Cleaned MAF, and car is slow again :(

[McDub]

i just checked the date of my original post, i've had this problem for 4 months now

ok since i last posted those dyno readouts, they were sent off to Unitronic in California. Their response was apparently:
-car is boosting as it should
-problem is with the intake, possibly new MAF is a dud

So we tried putting another MAF on the car, no improvement.
Then we tried running it with the airbox removed, no improvement.
The only thing left on the intake was then the TIP.
I'm guessing the thought was that the pipe may have been collapsing under vacuum... though i would have thought that the MAF would still give the correct reading for the airflow, perhaps only slightly out... so not sure how the A/F ratio would be wrong...

So anyway i was told to try a new TIP, so i purchased an APR one, about $250 delivered.
Installed it today (pain in the arse to do! coolant pipe bolted to the motor was a biatch!) and unfortunately, i havn't done new times but it hasn't made a noticeable difference to performance. the engine seems to begin to drown when you get to 4000rpm. The car does seem a little smoother now though, but that's the most i could notice and could have been in my head.

So what's been replaced/installed:
MAF
TIP
Sparkies
N75J
R1 diverter valve
Coolant temp sensor

result:
still ****

me:
not happy

Are we sure that the readings from the O2 sensor are not used at WOT?
Cos that's the only thing i could think of replacing. Other than that, maybe my fuel injectors are playing up for some reason and are spraying in too much fuel, or perhaps my ECU or the Unitronic program has played up.

My next step is to confirm the performance is still down (get another time), and then call up my VW mechanic and get him to speak to Unitronic again...

but any more ideas from you guys?

[Golf Loon]

Gotta be the lambda sensor mate.
Bring it down to us and we will diagnose and fix it without taking ages and costing you a fortune.

[Jmac]

Gotta be the lambda sensor mate.
Bring it down to us and we will diagnose and fix it without taking ages and costing you a fortune.

Before fitting the lambda have you actually read it live???? go for a drive and log it till it plays up, then read the data. The data wont lie. Man made man fix. As for time to diagnose i would be foolish to say it would take me 2 mins as i havent seen the vehicle , same as an internet and phone call diagnosis is. Faults can take 2 mins or however long. Speaking from lots of experience.
Hey McDub you are right at WOT u are back on open loop mate, lambda doesnt come into play , have someone read the MAF again, had a couple up here needing another MAF as the new one was Duff. Unfortunately some Bosch bits are made in china now. Read the live data, thats the way i saw the new Maf was duff mate, has happened more then once now with new bits, lots of wasted time but final result was good
Cheers
Jmac

[McDub]

thanks guys for your help.

as long as i know, it was logged during a drive, but i do not believe at WOT.
basically you have both confused me now and i don't know what to do...

in regards to MAF, the original after cleaning caused me the initial concern, i bought a new one after advice from my vw mechanic, it didn't change a thing, and then as a test we put in one from another persons car and it didn't change the time from 40-100km/h in 2nd gear.... (6 seconds exact), so pretty sure it's not the MAF (though can't say for certain, i'm an engineer and neverl will!!) Only other thing i can think of is that for some reason, the car SHOULD be running on open loop, but for some reason, it isn't, and as a result it actually is running off a bad signal from the O2 sensor.... i don't know that's the best i can think of..........

so now as i have said, i'm very damn confused, if it's not the lamda and not the MAF, what the hell is it??

[Jmac]

Air leak. Like i said before test the reaction of the lambda probe.If its going crazy u should have some codes. Trick the "dumb" computer by pulling secondary air watch it react then squirt some carby cleaner up it or clamp off the return line, this will richen up the system, watch the reaction of the lambda probe. WOT you are in open loop so no point testing it then
Pretty sure i mentioned ages ago on this very subject to have it smoke tested. This is the sure way to find ANY air leak in the system , be it a gasket ,seal or hose.
My next suggestion would be to flash it back to standard and see what its like, this would verify if in fact the software is the root cause
Jmac

[McDub]

