960 Head Gasket & Valve Timing

Hi all,

Well, without the aid of a manual or any special tools, I have been able to do the Headgasket on my 960 3.0 24v. (Halfway through I also found a better engine, so dropped that in too).

Anyway, started her up today and valves didn't come through cam carrier or pistons (Wa-hey!). However, seems to be idling at 1,100 to 1,200, and when I blip the throttle, revs are reluctant to come down, (same appplies when I hold the revs). They do come down, but in stages, and kinda clunky, and whilst revving at about 2,000, seemed to run a little rough.

Any ideas? The butterfly is very very fractionally open, but don't see that causing all this. I know that with some cars, if the engine management computer is disconnected from the battery for a while, (and this has been for 4 weeks), it takes a while to relearn (Jag XJ40 in my experience), but this doesn't seem like a good enough explanation.

Need to go away in it on Friday night, so any quick help would be much appreciated.

p.s. Should have said: The Lambda light is on, (and was before I did the head gasket, so I think this makes it run rich. Is this right? Would this explain it?

Cheers,

B-Ste.

[Mike Arnold]

I do not claim to have the answer but here are a couple of ideas. On my 960 the lambda light came on when I had a leak on the inlet manifold gasket (mixture too weak). Went away when I changed the gasket.

Secondly, I believe that the tickover speed of a 960 should be around 800 rpm and accurately controlled by the ECU through the idle control valve. Of course, the ECU only knows that it should do this when the throttle switch shows that the pedal is not depressed and therefore it should go into tickover mode. Alternatively, the butterfly stop may be too high so that the idle speed (without the valve operating at all) is above 800.

Just some thoughts...

[Peter Milnes]

First try resetting the codes on the diagnostic unit, that should get rid of the Lambda light and restore correct operation. However make a note of the codes displayed so that if they return you can then look at the items indicated by the code.

All the best, Peter

Thanks for the words of advice. All top end gaskets changed at time, (and double-checked the inlet last night, as I can see where you're coming from).

Read codes, and then reset. Socket 1 showing no faults. Socket 2 showing (before resetting) Cam Position Sensor and Idle Air Control out of tolerance codes (I think this is what they meant), and warm idling at about 1,100. (Idle Air Control makes a noise when the ignition is turned on, but thought it used to be silent).

Disconnected battery and reset codes. Lambda light stayed off for several seconds, then came back on. Drove 20 miles for Engine ECU to "relearn". During and after driving, idle speed at 1,500 (in neutral / park). Now shows socket 1 - no faults and socket 2 codes of: 3-1-4- and 2-1-2, which I think are the same as before. Cold idling is at correct speed (really), but warm idling is £1,500. Furthermore, engine gets up to temperature very quickly (less than 2 minutes, but doesn't overheat at all)

Incidentally, my diagnostic box, only has active sockets of 1 and 2, 3 onwards are empty holes - Is that right?

Any ideas would be much appreciated. (I'm guessing that IAC and O2 Sensor have both failed, but any advice would be much appreciated.) Am hoping to go away in it tonight, but not happy with driveability like that. If anyone wants to try to talk through the issue, please feel free to call me on (0775) 271 9600. (If you can give me a landline number, I will try to call you back.)

Cheers,

B-Ste.

[Peter Milnes]

I think that the inlet tract (from filter to manifold) could do with a thorough clean including the Idle Air Control Valve. Clamp one of the hoses to/from the IACV then read idle revs. If they are low (approx 500 rpm) then IACV is faulty. If the revs are incorrect then check the throttle switch and reset the idle revs whilst clamp still applied. When engine is warmed up the IACV should allow the revs to settle at about 750 rpm.

All the best, Peter