HELP!! Limp Mode

[larry_fopps]

So Here's the story including all pertinent details. 2004 1.8t quattro, 6 spd.

I upgraded from Unitronic stage 1+ to stage 2. During this time, i had been throwing a CEL for my rear O2 which decided to sh!t the bed. I ignored it, because this winter has sucked and figured I'd take care of it once spring came. I upgraded to Stage 2, was loving the extra little bump in power, and then i got the bright idea to hook the car up to vagcom and just make sure that i wasn't throwing any new codes since the tune upgrade. Now keep in mind the car was still running great, full power, full boost, no issues other than my check engine light being on, and my traction control light coming on occasionally for a open circuit at the brake light switch. (That also sh!t the bed and i'm replacing that as soon as it arrives) I just wanted to take a look in vagcom and make sure. Here is that log.

Address 01: Engine Labels: 06B-909-518-AMB.lbl
Part No SW: 8E0 909 518 AK HW: 8E0 909 018 A
Component: 1.8L R4/5VT G 0006
Coding: 0016711
Shop #: WSC 78901 281 394790
VCID: 79F3FC87334026E929E-513C

4 Faults Found:
18010 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
16523 - Oxygen (Lambda) Sensor B1 S2
P0139 - 004 - Response too Slow - Intermittent
16524 - Oxygen (Lambda) Sensor B1 S2
P0140 - 004 - No Activity - Intermittent
17522 - Oxygen (Lambda) Sensor; B1 S2
P1114 - 008 - Internal Resistance too High - MIL ON
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8E0-614-517.lbl
Part No: 8E0 614 517 A
Component: ABS/ESP allrad 3429
Coding: 04275
Shop #: WSC 06435
VCID: 2649E7FBC27E791134C-5120

1 Fault Found:
00526 - Brake Light Switch (F)
36-10 - Open Circuit - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 8E0-820-043.lbl
Part No: 8E0 820 043 AD
Component: A4 Klimaautomat 1219
Coding: 00000
Shop #: WSC 63251
VCID: 63CFBEEFF1CCCC39132-5120

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect. Labels: 8E0-907-279-8E2.lbl
Part No: 8E0 907 279 F
Component: int. Lastmodul USA 0517
Coding: 01013
Shop #: WSC 63251
VCID: 356B30B70FD802898D6-4B00

1 Fault Found:
02104 - Light Detection Sensor (G399)
29-10 - Short to Ground - Intermittent

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8E0-959-655-84.lbl
Part No: 8E0 959 655 C
Component: Airbag 8.4EP 2000
Coding: 0010607
Shop #: WSC 63251 000 00000
VCID: 37773ABF45D4F0999FA-513C

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 8E0-953-549.lbl
Part No: 8E0 953 549 N
Component: Lenks·ulenmodul 0308
Coding: 00042
Shop #: WSC 63251
VCID: 3E792F9B3AEEC1D15CC-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8E0-920-9xx-8E2.lbl
Part No: 8E0 920 950 L
Component: KOMBI+WEGFAHRS. RB4 D36
Coding: 03200
Shop #: WSC 00001
VCID: 32610BABFEB615B1A84-513C
WAUVC68E44A019101 AUZ6Z0C0132270

1 Fault Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 8E0-959-433-MAX.lbl
Part No: 8E0 959 433 BB
Component: Komfortger·t T7B 1311
Coding: 11852
Shop #: WSC 63251
VCID: 72E1CBAB3E3655B1684-4B00

Subsystem 1 - Part No: 8E1959801
Component: Tırsteuer.FS BRM 0003

Subsystem 2 - Part No: 8E1959802E
Component: Tırsteuer.BF BRM 0003

Subsystem 3 - Part No: 8E0959801A
Component: Tırsteuer.HL BRM 0003

Subsystem 4 - Part No: 8E0959802A
Component: Tırsteuer.HR BRM 0003

2 Faults Found:
00962 - Alarm via. Tilt Sensor
35-00 - -
01561 - Rear left door
59-00 - Can't Unlock

-------------------------------------------------------------------------------
Address 56: Radio Labels: 8E0-035-1xx-56.lbl
Part No: 8E0 035 195 H
Component: symphony II NP2 0260
Coding: 01001
Shop #: WSC 01024
VCID: 2C5D15D3DC924341E28-5072

