Audi B5 1.8T ... Slooww .. but whyyy ?!

The Overclocker

New member
the car is a 1999 audi b5 1.8t aeb tiptronic , bought the car with 94k , now has 113k

ever since i bought the car list of parts changed because of this power issue ..

sparkplugs
Forged Dv
N75
mass air flow
fuel pressure regulator
new vacum hoses
leak test,ok
added spring to the wastegate to help is close properly
was so despirate i Unitronic it ... did not even gain 1% of power...

im suspecting the cat to be clogged up
or
fuel pump not enough pressure
or
o2 sensor
or
bad turbo... but the car was owned by a old lady and had only 94k ..so i doubt it

im loosing my mind.. on this car but after all ther money ive put into it .... im not going to abandon this power issue but i need tips on what this could be


i have a 2003 jetta 1.8t as well BONE stoke at 100% ..

when i log the audi on vag com it says 126g/s peak air flow tough mass air flow ..

the jetta is at 167g/s .. the jetta DISTROYSS the audi in power .. but the audi is supposed to be at 18psi of boost .. so wtf !?
 
Old lady A4's are the worst A4's.

They put whatever kind of oil in the engines at those 15 min oil change shops, and never spooled the turbo. Did you check for play in the turbo, does it spin freely? Any evidence of sludge in the motor? Did you check the compression?
 
Well that sucks.

On the cat side. I damaged the 3" high flow cat on my turbo civic once and it fell right on its face.

Felt like the engine had 50hp instead of 300wp.
 
Last edited:
Old lady A4's are the worst A4's.

They put whatever kind of oil in the engines at those 15 min oil change shops, and never spooled the turbo. Did you check for play in the turbo, does it spin freely? Any evidence of sludge in the motor? Did you check the compression?


no play in the turbos shaft, no evidence of sludge when i changed my vc gasket last week , never did a compression test


Well that sucks.

On the cat side. I damaged the 3" high flow cat on my turbo civic once and it fell right in its face.

Felt like the engine had 50hp instead of 300wp.

the clogged cat idea has been fucking with my head since a longg time .. as much as the internal waste gate flap on the hot side of the turbo...

thanks for the info on you're experience


additional info

changed my fuel pressure regulator today because yesterday after pushing it for 2 km, i stopped popped the hood and smelled the engine , then i found a gas smell, came from the regulator, removed the vacuum hose and it was smelling preaty bad, diaphram was busted gas was going into the intake , back into the engine ..

im guessing to much excess fuel, some not gething burned, finding its way in the cat then its melt because of excesive heat !?

im just going with logic .. let me know if it makes sence
 
im really suspecting either Clogged cat or broken wastegate flap located in the hotside of the turbo

good thing is, separating turbo back from turbo will reveal both suspected issues

edit:

i think thats what i'm going to do , i have a Rdv in less then a hour at a reputed shop, im going to tell him to seperate those two for inspection and if all ok do a fuel pressure test

all this in 30 min should be possible in my guess and will be well worth it
 
tiptronic kill all the power of A4 ... even if the car was brand new ... even chipped

I've read this on many many audi/vw forum some years ago ... manual or nothing for a 1.8T ...
 
no codes from Tranny according to vag-com

How about torque converter? How is the oil level in the tranny?


Knowing how to check transmission fluid on Audio A4 2001 is important for standard maintenance on your vehicle. You should check the transmission fluid periodically to make sure you have no leaks and that it does not have any foreign material in it, which would signal a fluid leak. It is a bit more complicated to check the transmission fluid on your Audi since there is no transmission dipstick. Instead you must drain a bit out of the transmission and inspect it. Follow these steps to check the transmission fluid on your Audi A4, 2001.

To check your 2001 Audi A4 transmission fluid, you will need:

•Jack
•17MM hex key
•Drain pan
1.Start the engine and drive the car for approximately 15 minutes. This warms up the temperature of the transmission and transmission fluid to normal operating temperature.

2.Park the Audi A4. Shift through each of the gears, starting with "Park," one at a time. Place the vehicle in "Park." Leave the engine running.3.Jack up the front of the car so that you have access to the automatic transmission drain plug. Locate the fill plug.
4.Place a draining pan beneath the transmission. Clean the drain pan so that you can properly inspect the transmission fluid from the car.
5.Remove the fill plug on the drain pan using a 17mm hex key. If transmission fluid drains out of the fill plug then it has plenty of transmission fluid in the transmission. If not, you will need to add some using a special tool that siphons it into the transmission fill plug.
6.Insert the fill plug back into the transmission. Tighten the fill plug and remove the drain pan. Inspect the transmission fluid for any foreign substance. The fluid should be red and clean
.
 
tiptronic kill all the power of A4 ... even if the car was brand new ... even chipped

I've read this on many many audi/vw forum some years ago ... manual or nothing for a 1.8T ...

if the audi can perform like the jetta , witch is tiptronic as well , id be sooo happy !


