K series S1, Revs 'hang' on gear change

[2F45T4U]

Odd problem really. when changing gear (gentle driving) the revs hang about 2.5k rpm and take 5 or so seconds to fall back to normal idle speed.
idle is steady enough apart from a slight murmour type hesitation. it drives ok, i thought it was a bit sluggish lately but put that down to driving the other car for a while.
Ive cleaned the idle valve and the throttle body, done all the usual checking of leaks and hoses on the plenum and vacuum side and found nothing.
i have a feeling that it may be the ECT sender but having no way of interrogating the ECU i cant be sure.

does anyone know what the temp/V tables are for this sender and/or had this problem before?


cheers

[Rich H]

Mine used to do it on occasions but usually cleared after a bit (The Esprit too but the throttles just get a bit stuck!)

[r10crw]

I doubt the ECT and suspect an actual fault with the IACV. If you can access a second unit try it first, I can lay my hands on one if you like. Also I could give you a shot of an emerald to rule out the ect if you want?
Craig.

[kerryxeg]

This may be totally irrelevant, but I had a similar issue on the A4. This turned out to be a faulty clutch switch - the ECU wasn't getting the signal from the switch and therefore didn't cut the revs correctly prior to gear changes. No idea if there is such an arrangement on an S1 or if there is some other sender in use, but sounds very similar.

[graeme]

I had the exact same thing years ago. It was indeed the ECU temp sensor, not the IACV.

[2F45T4U]

thanks for the replies folks.
i'll fit a new sender anyway then based on Graemes experience. it may well explaing why it always struggles to pass the emmissions test as well.
i did think about plugging in the emerald to use it as a diagnostic so i might do that this afternoon if i get a chance.

FYI
I answered my other question below, might help someone tuning votage tables in an ECU or diagnosing future faults.

Temp Resistance Voltage
O/C 5
0 4.8k-6.6k 4.00-4.50
10 4.0k 3.75-4.00
20 2.2k-2.8k 3.00-3.50
30 1.3k 3.25
40 1.0k-1.2k 2.50-3.00
50 1.0k 2.50
60 800 2.00-2.50
80 270-380 1.00-1.30
110 0.5
120 Bang!
S/C 0.5

[thinfourth]

Wasn't there something with the plastic throttle bodies where if you tightened the jubilee clip too tight it caused a sticky throttle?

[Rich H]

Yep, usually caused by induction kits

[Stewart]

Wasn't there something with the plastic throttle bodies where if you tightened the jubilee clip too tight it caused a sticky throttle?

My S1 suffered from this and was completely standard - no induction kit. A used alloy throttle body of eBay did the trick.