Boost/Horrible fuel consumption problem

[redflagquattro]

Ok so im finally posing because i cant seem to figure this out. I have an 01 dbw with unitronic stage 1+, aeb head, testpipe, ghl catback, 034 ext manifold, forge splitter, tip, phenolic spacer and aem dryflow. I was having some boost problems with the car, it would sometimes hit 25 psi and but it wouldnt feel fast at all. The boost is just so damn inconsistent its all over the place. It would somtimes spike to 25 and hold it, and other times back of and settle at 15 or 10. This was also with a J valve. I finally got this straighteded out by fixing my injector seat leak, changing out my 6E's that were toasted with a black ring for some new 7E's, and switchched back to the c valve. Now the car boosts so much more consistently. I spike at about 18-19 and then settle to about 10-11, spmetimes 14 in some gears..this still seems low to me though as unitronic says it should hold 18psi. The car also seems to like it better when you roll onto the throttle into WOT as opposed to mashing it. I dont know i still think that the car is dropping boost way too much, because i get a nice pull when it hits 19, and then it just drops way too low. I cant see it having a boost leak either because i put the j valve back in to test it out, and i can get it to boost to about 22 and hold 20 in some gears.

The car has all new vacuum lines which i have gone over numerouse times, a new maf, new plugs as stated, new coolant temp sensor, and new valve cover and pcv hoses.

The one thing that is really killing me though is my horrible gas milage, about 17.4 an average. This is terrible. Also when i drive the car a little hard, the entire manifold, turbo, and front of the downpipe glows bright, molten red. I have gotten my 1.8T's to glow before, but nothing close to this severe and easy. The only thing i can think of is a bad o2 sensor. I logged block 030 last night and the numbers were still varying, im not exactly sure what i should be looking at with this value though. Could it really be the o2 sensor?. The only codes im getting are a below threshold because of my testpipe, and an ocasional intermitent signal for the second o2, i just figered these were for the testpipe. My dryflow airfilter is also about 2 years old, but ive cleaned it a couple times..i really doubt it would be that though. And i logged my fuel trims a while ago and they seemed to be fine, but im going to log them again.

Just need your 2cents guys.

[4BLKRNGS]

i can get as low as 19mpg but thats cause i drive WOT ALL the time

[audiness]

you're dumping way too much fuel in there somehow, the unburnt fuel is burning insidethe exhaust manifold and turbo. you need to get it sorted out asap, because this will severely decrease the life of the turbo, manifold, et.c

[B5A4Kevin]

i agree with audiness. that sound to be the most likely situation. are they OE injectors? try an injector cleaner service to see if that helps. one that runs directly on the rail (dealership or most shops) instead of through the gas tank is preferred. or, to be sure, get 4 GLASS (not plastic or paper) small cups. take the rail out with injectors still attached. put the injectors in the glasses. unplug all your coils (optional but suggested). make sure the glasses and injectors are secured so they dont fall over or spill, and that the glasses are large enough to accomodate the fuel. crank the engine for 30 seconds. see if one glass is more full than the rest, or if it keeps filling after you stop cranking. this would be the source.

[djwimbo]

My Unitronic Stage 1+ software(98.5 nDBW) is also an 18psi file. The previous owner claimed to have put in the J valve or "race valve", I ran the numbers and it's a stock one.

I boost 18psi spike and it tapered to 10-11psi at redline, holding 15-16psi from 3500-5300rpm. After the MBC(paired with the N75) install I peak and hold 17-18psi and taper to 14psi after 5300rpm up to redline.

As far as what you're seeing for boost, that's pretty normal. The small K0x turbos can't keep up with demand top end. For some odd reason this seems to be less of an issue in the MK4 world though.

As far as the manifold and turbo getting that hot, you have a serious issue. This is probably tied to the fuel consumption as well. Do you have a CEL? and what injectors are you using?
It's possible that you have an injector stuck open and dumping fuel 100% of the time. That would result in a lack of power, poor fuel economy and probably your afterburn in the manifold.

[biketsai]

I think you should be running the 6E's with your K03. Also, maybe a MBC would work and be more consistent than those different N75 valves.

[djwimbo]

I think you should be running the 6E's with your K03. Also, maybe a MBC would work and be more consistent than those different N75 valves.

true, I switched from the 7E's to the 6E's and noticed a lot smoother engagement of power, quality of idle and no change in MPG.
The 7E's are colder, if it's beating the hell out of the 6E's that pushes more for a fueling problem.

[redflagquattro]

Yeah the injectors are oem AWM injectors, and i do get a check engine light but its a below threshold code for the testpipe, thats it though. Yeah i never really thought about it being an injector problem. Now shouldnt i be able to diagnose the injector issue by looking at my fuel trims at idle though?

And as for the plugs, ive never ran a set of new 6E's with this setup. It trashed the 6E's that were in there so i figured id give the 7E's a try and have had good results with them. But i think with my current problem the plugs are somewhat irrelevant for the time being, since it is pointing to a pre-combustion issue.

[redflagquattro]

No one else has any input on this? This fuel thing is killing me.

[Audi_A4_1.8T]

check the condition of the coil packs...

[bob12312357]

As far as what you're seeing for boost, that's pretty normal. The small K0x turbos can't keep up with demand top end. For some odd reason this seems to be less of an issue in the MK4 world though.

They are completely diffrent turbo's and the V-dubs is larger...

[redflagquattro]

check the condition of the coil packs...

all four are brand new