Codes P0507 & P0122

[Recon189]

Hello, new here and seeking some help. This is going to be long so that maybe I've done something unknowingly has caused the problem. Here goes, replaced lower and upper intake gaskets in my '97 Lesabre, 3800 Series II. All went well, sort of. Forgot to put the hard plastic tube in the upper part of the intake. Ran just fine without it, no leaks and no check engine lights. But I figured that tube was there for a reason and took off the upper intake, put in the tube with a new gasket. After a couple of days the check engine came on. Took to Autozone and was told the MAP sensor was bad. Replaced MAP sensor and check engine light goes off. Couple of days later check engine back on. Another trip to Autozone shows Idle Air Control sensor bad. Replaced Idle Air Control sensor after checking plunger length. Installed IAC and turned on car. RPM ran over 4000. Disconnected battery and then tried running the car again. Still over 4000 RPM. Put old IAC back on and still got idle over 4000 RPM. I then removed old IAC and put new one back on and idle was now just over 1000 RPM. Check engine light now off. Couple days later check engine light back on. Autozone says codes P0507 and P0122. Autozone checked TPS sensor and said it was bad. Put on new TPS and still getting the same codes and TPS is not returnable as it's been installed. I've checked the TPS with a multimeter and it shows good, proper voltage and smooth raise and fall while working the throttle. Also good ground.

Again sorry about the length of this post but I wanted everyone to know what I have done so far and maybe be able to tell something I overlooked or didn't do or should have done.

I'm at a loss now and don't know what else to try. I'm hoping someone here could steer me on how to correct this problem. Any help would be greatly appreciated.

 

[Lubener]

Did you cleanup the throttle body when you had everything apart? Check for vacuum leaks, all vacuum lines, sensor connectors back in the proper places?

 

[Recon189]

Thanks for responding Lubener. Yes I cleaned the throttle body good, used about three cans of cleaner and a dozen rags but it's clean. Can't find a vacuum leak using propane and the plugs are in the correct places and look good. Also made sure I didn't kink the throttle cables and they don't appear to be sticking during travel when moving the throttle by hand.

 

[Lubener]

I think the best way at this point is to troubleshoot as if you have two separate problems. I was trying to think if one malfunction can set both of these, I cannot see a common denominator between the two faults, other than PCM which is doubtful. It wouldn't hurt to disconnect the battery and really clean up the ground connections. Since the lugs are stacked, clean them individually, sand the paint off around the stud. Over time, that point where the stud fastens to the sheet metal corrodes.There are several in the engine compartment and I seem to remember one behind the front passenger kick panel.

 

[Recon189]

I'll try that and see. I thought today I would get another upper intake from the salvage yard and try that, maybe I warped mine putting it on the last time and it just took a couple of days for it to start sucking air around the gasket. And maybe clean the throttle body again, maybe a piece of carbon is hidden somewhere causing the butterfly to not close all the way. If none of this works I'm not sure what to try next.

Thanks for the suggestion.

 

[Lubener]

Hang a vacuum gauge and verify if you have 18-22 inches of vacuum and steady. If you have that, I would look elsewhere. I wouldn't waste my time with a junkyard upper manifold. The OE units were faulty from the start and you likely would open another can of worms. If your is indeed warped, replace it with a new one. It is probably unlikely if you followed proper procedures installing it.I have used the ATP unit with good results.

 

[Recon189]

I checked all my vacuum lines again and didn't find a leak but then again it could be small enough I couldn't find it. I don't have a vacuum gauge, maybe Autozone has one to loan out.

I feel like the problem is in the throttle body but just can't figure out what it is. My voltage is good so I don't think it's the wiring or the computer.

Could the IAC be causing this and the code reader is mistaking it for the TPS?

I didn't get the chance to remove the throttle body yesterday but will try that today if I don't freeze.

Thanks for the suggestion. I'll let you know what happens after I clean the throttle body again.

 

[Recon189]

Update on my situation. Talked to a mechanic today. He said sounds like a vacuum leak, according to the codes. Suggested I soak all vacuum lines, lower and upper intake with break cleaner. Take oil cap off with engine running, if I felt suction then it's a vacuum leak. I didn't really feel suction but a paper towel would stay on the opening but wasn't sucked in. He also suggested that I slightly bend the prongs on the IAC so the plug will fit tighter.

Did all the above and still getting the codes. He said he'll put it on his computer for $35.00 to clear the codes and see if any new ones or the same ones come up again.

At this point its going to be worth $35.00 to figure this out.

It was too cold today to do much. Tomorrow is going to be warmer. So I'll try the throttle body cleaning again and see what happens.

 

[Ultra Ego]

I had rough running on my Ultra, and the code turned up as the maf sensor. I cleaned the daylights out of it, and it ran better, but still stumbled. I suspected an additional problem of a vacuum leak, and they don’t throw codes.

Bought and installed a new maf, and it is now running great. Sometimes there is no bringing old sensors back into spec.

 

[Lubener]

I remember a major vacuum leak on my 97 you might want to check. There is a long, plastic line that runs from a tee off point for the interior heating head. It was located behind the removable panel at the heater hose area on the cowl.. It runs over to the passenger side front corner of the car. It terminates under the battery area and connects to the vacuum storage tank. There is some sharp sheet metal edges under the battery, over the years, the plastic line rubbed on those edges and severed. I ran a new rubber line the entire length to fix. You might want to check out.

 

[Recon189]

OK I'll check on that. I have had the heater/AC control out of the dash but it's not vacuum controlled like some. It's electronic but I'll still check.

Thanks.

 

[Lubener]

It may not affect the heat/defrost since there is a check valve in the line. You still will have a storage tank up front.

 

[Recon189]

Update #2- going over the entire process in my head while looking at the engine. I then remember finding a PCV valve in my garage from years ago that I never used. It looked identical to the one in the car. I pop it in and think I'm good. Turns out it wasn't good (although still in the package unopened). Plus I didn't put the O-ring on it.

So, new PCV valve with O-ring, drove car for a few miles and check engine light goes out. Imagine that!

Anyway I hope it stays out.

Now onto my F150 with electrical problems and Tahoe with coolant leak.

Thanks Lubener and Ultra Ego for your input.

Now on to my next headaches.