Hi everybody.

I would like to get some help with one or two issues my X300 3.2 has developed recently.

When I am driving the car and waiting at, for example, a traffic light, the engine does only 700 RPM with the box in D.
As soon as I want to accelerate, and release the brake pedal and push the throttle, the RPM's sometimes drop even more.
Sometimes, the engine then stalls.
I can only keep the engine going by pushing the gas pedal really deep down quickly.

The above only seems to happen during the first 15 minutes after a cold engine start. After that, the problem doesn't occur.

If I remember correctly the RPM's when idling in D used to be higher than 700 too.

I don't know where to start looking.
Is it an ignition problem? Or something with air flow to the engine, or gas flow? Would one or more cylinders perhaps be misfiring or dead?
Please help.

 

The 3.2 is not usually that hissy.

Some things I have had with mine are:

TPS giving mixed signals to the ECU. An age thing now, as well as the gunk that runs down the throttle shaft and contaminates the TPS.

The throttle body itself is all gunked up on the inside.

The EGR system, if fitted, will also cause this.

Spark plugs past the use by date also enter the list.

Crank angle sensor is also on my mind.

Coolant temp sensor plays a big part on that warm up process. Not a known issue on the AJ16, but there is an update to the part number????

700rpm at idle in D is about normal.

 

Sage advice as always from Grant. The CTS and TPS ould be high on my list too.

One thing you can do is plug in a scanner if you have access to one. This will allow you to see in real time what the ECM sees in terms of engine temp, throttle position and many other parameters that affect the engine management. It may also alert you to any misfires though I would expect that you would be able to hear/feel those.

Factory specs for idle at normal operating temps is 700rpm in park/neutral and 580rpm in D, so 700 with a cold engine does not sound out of whack.

 

Thanks guys for the answers so far.

What is the CTS?
Googling CTS only brings me to a Cadillac...


About those OBDII kits, I see them on eBay all the time, are they any good?
You can get them for really little now, cable + software.

 

Matt:
I believe Allan was referring to the device referred to as the CKPS which is the crank position sensor. It is a passive electronic device mounted on the front of the engine where the crank extends- It "reads" the teeth on the damper, which is the hunk of steel that the crank pulleys mount to. They are known to fail intermittently and give symptoms such as yours. And they are not too expensive, either. I would not go for a used part in this case, as a significant number of folks are reporting failures on them.

 

Swap out the ecm relay, common problem.

 

The CTS is the coolant temperature sensor, it's mounted on top of the thermostat housing at the front of the engine. As your issue only manifests itself when the engine is cold, makes sense to check it out. During engine warm-up the ECM uses a different enrichment strategy based on info from the CTS.

The problem could be any of the items mentioned above or a combination thereof, that's why it pays to do some detective work first rather than just throwing new parts at the problem.

You can buy a wifi OBDII adaptor for about $20 and then use apps like OBD Fusion or Torque on your phone or tablet. The software is cheap too and works great.