# 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean



## JettAffair (Jan 7, 2004)

17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean 

Trying to figure out what is causing this code to come up. I've changed the 02 sensor, and the maf (although I used a "good" used one, so I'm not certain it was good). 
It's putting me in hard limp mode unless I unplug the maf, then it runs fine. 
This is why I thought it was the maf, but I suppose if the maf is unplugged it could be effecting readings "downstream". 
?????????????????


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## vwbubblehead (Mar 15, 2004)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (JettAffair)*

dude buy a new mass air meter. used mass meters? at my shop we replace alot of junk mass meters. always go new.







they are fragile
so handle with care. also make sure you do not have any vacuum leaks IE vacuum lines. being multiplicative I am 99.999% certain it lies in the mass or the wiring to the mass. check the connector plug
and related wires. good luck


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## Audi4u (Jun 29, 2002)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (vwbubblehead)*

change all vancuum lines and gas cap! $15 in parts


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## [email protected] (Jun 5, 2002)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (JettAffair)*

http://forums.vwvortex.com/zerothread?id=1201806


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## Junk T.I. (Sep 18, 2003)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean ([email protected])*

what are your readings in block 032??
vacuum lines could cause it, a gas cap cannot


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## BadlandZ (Sep 22, 2000)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (Junk T.I.)*

I have this problem in my 2000 GTI 1.8t (AWD), the 17536 P1128 Long Term Fuel Trim mult., Bank1 System too Lean code out of VAG-COM.
I replaced the front (pre cat) O2 sensor, didn't help. Block 32 says Idle O2 Adapt -2.0%, Run O2 Adapt 23.4%.
MAF? Vacuum? What is it!!


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## Audi4u (Jun 29, 2002)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (Junk T.I.)*

gas can can and will cause a cel.


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## jetta rocks (Mar 19, 2004)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (Audi4u)*

Yes you are correct gas cap will set the mil, but will not cause a lean condition. It is one of two things maf or the hose under the intake.


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## Audi4u (Jun 29, 2002)

Doesnt the gas tank have vaccum line going to it also?
what code does it give if the gas cap is not there or loose?


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## jetta rocks (Mar 19, 2004)

*Re: (Audi4u)*

It gives gross leak or small leak detected. On the running lean fault i would look real close at the intake hose where it bends and goes through the wrapping seen alot of them sucked shut or torn.


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## [email protected] (Jun 5, 2002)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (BadlandZ)*


_Quote, originally posted by *BadlandZ* »_I have this problem in my 2000 GTI 1.8t (AWD), the 17536 P1128 Long Term Fuel Trim mult., Bank1 System too Lean code out of VAG-COM.
I replaced the front (pre cat) O2 sensor, didn't help. Block 32 says Idle O2 Adapt -2.0%, Run O2 Adapt 23.4%.
MAF? Vacuum? What is it!!









The answer is in the link I posted.


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## BadlandZ (Sep 22, 2000)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean ([email protected])*


_Quote, originally posted by *[email protected]* »_The answer is in the link I posted.

Hi Andy. According to your comments, my first value, additive is in spec, pointing away from a vacuum leak. The multi is out of spec, and that would point to bad MAF.
My symptoms are lack of boost, and loss of break assist when cold. While running with a bad MAF would make me think it's not got the power it once had and a bad MAF, it's the second symptom that has me guessing.
I took it in twice, and both times they said there is no vacuum leak. However, the guy at the desk could never tell me how they figured that out, and I think he was looking for a fault code (which I had recently cleared).
I think I'm just going to take it into the VW dealership in town, and have them replace all the rubber vacuum lines ($150), and a new MAF ($300). Unfortunately, a vacuum leak when that only shows during cold may not clearly show in diagnostics? Am I wrong? But, the multi reading makes me think your right about the MAF. And, hopefully, doing both will solve things.
However, if I have no power assist after, I could have a vacuum leak in a more expensive place?
I would love to try to clean the MAF and see if that solves it, it's cheaper, but it's been months now and I haven't found the time to do it! I'm pushing 90k on my little GTI now, and don't want to let this go too long because I'd love to see another 90k! 
Once I've fixed this, I'm going to GAIC chip it, and Bailey Motorsport Alloy Diverter Valve. I've held off on that soo long waiting to diagnose this...
Thanks for the tips, let me know if there is anything else you can think of.



_Modified by BadlandZ at 5:21 PM 5-24-2004_


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## [email protected] (Jun 5, 2002)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (BadlandZ)*

What did you see at WOT for g/s of airflow?


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## Junk T.I. (Sep 18, 2003)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean ([email protected])*

its appears to me that your system too lean and your brake problem are 2 seperate problems, have you scanned the brake module for DTC?
by the way, VW is changing completely over to Pcodes now instead of factory faults


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## Consch-Hofman's (Feb 5, 2004)

*Re: 17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean (Junk T.I.)*

(by the way, VW is changing completely over to Pcodes now instead of factory faults}
Huh: Could you elaborate on this some more. What are the "p" codes for central locks, radio, instrument, etc,etc?
OTH I have seen some Bentlys which had only "P" codes in sect. 20 Engine electronics.


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## Audi4u (Jun 29, 2002)

Im now having the same problems
I get 113g/s in 2nd gear at redline.
and block 032 i get 1.5 %(add) and 24.1%(mult)
i change a couple of vacuum lines, ordered a new MAF. even though i have 113g/s


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## Audi4u (Jun 29, 2002)

does 113 g/s = a bad MAF??


