# 1.8T Throttle Body Malfunction



## Arijit (Apr 9, 2008)

Hi,
Recently I went through an 80K servicing from a reputed Store on my 2001 Jetta 1.8T. During which they changed the Engine Gasket and the MAP sensor. They said that oil was leaking through the engine gasket.
I have been driving it reasonably well for about 4 weeks. Although all this while I noted a small drop in thrust while accelerating and a mild hissing noise as if air was leaking from somewhere.
Day before yesterday things started going really bad. Intially the RPM would keep fluctuating while idling and even stalled few times on red lights. Yesterday morning when I started the engine the EPC and ASR lights came up. After turning on and off a couple of times both went out but the MIL came up blinking from time to time. After that the engine would rev up to 2k when I start and then fall to 1k RPM. This was accompanied by frequent misfires. I took it to the dealer and they extracted all the fault codes(13 of them) and suggested that I change the Throttle Body at first and then only they can proceed further saying that the Throttle Body was not able to adapt. Following are the fault codes that I got
1570	Contr.Module Locked
1297	Connection turbocharger - throttle valve pressure hose
1564	Idle Speed Contr.Throttle Pos. Low Voltage During Adaptation
1171	Throttle Actuation Potentiometer Sign.2 Range/Performance
1542	Throttle Actuation Potentiometer Range/Performance
0300	Random/Multiple Cylinder Misfire Detected
0303	Cyl.3 Misfire Detected
0304	Cyl.4 Misfire Detected
0507	Idle Control System Higher than Expected
0301	Cyl.1 Misfire Detected
0302	Cyl.2 Misfire Detected
1136	Long Term Fuel Trim Add.Fuel,Bank1 System too Lean
1128	Long Term Fuel Trim mult.,Bank1 System too Lean
I am going nuts







with all of them around and I am not able to decide whether to go ahead and change the TB from the dealer as it would cost about 800 bucks or whether to go after the Service Centre guys.
What I want to know is can the TB malfunction be connected to the Engine Gasket and MAP sensor replacement? And do the above symptoms mean that my TB is damaged beyond repair ?
I would really appreciate if someone can be my guiding star. I am heavily dependent on my car as I need to drive it close to 500 miles every week.
Thanking you in anticipation ....


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## coolvdub (Feb 19, 2000)

*Re: 1.8T Throttle Body Malfunction (Arijit)*

A throttle body can be purchased brand new from http://www.1stvwparts.com/ for $365 brand new. It is only held on by four bolts and remove the hose from the intercooler(one hoseclamp) a vacumm line on top of it, which can be removed with the clamp still on it and the electrical connector. I have had mine off and on in less than 5 minutes. The only thing you will need is VAG-COM to do a TBA(throttle body alignment) or if you don't have it. Just turn the key to the on position for 2 minutes without starting the car and then start it, wa-la free TBA.


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## Arijit (Apr 9, 2008)

Thanks a lot Don for your valuable suggestion. But I am little scared of laying my hands on any engine component. Apart from that I may not be having the proper tools. I would rather have it tended to by pros.
Can you tell me if the Throttle Body malfunctions is a fallout of the Engine Gasket or MAP sensor replacement. In that case it is the Service Center guys who should really be taking care of it. And if it is related then just changing the throttle body may not be good enough as the root cause would be something else.
Again thanks a lot for you recommendations. Indeed the website was very useful.


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## coolvdub (Feb 19, 2000)

*Re: (Arijit)*

Highly unlikely it's related. I was just fighting with a throttle body issue,got that fixed and immediately after, I have camshaft sensor problems. Go figure. Anyhow, you could still buy a new throttle body and have an independent shop replace it much cheaper than the dealer.


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## JettaRed (Aug 14, 2000)

*Re: (Arijit)*


_Quote, originally posted by *Arijit* »_Can you tell me if the Throttle Body malfunctions is a fallout of the Engine Gasket or MAP sensor replacement. In that case it is the Service Center guys who should really be taking care of it. And if it is related then just changing the throttle body may not be good enough as the root cause would be something else.
Again thanks a lot for you recommendations. Indeed the website was very useful.

