hi all, the aj6 in my campervan is alive. See also https://www.jaguarforums.com/forum/x...107712/page12/

but it Idles high. I don't have a tach, but sounds like 1200 or so. drops when I put it in gear, but also then it seems to be running at higher RPM than it should when in gear.

I checked
- vacuum leaks, none found
- throttle cable -> the valve returns completely and closes fully

what else should I check?

thanks!

 

Hi Wilfred,

The Idle Air Control Valve (IACV) is one suspect. It tends to clog up with carbon, which prevents it from closing all the way. You can carefully remove the stepper motor and clean the pintle and the port inside the valve body. Take care not to power the stepper motor while it is detached from the valve body or the pintle can thread all the way out.

A leak anywhere between the MAFS and the intake manifold gasket can cause high idle. Check all your hose connections carefully. A common leak point is the underside of the plastic intake elbow. If you overtighten the hose clamp, the plastic elbow kinks inward, usually at the bottom, causing an air leak. Also check all of the crankcase breather hoses and connections, and check to be sure the EGR valve is not stuck open.

Another possibility is that your Throttle Position Sensor (TPS) needs to be adjusted. Details are in the Workshop Manual or Haynes.

I can't recall if you are using the original instrument cluster, but if so, you can check for diagnostic trouble codes with the Vehicle Condition Monitor. With the ignition in position II (ignition ON but engine not running), press and release the VCM button on the trip computer near the steering wheel. Watch for a message in the odometer/mileage counter window below the speedometer. DTCs appear in the form of Fuel Fault or FF and a one- or two-digit number depending on the year of your AJ6. Codes look like Fuel Fault 69 or FF 69.

You can look up the definitions of the codes in the Haynes manual.

Cheers,

Don

 

hi, thanks for the input.

I have removed the Idle air control valve and cleaned it. Runs better now, but still too high.

Also, I am thinking it's temperature related. I noticed, the idle gets higher after running for a bit. In my search, I also noticed that the thermostat is either missing, or stuck open. So I have to replace that, and also going to replace the temperature Sensor. The one that gives input to the ecu.

I am not running the original dash, so no fault codes.

 

thanks for all you input. I still have the issue. Will connect a tach, to get some numbers but it is definitely idling too high.

I checked/did/replaced the following:

- vacuum leaks. Also sprayed with brake cleaner in suspicious areas but no leaks found
- cleaned IACV completely.
- replaced thermostat that was stuk open
- replaced the coolant temperature sensor that gives input to ecu
- adjusted the tps. that showed 0.69 volt at idle, which is on the high side. now it shows 0.55 at idle.

My next step will be, especially after adjusting the tps, to reset the IACV.

any other suggestions?

 

Set the throttle body butterfly to spec with feeler gauges if you haven't already.

Larry

 

Check to be certain the brake cleaner you use is flammable. The CRC Brākleen that I use is non-flammable, so it's no good for vacuum or air leak detection. Starter fluid is better, a smoke test is better yet.

Cheers,

Don