Air leak. Like i said before test the reaction of the lambda probe.If its going crazy u should have some codes. Trick the "dumb" computer by pulling secondary air watch it react then squirt some carby cleaner up it or clamp off the return line, this will richen up the system, watch the reaction of the lambda probe. WOT you are in open loop so no point testing it then
Pretty sure i mentioned ages ago on this very subject to have it smoke tested. This is the sure way to find ANY air leak in the system , be it a gasket ,seal or hose.
My next suggestion would be to flash it back to standard and see what its like, this would verify if in fact the software is the root cause
Jmac

but you're saying that at WOT, there is no point testing it, well that is when i notice problems with the car, at WOT... so i don't see the point then
and yep i took on board your suggestion for leak testing, though i figured that there is now no problem with the intake, and i don't see that there would be a problem after the turbo because the car is boosting very well, am i right to think that?
and yeah i suggested "reflashing" the car to my mechanic but he didn't think it was the problem...

[Jmac]

Ok ok my bad for trying to explain how to check an O2 sensor At the same time my bad for not reading your post properly, ok then you are only experiencing this drama at WOT. The ecu will disregard the o2 sensor at that time. Take the car out and log it again, read the MAF. On a tuned 1.8T it shold be reading around 160g/s 2nd gear close to redline, if this is significantly lower then the MAF is suss. Now you have fitted a new one. I did to one last week and the new one was duff. Other side of that coin is the MAf might be ok , but what about the wiring to and from it. Wouldnt hurt to check fuel pressure too. Hook up a gauge and stick it under your wiper and go for a drive. Pressure might be ok , check the flow too. I would also be tempted as before mentioned to revert to standard program to see what its like. I gather this is very noticeable???
Jmac

[brodzta_GTI]

id be inclined to have the Altitude sensor checked.. i work at a vw dealer ( or stealer as ive read a fair bit ) and we've had a few 02/03 GTI's come in, not boosting.. run our usual tests on any faults then find the altitude sensor has failed ( Note: It wont throw any faults at all).. my 01 gti's sluggish every now and again and im slowly working through the test plans for the fault ( 00561 Mixture Adaption Value too high.. does your have that fault?? check for any exhaust leaks above the lambda probe, could be the fuel pump, the activated charcol canister purge valve or it could be the fuel pressure regulator ( these are the componets the VW scan tool says to check).. with the thermo fans staying on, it could of been the coolant was still hot or it could of been the coolant temp sensor ( the black ones were superceeded to green ones as they were failing causing the gauge to become erratic, poor fuel economy and the thermos staying on.. hope all this helps

[McDub]

i bring good news.

car is fixed! (well pretty sure it is, still want to check it on a dyno to make sure the air fuel ratio is good)

after 5 months (mostly me being too lazy), around $1600 in parts (including the faulty part, and many parts which where probably due for replacement anyway), the $100 spent proving it was stuffed by getting it tested on a dyno, and only about 4 hours charged in labour (a lot more time was actually spent trying to find the problem...) the culprit was>>>>>

THE STUPID THROTTLE BODY

Everything about the throttle body apparently showed it to be working fine throught the computer, it performed the adaption process and all that.
basically, because they had gotten to the stage where they had logged just about everything, even repeating the log runs on a hot day to see if the issue was more obvious at high ambient temps (plus car felt a lot more sluggish on hot days), it got to the stage where as just about most things had been changed, eg. maf, coolant temp sensor, diverter valve, n75 and so on, it was a case of simply trying to replace the remaining parts in a last hitched attempt to diagnose, like the o2 sensor, inlet temp sensor and so on. in the end, a new throttle body was put in, and bingo, car got it's grunt back, and this showed on the maf readings also, with the readings increasing from around 140 to 180.
if none of these replacements were going to fix it, they were going to re-write the program to adjust the fuel pulsing or something like that... good thing the fault was found beforehand.

so now i've got my old throttle body which is a complete mystery, it seems to work, but replacing it fixed the car...
anyone heard of such a problem before?

[schwartza3]

throttle body
what angle was it opening to before vs now?
180g/s is a very good reading!