1st: Do these "Service Center guys" work on VWs/Audis regularly?
2nd: Why was the MAP sensor replaced?
3rd: By "engine gasket" do you mean valve cover gasket?
It does sound like a throttle body problem, but you should first have someone do a throttle body adaptation (TBA). Often, if the throttle body is electrically disconnected, it needs a TBA done after reconnecting to prevent the types of problems you are seeing.
The dealer is quick to replace parts instead of figuring out what is really wrong. It's easier and more money for them.
If you are going to own a VW or Audi and are not filthy rich, you need to get a few things, such as a Bentley manual and a VAG-COM. You will end up saving tons of money.


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## Arijit (Apr 9, 2008)

Thanks for your inputs Don.


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## Arijit (Apr 9, 2008)

I am not sure if FS works on VWs and AUDIs regularly or not but I have seen few of them standing outside their store regularly.
It is the valve cover gasket that was changed.
This is the course of events for the MAP sensor replacement. After the 80K servicing they recommended changing the VC gasket. Since they didn't have the parts I had to drive as it is for about 2 weeks. After that when I got the VCG replaced the MIL came up. They said the P code indicated a MAP Sensor error. So they recommended changing the same. When the old one was taken out they noticed oil inside the sensor and concluded that there was some hairline crak somewhere in the sensor.
The dealer mentioned that the TB was damaged beyond adaptation. But now I think that is bogus. I will first try to get the TBA done. 
Thanks for your suggestions. Also is it safe to drive the car in this condition ?

_Modified by Arijit at 5:44 AM 5-9-2008_

_Modified by Arijit at 5:45 AM 5-9-2008_


_Modified by Arijit at 5:49 AM 5-9-2008_


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## JettaRed (Aug 14, 2000)

*Re: (Arijit)*


_Quote, originally posted by *Arijit* »_I am not sure if FS works on VWs and AUDIs regularly or not but I have seen few of them standing outside their store regularly.
It is the valve cover gasket that was changed.
This is the course of events for the MAP sensor replacement. After the 80K servicing they recommended changing the VC gasket. Since they didn't have the parts I had to drive as it is for about 2 weeks. After that when I got the VCG replaced the MIL came up. They said the P code indicated a MAP Sensor error. So they recommended changing the same. When the old one was taken out they noticed oil inside the sensor and concluded that there was some hairline crak somewhere in the sensor.
The dealer mentioned that the TB was damaged beyond adaptation. But now I think that is bogus. I will first try to get the TBA done. 
Thanks for your suggestions. Also is it safe to drive the car in this condition ?


I suggest finding another shop that is familiar with VWs and Audis. The oil on the MAP sensor is not due to a crack, but the fact that some small amount of oil blows through the intake as a result of crankcase ventilation. If you remove the lower intercooler pipe or even the throttle body, you will notice a small amount of oil that has accumulated. This is NORMAL. And it should not have taken two weeks to get a VC gasket!
Do you happen to know what the P code was? While most P codes that start with "0" are universal across manufacturers, you need to look up or check P codes specifically for VWs or Audis. There is a list of P codes in this document.
If you can't get someone to do the TBA, do what was suggested, only first disconnect the battery for about 10 minutes. Make sure you have your radio code first. Then, after reconnecting the battery, turn the car to "on", do NOT touch the gas pedal, do NOT start the engine. Leave it in the "on" position for at least a minute. Turn it off and try starting it. If that doesn't work, then you will need to do a TBA.


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## bpfoley (Nov 30, 2000)

*Re: (JettaRed)*

you cannot perform a TB alignment without VAG-COM


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## JettaRed (Aug 14, 2000)

*Re: 1.8T Throttle Body Malfunction (Arijit)*

Don't know if this will work, but I will try.
*Nevermind. That didn't work. I tried to post troubleshooting steps for each of your codes. *



_Modified by JettaRed at 1:46 PM 5-9-2008_


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## Twintigklepper (Sep 18, 2005)

*Re: (bpfoley)*


_Quote, originally posted by *bpfoley* »_you cannot perform a TB alignment without VAG-COM

I never did one.
Only thing i did was turn te key for contact a few seconds,
after mounting an new tb.
I have no code in vag-com.


