0.0 long term, everything I can see looks good in the data the only thing I could see was the MAF seemed a bit low at idle? 2.0-2.2g/s, Im getting no codes at all in VCDS and no light flash or anything when the hesitation happens, I'm completely stumped to the point Im getting a bit depressed about it, I just want it to run right and I cant keep throwing money and time at it.

heres a couple of pics of Torque Pro monitoring at idle.

Do I now move onto the N75 or fuel side and hope that replacing the fuel pump, FRP or the fuel filter will cure it? (fuel filter done 6 months ago)

please any help would be greatly appreciated before I burn it.

 

[Connor H]

jesus you must have spent a fortune mate

N75 solenoid controls the boost, try changing that.
You've bypassed the n249 but is it mapped out?

Other than that you'd be better off spending your money on an expert with VCDS. Or spend a day with your tuner to find where the hesitation comes in and whether the hesitation is the ecu pulling back or something mechanical holding it back. "Hesitation" really could be anything.

 

[ExiledWeegie]

Thanks for the reply, thankfully I do all my own work so saving a lot on labour but the parts cost is starting to rack up.
I havent had the N249 mapped out, Ive left the valve plugged in so as not to throw any codes but theres no vac lines attached to it at all.
I did try a new Febi N75 part number 107865 but it didnt make any difference and the hesitation was still there, might have a been a duff part?
I have VCDS but I'd deffo need pointed in the right direction of what I'd have to do with it or log with it to show here.
The guy who mapped it stays quite a bit away and he was already good enough to put it back to standard to see if the hesitation was still there (and it was) so I dont think its because of the map tbh, but who knows at this point.

 

[Connor H]

Funnily enough i used a Febi n75 as a replacement before tuning mine and the sensor went straight in the bin on tuning day. Try to get genuine sensors where you can, but n75 is one that 100% has to be genuine. For VCDS help most people will steer you to the Rosstech forums, but you're in for a lot of learning.

 

[ExiledWeegie]

I will give it a try mate, do you know if Im best just getting a like for like replacement or do I need to upgrade it to one of the different versions like the J valve?

edit: cant find a genuine one at all, looks like they were made by Eaton but not finding any for sale anywhere, plenty Febi and other brands out there but none that fill me with much confidence

 

[Connor H]

Go to any VAG dealership wit hthe part number mate, only place im aware of these days. Maybe TPS if youre a trade

 

[nd-photo.nl]

- Is the N112 still connected electrically? It sits on the same bracket as the N249 valve (the bracket connected to the intake manifold).
- 100% agree, get an OE N75 valve. Just get the latest revision, not the J-version or anything weird.
- Is the jet suction pump still connected (connected to the brake booster hoses & intake manifold)

I think you need to log, especially with requested boost vs boost delivered

Especially the long term fuel trim is interesting. Having it sit on 0.0 is a bit sus though.

 

[ExiledWeegie]

The N112 is still connected electrically, but no vac hoses attached, everything under the plate has been deleted.
The suction jet pump is gone too, PCV system has been simplified to a aluminium PCV valve, 2 silicone hoses and the PRV valve (pancake)
The ECU was reset just before I took the pics of Torque Pro so I had only done a couple of miles, the usual long term fuel trim is around -4.7% to -6.4%.

I'll see what my local Seat dealership says about a new N75, the only one Ive been able to find so far from Eaton is second hand on Ebay, theres another listing which shows the Eaton one in a new VW box but its a foreign seller with bad feedback and their only a tenner each so set alarm bells ringing.

 

[nd-photo.nl]

Ok, reason I asked about the suction pump was that it tends to leak. So good decision there, I also deleted it back in the day. I used a wheelbolt to plug up the hole haha

Eaton is OE supplier for N75, thats correct. Luckily I create pictures for almost everything

I cant remember correctly, but I think you cannot just disconnect the N112 with the hoses. It might be that it should be mapped out. But the N112 needs to stay connected electrically, else your primary lambda correction will not work (something I found out when I went to stage 2).

Long Term fuel trim could be a little lower, so that might be an indication of something

 

[nd-photo.nl]

If I recall correctly, there is a simple test you can do with the N75. It should allow air to pass through 1 or 2 of the 3 holes (in total). Air should pass freely, if you notice resistance, that could indicate that it needs replacing.

