Did something bad when changing my cambelt

[SimonR]

Everything was working hunky-dory until I changed my cambelt a week ago.

 

Now it is running pig rich and isn’t going into closed loop (no wavy behavior on the AFR gauge) once warm. The Emanage (blue) confirms that the ECU is throwing fuel in at three times the normal rate.

 

My understanding is that the switch from initial open loop to closed loop is based on engine (ie coolant) temp. I did have the rad out to change the belt so I’ve checked the temp sensor on the rad and it seems to be properly seated – but I honestly can’t remember whether it’s the sensor on the rad or at the top of the engine that feeds the ECU (as opposed to the dash gauge) edit - it's the top one. The top sensor looks OK as well, in any case it wasn’t removed for the belt change.

 

An ECU reset hasn’t made any difference.

 

Any ideas what else I should be checking please? Earthing problem? Air bubbles?

 

(It's a Soarer, but most of the parts involved are the same as the MKIV).

Edited January 10, 2009 by SimonR (see edit history)

[Ian C]

Does it cold start OK and then go downhill from there? Whats the inj duty cycle in ms that you are seeing?

[gordy.r]

I'm not the most technically minded - but I had a similar problem with my Skyline and it turned out to be the timing was 2 degrees out....

 

Just my 2p

[SimonR]

This had sort or worked itself out and I'd forgotten about it. Now that I know that I had a blown head gasket between 5 and 6 (caused emissions failure) but I don't know how long it has been there, I'm guessing that this problem was because the ECU had reset during the cambelt chnage and the rich reading was becasue of the resulting misfire. I'm also guessing that the ECU had then corrected which masked the problem.

 

Shame there isn't an ECU error code for "something bad has happened but I'm adjusted your mixture to compensate"