A3 1.8T Revo Mapped...Not fully boosting

Matt_Turbo

Matt_Turbo

Registered User
Joined
Nov 12, 2010
Messages
19
Reaction score
0
Points
1
Location
NULL
My 1998 S plate A3 1.8t has been mapped for about 18 months now. When my mate had it done it was great, pulled hard. But over the past 18 months he hasn't hardly driven it hard maybe once in a while. Anyway I bought it from him yesterday afternoon and it's only running 7-8 psi so pretty much standard. Anyone ever experienced this before?

Regards,
Matt.
 
The best thing to do would be a vag com scan to see if anything comes up on there. Theres a lot that can cause your symptoms if the cars not running right it wont boost properly. You could also check the dv and look for any obvious boost leaks as well.
 
Just scanned if using a sealey vag scanner. I got codes 00561 and 16514. I do have a rough, hunting idle at times. Today i replaced the blue coolant temp sensor to get the gauge working. Getting really annoyed with it now
 
obviously faulty lambda. has it been decatted or anything? The 2 faults are probably related

Also you are probably only getting 8psi because of the misture deviation throwing it into limp or softlimp mode
 
Last edited:
Standard exhaust system no decat or anything. It doesn't go into limp mode as it still revs all the way round just feels like its on a standard map.
 
The 00561 code is a vac/boost leak iv had this come up many times in fact its coming up again on mine due to a leak between my throttle body and inlet manifold its a pain in the **** as you will have to go over all the vac lines and boost pipes to check for splits this would give you a rough idle as well. The lambda code could be thrown due to this but i wouldnt rule out a new lambda sensor yet but replace whatever pipes are split first and see if it comes up again.
 
A bad maf has thrown this code on mine before but i would sort out the vac lines first as they are cheaper if yours is an agu the mafs are over £100 even with an exchange basically start with the cheaper things first for obvious reasons. The most common are the pipes which are connected to the inlet manifold but tbh if they havnt been changed id do them anyway as the splits are not always obvious.
 
Checked all vac lines, all boost pipes and no splits or leaks. I need to pressure test the system really to check the intercooler as I've had a split intercooler before. Will also try unplugging the maf and driving it later see if the running changes at all
 
lol dude its showing up a blatent fault with the lambda, either a short or open circuit. This definately should be your first port of call
 
My guess would be something is upsetting the afr which is why the lambda code is coming up as it's seeing a difference in normal values. So i think i need to find out exactly what's going on with the live datafeed from vagcom?
 
As there are no boost/vac leaks the only things i can think of are the temp sensor , maf , iat sensor and maybe a clogged air filter i wouldnt rule out the lambda but as you know if the af ratio is way out it will log a lambda fault. This should help you out a bit but its hard trying to diagnose a problem from a computer screen lol.
 
I understand lol. A friend who recently sold his cable throttle golf 1.8t has his mapped and reckoned that only ran 6-8psi. Im sure it should run just over a bar one stage1?
 
I cant comment on boost pressure as i dont have a boost gauge something else i havnt got round to doing lol but i think its down to the map for how much boost there is but im not 100% im sure someone who knows more can verify this.
 
Just read your actuator thread. Going to check mine later never thought of it coming loose, however i did think of turning it up slightly yesterday
 
You could take a look at it but it doesnt explain the fault codes though when mine was slack it would build up boost and at about 3k rpm when it normally picked up more instead it was as flat as a witches tit and i was getting no codes.
 
The free things are always worth checking first. If it helps then i shall replace the lambda sensor as well. Will also check the maf tonight
 
Just ran the car with no maf and it idled perfect. Ran with no boost so i think that's where my problem lies!
 
Ok little update.

Bought a new MAF today and pulls alot harder. The 007p valve is still very quiet with the drilled box though which I find interesting, as I'm sure with a drilled box the recirc valve is normally quite loud still?
 
It looks like you have sorted it has the lambda code gone aswell? As for your dv you can turn it around and its supposed to make it louder you swap the end in the tip to go to the turbo and vice versa and your vac line will be on the side instead of the top if you understand me lol. I was going to do it today on mine but my driveshafts f****d up :haha: sorry for the technical term lol.
 
Haha i will give that a go tomorrow! Not had my ecu scanned again yet, but i guess the codes will still be there as i drove the car last night and today. It feels so good to have boost back, can't wait to route the boost gauge hose better so the door doesn't crush it anymore. I still can't believe how different it is it feels like a completely different car. I still have a rough idle though hunting etc think its overdue a service to be honest
 
Clean your throttle body as well makes a big difference if its full of crap it causes a bad idle.
 
Matt_Turbo said:
I understand lol. A friend who recently sold his cable throttle golf 1.8t has his mapped and reckoned that only ran 6-8psi. Im sure it should run just over a bar one stage1?
Click to expand...

yeh mine boosts at 16ish psi r-tech stage 1

also if you turn it around it makes a high pitched ping noise aswell lol i werent a fan so left mine but my induction gives a good noise anyway.
 
Last edited:
You must log in or register to reply here.

Similar threads

T
what should an a3 1.8t be boosting at?
Replies
4
Views
855
Welly
Welly
loafofbrett
Surging feeling, not boosting properly
Replies
8
Views
980
audi_a3_turbo
A
GregerseN
Finaly got my 1.8T AUM mapped.. but...
Replies
22
Views
4K
badger5
badger5
H
Car not boosting after FMIC install
Replies
3
Views
654
vivalacoulter
vivalacoulter
J
A3 1.8T (1999)- REVO S1, for sale
Replies
8
Views
1K
JB_A3_Turbo
J
Top
Back