does this sound like lambda failure

[chris]

1994 s4 v8 4.2,
car starts and warms up ok , as soon as the temp gauge starts to rise , and as it is fully warm,[gauge reading a little higher,90 c as i would expect as the ambient temp rises]
suddenly the throttle response is jerky especially on trailing/light throttle almost getting unwanted surges,,
coupled with the instant computer read out showing worse mpg, although is normally pretty poor
full throttle is ok,
never changed the lambda on this[yet] and am without code reader , , any helpful pointers welcome

[UrS4boy]

Info on pulling codes for a 4.2L V8 UrS

1994 s4 v8 4.2, car starts and warms up ok , as soon as the temp gauge starts to rise , and as it is fully warm,[gauge reading a little higher,90 c as i would expect as the ambient temp rises] suddenly the throttle response is jerky especially on trailing/light throttle almost getting unwanted surges, coupled with the instant computer read out showing worse mpg, although is normally pretty poor full throttle is ok, never changed the lambda on this[yet] and am without code reader , , any helpful pointers welcome

Chris: As you know, I also have a 94 S4 with the 4.2L V8 (one of 1456 built between 1992 and 94, just sayin'). Fortunately, I haven't had any running issues (now that I changed the clutch). So basically, I can't really help you with your diagnosis based on direct experience. However, I can direct you to this website:

http://www.sjmautotechnik.com/troubl...ng/ecufv8.html.

The trick is if your 94 S4 Avant likely doesn't have a check engine light that can be used to blink out the codes (I just went out to my avant and turned the ignition on - no check engine light). All is not lost. Either find somebody with a VAG scan tool and connect to the white and black connectors in the fuse and relay panel ("lunch box") under the hood.

This is a photo of my AAN fuse box but I just checked the V8 fuse box and it has the same black and white connectors:



If you can't find a VAG scan tool, you could rig up an LED light to get the blink codes using something like this as a guide:


Source: http://www.sjmautotechnik.com/troubl...uf20v.html#led


Info on the C4 AAN diagnotic ports is found here:

http://forums.quattroworld.com/s4s6/msgs/90409.phtml

[spink]

buy this http://www.ebay.co.uk/itm/Volkswagen...item43c5a0128c

and a 2x2 cable

[UrS4boy]

buy this http://www.ebay.co.uk/itm/Volkswagen...item43c5a0128c
and a 2x2 cable

Here is where that OBDII to OBD 1 cable that Paul N. was selling would be handy

[JP]

Unplug the lambda if it solves the issue then replace it.

[chris]

s4

thankls will try all of the above,,