Error code: P0303 & P0505

[gnailuh]

ok, 84K miles and check engine light never came on, and now i just finished all kinds of maintenance and the check engine light comes on. i recently cleaned the throttle body and the dealer just changed my timing belt. according to the scan too i borrowed:

P0303 - Cylinder #3 misfire
P0505 - Idle air control motor circuit malfunction

after the throttle body cleaning, the car is running great as ever. and idles nicely at 750/800 rpm. i did have unplug the iac connector to clean the throttle body, but that was a week ago. but i dealer did change my timing belt and the check engine light came on 2 days later... any relations you think?

if my car is running and idling perfectly, should i even worry? how can i check to see if cylinder #3 is actually misfiring? the plug wire is fine and the plug looks great. should i just erase the code and see if it comes back on in a few days or weeks?

any suggestions would be greatly appreciated.

thanks!

 

[NickBsGST]

Dealer might have ####ed up installing the timing belt?

 

[painmaster]

If the car is idling perfect then I dobt that it is missfiring, unless its happening with load and more throttle. When did you notice the CEL come on?

Clear the code and see if it comes back at idle. If it doesnt come back at idle then go for a spirited drive and see if you get a missfire or if the CEL comes back on.

 

[99cleanGST]

I just had the idle motor go out on my gst and it runs like s**t still. I took it to the dealer and $440 later it's still the same. They didn't even fix it, i haven't had my car for over a week now because they can't figure out what's wrong with it. It'll shut off whenever i start it and the only way to keep it on is to tap the gas and when i try to step on it a little bit it studders. It's not the spark plugs because i just changed them with the ones from the dealerships. I'm having problems to. Does anybody know about this??????ANY HELP WOULD GREATLY BE APPRECIATED

 

[painmaster]

Originally posted by 99cleanGST
I just had the idle motor go out on my gst and it runs like s**t still. I took it to the dealer and $440 later it's still the same. They didn't even fix it, i haven't had my car for over a week now because they can't figure out what's wrong with it. It'll shut off whenever i start it and the only way to keep it on is to tap the gas and when i try to step on it a little bit it studders. It's not the spark plugs because i just changed them with the ones from the dealerships. I'm having problems to. Does anybody know about this??????ANY HELP WOULD GREATLY BE APPRECIATED

Sounds like your dealer sucks. They should have all the tools and knowledge to fix your problem. If a sensor is bad they should know, maybe you should take it somewhere else.

 

[98RedGs]

Cyl 3 misfire? Check your plugs/wires make sure there gapped correctly .028 and make sure your wires are snugly applied.

The other I would clear and hope to god it dosen't come back.

 

[gnailuh]

ok, here's the deal. like i said before, the car runs like a champ... so noway there could be a misfire. i have the scan tool on loan from autozone (free by the way for 90 days!). so i cleared the codes and drove it around a bit...

... well, the light came back on again. this time, the cylinder 3 misfire is gone. but it still showed 2 codes, P0505 (idle air control motor) and P0505 again... what's up with that? the only difference is that on the second P0505, there's a small little pd symbol on the right most part of the scanner display. it's a OBD II AutoScanner. the manual says something about MIL (malfunction indicator lamp) and the "pending" status. not sure what that means... any ideas?

it idles just fine... any way to reset the IAC motor unit? like i said, i did unplug that unit to clean the throttle body...

thanks again.

 

[painmaster]

Try the http://www.vfaq.com/index-main.html

There is a section under Intake, throttlebody, ISC that should help you! I would also check your BISS.

I have no idea about the double codes.

 

[psychlow]

I believe on OBD-II vehicles, there's two steps of "clearing" codes.

"Pending" codes can clear themselves after an successful driving cycle. Non-pending codes stay until cleared. I can't remember if removing battery power clears what type of code, if any.

 

[gnailuh]

i'm not sure what you mean by two steps... the OBDII book just says choose the "erase" option and confirm. then the code is gone.

well, i read the vfaq regarding idel controller. i did not do the actual tests, but did plug the connector a few times to reseat it. also, i noticed that my throttle cable was not fully settled in the little hole... so i fix that and erased the code with the scanner again.

let's see if this stupid P0505 comes back again. let's say the idle controll motor does have something wrong with it... what should the symptoms be? should the idle surge? drop? fluctuate (if so, by how much)?

also, what is this TPS connector also connected to the throttle body? i had mistaken it for th IAC connector before. i actually accidentally started the car without the TPS connector connected, but the car idled fine... what does TPS stand for and what does it do?

thanks.

 

[painmaster]

The TPS is the Throttle Posisition Sensor. It is used by the ECU to tell how much the throttle is open. This tells the ECU if you are trying to accelerate. The car should idle without the TPS, because it uses the idle switch to tell if the car needs to be idleing, not the TPS. The idle switch is also located on the TB, it should have one wire running to it.

Here is a pic:

 

[painmaster]

As for the ISC. Theres no telling what it could be doing. Do the test procedure and see what happens. If it still pases you should find a local DSM'er that has one lying around that you could try. I can't remember how much they are, I think they are $150ish, so you want to be sure that its your problem before you go out and buy one.