P0507 and low Idle

[drcmrn]

I have a 2003 STS that the idle has been acting strange. First problem, when starting the engine would start and then die, no/low idle. I cleaned the throttle body and it worked fine for a couple weeks. Now it is idling at 11-1200 and tripped the P0507. any help/guidance would be greatly appreciated. The guy at autozone said to replace the TPS, i dont believe that controls Idle.

[rockfangd]

kind of sounds like an intake problem, does it sound like it has a misfire?

[JimD]

I have a 2003 STS that the idle has been acting strange. First problem, when starting the engine would start and then die, no/low idle. I cleaned the throttle body and it worked fine for a couple weeks. Now it is idling at 11-1200 and tripped the P0507. any help/guidance would be greatly appreciated....

Cleaning the throttle body is a good idea.

Removing and cleaning the Idle Air Control (IAC) valve and the associated air passage in the throttle body is another good idea.

P0507 does not tell you anything you don't already know.

[Cadillac Jim]

Also check for vacuum leaks. Possible sources include hoses off the throttle body or the other end of hoses off the throttle body, PCV valve pulled out of the cam cover, oil filler cap loose or off, loose or missing dipstick, and loose intake manifold bolts

Also, the EGR valve could be stuck open.

[drcmrn]

kind of sounds like an intake problem, does it sound like it has a misfire?

No runs smooth

[BodybyFisher]

The throttle body throat and throttle plate has to be cleaned really good, especially the back and edges of the plate.

Anything that holds the plate open, that includes kinked linkage, etc. Make sure that the plate closes and sits on its stop

It should take about 30 minutes to clean the TB and plate

Once that is done, disconnect the negative battery cable and reconnect

[scott y]

Is that with the TB on the car or does it require bench cleaning?

[drcmrn]

Also check for vacuum leaks. Possible sources include hoses off the throttle body or the other end of hoses off the throttle body, PCV valve pulled out of the cam cover, oil filler cap loose or off, loose or missing dipstick, and loose intake manifold bolts

Also, the EGR valve could be stuck open.

will take it all apart tomorrow and give a good cleaning and inspection. looked for a PCV and cant find it

[JimD]

....looked for a PCV and cant find it

Your year uses a fixed orifice in place of a PCV valve.

[drcmrn]

....looked for a PCV and cant find it

Your year uses a fixed orifice in place of a PCV valve.

thanks, is there a way to clean it?

[BodybyFisher]

Is that with the TB on the car or does it require bench cleaning?

That is with the TB on the car, to me its harder to do with the TB in place. Be careful NOT to spray too much O2 save carb cleaner into the TB we have seen a TECH hydrolock an engine.

But, the cleanest I ever got my TB was when I removed it and soaked it in a good carb cleaner, remove all electronic parts, it can get pretty dirty as it ages look at how restricted it was

Close up of restriction

It looked really bad

It looked really good when I cleaned it, I used a dremel tool to polish it. The backside of the throttle plate is always bad, but when I was done it was shiney.....

Make sure you have a new seal for where it attaches to the intake

It was looking good

[scott y]

Thanks for that info BBF, I think i will try that out on Monday....

[WarrenJ]

If you do it on the car using a toothbrush, for example, don't forget to tie a string onto the brush's handle in the event you get a case of the "dropsies."

[winterset]

If you do it on the car using a toothbrush, for example, don't forget to tie a string onto the brush's handle in the event you get a case of the "dropsies."

and put a rag over those wires to capture the runoff. carb cleaner has a tendancy to melt the insulation on wires and/or make them brittle over time. it will definately melt the electrical tape.

[drcmrn]

Is that with the TB on the car or does it require bench cleaning?

That is with the TB on the car, to me its harder to do with the TB in place. Be careful NOT to spray too much O2 save carb cleaner into the TB we have seen a TECH hydrolock an engine.

But, the cleanest I ever got my TB was when I removed it and soaked it in a good carb cleaner, remove all electronic parts, it can get pretty dirty as it ages look at how restricted it was

Close up of restriction

It looked really bad

It looked really good when I cleaned it, I used a dremel tool to polish it. The backside of the throttle plate is always bad, but when I was done it was shiney.....

Make sure you have a new seal for where it attaches to the intake

It was looking good

I was told once to do top engine clean with SeaFoam, do you reccomend it? also, when i was at Autozone they said i should replace the TPS, didnt think that would help but for $34 it couldnt hurt, what do you think??

[BodybyFisher]

With regard to the Seafoam, we had a member use it, and he began burning oil immediately, and had the engine rebuilt

What made Autozone make that statement that you needed to replace the TPS? If you are NOT setting a code for the TPS, you don't need one, what symptom do you have that makes you think you need a TPS? Are you getting a code for the TPS?

DON'T and NEVER just parts replace. Your very advanced Cadillac has an on-board computer that analyzes its systems, it will tell you what is wrong with itself!!

Have you extracted the codes?

How good did you clean your throttle body?

You completely ignored the prior posts, you said nothing about cleaning the TB well, we are sitting here in the dark... you need to give feedback and stay out of Autobarn.

Did you clean the IAC plunger?

