agbio Posted July 27, 2006 Share Posted July 27, 2006 Hi, I was wondering where to begin in fixing this problem. I have had the check engine light come on in my 95 Legacy 3 times in the last 2 months. I have 108000 miles on the car and each time I read the code the scanner spits out PO505 idle control system malfunction. I did charge the a/c about the time the CEL first came on and have had some problems with the a/c compressor going on and off irradicately. As far as the engine idleing poor it has been hardly noticable. Also CEL has come on every time I travel in extreme elevation change. I'm thinking this is just coincidence and that the A/C is contributing to the problem? Who knows. I did have this same code come on years ago and changing the air filter actually kept the CEL from coming back on. I tried this, this time and it did'nt seem to work. Any suggestions, comments, previous experience with same code? Mark:confused: Quote Link to comment Share on other sites More sharing options...
nipper Posted July 27, 2006 Share Posted July 27, 2006 Sounds like your IAC motor is either dirty or tired. beleive it or not they are all related. nipper Quote Link to comment Share on other sites More sharing options...
agbio Posted July 28, 2006 Author Share Posted July 28, 2006 Sounds like your IAC motor is either dirty or tired. beleive it or not they are all related. nipper Are you saying IAC Motor or sensor and is this the same thing as the throtle body? I did clean up the air flow sensor that was a bit dusty. I have my own scanner so I turned the CEL off again yesterday and notice that the A/C turned on full blast would recycle alot of times (3 times a minute). When I hooked up a guage to the a/c, when a/c was running, it read 30 when the a/c compresor turned off the idle would go down way below 500 and would idle low until my system reached 45psi. then the compresser would turn back on again. This happened many times and the CEL did'nt come back on but I'll put some miles on the car today and see what happens. Mark:-\ Quote Link to comment Share on other sites More sharing options...
nipper Posted July 28, 2006 Share Posted July 28, 2006 Are you saying IAC Motor or sensor and is this the same thing as the throtle body? I did clean up the air flow sensor that was a bit dusty. I have my own scanner so I turned the CEL off again yesterday and notice that the A/C turned on full blast would recycle alot of times (3 times a minute). When I hooked up a guage to the a/c, when a/c was running, it read 30 when the a/c compresor turned off the idle would go down way below 500 and would idle low until my system reached 45psi. then the compresser would turn back on again. This happened many times and the CEL did'nt come back on but I'll put some miles on the car today and see what happens. Mark:-\ any codes? also when was the last time you had the AC checked with gauges. The idle air control motor allows more air into the engine at idle to compensate for load and altitude amoung other things. Thats why i think it is all related. nipper Quote Link to comment Share on other sites More sharing options...
BigMattyD Posted July 28, 2006 Share Posted July 28, 2006 I have the troubleshooting diagrams for the trouble codes on my computer at home. This evening, I will try to post a diagram or some instructions regarding this code. Matt D Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted July 29, 2006 Share Posted July 29, 2006 Dude the IAC is dead easy to clean; I just unhooked the hoses and poured some warmed Fuel Power FP60 down in there. I think sometimes if they're really caked up, the IAC will be fully open or nearly fully open and that's just not enough when the A/C is on? my '96 manual says for this code PO505, check air intake system, check output signal from ECM, check idle air control solenoid valve, check power supply to idle air control solenoid valve, check harneess between ECM and idle air control solenoid valve connector, and then step by step instructions on each. --Louis Quote Link to comment Share on other sites More sharing options...
agbio Posted July 29, 2006 Author Share Posted July 29, 2006 any codes? also when was the last time you had the AC checked with gauges.The idle air control motor allows more air into the engine at idle to compensate for load and altitude amoung other things. Thats why i think it is all related. nipper I have my own scanner an the code is PO505, I also have a a/c guage but not what the dealers use just a presure gaues that comes with the 134a kit. Guage reads 35 psi when compressor is in and reads as I have explained in the previous thread. Where is the idle control motor? Mark:-\ Quote Link to comment Share on other sites More sharing options...