Do you also tested the Forge 007 with the finger test? Push in the piston, hold your finger on the vacuum nipple. The piston should stay in place, if not it should be serviced.

Also the latest service kits from Forge added a rubber O-ring on the piston, which allowed for better seal. I ran with a Forge DV006, which flowed better than the 007.

Forge 006 service kit

Forge 006 new vs old piston

 

[ExiledWeegie]

thanks for the help you guys, we could be getting somewhere.

regards the 007p, I just serviced it with new grease and new yellow spring from Forge, I also made sure that when I press the piston and cover the vac port the piston holds, then pops back down when I release my finger so seems all good.

Im just this minute back from a 15 mile run, the long term fuel trim is sitting at -4.7% when I got home so roughly the same numbers as always, seems to be running a bit rich.

Also I did some foot flat to the floor tests and it seems like boost cuts in and out and the boost gauge vibrates big time during this and the car is jerky, so deffo a sign of a dodgy N75?

The N112 is still connected electrically and I get no codes at all with VCDS.

heres some pictures of the engine bay see if anything can be spotted...

 

[ExiledWeegie]

started stripping all the blue hoses out around the N75 to see if anything was burst or if the clamps werent done up tight, everything seemed to be fine but now that Ive put everything back on and took it for a 10 mile run it seems the hesitation is gone from full throttle, the turbo peaks at 20psi and holds steady at around 17psi, didnt feel anything that felt like it was cutting boost and now theres no juddering boost gauge either, I wonder if one of the clamps was stuck and although it felt tight it just wasnt tight enough to be holding above a certain psi. (im not going to count my chickens with this too early though, will see what its like over next couple of days before i call that fixed)

did notice a slight hesistation in 2nd gear when pulling away at a junction though, around 2500rpm like a flat spot, it did it 3 times on that run, wondering if thats something to do with the car running rich, I was monitoring the fuel trims as I went and the short term fluctuates a bit from -3% to +3% and at idle its usually 0.0% to -0.8%, the long term is still sitting at -4.7% after that 10 mile run.

 

[ExiledWeegie]

had to go out tonight and the car got another 20 miles on it and the long term fuel trim is up to -5.5% so day by day since the last reset its getting richer, it usually peaks between -6.2% to -6.5%, any ideas? could it be fuel filter or fuel pressure regulator? its got new injectors in it but could it be them? I wouldnt imagine its the fuel pump it seems to be much better driving and on boost now after todays messing with hoses.

 

[nd-photo.nl]

Are the injectors the same spec as the ones before, or did you need to upgrade them?

Could very well be that you need to code/adjust fueling a bit

 

[ExiledWeegie]

the injectors are same part number as the originals, although their aftermarket ones, the originals were bosch, i made a **** attempt to service them that resulted in 2 of them dumping loads of fuel through that it was shooting from the exhaust, so bought a set of ones from Ebay but they came in a brown box with just VW part number printed on the body of the injectors.

to adjust the fueling id obviously need to go back to the guy who mapped it for me and see if he could bring it down slightly in the map?

could the MAF reading low be causing the rich running? to me the 2.0g/s-2.2g/s at idle is low, shouldnt it be around 3.0g/s-3.5g/s?

 

[ExiledWeegie]

well.... took the car for a blast earlier and foot to floor it started juddering and cutting on and off boost, but this time the engine management light started flashing and all i had to scan it at the time was torque pro and it picked up a code for misfire cylinder 3, i cant see it being coils as these ones are new and the same happened with the old vw/audi coils, i dont know about spark plugs, i had super 4s in before and it misfired at idle quite regularly, now its ngk pfr6q, im starting to think with the long term fuel trims being rich and it having a set of no brand injectors in it its got to be them causing it so ive just bought a set of refurbed bosch injectors and a bosch frp and will see how it goes with them when they arrive.

honestly this car is killing me, sick to death of it.

 

[nd-photo.nl]

Swap the coil from cylinder 3 to another one and see if the misfire goes to that cylinder, thats the way to rule out coils. I also suspect the injectors at this point.

You will probably need to get the fueling adjusted, as the new ones will probably flow different than the previous ones.