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## JettaRed (Aug 14, 2000)

*Re: (Twintigklepper)*


_Quote, originally posted by *Twintigklepper* »_
I never did one.
Only thing i did was turn te key for contact a few seconds,
after mounting an new tb.
I have no code in vag-com.

A few seconds is not enough. You need at least 40-60 seconds. You will not necessarily get a DTC stored for not doing a TBA. If you have a VAG-COM, do a TBA.
The process is in the TTweakers Guide.


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## 2002JettaMike (Jan 20, 2008)

*Re: (JettaRed)*

Hey, IMO those multiple misfires and lean codes look like a vac leak.
Check the "Y" hose on top and the small hose under the tray at the engine front for splits and leaks. The hose runs from the underside of the intake to the PCV "T" at the engine front.
You'll get both lean codes and multiple misfires if one of the hoses goes bad.
Pretty easy to find and fix once you know about them.
Best of luck.


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## Arijit (Apr 9, 2008)

Hi thanks for all your valuable inputs. I was able to make the service agents to perform the checks as part of the service warranty. This was a different center in the same chain. Mike you got it right. They diagnosed a leaking vacuum hose. This had spoiled the Mass Airflow Sensor and Crankcase Gasket which also need to be replaced.
It turns out that the different codes were a fallout of multiple engine component malfunctions. Even the valve cover gasket and the MAP sensor that were changed were not done properly. I hope these guys will be able to sort out the things.
Thanks again for all your suggestions.


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## 2002JettaMike (Jan 20, 2008)

*Re: (Arijit)*

That supports my "Theory" about VW autos. 
I'm of the belief that small things go wrong with these cars, O2 sensor changes value, MAF wears out, TB gets dirty...ETC. but the computer system adjusts to correct to keep the car running well.
Until it can't adjust any more...Then you find the multiple problems.
That would explain why we get a CEL and then find multiple problems.
That's my story and I'm sticking to it!


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## BassNotes (Mar 16, 2005)

*Re: (JettaRed)*


_Quote, originally posted by *JettaRed* »_
A few seconds is not enough. You need at least 40-60 seconds. You will not necessarily get a DTC stored for not doing a TBA. If you have a VAG-COM, do a TBA.
The process is in the TTweakers Guide.

I agree, a TBA does not take much time to do and can potentially solve a number of issues.


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## Space9888 (Mar 18, 2002)

*Re: 1.8T Throttle Body Malfunction (Arijit)*


_Quote, originally posted by *Arijit* »_Hi,
Recently I went through an 80K servicing from a reputed Store on my 2001 Jetta 1.8T. During which they changed the Engine Gasket and the MAP sensor. They said that oil was leaking through the engine gasket.
I have been driving it reasonably well for about 4 weeks. Although all this while I noted a small drop in thrust while accelerating and a mild hissing noise as if air was leaking from somewhere.
Day before yesterday things started going really bad. Intially the RPM would keep fluctuating while idling and even stalled few times on red lights. Yesterday morning when I started the engine the EPC and ASR lights came up. After turning on and off a couple of times both went out but the MIL came up blinking from time to time. After that the engine would rev up to 2k when I start and then fall to 1k RPM. This was accompanied by frequent misfires. I took it to the dealer and they extracted all the fault codes(13 of them) and suggested that I change the Throttle Body at first and then only they can proceed further saying that the Throttle Body was not able to adapt. Following are the fault codes that I got
1570	Contr.Module Locked
1297	Connection turbocharger - throttle valve pressure hose
1564	Idle Speed Contr.Throttle Pos. Low Voltage During Adaptation
1171	Throttle Actuation Potentiometer Sign.2 Range/Performance
1542	Throttle Actuation Potentiometer Range/Performance
0300	Random/Multiple Cylinder Misfire Detected
0303	Cyl.3 Misfire Detected
0304	Cyl.4 Misfire Detected
0507	Idle Control System Higher than Expected
0301	Cyl.1 Misfire Detected
0302	Cyl.2 Misfire Detected
1136	Long Term Fuel Trim Add.Fuel,Bank1 System too Lean
1128	Long Term Fuel Trim mult.,Bank1 System too Lean
I am going nuts