2 Faults Found:
65535 - Internal Control Module Memory Error
08-10 - Control Limit Surpassed - Intermittent
65535 - Internal Control Module Memory Error
08-10 - Control Limit Surpassed - Intermittent

End-------------------------(Elapsed Time: 05:45)--------------------------


After saving the log, I then cleared all DTC's and at that instant is when my car has since been restricted to 15psi. Is it possible my upgrade to stage 2 got wiped and the ECU reverted itself back to stage 1, or am I in limp mode? Anyone have any thoughts whatsoever? I'm baffled at this point.

Now, since there were a few codes in that scan that I had never seen before, after driving the car all weekend and all over the state, I decided to scan the car again, this time I only got the rear O2 code and the brake light switch code. I'm not sure where the alarm tilt sensor, ECM no communication, light detection sensor, and power supply terminal 30 codes came from. I'm thinking when the shop had it maybe they just ran the battery down at some point. However, none of those codes have showed up again.

Now tonight, I changed that rear O2 sensor hoping thats what was causing it and that would restore the power I am currently lacking. It did not. I haven't drove it enough for readiness to set yet, but i'm thinking thats irrelevant. Anyone have anything? I'm stumped.

[larry_fopps]

Anyone?

[texasboy21]

What is your vacuum reading at idle? How much boost pressure is your tune requesting? Clear all the codes again and see what comes back.

Limp mode is 5psi.

In the colder months its normal for peak boost pressure to be lower because cold air is more dense and therefore oxygenated.

Edit, added the appropriate fuel injectors with the 1+ to 2 upgrade correct?

[larry_fopps]

Yes brand new TT225 injectors. the car was spiking 22 and holding 18 and did it consistently. There were no issues, i out of the blue decided to clear codes. As soon as I cleared DTC's its now being restricted to 15psi. That was the only variable. At idle, Vaccuum is reading 20 as it should. It was just as cold if not colder previously and didn't cause any issues.

[jjvwg]

You're not in limp mode if you're hitting 15psi. Do a pressure test.

[texasboy21]

A pressure test is the next step, but I would first log the actual vs requested boost.

http://www.a4mods.com/index.php?page...boostleak.html

Be sure to watch the boost gauge on the car and test up to at least 22psi. Your vacuum should be -21/22.

[larry_fopps]

Actual vs. requested boost have been logged. Both are 15psi. That's what I meant when I said the car is being limited to 15psi.

[alexza4]

First, you're not in the limp mod. The codes you're throwing are very much looking like a cat issue. Are you running a stock cat?

[larry_fopps]

Alright so it isn't in limp mode. I didn't realize limp was 5psi for some reason I thought it was 15 which obviously doesn't make sense thinking back at it, seeing as though these cars do not boost that much stock. I guess maybe i thought it was some sort of soft limp being that its stage 2. I must of thought wrong. The cat is a brand new 3000 mile 034 HFC. The codes were not because of a failing cat. The codes were because the rear o2 was bad. That rear o2 was replaced last night. Once I get through readiness, I'll scan the car again and post that log. I should no longer have that rear o2 code.

[texasboy21]

Alright so it isn't in limp mode. I didn't realize limp was 5psi for some reason I thought it was 15 which obviously doesn't make sense thinking back at it, seeing as though these cars do not boost that much stock. I guess maybe i thought it was some sort of soft limp being that its stage 2. I must of thought wrong. The cat is a brand new 3000 mile 034 HFC. The codes were not because of a failing cat. The codes were because the rear o2 was bad. That rear o2 was replaced last night. Once I get through readiness, I'll scan the car again and post that log. I should no longer have that rear o2 code.

The codes wont go away unless you clear them, and when you clear them the readiness monitors will reset to 'not ready'.

If the ECU is asking for 15 and you are getting 15 you might not have an issue. Like I mentioned above, cold air is more dense, so your peak boost figures will drop (and rise) with the ambient temps.

