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CamrideA4
06-20-2011, 10:34 AM
Ok, so I'm out of town for work and randomly when I left the other day my car started doing the following:

From a stop if I get on the gas it will not build more than 1-2psi of boost unless I floor it, in which case it acts completely normal. All other times the car runs exactly like it did before, still hit ~22psi if I nail it and if I'm already cruising and get on the gas a little it builds boost like normal. The only time it does this is from a stand still and it will continue to feel choked as long as I stay in the gas. And when it's choking like this you can't hear any boost, it just sounds like the turbo isn't spinning up much at all (no massive boost leak or anything).

Now for the even weirder part. If I am on the gas from a standing start and I'm getting the no boost issue I can fix it by quickly letting off the gas (enough to dump the little bit of boost I have out the DV) and getting back on it, then it runs just like normal until I get to another traffic light. [headbang]

I haven't had a chance to do any logging to see what requested/actual boost is.

Relevant data: Most anything related to boost is only a couple months old (N75, DV, turbo, etc). I'm using a standard N75, not a race version. I've got a custom tune so no limp mode. The car runs exactly the same in every other way, it's just standing starts that are affected.

Any ideas? It's making the car really annoying to drive in traffic.

CamrideA4
06-21-2011, 09:10 PM
No idea's?

CamrideA4
06-27-2011, 07:06 AM
Monday bump. Still haven't had a chance to log (working a ton right before I leave for vacation tomorrow) but I will try to do it this afternoon. This crap is driving me crazy.

2001A4QUATTRO
06-27-2011, 07:37 AM
When you log check the throttle input and the throttle percentage. Sounds like either a software issue or a throttle input (pedal sensor) OR Throttle body issue. GL

somebody5788
06-27-2011, 07:55 AM
Or much more likely a bad waste gate.

Audi_A4_
06-27-2011, 07:57 AM
I second the bad waste gate.

Sent from my HTC EVO using Tapatalk

M-Hood
06-27-2011, 08:35 AM
Could be the BPV sticking open. What BPV are you running? If it is a piston type valve it might have a spring in it that is too soft and is not forcing the valve completly closed when your only at part throttle.

CamrideA4
06-28-2011, 08:53 AM
WG is new (FrankenTurbo). It might be the DV, I forgot I had changed the spring a while back but it was over a month ago and this problem didn't happen til it got really hot (last week and a half or so) . I'll swap in the stiffer spring (I had put a softer spring in for testing on another issue) when I get back from vacation and see if that does the trick.

CamrideA4
07-27-2011, 06:41 PM
Still having this issue. I swapped the N75 and that had no effect. I took the DV out and put in the stiffest spring and made sure it was installed with the side port towards the pressure side. I even unplugged the MAP sensor (thinking it might be reading wrong) and that had no effect either.

I'm at a bit of a loss. I haven't had a chance to check the WG, but I'll do that this weekend (though the turbo is only a few months old, so I doubt that's it). It's really strange because this just came out of nowhere one day. The morning it happened the car drove like normal and when I left work this started. The only difference is it was really hot out (102*) that day. Oh, I did recently change out my O2 sensor as well, but I wouldn't think that would have any impact on this issue (I did get an original Bosch unit, not a universal).

I did take a log a few weeks back, I can get another tomorrow. But I'm not sure what groups I should be logging for this so if anyone has an idea of what I should be logging please let me know.

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/boostissuelog.jpg

You can see I shifted (tiptronic) between 211 and 212 and it keeps doing it. Until I let off the gas it will continue to have no boost.

Keep in mind that during this log my boost gauge never read above 3psi. As soon as I take off it'll go up to about 3psi for a split second and then go back and sit right at 0psi. I find it really odd that the actual boost is showing 590mbar (~8psi) but my boost gauge is showing nothing. Again, everything is fine at WOT and I hit 23psi without issue.

walky_talky20
07-27-2011, 06:47 PM
Hmm. I wonder if perhaps the wastegate is adjusted improperly. Have you tried unplugging the N75 electrical connector? Doing that will basically connect the compressor directly to the actuator so it will run at spring pressure. Then you can see what it is set at.