How about torque converter? How is the oil level in the tranny?


Knowing how to check transmission fluid on Audio A4 2001 is important for standard maintenance on your vehicle. You should check the transmission fluid periodically to make sure you have no leaks and that it does not have any foreign material in it, which would signal a fluid leak. It is a bit more complicated to check the transmission fluid on your Audi since there is no transmission dipstick. Instead you must drain a bit out of the transmission and inspect it. Follow these steps to check the transmission fluid on your Audi A4, 2001.

To check your 2001 Audi A4 transmission fluid, you will need:

•Jack
•17MM hex key
•Drain pan
1.Start the engine and drive the car for approximately 15 minutes. This warms up the temperature of the transmission and transmission fluid to normal operating temperature.

2.Park the Audi A4. Shift through each of the gears, starting with "Park," one at a time. Place the vehicle in "Park." Leave the engine running.3.Jack up the front of the car so that you have access to the automatic transmission drain plug. Locate the fill plug.
4.Place a draining pan beneath the transmission. Clean the drain pan so that you can properly inspect the transmission fluid from the car.
5.Remove the fill plug on the drain pan using a 17mm hex key. If transmission fluid drains out of the fill plug then it has plenty of transmission fluid in the transmission. If not, you will need to add some using a special tool that siphons it into the transmission fill plug.
6.Insert the fill plug back into the transmission. Tighten the fill plug and remove the drain pan. Inspect the transmission fluid for any foreign substance. The fluid should be red and clean
.

i will definitely do that since im wondering on the tranny's oil level, thank you

but this could affect the power ? my power problem feels like huge turbo lag basicaly i feel like the tranny on a other hand is very strong and does not slip
 
ok the update is that i forgot to mention that i hade 2 dtc that i cleared p1136 + p1556

cleared it .... came back just in time for the mecanic to see it ..


he told me usually thats related to the crank case pcv valve

at idle i'm at 14.8% over fueling ... thats wayy to much according to him

he test drove the car , wot couple of time and he didint feel like the cat is clogged up he told me the car would be moving a lot less

so now i'm leaving the car cool down

then attacking that crank case pvc valve !!

please share toughts and ideas on what else should i check
 
Cat clogged
Diverter Valve
MAF sensor (did you buy a Bosch?)
Spark Plugs (Don't buy Champions)
Shaft play in turbo
Dying O2 sensor
 
pour tester un o2 sensor ... vag com doit être en mesure de logger le voltage non ?

Après que l'auto ai idle pendant 2-3 minutes (le voltage devrait etre asser fixe pendant ce temps la ces normal). Après le voltage devrait fluctuer constamment entre 0.1 et 0.9 volts.

0.1 étant lean et 0.9 étant riche.

Si le voltage reste fixe ye mort, si le voltage ne monte jamais en haut de 0.5v ye mort, si le voltage depasse 0.9 volts ye mort, si le voltage ne fluctue pas apres 3-4 minutes ye mort.

après quelques minutes de idle et si toute es beau essaye de peser sur le throttle, voir si le voltage bouge accordement.
 
Sur mon ancien GTIR j'avais un mega power loss ... meme en boost je le sentait pas.

Le problème était mon o2 sensor ! Je l'ai remplacer et boom, toute était revenu normal.

Sinon ta aussi le Knock sensor qui peut faire chier.... ton vag com détect tu le Knock voir si tu tombe dans les safe maps ?

As tu jouer avec le timing tu moteur ?
 
I know my B6 A4 1.8T was slow as shit and it was reflashed and had a test pipe. It was a tiptronic quattro. My friend had a B6 A4 1.8T quattro as well but manual and he was just a bit faster. These cars are just slow. Is your Jetta 4motion? Or is your A4 FWD? The Jetta is probably faster because it weighs a lot less.
 
i think i found one of the problems


the 034-129-101B valve , if i blow both ways or pull both ways there is no restriction .... could this be the issue im having !?

and second issue -->

and did the leak test , removed the 034-129-101b valve, blocked the port

i found a small leak i fixed it , but i hear bubbling sound from the engine , don't know if its the oil or antifreeze bubbling

is this normal as well ?
 
i think i found one of the problems


the 034-129-101B valve , if i blow both ways or pull both ways there is no restriction .... could this be the issue im having !?

and second issue -->

and did the leak test , removed the 034-129-101b valve, blocked the port

i found a small leak i fixed it , but i hear bubbling sound from the engine , don't know if its the oil or antifreeze bubbling

is this normal as well ?

The Pressure Control Valve provides a one way exit for gasses built up in the crankcase. Over time, contamination might cause reduced air flow and cracks can occur in the housing. If your car is experiencing a loss of boost pressure or a decrease in performance with a rough idle, this valve might to be blame. This valve sits on the intake hose for the turbo inlet.

Check ALL of your crankcase hoses, positive crankcase valve etc. That pressure control valve or pancake valve prevents boost from going into crankcase. So does the positive crankcase valve ''PCV''
 
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