Alright my girlfriends saturn has always had the whole camshaft/misfire code going on, so we left it until this month to fix it (because it was always just the one code on and off) and of course it's due for inspection.

We checked the codes earlier in the month and guess what 7 CODES!
2 of them were duplicates (pending)

So we changed out plugs, coils and cleaned up the ignition module, new pcv/crank case hoses and pcv valve.

That got it down to one code, P0507

Idle Air Control (IAC) System RPM Higher Than Expected

So we decided we would change out the idle air control valve

Got a new one, cleaned out the whole throttle body, put the new one on and checked out the TPS too. Put that back on and started it. Immediately it shoots up to about 4100rpms and just revs there.

So I was like ok I guess I put the TPS on wrong, it thinks we are flooring it, uninstalled and reinstalled it and same thing. So I pulled it off the shaft (so it was at the 0 location), put everything back together and ran it and same thing.

Here are the things I did

Removed throttle body (put new gasket on)
removed idle air control valve (put new one in with new oring)
removed egr valve (full of carbon buildup, reinstalled with original gasket)
removed TPS

These are the ONLY things I have touched and I even tried a second TPS to see if it was bad or anything with no luck.

My gf currently has no car and we both work the same shifts so this is going to get interesting.

Any suggestions?

 

Did you happen to clean all the carbon off the EGR valve or did you just leave it like that? You may have missed reconnecting a vacuum line somewhere, though, because it sounds like you've got a huge vacuum leak, really. But, keep in mind that I'm NOT a mechanic nor have I ever claimed to be one. I've just kept my own cars running for 40 years.

 

I did not clean the egr, what's safe to use on them?

I am actually thinking it was not reinstalled properly so I am going to buy a new gasket tomorrow and try it again.

Note this was not happening before we pulled it in the garage to change the idle air control valve so it has to be from one of the following:

Removed throttle body (put new gasket on)
tried to clean out some of the intake past the throttle body with brake cleaner and a rag
removed idle air control valve (put new one in with new oring)
removed egr valve (full of carbon buildup, reinstalled with original gasket)
removed Throttle position sensor

After I did this stuff is when it happened so it has to be related to something there which is leading me to believe I should be focusing my attention on the EGR valve since I reinstalled it with the original gasket

I doubt a vacuum hose fell apart or something with it parked, and I connected everything i took apart back to the car.

 

most definitely sounds like a vacuum leak -- car is sucking air from somewhere -- if you had the code before dissasembly then likely it was already a small problem (or a code triggered as a byproduct of the others already there (not all of which you listed).

On a cool-ish engine, spray some throttle body cleaner around the mating surfaces of the parts you disconnected, being careful to avoid dousing electrical connections. If it affects the idle, you've found your vac leak.

Carb/choke cleaner can be used to clean out the egr buildup. The pintle (center) should move freely up and down. You can use a SMALL screwdriver to scrape at the carbon off the bore. Do NOT damage/distort the pintle while cleaning unless you want to by a new EGR valve.

Also clean the ports where it attaches. Make sure the mating surface is clean before reattaching

 

I am about to put it all back together again, for some reason there were 2 EGR gaskets on it, one of the valve and one on the mounting plate which leads me to believe there was probably a leak before at some point.

Anyways I can't really do the carb/choke cleaner test until I get the thing to idle somewhat normal, it's almost redlining when it's supposed to idle

 

Ok it must have been the egr valve having 2 gaskets on it and not being torqued enough. I got it back to normal idle which is wicked high (still 1800rpms but this was always normal for this car to idle wicked high!)

I put the new IACV on and it revs the engine like crazy, because it is not extended like the original one.


So I put the original idle air valve on and it runs at the 1800 mark again which was the original normal for the car

But from what I have read that's still 1000rpms over what it should be at correct?

The weird part is the car has been like this for a long time, but never threw an "rpm too high" code until now


I did a test and it seems it has leaky intake manifold gaskets as the idle picks up slightly when I spray back there, what a chore that looks like from the haynes manual!! It revs up a little higher, not horrible but picks it up enough to notice. But we have to remember its already 1,000 over so that's why it doesn't seem to idle much higher.

Joy oh joy!

 

That intake gasket leak is obviously pulling the vacuum too high. If you want to get it back to a normal idle, you're going to have to bite the bullet and replace it.

 

Sounds like the first owner may have had problems in this area, and messed up when they fixed it originally. If you don't do it right, you'll just be compounding the problem

 

Well I did some further testing

idle is at 1650-1750 rpms (double what it should be right? it's supposed to be round 800?

When I spray air intake cleaner down the intake area behind the motor by cylinders 1/2 it picks up to about 1950 rpms

So what I am guessing is the intake gasket leak is causing the idle to increase from 800ish rpms to 1650-1750 rpms and when I add flammable vapors to that leak it boosts it up another 200-300rpms

Also, I let the car run for probably 10 minutes and it doesn't go above the line between Cold and the halfway mark

Both radiator hoses are not warm, but the hose going to the overflow is very hot

Also the coolant has debris in it and residue in the overflow tank




So I guess what it's going to come down to is doing the intake gaskets but while I have to drain the cooling system and everything it will turn into

intake gasket change
coolant drain
thermostat and gasket
coolant temp sensor
coolant flush
coolant replacement


Sounds like fun!


anyone know about how long the job takes? I know you gotta drain the coolant system, remove some stuff, undo the power steering pump bracket and such.
Is it something I can accomplish in one day?

 

You should be able to do that in one day's time as long as you know what you're doing. If this is the first time you've attempted a repair like this, then plan on two days just to make sure you do it right the first time. I highly recommend running some Prestone radiator flush thru the system before draining the radiator. Since you have debris in the over flow jug, it sure as hell won't hurt and may loosen up other crap in there. Do it right the first time and you'll have no regrets. Rush it and you may miss something.