CamrideA4
07-27-2011, 06:57 PM
Hmm. I wonder if perhaps the wastegate is adjusted improperly. Have you tried unplugging the N75 electrical connector? Doing that will basically connect the compressor directly to the actuator so it will run at spring pressure. Then you can see what it is set at.

Haven't tried that, I'll give it a shot in just a minute and report back....

Nope, with the N75 unplugged it still does the same thing.

Would hooking the WG up directly to the pressure port on the turbo help troubleshoot anything? That should boost up to the crack pressure on the WG and then build no more right? So if my wastegate was set to a 8psi crack pressure (which I think it is) then it should boost to 8psi and stop.

walky_talky20
07-27-2011, 07:41 PM
Wait, wait, WAIT. You unplugged the N75's electrical connector, and then drove your Audi, with the N75 completely unplugged, and it was "the same"?

Please elaborate.

Unplugging the N75 electrical connector should give absolute minimum boost. Wastegate spring pressure boost, whatever that is set at on your modified turbo. So if it is set at 7 psi, it will make 7 psi and hold there. Factory K03 spring pressure is like 3 psi.

CamrideA4
07-27-2011, 08:00 PM
I'm not sure how to elaborate any more, but I didn't drive it far. I took it out of the neighborhood and hit it about 50% throttle and got no boost. I then hit it about 90% and once it started to build boost (like it usually does) I let off. It didn't get above 8psi, I'm guessing it would have held there though assuming the WG pressure is set at 8psi like I'm pretty sure it is.

So does this mean my WG is f*cked?

walky_talky20
07-27-2011, 09:16 PM
No, that is correct behavior. Assuming the boost would have stopped at 8psi, and that is what the FT is supposed to be set at.

I looked at your log there. It is interesting. There is no boost request, no N75 activity at all. However, I probably wouldn't expect there to be any n75 activity when the actual boost is above the spec boost the entire time. So that is the real question - well, there are 2 real questions here:

1) Why is the spec boost not higher than that?
2) Why is it showing actual boost, but your gauge does not?

I'm wondering the following:
- How is boost gauge connected?
- How is the N75 connected (pressure lines)?
- Wassup with the Map sensor mounting? Where is it?
- I'd like to see a log of this entire thing. You hitting the gas, no boost, letting off and re-applying, boost is there. The entire thing.

The blocks you logged were good. I'd like to see 1 log with all 3 of those (003, 118, 115) and one with just 003 and 118.

M-Hood
07-28-2011, 01:12 AM
His spec boost isn't higher then that because he is not WOT. Running the car at 25% throttle isn't going to produce much boost.

Aragorn
07-28-2011, 02:02 AM
The ECU uses torque demand, so applying 25% throttle may well simply mean its decided it doesnt need any boost to provide that level or torque.

What happens if you open the throttle up, not to 100% but to say 50 or 60? it should then up the duty cycle.

The other point is that the ECU is seeing 0.5 bar of boost almost the whole time, yet your guage is not. Perhaps this implies that either the map sensor or your boost guage isnt working properly. If the map sensor were overreading it would make the car feel very flat, as the ECU THINKS its reached (and exceeded) its spec boost, but hasnt. ECU will be working to try and reduce the boost, when infact theres nothing to reduce.

If it were mine, i'd be looking to verify the operation of both the boost guage and the map sensor.

CamrideA4
07-28-2011, 06:16 AM
No, that is correct behavior. Assuming the boost would have stopped at 8psi, and that is what the FT is supposed to be set at.

I looked at your log there. It is interesting. There is no boost request, no N75 activity at all. However, I probably wouldn't expect there to be any n75 activity when the actual boost is above the spec boost the entire time. So that is the real question - well, there are 2 real questions here:

1) Why is the spec boost not higher than that?
2) Why is it showing actual boost, but your gauge does not?

