# '90 Passat 2.0L 16V CIS-E Motronic Fuel System



## Zweibb (Jun 6, 2006)

Starting to do repairs on a '90 Passat that I purchased new in 1990. I notice the boot that connects to the throttle body has two (2) ports with one (1) having a 90° bend and the 2nd port having a brass orifice/restrictor that is positioned on the inside of the boot (is the correct term a throttle body boot?). Anyway neither port had a hose line attached to them, Bentley manual and VW illustration 36-40 indicates the 90° port should have a hose line running to the "intake air temperature regulator flap" and the port with the orifice/restrictor should have a hose line to a "check valve" port. This check valve has four (4) ports, one (1) small port for connection to the throttle body boot, a 2nd small port which appears to connects to a box type device (ECU???), 3rd large port connecting to the intake manifold, and a 4th port which I am unable to identify where it terminates at. Anyway the 2nd small port on the check valve have been broken off and sealed off with a silicone type sealant. I would appreciate inform stating what effect these missing hose lines/connections is having on the engine performance.
I have experienced intermittent power surges and losses. Replaces both fuel pumps (main & transfer), O2 sensor, knock sensor, coolant temp sensor, plus confirm fuel system is within spec.
In addition to the missing hose line, I notice the clear plastic type line that connects to the charcoal canister and runs to the gravity valve is broken. What is the malfunction/problem with this type of occurence.
Thanks


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## Southcross (Jul 2, 2004)

*Re: '90 Passat 2.0L 16V CIS-E Motronic Fuel System (Zweibb)*

wow... I'll try and tackle this

_Quote, originally posted by *Zweibb* »_Starting to do repairs on a '90 Passat that I purchased new in 1990. 
I have experienced intermittent power surges and losses. Replaced both fuel pumps (main & transfer), O2 sensor, knock sensor, coolant temp sensor, plus confirm fuel system is within spec.
I notice the boot that connects to the throttle body has two (2) ports with one (1) having a 90° bend and the 2nd port having a brass orifice/restrictor that is positioned on the inside of the boot (is the correct term a throttle body boot?). neither port had a hose line attached to them
Bentley manual and VW illustration 36-40 indicates the 90° port should have a hose line running to the "intake air temperature regulator flap" and the port with the orifice/restrictor should have a hose line to a "check valve" port. 
This check valve has four (4) ports, one (1) small port for connection to the throttle body boot, a 2nd small port which appears to connects to a box type device (ECU???), 3rd large port connecting to the intake manifold, and a 4th port which I am unable to identify where it terminates at. the 2nd small port on the check valve have been broken off and sealed off with a silicone type sealant. 
I would appreciate information stating what effect these missing hose lines/connections is having on the engine performance. In addition to the missing hose line, I notice the clear plastic type line that connects to the charcoal canister and runs to the gravity valve is broken. What is the malfunction/problem with this type of occurence.
Thanks



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The Air Flap, if I know what your talking about is a warm/hot air intake flap (gets its air from around your exhaust manifold) this helps with engine warm up in the winter (as well as winter fuel economy). The others sound like an emission type of connection... a lot of cars have these deleted. I'm not 100% sure, but I'd guess neither will affect engine performance like your experiencing.


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## Zweibb (Jun 6, 2006)

*Re: '90 Passat 2.0L 16V CIS-E Motronic Fuel System (Southcross)*

You stated "Air Flap", is this where the 4th port on the check valve terminates at??
Thanks


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## Southcross (Jul 2, 2004)

*FV-QR*

no... you already stated where that one goes:

_Quote »_Bentley manual and VW illustration 36-40 indicates the 90° port should have a hose line running to the "intake air temperature regulator flap"

since most of your questions are specific to your B3 Passat (i.e. vacuum diagrams in your Bentley), you might want to research in the B3/B4 Forums:
http://forums.vwvortex.com/zeroforum?id=7
Once you've determined if and what those vacuum connections do/go to, we can trouble shoot the CIS injection issues from there.


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## Zweibb (Jun 6, 2006)

*Re: FV-QR (Southcross)*

Thank you for the help thus far and may be back after the B3/B4 forum inquiry.


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## wclark (Mar 28, 2001)

*Re: '90 Passat 2.0L 16V CIS-E Motronic Fuel System (Southcross)*

The 9A I took from a '90 Passat had one of these on the bottom of the boot. It looks like it is some sort of thermo-vacuum control and ETKA calls it a "dual thermostat". I didnt hook it to anything and on the off chance it might leak air into the TB, I put a small hose between the 2 nipples.


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## Southcross (Jul 2, 2004)

*FV-QR*

ya'know... funny, I never really paid attention. I have one of those boots on my boosted Dasher, never capped them, never ran lines to anything, just left them "open"


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