1999 Carrera Cab Low Idle Culprit ?

[Pressed]

Hey guys. I need some thoughts on a relatively low idle situation that has plagued me since I purchased my 1999 Carrera 6spd Convertible @ 3 years ago. I purchased a used Throttle body on ebay last week. placed it on and am experiencing an even lower idle (@ 600 + RPM's (my original held the idle @ 625-650 RPM's with occasional blips to 700 RPM's when the car was hot) No fault codes seen on my scanner tool. Good acceleration and the car "breathes" well. I must admit I took the IAC valve and the TPS from the ebay purchase and placed it on my Throttle body.  I did not place the purchased throttle body on my car since it was from an earlier Boxster 2.5l and I thought that the diameter would be less than that for a 3.4L Carrera throttle body. I had cleaned the my throttle body and IAC valve months ago and it didn't have the effect that I had expected..............still low idle. Well, this time I noticed some corrosion on the contacts which has me thinking that I should return the recently purchased Throttle body, IAC valve and TPS. I have attached a picture of my IAC valve after soaking it thoroughly with Carb cleaner and using a Q Tip to get to areas on it that I had neglected during my first cleaning. Do you guys thing that this corrosion can be the culprit of my low idle woes.?

[JFP in PA]

No picture attached.

 

Quite often, erratic idle issues are MAF related, a dirty sensor or corrosion at the electrical connectors being a common fault.

[Pressed]

But I'm not getting any fault codes.

[JFP in PA]

11 minutes ago, Pressed said:

But I'm not getting any fault codes.

 

That does not mean anything.  You need to take a look at your MAF, looking for dirt build up.  If it is there, you need to use a correct MAF cleaner to remove it as you cannot touch the sensor itself.  Another alternative would be to check your MAF values using a Porsche specific scan tool.

[Pressed]

I have read many posts regarding low idles on this MY where installation of a new MAF sensor didn't rectify the situation. Those MAF's cost a good penny also. I just wanted to see if there were alternatives to replacing the MAF and hoping for a higher idle. Perhaps a new oil filler cap and cleaning of the IAC valve contact. I would just be severely po'd if I installed a new MAF and no go on the idle.

[JFP in PA]

 

30 minutes ago, Pressed said:

I have read many posts regarding low idles on this MY where installation of a new MAF sensor didn't rectify the situation. Those MAF's cost a good penny also. I just wanted to see if there were alternatives to replacing the MAF and hoping for a higher idle. Perhaps a new oil filler cap and cleaning of the IAC valve contact. I would just be severely po'd if I installed a new MAF and no go on the idle.

 

I am not even remotely suggesting a new MAF, I'm suggesting that experience has shown that a dirty MAF, or one with resistance in the circuit can result in idle issues that do not throw codes,  Futher, I am suggesting that you do more diagnostics, such as reading the MAF values vs. specs, and looking at the MAF sensor to see if it is simply dirty. Far too many people simply throw expensive parts at a vehicle without really knowing what it needs...........

[Pressed]

okay, I'm reading you loud and clear on this . Off to Advanced auto tomorrow for some CFC MAF sensor spray cleaner. I have a cheapie OBD scanner that doesn't read MAF values so I have really nothing to go by except for symptoms (in this case relatively low idle). Sure it will read long term / Short term trims , Freeze frame data and generic codes but nothing heavy duty ie: MAF readings (ya get what you pay for y'know ?) I really didn't want to invest in a costly scanner but for accurate information in pinning down the nature of issues that arise, I think it would be a wise choice. One more question though, what type of scanner would you advise for <

[JFP in PA]

Your choices are limited by Porsche's rather unique diagnostic logic protocols,  a PIWIS would be the best but is a lease only item and starts at $18K for the first year.  Next would be the Durametric software system, which has around 80-85% of the PIWIS capabilities and sells for less than $300 with unlimited update capability.  There are a couple of other after market stand alone scanners out there as well, but they have considerably less diagnostic capability than the Durametric system.

[Pressed]

Thanks, JFP. I really appreciate the advice on my idling issue and the durametric tool, the latter of which lies in my realm of affordability . Thanks again.