Here is my situation, I have a 2000 Blazer, 4dr, 4x4 automatic. I recently found that I had to replace my lower intake manifold gasket. I took a lot longer to change the gasket, as this is my first time doing any work on a Blazer, and I didn't want to screw it up (the distributor was the only thing that worried me, I have never had to get a GM back to proper timing) and I couldn't afford to take it to a shop (was quoted between $400 for a shade-tree mechanic, and around $800 and up for the local shops). I made absolutely certain to clean out the oil valley, and remove all the loose gasket material (I can hardly believe I didn't have an issue sooner). there was some minor pitting around the water ports at the rear, they were plugged solid for around 3"-4" into the block. I cleaned out those ports with a wet dry shop vac and a scratch awl. I even sucked ALL the coolant out of the ports. I cleaned the gasket mating surfaces, with break cleaner, throttle body cleaner, razor and paper towels. After that I cleaned out the intake plenum with tb cleaner and a toothbrush. I took the throttle body off the intake and cleaned it by spraying tb cleaner in the tb, and I guess I should have taken out the IAC motor before cleaning it, because after re-assembly, flushing & filling the cooling system, and firing it up, everything was fine, until it got up to temp. It ran a little rough, and then smoothed out, got up to temp, and I took it for a test ride through our neighbor hood, brought it home, let it cool down, topped off and checked the coolant, checked the oil, and drove it to the nearest town where the Service Engine Soon Light came on.

This is the part where the P0507 comes into the picture.

I drove it to O'Reilly Auto Parts, and they let me use an OBDII scanner (an auto X-Ray model) and it was pulling a P0507 high Idle condition. I asked the guy at the counter and he said that from what I described, that it was the pintle in the IAC and recommended that I replace it. So I bought a Borg Warner (cost was a factor, but I wasn't cheap enough to get the made in China one that was $24. it even felt like junk, and I don't have Rich Uncle Penny Bags springing for the $100+ Delco part so a $50 BW did it for me). I went home I removed the TB, and IAC. I thoroughly cleaned the TB with TB cleaner spray, and paid special attention to the IAC chamber area until it looked like a re-manufactured TB. I reassembled, and started the ride. Immediately it went right up in RPM til it sounded like it was at WOT, so I shut it off (not knowing if I had done something wrong), I called O'reilly and the guy said to start it again and it would drop, that the ECU just had to re learn the new IACs limits. I restarted the Blazer and it did drop in RPM and then went down to what sounds like idle rpms (no tach in the dash on this ride... lame). But after driving it around it feels a little higher than it should be. I took it back to O'Reilly and cleared the code, it stayed off for a few days, then just suddenly re-appeared but with a few friends, a P0171, and P0174 (bank 1 and 2 lean condition) and P0452 (Evap. emmision control sys pressure sensor low input). We cleared em again and he said could have been from replacing the IAC.

It has come on intermittently ever since (the P0507 code that is) but I have discovered the pattern to when it will come on. If I clear the code I can drive for a week and not have the light come on... unless, I leave the vehicle parked and idling, say long enough to go into a gas station and get a drink, and after putting it into drive the light will come on when I get up to around city driving speeds. I also noticed that when I shut the engine off it isn't smooth, it kind of does a shudder like dieseling for a fraction of a second before completely shutting off.

I have replaced, the LIM gaskets, the valve cover gaskets, and all the gaskets that came with the Fel-Pro Perma Dry set, all the vacuum lines that I could find and access, re-attached the vacuum reservoir (was disconnected) IAC motor, ran Sea-foam through the gas tank with a fill up of 93 octane, cleaned all the connections I could access under the hood with contact cleaner pens/wands. I have sprayed all around the intake plenum with starter fluid, to see if I could find a leak by listening for revs to go up. I don't really know where to go from here. I have already searched the forums and the best info I could find was: https://blazerforum.com/forum/diagnostic-trouble-codes-dtcs-49/p0506-p0507-explained-35140/
But I am afraid I really don't understand what I am reading on there if someone who has had this issue, or symptoms like mine, please let me know if and how you resolved it. I would really like to get this to go away (I hate SES lights, and I am really OCD about getting them fixed.) THank you in advance.