I'm wondering the following:
- How is boost gauge connected?
- How is the N75 connected (pressure lines)?
- Wassup with the Map sensor mounting? Where is it?
- I'd like to see a log of this entire thing. You hitting the gas, no boost, letting off and re-applying, boost is there. The entire thing.

The blocks you logged were good. I'd like to see 1 log with all 3 of those (003, 118, 115) and one with just 003 and 118.

How is boost gauge connected? - It's currently T'd off the FPR vac line.
How is the N75 connected (pressure lines)? - I re-used the stock line from the pressure port on the turbo to the top connector on the N75 (as it was/is in good shape when I installed the FT) and I've got a new silicone line running from the short side to the wastegate. The long side is in the TIP.
Wassup with the Map sensor mounting? Where is it? - Stock SMIC, it hasn't been touched or moved.

I'll get those logs later today. But that's the part that has me stumped, I would also assume that when the boost actual is showing higher than request that the N75 would sit there and do nothing. My DV is plugged straight into the IM so the N249 is out of play here (thought I should mention that). So the bigger question is why is the ECU seeing higher actual boost than there is, when my gauge is reading nothing...



His spec boost isn't higher then that because he is not WOT. Running the car at 25% throttle isn't going to produce much boost.

The way my car is tuned I typically hit 10psi at 25% throttle by 2500rpm. This behavior is not normal as far as how the car has been running up until I posted this. But the thing is it doesn't matter if I've got the pedal at 25% or 70%, it still doesn't show any boost. I'll get a better log today to show that.


The ECU uses torque demand, so applying 25% throttle may well simply mean its decided it doesnt need any boost to provide that level or torque.

What happens if you open the throttle up, not to 100% but to say 50 or 60? it should then up the duty cycle.

The other point is that the ECU is seeing 0.5 bar of boost almost the whole time, yet your guage is not. Perhaps this implies that either the map sensor or your boost guage isnt working properly. If the map sensor were overreading it would make the car feel very flat, as the ECU THINKS its reached (and exceeded) its spec boost, but hasnt. ECU will be working to try and reduce the boost, when infact theres nothing to reduce.

If it were mine, i'd be looking to verify the operation of both the boost guage and the map sensor.

As mentioned the car does the same thing at 60% as it does in the log you see above. I will get a better log today to show that. The boost gauge works perfect at WOT, so I don't think it's the gauge. I am thinking right now it's the MAP sensor, maybe the heat damaged it? I am seeing some ridiculous IATs because of this weather and because I am still on the stock SMIC (damn work, FMIC is sitting in my garage and I haven't had time to install it).

Is there any good way to test the MAP sensor?

I'll also take some video so you can see what I'm talking about, I'll take the video of the same run I log.

Aragorn
07-28-2011, 09:08 AM
Presumably the simplest way to test the map sensor is to compare it against a known good boost gauge.

CamrideA4
07-28-2011, 05:45 PM
Ok, now it's just all over the f*cking place....

So I just took it out for a spin to get logs and video. I cleared codes before I set out (I've cleared codes at least 5 times since this problem started) as I had N75 and MAP errors from unplugging stuff last night. I start out and it doesn't do it, seems to boost like normal. Weird. I stop and then start again, now it's doing it again, but it's sitting around 2-3psi instead of 0. It's still obviously choking though. So then I nail it, mostly from frustration but now I'm hitting just under 30psi at WOT! [o_o] Not good. Something is definitely wrong.

Anyway, it was hard to take vids, mostly because I don't have any good empty roads around here and I was trying not to run into anyone. Here's what I got.

This vid is at a good 50-60% throttle, you'll notice it jumps up to 10psi until I change gears, then goes back down to ~3psi (I didn't change the throttle input at all).

http://www.youtube.com/watch?v=IHAQB-mm4ZA

Next, another vid, you'll see it hitting around 10psi then start to swing wildly all the up to around 25psi (I should not be hitting more than 23psi). Again, throttle input didn't change during this.

http://www.youtube.com/watch?v=6bvHUY56J-c

More weirdness, looking at the logs I'm seeing where I was keeping the throttle steady the log will show a 100% throttle input right between two much smaller values:

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/weirdthrottleinput.jpg

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/weirdthrottleinput2.jpg

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/weirdthrottleinput3.jpg

I'm wondering if there's something wrong with my throttle sensor or something to start with? This ish is weird.... Another note, there are a bunch of places in the logs where it shows like 15% throttle where I know I was hitting the gas more than that.