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## drunkmike (Jul 13, 2004)

*Re: (jetta rocks)*

are you talking about the hose behind the pass side headlight where it goes right to the IC? Mine is kinda soft and squishy when the car is turned off, but it doesnt look cracked or torn or anything.. any idea on a part number and a price for this so I can pick one up from VW? I think its either dead or ready to go on its way. Thanks!


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## kfzmeister (Apr 16, 2004)

*Re: (drunkmike)*

Sounds to me like MAF. Check with your dealer about extended warranty on your MAF (7/70?). They will need to see the 1128 code, so you'll have to go in with MIL on. Typically the upper reading in MVB 32 indicates a vacuum leak and lower reading points towards MAF. We've replaced alot!


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## drunkmike (Jul 13, 2004)

*Re: (kfzmeister)*

let me ask another question.. I have heard that running without a MAF can be good.. some say it can be bad.. Can running without a MAF or with a bad one do any damage in the long run?


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## Lotust (Apr 5, 2002)

*Re: (drunkmike)*

Another question. I just ran the vag com

the first Lambda value was -8.6 <--- this means the motor is actually runing rich?? 

the second Lambda value was 24.2

I read this thread http://forums.vwvortex.com/zerothread?id=1201806 but i dont understand it fully. can anyone help me. I can send you the logs i took. 


_Modified by Lotust at 10:14 PM 9-22-2004_


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## [email protected] (Jun 5, 2002)

*Re: (Lotust)*


_Quote, originally posted by *Lotust* »_the second Lambda value was 24.2

Log your airflow and if necessary, replace your MAF.


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## Lotust (Apr 5, 2002)

*Re: ([email protected])*

Thanks so much Andy. Ill log it tonight. and do that test where i Times .80 by the air flow to get the HP.


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## Lotust (Apr 5, 2002)

*Re: (Lotust)*

Ok I think my MAF is bad. 

@6360RPM my airflow is only 69.23








69X .80 is only 55.2hp
I should have goten my total HP of 115 or Wheel HP 95 ?


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## [email protected] (Jun 5, 2002)

*Re: (Lotust)*

Yep, get a new MAF. The HP guesstimate is crank, not wheel. So a 115 hp engine should show about 92 g/s peak.


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## Lotust (Apr 5, 2002)

*Re: ([email protected])*

Awsome thanks andy. You were correct http://****************.com/smile/emthup.gif All better now.


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## 99txturbo (Oct 1, 2004)

New MAF's only run about $65.00 now and with extended warranty, it might be free. 99txturbo


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## tupacboy (Feb 12, 2001)

*Re: (99txturbo)*

i have this same code problem... but i have a question... in the morning when i start my car... it shakes and the rpms go up and down... it does this until the turbo stops... it only does before my car warms up... afterwards its fine alll day... anyone know why?


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## Lotust (Apr 5, 2002)

*Re: (tupacboy)*


_Quote, originally posted by *tupacboy* »_i have this same code problem... but i have a question... in the morning when i start my car... it shakes and the rpms go up and down... it does this until the turbo stops... it only does before my car warms up... afterwards its fine alll day... anyone know why?

mine did the same thing till i replaced the MAF sensor.


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## tupacboy (Feb 12, 2001)

how much did MAF sensor run you? i think i have the same problem... when i checked it... it has 2 wires but only 1 yellow block.. the other (i'm assuming it should be there) is missing. also did you get codes for misfiring in some of your cylinders? i think they were p300 301 302...etc


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## tupacboy (Feb 12, 2001)

oops i forgot to ask... i have a 2000 passat... what the warranty on the MAF... i called puente hills VW and he told me 5 years 50k miles... is that true? i was under the impression of 70k


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## 7even18 (Dec 20, 2006)

*Re: ([email protected])*

I replaced the maf and still having the 1128 code show up.
My friends machine is reading the Short term fuel trim reading different values, but the long term trim doesn't read anything. 
My boost gauge current shows at idel 10-15, normal is suppose to idle at 20 in.hg. So theres some sort of leak somewhere. Are there any common hoses that leak that I can save some time in replacing? 
Can this cause the problem of having code 1128 also trying to compensate for fuel? 
Another question: If the o2 sensor has been effected by black smoke being produced when running rich due to (vacum leak-maf etc) would this affect the ecu from the mixed signals from the 02 sensor? 
Or if one part is replaced ex: hoses, the engine will read that the vacum is normal now and burn properly?
Thanks


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## customride (Feb 18, 2007)

Hi, I get the same fault code (17536 P1128 Long Term Fuel Trim mult.,Bank1 System too Lean ) and I have replace the first o2 sensor but I still get the same probleme: the car feel like a 80hp beater and when i monitored the lambda sensor I get -1.6% at the idle and the same value when I try to accelerate at 6500 rpm!!!! 
Can it be the MAF, the lambda sensor or just a leak that make my car runing like a old Chevrelet Cavalier!!?










_Modified by customride at 12:09 PM 2-18-2007_


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## 7even18 (Dec 20, 2006)

*Re: (customride)*

It currently seems as if my problem with the fuel trim is fixed: 
I took the time to examine all the vac hoses I can get to, esp the ones underneth the plate behind the intake manifold (i honestly have never fixed a car that had so many ridiculous clamps). 
It can also be a kinked hose that causing the problem. I had a few that didnt't look proper at all, so I trim them shorter and refited them. If you have a boost gauge, post say that the readings should be at 20 in.hg. I've gotten mines to sit 18 in.hg. 
Mind you, the person that installed the boost gauge didnt do it properly either so that hose had a kink on it also.
This fuel trim problem was giving me horrible fuel millage, and right now has possibly ruined my O2 sensor because of all the unburned fuel in the exhaust. The LT fuel trim also puts your car into limp.
Maybe this might help...


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