I saw that my gasket for my intake tube (where it mates up to the TB is getting kinda... well it just looks like it wont be long before it needs replaced (I tried the starter fluid around the TB/intake tube and no rise in RPMs) but could this have anything to do with my issue?

Now I had it out and about earlier and the same thing happened. I drove at hwy speeds for about 15 miles, went into the gas station and left it idling, cam back out and left the lot, drove about a block before the service engine soon light came on. Wouldn't you know... it's that P0507 code again. We cleared it, but I know it'll be back and I want to find out the issue. I hate having a service engine soon light lit, on a vehicle I still have a loan on.

 

You really have to work through the diagnostic steps. Part of working on your own modern vehicle is getting proficient in the terminology and understanding how the various systems operate.

Do you have specific questions about the DTC check list that we can help answer?

Have you checked for vacuum leaks?

Does your throttle blade still have the deflector on the underside of the front half of the blade (open the throttle fully) or has someone removed it? If someone has removed it completely, they have inadvertently opened up a larger idle bleed hole in the blade.

 

Well I guess for starters, what is "the DTC"?
I guess I will need a scan tool that has more bells and whistles, than the one that I get on loan from O'reilly. The throttle body does have the little lip deal you were speaking of.

I don't know exactly how to check for a vacuum leak on this vehicle. I figured that if there was a bad line or connection, that it would be where I was working on the vehicle, and probably not in the dash or what not. I do have to get in the dash to work on some wiring for my custom electronics, so I can make sure there is nothing disconnected behind there. Is there a specific gauge or set of tools, and a specific location to check the vacuum at? (I guess a hand held vacuum pump with gauge would be the appropriate tool, but where to check it at?)

How do I perform the powertrain onboard diagnostic system check?

My particular model is an automatic and doesn't have a tach in the dash, do more advanced scan tools have a tach on them?

What type of test light is used for step 5? Just a simple 12v automotive test lamp? where can I get the connectors so I can make jumper leads so as not to damage the factory wiring harness? (a hard lesson learned on a previous vehicle, I wont do that again)

Does GM actually make a factory service manual for the second gen Blazer? I have a Haynes manual... it's a joke and I wish I had never purchased it, I have found more useful information on the boards here.

My former vehicle was a little 93 Mazda MX-3 GS, I could do any diagnostic work on that vehicle, with a piece of a paperclip, a volt ohm meter, a timing light and a test lamp. I could remove and replace the engine and transmission by myself in less than 8 hours (with enough time to watch an episode of King of the hill while I eat a snack.) I am not afraid of doing the wrench turning on the Blazer, but the electronic end of it is leaving me feeling ill-equipped for troubleshooting. The shops in the area charge a minimum of $40-$50 just to check the SES light. I can't even imagine what they would charge for diagnostic work. I have a little bit of a cash flow problem as I have been off work on a short term disability. I go back to work next week and wont even get a check coming in for about two more weeks. (That's why you keep enough bill money in savings to float you through a rough spot kids!) But I really want to learn how to diagnose and repair my Blazer on my own. I have wished through the last few repairs I just got an older full-size... but those have their own set of problems (we had a '86 K-5 4x4, it was a lot of fun, and headaches as well)

Also was there a specific way to replace the IAC? I was informed by the auto parts guy it's just a remove and replace thing.

 

"the DTC" is the P0507 code you received. DTC == diagnostic trouble code.

You can check for a vacuum leak with some starter fluid or an unlit propane torch. With the engine running spray starting fluid over your lines and along the intake gasket surfaces or trace along them with an unlit propane torch. Listen for a change in the speed of the engine.

Yes, a standard test lamp is used to perform the testing of the IAC connector, however, a full feature scan tool is required to command the conditions required to perform a number of those tests. A full feature scan tool can also display the engine RPM.

The particular test described in step 5 is done with the connector disconnected. If it were to be with the connector attached, you can pickup back-probe tips for your multimeter that are very thin, long adapters that can safely push past the weather pack seal on the back of the connector to reach the terminal further in.

One thing you can do is test the wiring between the IAC valve itself and the PCM. The wire colors and connector pin locations are shown in the wiring diagram at the top of the DTC listing you linked to above.

The diagnostic system check is what you have done by reading the codes.