I won't be able to get any more logs tonight, but probably tomorrow if you guys have any ideas. I'm working from 9pm-4am tonight. [mad]

Full logs are posted in Google Docs if anyone wants to look through them: https://docs.google.com/leaf?id=0BzJsJH7VYC-pZDY2YjQyNjEtODhlOC00ZWJmLWFiZWEtMWRjMjBmNTE0Mzlj&hl=en_US

walky_talky20
07-28-2011, 05:57 PM
Wow, that is weird. I'd like to watch the throttle angle values with the engine off and just moving the pedal smoothly through the range. If the TPS is wacky, it will probably show up that way.

Also, I'm wondering what that block is actually measuring, "throttle angle %". Is that your pedal position? Or Throttle plate position? I think there are some other values to log to with those in the 060-ish range that have to do with the throttle stuff.

I'm also noticing the MAF values spiked to almost 200 g/s during these weird situations. Something is definitely wrong here.

CamrideA4
07-28-2011, 06:33 PM
Well boost moved according to the throttle input. You can see in that second video the boost just start to spike up randomly. It's really strange. But the FT will move some air, I've logged 220g/s before with things running well.

I'll look into testing the throttle angle stuff tomorrow. Maybe that will show something.

Dur, I just realized that the stupid boost spike is because I put the only other N75 valve I had in for a test, which was a "race" N75. I'll get that pulled out and the stock N75 put back in tomorrow.

walky_talky20
07-28-2011, 06:48 PM
^ Yeah, I didn't mean that 200 g/s is too high of a reading. It just suddenly went way high, then came back down right along with the throttle angle, when you didn't move your foot. Very odd.

M-Hood
07-28-2011, 08:47 PM
Wow, that is weird. I'd like to watch the throttle angle values with the engine off and just moving the pedal smoothly through the range. If the TPS is wacky, it will probably show up that way.

Also, I'm wondering what that block is actually measuring, "throttle angle %". Is that your pedal position? Or Throttle plate position? I think there are some other values to log to with those in the 060-ish range that have to do with the throttle stuff.

I'm also noticing the MAF values spiked to almost 200 g/s during these weird situations. Something is definitely wrong here.

The throttle angle reading should be the TB seeing that is where the throttle position sensor is located.

walky_talky20
07-28-2011, 09:13 PM
The throttle angle reading should be the TB seeing that is where the throttle position sensor is located.

His car is DBW, though. So there is also a potentiometer (or 2, probably) on the gas pedal itself. But, I believe you are right, it is reflecting actual throttle plate position. Usually the pedal position is referred to as "accelerator", not "throttle" anyway. On the DBW cars there can certainly be a discrepancy between pedal position and plate position because it is all decided by the computer. I was wondering if that was coming into play here, perhaps.

M-Hood
07-28-2011, 11:54 PM
His car is DBW, though. So there is also a potentiometer (or 2, probably) on the gas pedal itself. But, I believe you are right, it is reflecting actual throttle plate position. Usually the pedal position is referred to as "accelerator", not "throttle" anyway. On the DBW cars there can certainly be a discrepancy between pedal position and plate position because it is all decided by the computer. I was wondering if that was coming into play here, perhaps.


Well he can try logging block 117, this block has the following readings which should be throttle pedal and throttle body.

Block 117

117,0,Charge Pressure Control
117,1,Engine Speed
117,2,Throttle Position,Sensor (G79),Display Range: 0...100 %
117,3,Throttle Drive,Angle Sensor 1,for EPC (G187) | Display Range: 0...100 %
117,4,Boost Pressure,(specified)


The throttle drive is the same one listed on block 003 which should be the TB.