Did you disconnect the negative battery cable like I asked?

Exactly what have you done?

[BodybyFisher]

See this link for a little background

http://www.obd-codes.com/p0507

[drcmrn]

With regard to the Seafoam, we had a member use it, and he began burning oil immediately, and had the engine rebuilt

What made Autozone make that statement that you needed to replace the TPS? If you are NOT setting a code for the TPS, you don't need one, what symptom do you have that makes you think you need a TPS? Are you getting a code for the TPS?

DON'T and NEVER just parts replace. Your very advanced Cadillac has an on-board computer that analyzes its systems, it will tell you what is wrong with itself!!

Have you extracted the codes?

How good did you clean your throttle body?

You completely ignored the prior posts, you said nothing about cleaning the TB well, we are sitting here in the dark... you need to give feedback and stay out of Autobarn.

Did you clean the IAC plunger?

Did you disconnect the negative battery cable like I asked?

Exactly what have you done?

I posted earlier that i will be working on this tomorrow. last time i cleaned the throttle body i just cleaned the the throttle plate and probably not as well as i should have. only code i got was P0507. will stay out of autobarn, just asking questions. need to see if i cna find IAC plunger on alldata. appreciate your help

[BodybyFisher]

Here is a photo of your IAC it is attached to your TB, remove the two torx screws and clean the 'pindle' and its port.

But by all means clean the throat and throttle plate, especially the edges and rear of the plate and where it seats thoroughly

[drcmrn]

Here is a photo of your IAC it is attached to your TB, remove the two torx screws and clean the 'pindle' and its port.

But by all means clean the throat and throttle plate, especially the edges and rear of the plate and where it seats thoroughly

Is there a cleaner that you recommend? i have an old can of STP carb cleaner in the garage

[drcmrn]

cleaned it all out and found a loose bolt on the intake manifold, seems to be running good, time will tell. the problem is intermittent, so not sure if its fixed. bottom screw is stripped on the IAC and was unable to remove the IAC to clean it. some corrosion. top screw came out pretty easy. any suggestions appreciated on that one. thanks for everyones help

[BodybyFisher]

cleaned it all out and found a loose bolt on the intake manifold, seems to be running good, time will tell. the problem is intermittent, so not sure if its fixed. bottom screw is stripped on the IAC and was unable to remove the IAC to clean it. some corrosion. top screw came out pretty easy. any suggestions appreciated on that one. thanks for everyones help

The head is stripped?

I believe they are torx bolts no?

I believe there is on o-ring on the IAC, but maybe you were leaking vacuum if the upper screw was loose

I would try to get the lower screw out, see if you can grab it with a vice grip, and twist it, I have a mini-vice grip that works great for those types of problems

[drcmrn]

cleaned it all out and found a loose bolt on the intake manifold, seems to be running good, time will tell. the problem is intermittent, so not sure if its fixed. bottom screw is stripped on the IAC and was unable to remove the IAC to clean it. some corrosion. top screw came out pretty easy. any suggestions appreciated on that one. thanks for everyones help

The head is stripped?

I believe they are torx bolts no?

I believe there is on o-ring on the IAC, but maybe you were leaking vacuum if the upper screw was loose

I would try to get the lower screw out, see if you can grab it with a vice grip, and twist it, I have a mini-vice grip that works great for those types of problems

yes, stripped, philips head took out the top screw the bottom had corrosion. top screw on IAC was not loose. one of the intake manifold bolts was loose, tightened it. i tried my needle nose vice grips, couldnt grab the screw on the IAC, will try and find a better vise grip tool, tight area. STS fired up good today at 35 degrees and ran fine. hoping the manifold leak was cuse of the problem. have carbon problem, WOT blows a black cloud. go through about a QT every 5-6 miles 112,000 mi, so i cant expect the best

[JimD]

....have carbon problem, WOT blows a black cloud.

My high mileage experience tells me to do a few more WOT exercises when I see a BROWN cloud.

A black cloud would indicate a very rich fuel mixture and average fuel mileage less than ~~13 MPG.

....go through about a QT every 5-6 miles 112,000 mi, so i cant expect the best

A quart of what?? Certainly not oil unless you left 3 zeros off your number and expect us to understand what you mean.

Your 112,000 miles is not a "high mileage" figure for a modern engine. Repair your known problems and try a dose of optimism.

[drcmrn]

....have carbon problem, WOT blows a black cloud.

My high mileage experience tells me to do a few more WOT exercises when I see a BROWN cloud.

A black cloud would indicate a very rich fuel mixture and average fuel mileage less than ~~13 MPG.

....go through about a QT every 5-6 miles 112,000 mi, so i cant expect the best

A quart of what?? Certainly not oil unless you left 3 zeros off your number and expect us to understand what you mean.

Your 112,000 miles is not a "high mileage" figure for a modern engine. Repair your known problems and try a dose of optimism.

sorry Jim, it should have read 500-600 miles i use a qt of oil and its not leaking, clean driveway and not blowing smoke except at WOT and after a couple of those no cloud. gas mileage on a highway trip 22-24 MPG around town 17-18MPG