agbio Posted July 29, 2006 Author Share Posted July 29, 2006 Dude the IAC is dead easy to clean; I just unhooked the hoses and poured some warmed Fuel Power FP60 down in there. I think sometimes if they're really caked up, the IAC will be fully open or nearly fully open and that's just not enough when the A/C is on? my '96 manual says for this code PO505, check air intake system, check output signal from ECM, check idle air control solenoid valve, check power supply to idle air control solenoid valve, check harneess between ECM and idle air control solenoid valve connector, and then step by step instructions on each. --Louis Where do you get this Fuel power FP60 I have tried a few autoparts stores, ie kragen, napa and they have never heard of it. I'm thinking it's a typical California thing where it is restricted here. Mark:-\ Quote Link to comment Share on other sites More sharing options...
agbio Posted July 29, 2006 Author Share Posted July 29, 2006 I have the troubleshooting diagrams for the trouble codes on my computer at home. This evening, I will try to post a diagram or some instructions regarding this code. Matt D Thanks that will help alot before I really start digging in to this checking all sensors needed. I have fixed many things on this vehicle but when it comes to the OBD II stuff I tend to get frustrated. The only tools I have to fixe the problem is my ohm meter and my scanner tool and when everything checks out and it's intermitant there's not much I can do but go have a beer. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted July 29, 2006 Share Posted July 29, 2006 On my '96 Legacy Brighton Wagon, the idle air control valve is as shown in the pic below. Mark I got the FuelPower FP60 from their Web site. It's actually a gasoline additive. I don't think it's sold in retail stores. It seems to work very well as a cleaner when warmed. I've used it to clean the throttle plate, etc. RedLine SI/R-I fuel system cleaner works very well too, and that you can get at I think Parts America, or from Summit. Anyway, I would think people would typically use a throttle body cleaner for this kind of work, but I didn't have any when I cleaned mine hence my use of alternates. I don't know what this board thinks of AllDataDiy, but you can get the trouble codes on there too, at least I can for my '96. I also poured you a beer!!! Quote Link to comment Share on other sites More sharing options...
nipper Posted July 29, 2006 Share Posted July 29, 2006 I have my own scanner an the code is PO505, I also have a a/c guage but not what the dealers use just a presure gaues that comes with the 134a kit. Guage reads 35 psi when compressor is in and reads as I have explained in the previous thread. Where is the idle control motor? Mark:-\ You need to see the low side and high side reading. That gauge that cames with the can has almost no accuratcy as far as gauges go (trust me i used to calibrate gauges for a defense contractor. Taking only the low side is like taking ony half your blood pressure, and thats the bottom number. nipper Quote Link to comment Share on other sites More sharing options...
BigMattyD Posted July 31, 2006 Share Posted July 31, 2006 Here is a pdf of the relevant diagnostic charts for P0505 MattD p0505.pdf Quote Link to comment Share on other sites More sharing options...
agbio Posted July 31, 2006 Author Share Posted July 31, 2006 You need to see the low side and high side reading. That gauge that cames with the can has almost no accuratcy as far as gauges go (trust me i used to calibrate gauges for a defense contractor. Taking only the low side is like taking ony half your blood pressure, and thats the bottom number. nipper Thanks for the info, I hate taking my car in to be worked on by someone else but me. Thats why I have all my tools and I really enjoy it but buying a professional A/C gauage is going to cost alot more than taking the car in to get the A/C checked. So I guess I have no choice this time. Mark Quote Link to comment Share on other sites More sharing options...
agbio Posted July 31, 2006 Author Share Posted July 31, 2006 Here is a pdf of the relevant diagnostic charts for P0505 MattD Thanks for the diag charts, this will help immensly. Mark Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted July 31, 2006 Share Posted July 31, 2006 Dude I don't know if you have a Harbor Freight near you but they have A/C manifold gauge set on sale right now I think for $39.99 plus if you sign up for e-mail specials you'll get coupons every week usually one of which is 20% off any single item. Quote Link to comment Share on other sites More sharing options...
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