Block 003

003,0,Basic Functions
003,1,Engine Speed
003,2,Intake Air Mass
003,3,Throttle Drive,Angle Sensor 1,for EPC (G187) | Display Range: 0...100 %
003,4,Ignition,Timing Angle

Aragorn
07-29-2011, 04:36 AM
Those Throttle Angle readings are defo the throttle flap itself, not the pedal.

Looking at the logs, its sort of expected. Your Spec boost jumps up to ~2400 and as a result the ECU winds the thottle open to deliver that.

Remember the pedal provides torque demand, not throttle position. Its entirely feasible that the car could ramp the throttle open then cut it back to deliver your requested torque.

The huge overboost again could indicate a faulty MAP sensor. I'd probably be looking at either changing it or borrowing a known-good one and trying the car with that.

walky_talky20
07-29-2011, 07:03 AM
Yep, just double checked. "G79" (along with G185) is the accelerator pedal position sensor. "G187" (along with G188) is the throttle body butterfly valve position sensor. Logs of block 117 would certainly be interesting here.

demonmk2
07-29-2011, 03:17 PM
by any chance are you running the N75 "race" valve are you? if you are you need to chunk it if your gonna run the Frankenturbo. and get a real N75 valve

M-Hood
07-29-2011, 05:06 PM
by any chance are you running the N75 "race" valve are you? if you are you need to chunk it if your gonna run the Frankenturbo. and get a real N75 valve

From his posts on this thread. So a few Cliff Notes for you [:p]

Main post

Relevant data: Most anything related to boost is only a couple months old (N75, DV, turbo, etc). I'm using a standard N75, not a race version. I've got a custom tune so no limp mode. The car runs exactly the same in every other way, it's just standing starts that are affected.



Post #21

Dur, I just realized that the stupid boost spike is because I put the only other N75 valve I had in for a test, which was a "race" N75. I'll get that pulled out and the stock N75 put back in tomorrow.

CamrideA4
07-29-2011, 06:05 PM
Yeah, I only put in the race N75 because I had nothing else to test if the new N75 I had was faulty. The normal valve will go back in tomorrow.

If I have a chance I'll also get some logs of 117 tomorrow. I didn't drive the car today at all.

walky_talky20
07-29-2011, 06:47 PM
With the kind of throttle body / ecu faults we are postulating here, I would make sure to be careful when driving this car. If the thing is misbehaving like we think it may, this could turn into an "unintended acceleration" problem pretty quick. Just be ready to clutch in and kick off the key should the need arise.

I really doubt this could happen, but then I thought it was at least worth mentioning. If something were to happen, at least I said something.

demonmk2
07-30-2011, 05:06 AM
you could get some electrical connector cleaner and clean all you electrical plugs under the hood ( use a clean tooth brush) and clean your MAF sensor if you have not already. and just out of curiousity check all your *check valve's* for cracks or damage of any kind. GL if you where just a little closer I'd try to help you out. I'm in Charlotte

demonmk2
07-30-2011, 05:08 AM
even though the guage is all over the place can you even feel the boost come in when it does?

CamrideA4
07-30-2011, 09:10 AM
even though the guage is all over the place can you even feel the boost come in when it does?

Yeah, this is why I'm sure the boost gauge is fine. If the boost gauge is showing 0 the car feels like it's choking. When it swung up to 25+psi it went like balls. I've never had the boost gauge show something different than how the car felt.

MAF and sensor are new. It probably wouldn't be a bad idea to clean up the connectors in the bay, but I don't have any codes showing up. The only code I have is from the SAI because I haven't finished deleting it yet and getting it coded out.

CamrideA4
08-01-2011, 12:29 PM
Here is a log with 117 from this morning:

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/weirdthrottleinput4.jpg

I had the gas pedal down at least 50% taking this log, yet it only shows right around 20%... wtf. There is definitely something off here and I'm wondering if the same issue is causing my random boost loss (car is accelerating at 10psi then will just dump all boost with no change in throttle) and the fluctuation at load on a hill (vid, 12 seconds in: http://www.youtube.com/watch?v=p1oMHDsmAXU ).

