[CREWZIN]

MJB457,

Here's some reading I found for you....

I recently purchased a pre-owned 2002 TE PT with 77k miles for my wife, which appears to be in good running condition. Our last (fuel injected) vehicle used a cold start injector, but the PT does not appear to have one. Am I missing something? – Ken, from Washington.

On the PT and most vehicles with newer engines the cold start injector is no longer used. Instead, the PCM looks at the coolant temperature sensor to determine if the engine is hot or cold. If the engine is cold and needs extra fuel to start, the PCM increases the cycle time of the fuel injector pulses to supply more fuel to the engine.


I have a (domestic import) 2001 pre-owned TE PT with 40k miles. I've experienced problems with cold starting/stalling since I took possession of the vehicle in 2005. If the vehicle sits overnight, or for more than a few hours, it will usually stall or stumble when I start it. I have to rev the engine a bit for about 20 seconds or so before driving off. This occurs regardless of whether I'm in drive or reverse. After it warms up a bit it's ok. I had the sparkplugs, wires and EGR changed, but it hasn't helped. Last week I had the idle motor valve cleaned, de-carboned after a mechanic suggested I try it as a remedy. The car runs smoother, but the problem with stalling persists. Currently the idle runs at about 800 RPM. The folks at DC say that the idle motor may need changing. As it would mean spending another couple of hundred dollars I kindly ask your advice for this persisting problem. What should the RPM in idle be for my car. Should I have the idle motor replaced, is it likely to cure the stalling problem? Thanks for your help. – Robert, from Czech Republic.

As we discussed in a previous email, stalling can be caused by a low idle speed, incorrect fuel mixture, intake manifold leakage or faulty ignition coil(s). Under the right conditions there are a number of components (ECT sensor, fuel injectors, MAP sensor, idle air control motor, throttle body and O2 sensor) that can contribute to stalling issues with a cold engine.

You indicate that the sparkplugs, wires, and EGR were replaced and it didn't help. Then the idle motor valve was cleaned after a mechanic suggested it as a remedy, but the trouble with starting persists. The idle speed is controlled by the PCM and various inputs. Target idle is determined by the following inputs:

Gear position
ECT Sensor
Battery voltage
Ambient/Battery Temperature Sensor
VSS
TP sensor
MAP Sensor


Based upon other PT's I've seen, normal idle, without the A/C running, is about 1000rpm. As previously discussed, a malfunctioning IAC motor can cause stalling, but low idle can also be caused by one or more of the inputs mentioned above.

If you had brought it to the DC dealer initially, and they determined that the IAC was faulty they would simply replace it. They would not have bothered to service it. At this point it is difficult to know with any certainty if the IAC motor is faulty, or possibly one of the other inputs that is causing the low idle condition without further testing. What you really need is a skilled diagnostician.