Not making boost?

[Bimmerman]

So my does not really have any power, and it feels like it is not making boost.

I replaced the BV with a new 710N, and unplugged the N75 but the car still feels as if it is not making boost. I do not have a boost gauge, but have ordered one and it will be here at the end of this week.

So if the BV and N75 are not bad what should I be looking at next?

[biketsai]

Check for boost leaks, thats definitely a killer

[Bimmerman]

Check for boost leaks, thats definitely a killer

I checked all the hoses and they all look good. I drove the car tonight with the radio & a/c off and all the windows down and I swear I do not hear anything and the car has no pull to it at all.

[biketsai]

You may not hear it while you are driving. I would seriously do a boost leak test to make sure, you never know with those hoses. Double check your intercooler pipes too. Do you have a VAG? You could even be in a limp mode.

[Bimmerman]

You may not hear it while you are driving. I would seriously do a boost leak test to make sure, you never know with those hoses. Double check your intercooler pipes too. Do you have a VAG? You could even be in a limp mode.

I have a cable from some time ago but my laptop died on Friday and I will not have it back till this Thur-Fri.

Limp mode would make sense, I have a standard OBDII scanner and checked for codes and there aren't any.

I looked the hoses over today while installing my HID kit's and they all looked pretty decent and seemed to be tight.

I am busy all this week so it maybe toward the end of the week before I can boost test it, plus I need to gather the parts to build a tester.

[Inval1d]

Sounds like its in limp mode. A boost gauge will definitely help. What I did was take all the piping off and re installed them making sure all the connections were tight. Inspect the lines as well for cracks or torn pieces and replace them.

[Bimmerman]

How would I clear the limp mode, is is possible with out a VAG?

[texasboy21]

How would I clear the limp mode, is is possible with out a VAG?

Disconnect the negative battery terminal for 2-5 minutes, that will clear all codes and reset the ECU. Go do it and let us know if that was the problem!

[texasboy21]

OHH and its DV, divertor valve, not BV

[Bimmerman]

Disconnect the negative battery terminal for 2-5 minutes, that will clear all codes and reset the ECU. Go do it and let us know if that was the problem!

Left the cable off for about 3-4 mins, does not feel much diff if any at all. I just going to wait till the boost gauge gets here so I can actually see what is going on.

[hauff a4]

as much as you say u checked the lines...you have a boost leak or a vaccum leak. i had the same problem...the smallest leak in the right place will make your car crap

[mike-2ptzero]

OHH and its DV, divertor valve, not BV

He most likely meant to put BPV(ByPass Valve).



OP - If you pulled the vac line off the N75 that goes to the turbo or to the WG actuator and still didn't make any boost/power then your WG arm might be broken causing the WG to blow open.

[Bimmerman]

I unplugged the N75 and drove the car last night, could not tell a diff.

[mike-2ptzero]

I unplugged the N75 and drove the car last night, could not tell a diff.

Then you need to check the WG arm, plenty people have had it break. Just see if the arm moves if you touch it.

[Bimmerman]

Then you need to check the WG arm, plenty people have had it break. Just see if the arm moves if you touch it.

Just got back to the house, when it cools a bit I will check it.

[walky_talky20]

What exactly did you unplug from the N75? You should unplug the vacuum line that goes from the N75 to the wastegate actuator (can). That will give you unlimited boost pressure (no boost control at all, so be careful).

If you unplug the electrical connector from the N75 the valve goes fully open and the expected outcome is zero boost pressure.

[Bimmerman]

I did not unhook the vacuum line, I will have to try that.

[mike-2ptzero]

I did not unhook the vacuum line, I will have to try that.

Yeah you cant just unhook the N75 harness because thats how the ECU controls it. This is why I asked if you unplugged the vac/pressure lines that go from the N75 to the WG and turbo.


Just make sure you only do a test run in 4th or 5th gear and keep your eye on the boost becaue it can shoot up quickly and not stop so you will want to get off the throttle quickly if it does.

[Altech75]

There's always the off chance that your wastegate plug fell off. If it did then you'd have virtually no boost whatsoever. Unfortunately it's also not easy to fix. If you have the spare time you can take your cat off the turbo and check with your finger.

[wesleyfbm]

how exactly do i fing the waste gate. im have boost problems aswell but with rising boost up to 17+ with the vacuum line off the n75.

[allspooledup]

Did you check your MAF. If that goes out on you, you can go into limp mode. 5 psi is not very much fun. Ask me how i know.

[Bimmerman]

Did you check your MAF. If that goes out on you, you can go into limp mode. 5 psi is not very much fun. Ask me how i know.

How do I check it? I have no codes or c/e light on.

[slopoke]

yep my wastegate flapper tooka shit and same thing... No spool no wistle no nothing...

you may need a turbo...

[Altech75]

Did you check your MAF. If that goes out on you, you can go into limp mode. 5 psi is not very much fun. Ask me how i know.

0 psi isn't very much fun. Ask me how I know.

[allspooledup]

How do I check it? I have no codes or c/e light on.

Get a boost gauge installed so we can see if you have any boost at all. Find someone local who has vag com that can log it for you.

my MAF just decided to take a vactaion and left me in limp mode (5psi). i had a friend VAG it was only reading ~90 g's per sec. We put his MAf in my car and i got my boost back (21psi) and logged it again and it was reading ~160 g's per second. i forget which block it was but someone will chime in.

do you see why a boost gauge is important?

[allspooledup]

0 psi isn't very much fun. Ask me how I know.

haha ive been there before too. the only thing more painful than a stock 1.8t is a broken 1.8t.

[Turboe30FTW]

I am in a similar boat, cannot make more than 10psi boost on a giac chip :( It holds 7psi, then creeps to about 10 above 4500rpm

with standard obd2 reader, while viewing data, MAF reads -000-, nada.