[larry_fopps]

The codes wont go away unless you clear them, and when you clear them the readiness monitors will reset to 'not ready'.

If the ECU is asking for 15 and you are getting 15 you might not have an issue. Like I mentioned above, cold air is more dense, so your peak boost figures will drop (and rise) with the ambient temps.

Yes I am quite aware. I have vagcom and me clearing the codes is what caused this issue in the first place. After replacing the rear o2 last night I cleared the codes again. Like I said, immediately before clearing codes the first time, the car ran fine and was reaching full boost. Immediately after clearing the codes it was being limited to 15psi. The car is severely lacking in power throughout the entire curve. I really do not think temperature is to blame. Yes it has been cold here in the north east, but its been cold all winter and it hasn't been a problem. Also yesterday it was like 45 degrees and still had the same issue. There is definitely an issue of some sort going on Barrett. I cannot stress enough, that the car was running perfectly, full boost no issues at all i just out of nowhere decided to hook up vagcom and clear codes. Immediately after clearing codes i'm limited to 15psi. That is the only variable here.

Now here's a question. If requested is 15psi and actual is 15 psi, that confirms the N75 is good correct?

[texasboy21]

Yes I am quite aware. I have vagcom and me clearing the codes is what caused this issue in the first place. After replacing the rear o2 last night I cleared the codes again. Like I said, immediately before clearing codes the first time, the car ran fine and was reaching full boost. Immediately after clearing the codes it was being limited to 15psi. The car is severely lacking in power throughout the entire curve. I really do not think temperature is to blame. Yes it has been cold here in the north east, but its been cold all winter and it hasn't been a problem. Also yesterday it was like 45 degrees and still had the same issue. There is definitely an issue of some sort going on Barrett. I cannot stress enough, that the car was running perfectly, full boost no issues at all i just out of nowhere decided to hook up vagcom and clear codes. Immediately after clearing codes i'm limited to 15psi. That is the only variable here.

Now here's a question. If requested is 15psi and actual is 15 psi, that confirms the N75 is good correct?

Simply clearing stored codes will not create an issue. A better way to test the N75 is to log the duty cycle, and/or check its voltage with a multimeter.

[larry_fopps]

This is why it makes no sense in my head. Car was fine full power. I pulled in my driveway, scanned and cleared the codes, and instantly i've been having this issue. But, you didn't answer my question. If the ECU is requesting 15psi and actual is 15psi, is that not a tell tale sign that the n75 is good? Its doing exactly what the ECU is telling it to.

I'm still going to log the duty cycle and test resistance with a multimeter. Voltage will not really answer questions, the resistance is what will determine if it is good or bad.

[texasboy21]

This is why it makes no sense in my head. Car was fine full power. I pulled in my driveway, scanned and cleared the codes, and instantly i've been having this issue. But, you didn't answer my question. If the ECU is requesting 15psi and actual is 15psi, is that not a tell tale sign that the n75 is good? Its doing exactly what the ECU is telling it to.

I'm still going to log the duty cycle and test resistance with a multimeter. Voltage will not really answer questions, the resistance is what will determine if it is good or bad.

Are you still throwing any codes?

[larry_fopps]

You still didn't answer my question…

I don't have an answer to yours yet. We got 7 inches of snow yesterday so I couldn't do enough driving to get all monitors to set to ready. By the end of this weekend I can answer whether or not i'm still throwing codes. My brake light switch should be the only cause of a code at this point. The new one arrives today, and I will put it in tomorrow, clear codes again, and drive enough to get through the drive cycle. I'll report back.

But can you answer my question? "If when logging through vagcom, I find that the ECU is requesting 15psi and actual is 15psi, is that not a tell tale sign that the n75 is good since Its doing exactly what the ECU is telling it to?

[texasboy21]

You still didn't answer my question…

I don't have an answer to yours yet. We got 7 inches of snow yesterday so I couldn't do enough driving to get all monitors to set to ready. By the end of this weekend I can answer whether or not i'm still throwing codes. My brake light switch should be the only cause of a code at this point. The new one arrives today, and I will put it in tomorrow, clear codes again, and drive enough to get through the drive cycle. I'll report back.