I'm going to log 062 on my way home from work and see if that sheds any light on this.

Something else I just noticed, on Ross-Tech is says the second column in 117 is supposed to be gas pedal position ( http://www.ross-tech.com/vag-com/m_blocks/110-119.html ). My log shows engine load in that column, but I'm wondering if it's the same thing because it's showing 60-70% in that column where the throttle angle is 20%.

M-Hood
08-01-2011, 12:41 PM
Well you can test to see if it #2 is labeled correctly just by going WOT and see if the readings match your foot or if the are in fact the engine load.

CamrideA4
08-01-2011, 12:50 PM
http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/WOT.jpg

I logged my entire drive to work... These are the WOT logs I recorded. Something seem off? Even if that's not labelled right it wouldn't be right for engine load, it's not consistent at all with the throttle angle or the boost.

walky_talky20
08-01-2011, 01:45 PM
Can you try block 062?

Please see this thread, we are discussing some Throttle Body issues in there as well. Block 062 is cool because it gives you direct pedal position and Throttle body position in the same block:
http://www.audizine.com/forum/showthread.php/442217-01.5-Avant-won-t-start-at-my-wits-end!!!-Help!

Try logging just 062 by itself for a bit, try to get the following logs:
-try and vary the throttle throughout the range, from Zero to WOT and back, slowly if possible (so a high gear for this one probably).
-do a log where you try and aggravate the throttle response/boost issue that you have.

Then try the same types of logs along with block 115.

M-Hood
08-01-2011, 01:52 PM
Well everything I can find says #2 should be for your gas pedal position, so it could be tha throttle position output is just wrong.

117
Boost pressure control



RPM
Gas pedal position
Throttle valve angle
Boost pressure specified





http://www.ross-tech.com/vag-com/m_blocks/110-119.html


Here is block 062

062
E-Gas, potentiometer voltage relationship U/Uref


Angle sensor 1 for throttle valve drive

(0->100%)
Angle sensor 2 for throttle valve drive



(0->100%)
Sensor 1 accelerator pedal position

(0->100%)
Sensor 2 accelerator pedal position

(0->100%)

CamrideA4
08-01-2011, 02:23 PM
http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/weirdthrottleinput6.jpg

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/weirdthrottleinput5.jpg

These were more part throttle runs. I can't even figure out what the 062 sensors are supposed to be reading. There were also several times (as you can see) where the boost just randomly kicks in (throttle angle 100 next to much lower values) like I nailed it, though I haven't moved my foot from part throttle.

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/WOT062log.jpg

Two WOT runs (short, I know), the throttle values don't even look consistent here. I'm now thoroughly confused.

edit

Didn't have time to throw these up earlier. Here is me running the pedal up and down the entire pedal travel with the engine off:

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/Throttletest1.jpg

http://i110.photobucket.com/albums/n89/camride/2001%20A4%20Turbo%20Swap/Throttletest2.jpg

CamrideA4
08-03-2011, 05:57 AM
Bump for more ideas.

CamrideA4
08-12-2011, 03:36 PM
In case anyone wanted to know, it was the f*cking brake light switch.....

walky_talky20
08-12-2011, 06:19 PM
Was there a code for that? Or where the brake lights on all the time? How did you figure that out?

CamrideA4
08-14-2011, 02:50 PM
Was there a code for that? Or where the brake lights on all the time? How did you figure that out?

No codes until this past week, really odd. I finally got a "16955 - Brake Switch (F): Implausible Signal P0571 - 35-00" and it didn't hit me at first. Then I randomly woke up at 5am one morning and realized that the car doesn't let me brake torque it (it won't build any boost), so if the brake switch was acting funky it might kill the boost. I couldn't easily get to the switch so I checked the fuse and it was blown. Replaced it and drove to work, no boost issue. On the way home from work it obviously blew again right before I got home because it started doing it again (fuse was blown when I got home and checked).

Brake lights were out (and I'm assuming they have been for the last 2 months I've been having this issue).

$20 part, 2 months of headaches.