Lately I've been getting a P0507 code. It went away for a while, but now it's back again. It seems like it pops up more frequently when I'm driving in overdrive for some reason.
I have changed the ICV but that didn't help. I have had a look at the "idle screw" but I can't find anything to adjust in that area.
Anyone got some pointers on what I can try next? I have also looked over most of the vacuum lines, I think, but I do not have diagram.
What about the fact that it seems to come on more often when I'm driving in overdrive?!

 

P0506/P0507 - Idle Control System RPM Lower/Higher Than Expected

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This would indicate a vacuum leak of one sort or the other. Run through the diagnostic chart in the link above as far as you can. Check some of the intermittent condition causes.

 

I have followed that diagnostic chart as close as I can, but I don't have a diagnostic tool that can do all that. And that way I can't say that it did any good.

Any concrete suggestions that I can try next?

 

Ok, I took another look and according to step 3 and 4 in the diagnostic chart there should be from 40-80 Ω accross pin A-B, C-D, A-D, B-C. I can only get a reading accross A-B, that reads 56 Ω. Will try a new IAC valve, hopefully that will cure my P0507 code

 

Yeah, if you cannot get a reading across coil A (pins C & D), then that side of the stepper motor has failed. That can definitely explain your problem.

 

Sorry to say but a new IAC valv did not fix my P0507!
I have at this point no other suggestion than a vacuum leak.
Any one have a vacuum diagram for this blazer? I have tried the carburator cleaner thing, but with no success....

I'm thankful for all the help I can get

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Sprayed some more carburator cleaner today and got an higher idle when i sprayed around the Intake Manifold Gaskets, is this hard to replace?

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OK, I got to take some time to breathe here and collect my thoughts!
In my desperation I'm going in and out of the house trying to fix this!
I think my "Intake Manifold Gasket" problem was a false read! Did it again and this time NO higher idle!
I do have some white smoke from the exhaust but only on startup.
I disconnected the vacuum line from the vacuum canister and put my finger on the line! It remains tight and will not let go of my finger as long as I lasted!
I have also tried to pull the same line from the vacuum canister in the morning and after a long night it still has not lost any vacuum. Could this be an indication of NO vacuum leak.
Does this also mean that I do not have a blown intake gasket? Or are these two very different things?

 

There is a check valve in the vacuum system once it splits off of the engine. As such, the presence of vacuum in the system is normal and does not mean that you do not have a vacuum leak in the engine.

There are quite a few write ups for the LIM (lower intake manifold) gaskets here. The D-tips article is one that I like.

 

The solution: https://blazerforum.com/forum/showth...466#post231466

 

Wish it wasn't so but the #&#"%&) problem is still there.
I'm at this point out of solutions and sorry to say, I do not have the $$$ to let a shop fix it.
I will here list the symptoms, my actions and my obervations and hope that some of you may have
some pointers on what to do next.
* I have searched for vacuum leaks, I can't find any but that doesn't mean that it's not there.
* Replaced PCV, PCV grommit, EGR, ICV, TPS, fuel filter, air filter, catalytic converter(CC was all clogged up), spark plugs and spark plug wires.
* When I pump the break at idle the idle sometimes climbs 100-400rpm.
* The fuel pump now has a high pitching noise. This problem is resent.
I have heard it before but now it's so loud that I can hear it even when the stereo is on.
* It idles at 1000rpm at first startup with cold enginge, that's as good as it gets. The hotter the engine, the higher the idle. Shutting the engine off and on puts it back to 1000rpm, but it climbs right back up seconds later.
*Idle is not stable. It goes up and down between 1100-1500rpm.
*It overheats over time at idle, even faster if the AC is on.
*Switching on the AC makes the idle go down to 900rpm.
*AC compressor kicks in when I use defrost.

So than the question is, how do I go at this to fix these problems?
My guess is that all these are related to the same defect!