But can you answer my question? "If when logging through vagcom, I find that the ECU is requesting 15psi and actual is 15psi, is that not a tell tale sign that the n75 is good since Its doing exactly what the ECU is telling it to?

That would be a good indication that everything is fine. IE, N75 doing its job, no boost leaks, and the tune is requesting more than stock boost.

[larry_fopps]

Yes, that's why I am baffled, because yes the tune is requesting more than stock, and yes it seems the n75 is doing its job. However, with Unitronic Stage 2 i'm supposed to be spiking at 22psi holding 18, which i was. Until I cleared codes. Now its down to the 15psi that I was at before upgrading for 1+ to Stage 2. I'm going to do everything mentioned above this weekend and see what codes come back, but i'm really thinking that something happened with the tune upon me wiping codes, that reverted it back to 1+. Maybe the shop rand the battery down and that's why I had the power supply terminal 30, as well as the ecu code. Not sure if thats possible, but its literally the only thing i can think of at this point. If requested was different than actual, i wouldn't think this way and would suspect an issue, but that isn't the case. Also, i'm not understanding why its requesting 15psi, when it should be requesting more.

[lyates1987]

I'd give unitronic a call and see what they have to say. Won't hurt.

[texasboy21]

Yes, that's why I am baffled, because yes the tune is requesting more than stock, and yes it seems the n75 is doing its job. However, with Unitronic Stage 2 i'm supposed to be spiking at 22psi holding 18, which i was. Until I cleared codes. Now its down to the 15psi that I was at before upgrading for 1+ to Stage 2. I'm going to do everything mentioned above this weekend and see what codes come back, but i'm really thinking that something happened with the tune upon me wiping codes, that reverted it back to 1+. Maybe the shop rand the battery down and that's why I had the power supply terminal 30, as well as the ecu code. Not sure if thats possible, but its literally the only thing i can think of at this point. If requested was different than actual, i wouldn't think this way and would suspect an issue, but that isn't the case. Also, i'm not understanding why its requesting 15psi, when it should be requesting more.

Our ECUs request torque, not boost pressure. Back to cold air being more dense..

See what codes pop up, and report back.

[larry_fopps]

The airs density/temperature is irrelevant in this case, please stop suggesting that. There was a 5 minute 45 second interval from the time the car was running perfect, me scanning and clearing codes, and then it not boosting beyond 15psi. Air pressure/density/temperature theory holds no water in this case.

I actually tried opening up a ticket with unitronic online when this issue first started happening. They haven't gotten back to me. I may give them a call tomorrow and try that way. If my last few attempts don't solve it I may also bring it back to the Uni dealer that flashed it.

[larry_fopps]

Welp i was on my way to my buddies house tonight after work to swap his N75 in to see if that helped the issue. I did a few WOT pulls from 1500rpm-6000 and little by little my boost built higher and higher on the way there. By the time I was half way there, full power had been restored. I have zero clue as to what the issue was. But i'm anticipating it returning. I'm going to swap the n75 anyway to see if there is any difference at all. Mine could very likely be the original, his is literally brand new. I'm baffled.

[texasboy21]

Welp i was on my way to my buddies house tonight after work to swap his N75 in to see if that helped the issue. I did a few WOT pulls from 1500rpm-6000 and little by little my boost built higher and higher on the way there. By the time I was half way there, full power had been restored. I have zero clue as to what the issue was. But i'm anticipating it returning. I'm going to swap the n75 anyway to see if there is any difference at all. Mine could very likely be the original, his is literally brand new. I'm baffled.

What type of DV do you have?

If it is serviceable, it would not hurt to clean it. A sticking DV can cause low boost.

[larry_fopps]

I have the APR R1 diverter valve. Idk if maybe somehow there was frozen condensation in it or something. Just very strange.

[larry_fopps]

Well, I did another O2 sensor swap last night since i finally got the correct part. After install, cleared DTC's. And again, immediately after clearing DTC's The car reverted back to the stage 1+ characteristics. I just opened up another tech support ticket with Unitronic, idk what the hell is going on.