It is a brand new MAF, going to swing down to where I bought it and swap it for another, but can't tell if the wiring loom is pinched or what. Car repeatedly throws the same 6 codes.

Note: new 710n, new n75, new ko4, no cat, boost leak tested, new maf, giac ko4 j15

[walky_talky20]

I am in a similar boat, cannot make more than 10psi boost on a giac chip :( It holds 7psi, then creeps to about 10 above 4500rpm

with standard obd2 reader, while viewing data, MAF reads -000-, nada.

It is a brand new MAF, going to swing down to where I bought it and swap it for another, but can't tell if the wiring loom is pinched or what. Car repeatedly throws the same 6 codes.

Note: new 710n, new n75, new ko4, no cat, boost leak tested, new maf, giac ko4 j15

What are the codes?

[Turboe30FTW]

P1425- Tank Ventilation Valve Short To Ground- N80 EVAP
P1472- EVAP Control System LDP Circuit Short To Ground
P0102- Mass Air Flow (MAF) (G70): Signal too Low
P0134- 02 Sensor Circuit No Activity Detected (Bank I Sensor 1)
P1196- O2S Heater Circuit Bank 1 Sensor 1 Electrical Malfunction
P1198- O2S Heater Circuit Bank 1 Sensor 2 Electrical Malfunction

This was after I cleared, drove around the block, and what has now shown up in the pending codes. The n75 used to throw the short to ground also, but I don't have access to a vagcom until the weeked.

--This was the last VAG session I ran, with my unchipped ECU.--

Address 01: Engine Labels: 058-907-55x-AEBN.lbl
Part No: 8D0 907 557 P
Component: 1.8L R4/5VT MOTR HS D02
Coding: 06201
Shop #: WSC 06335

8 Faults Found:
17833 - EVAP Purge Valve (N80): Short to Ground
P1425 - 35-00 - -
17955 - Boost Pressure Regulation Valve (N75): Short to Ground
P1547 - 35-00 - -
17880 - EVAP Leak Detection Pump: Short to Ground
P1472 - 35-00 - -
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-00 - -
16716 - Knock Sensor 2 (G66): Signal too Low
P0332 - 35-10 - - - Intermittent
16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
P0134 - 35-10 - - - Intermittent
17604 - Oxygen (Lambda) Sensor Heater Circuit: B1 S1: Electrical Malfunction
P1196 - 35-00 - -
17606 - Oxygen (Lambda) Sensor Heater Circuit: B1 S2: Electrical Malfunction
P1198 - 35-00 - -
Readiness: 0010 0101


Is it mere coincidence that the MAF, n80, and n75 share the same wiring loom?

[walky_talky20]

@Turboe30:

Well, after a quick look at the diagram, it looks like your fuse #29 is blown. That is a 20A on the side of the driver's knee bolster. That would explain every code you have except the knock sensor.

Fuse #29 supplies power only to the following:
-EVAP purge valve (N80)
-Bypass Regulator Valve (N75)
-EVAP Leak Detection Pump
-Mass Airflow Sensor
-Oxygen Sensor #1 Heater
-Oxygen Sensor #2 Heater

"Short to Ground" codes generally refer to a blown fuse as there is no current flow in the circuit. The code is hinting that a short to ground has caused the fuse to blow.

[Turboe30FTW]

Awesome! Thank you for the info. Tomorrow morning I'll replace the fuse before work and report back.

[Bimmerman]

do you see why a boost gauge is important?

I know they are, I just bought the car and have one on order, it will be here this week.

[allspooledup]

I know they are, I just bought the car and have one on order, it will be here this week.

Good job. Get that sucker in and report back.

[f15046]

You should have went to Summit Racing and picked one up. You live close to it.

[Bimmerman]

You should have went to Summit Racing and picked one up. You live close to it.

Yea they are close, but also pricey. Plus they do not have the gauge pod. I got the VDO gauge that matches the interior gauges and pod for under $80 shipped.

[b5a4lover]

how exactly do i fing the waste gate. im have boost problems aswell but with rising boost up to 17+ with the vacuum line off the n75.

its inside the turbo. but the actuator is the brass looking thing towards the bottom right of the compressor of the turbo. just look straight down on the exhaust side of the engine towards the front. if you take the vacuum line off, the wastegate can never open so you boost until you blow your turbo

Awesome! Thank you for the info. Tomorrow morning I'll replace the fuse before work and report back.

you should also diagnose as to why you blew the fuse in the first place. there is most likely a short to ground on one of those circuits for that fuse. it'll probly blow the fuse again soon

[Turboe30FTW]

you should also diagnose as to why you blew the fuse in the first place. there is most likely a short to ground on one of those circuits for that fuse. it'll probly blow the fuse again soon

Too true, worked fine, but have gone through 4 fuses in a week's time. First fuse worked for 3 days, a few lasted for 5 seconds. Split open the harness and cannot find anything there >.< Maf is new, as is n75, only thing that could be wrong otherwise I guess is the o2 or n80 valve. Have to do more diagnosing + voltmeter time to figure it out.

[Turboe30FTW]

Thing only blows when it rains or condensation in the AM, was fine for a week then had my 15amp fuse malfunction and melt in the fuse block

[Aaron5280]

Hey I have a 02 Audi a4 and I'm making no boost I can here the turbo spooling but have no boost and hardly any power and the only code I'm getting is for the maf does anybody know if the maf sensor not working would cause me to have no boost

[walky_talky20]

We would need to know the actual code.

Also you have a 2002 A4, which is a B6. So you should post in the B6 Forum. That forum has a bit more activity, so you may get more and better helps.