with all of them around and I am not able to decide whether to go ahead and change the TB from the dealer as it would cost about 800 bucks or whether to go after the Service Centre guys.
What I want to know is can the TB malfunction be connected to the Engine Gasket and MAP sensor replacement? And do the above symptoms mean that my TB is damaged beyond repair ?
I would really appreciate if someone can be my guiding star. I am heavily dependent on my car as I need to drive it close to 500 miles every week.
Thanking you in anticipation ....

you have a weak battery, your throttle will not adapt below 11.8 volts

you have faults for the throttle valve potentiometer angle sensors that is your gas pedal sensor, not your throttle
you have fuel trim problems this could be due to multiple bad engine load sensors 02 sensor. 
you have missfires this could be ignition coil related, or it could be mixture related. 
you need this diagnosed, or like many others you will be spending money to replace parts that will not fix your car. 
get your battery tested by autozone or someone that does not charge you drive there if you can so they can do it in the parking lot (ckeck your alternator too) 
then move on from there, have the codes cleared and see what happens after being sure battery/ charging system is ok. 



_Modified by Space9888 at 2:48 PM 5-11-2008_


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## 2002JettaMike (Jan 20, 2008)

*Re: 1.8T Throttle Body Malfunction (Space9888)*

For what it's worth, system too lean and multiple misfires = vac leak.
Throttle body issues may need a cleaning and adaptation, but could be more than that. 
And nothings going to work without electricity so... http://****************.com/smile/emthup.gif What he said about the battery. Or just change it, it's probably due anyways.
It looks like you have a few problems here so it's going to take some time to fix it unless you take it somewhere and it's going to cost.
What I'm saying is fixing this will be a process to eliminate the codes and not a 1 shot repair. 
so, battery, Tb cleaning and adaption and hunt for the Vac leak.
Here's what I went through: 
http://forums.vwvortex.com/zerothread?id=3643370
Good luck.


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## BassNotes (Mar 16, 2005)

*Re: 1.8T Throttle Body Malfunction (2002JettaMike)*


_Quote, originally posted by *2002JettaMike* »_For what it's worth, system too lean and multiple misfires = vac leak.

A couple months ago I had idle and startup symptoms that resembled those of a vacuum leak, together with error codes that reported misfires, lean mixture, and a pressure drop between the turbo and the throttle.
I searched but found neither a pressure leak nor a vacuum leak. Then I read about throttle body alignment on the ross-tech.com web site, so I tried it with my vag-com. It cleared the problems completely; the engine runs much better and the CEL has been dark ever since.


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## Jetta4Life (Sep 5, 2001)

*Re: (bpfoley)*


_Quote, originally posted by *bpfoley* »_you cannot perform a TB alignment without VAG-COM
 or APR's TBA feature


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## Arijit (Apr 9, 2008)

Hi Folks. I got back the car after repairs today. 
This is all that they changed
Vent Hose - as predicted by you guys
Crank case valve
Air Tube assembly
Mass Air flow sensor
During the 80K servicing they had changed the spark plugs and installed 41-800 platinum plugs. According to the current technicians they are not compatible with my car and that's what caused those multiple misfires. So they replaced them with NGK BKR6E V-Power spark plugs.
My car is running smoothly now (touch wood) but I will get the batteries checked from Autozone as recommended. 
I checked the price of the Mass air flow sensor online and found it to be around $ 200 cheper than that from the dealer which these guys installed. Are these online websites bonafide ?
Thanks again and again for all your suggestions. I will keep updating this post with the progress.


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## BassNotes (Mar 16, 2005)

*Re: (Arijit)*

Depends on the web site. I've bought numerous times from 1stvwparts.com and bestpricecarparts.com and am satisfied with the prices and genuine VW parts.


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