Idle way to high - Car isnt taking to procedures

[CanuckQx4]

Basically my car idles to high. My iacv failed on me, and the car would not run, it would die as you started it. I removed the iacv and saw the end cap had broken. So I found one at the junkyard off a clean looking engine.

Installed it, and now my idle jumps to 2200 when I start the car, and when fully warm only goes to 1300. No big deal I thought, I figured I could simply do the Idle Volume Air Relearn test on page EC-60 of the FSM, which is fairly simple, but my car will not take to that test. When I get to step #7 which is:

7. Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.

As soon as I disconnect that connector my idle shoots up to 2000rpm and surges (bounces) like its hitting a limiter over and over. And as I plug the connector back in, the idle only drops to where it was before, about 1300.

Is this an idication that something obvious is out of spec??

After failing to do that test several times, I started diagnosing, and diagnosis step #4 on EC-60 says to check THROTTLE POSITION SWITCH CLOSED POSITION, and the procedure for that without consult II ends up being page EC-108. I did the test with the multimeter and I was not within tolerance, my car showed continuity until the throttle was openned .013" (quite out of spec), so I followed the procedure to adjust it, and got it bang on, and verified quite a few times after tightenning it. I then followed the RESET THROTTLE POSITION SENSOR IDLE POSITION MEMORY procedure, on page EC-110 #12 which is quite involved with turning the key on and off 20 times, and I believe I did it right but theres no way to tell.....

Then again I tried the Idle volume air relearn test and it did the same thing where the rpms jumped and surged when I pulled the connector off.

I am hoping someone can help me diagnose what is going on and what my ECU is upto with this. Im hoping Im just missing something easy, or something needs to be reset. Im thinking of maybe disconnecting the battery negative overnight... but dont want to mess anything else up. Appreciate any help!!

[Towncivilian]

There is a fuel-cut off at 1800RPM in park/neutral.

This probably won't help, but adjust your accelerator and cruise wires. Follow FE-3 and EL-236 of the 2001.5 FSM for this procedure.

[CanuckQx4]

I can do that, Im pretty sure there perfect though.

[CanuckQx4]

anybody?? Im gonna go adjust the throttle wire and try these tests again, but I doubt itll help anything

[CanuckQx4]

Well throttle cable is bang on perfect, but the car still idles sky high

Any takers on what it could be??

I think the main give away would be why does my idle jump and surge when I pull the brown plug off the throttle body during the idle air volume relearn test. Is it saying theres a leak??

[CanuckQx4]

Could a faulty PCV cause the idle air volume relearn test to not be successful?

It is in the list of possible faults, but why would it affect this test from taking.

I have a new one, but its a multi hour job for the $3 part

[Towncivilian]

The intake manifold sucks blow-by gases through the PCV valve, and thus expects a metered air leak which bypasses the throttle and IACV. If the ECU isn't getting the expected amount of air, it makes sense that idle issues can crop up.

I'm dubious of your $3 PCV valve. For a part that is definitely buried, I wouldn't cheap out and save $10 by getting a non-OEM PCV valve. I agree it's in a stupid location, but if you've taken the upper/lower intake manifolds off before it shouldn't take you long to replace the PCV valve.

[CanuckQx4]

I only removed the upper intake manifold when I did the power valve upgrade

PVC is below that isnt it??

I get what your saying about the ECU being finnicky, which made me think, when I made my cold air intake I didnt attach this one fat hose that vented the back driver valve cover. The stock intake tube had a bung for this hose to recirculate that venting back into the intake. I just left the hose disconnected.... Its been like that for a year though

[Towncivilian]

The PCV valve is accessed by removing the upper and lower intake manifold covers. The PCV is on the passenger side valve cover. It's the beige valve in this picture:



If you do replace the PCV valve, be sure to replace all three manifold gaskets and the throttle body gasket. The PCV valve has its own rubber grommet that goes around it (our 2001.5s don't have a threaded PCV valve). I also suggest installing a PCV oil catch can in-line with the PCV hose so that oil vapors in the blow-by don't enter the intake manifold and potentially pool there. It also has the benefit of keeping the throttle body significantly cleaner. See Pwnin O'Brien's setup here. I assume you've already put threadlocker on the power valve screws; if not, do it while you have the UIM removed. If you're due for spark plugs, replace them while you have the manifolds removed since it's much easier to access everything.

PCV parts list. You can find a cheaper aftermarket manifold gasket set (Fel-Pro brand), but it misses the throttle body gasket and it contains a gasket you won't use.

[CanuckQx4]

Well crap Im not even sure my PVC is busted. I just dont understand why my idle surges when Im doing that idle air volume relearn test.

I was just trying to eliminate some things off of the fsm's checklist

[Towncivilian]

I'm not sure either, but I can't think of a way to test it other than removing the PCV hose and sticking your finger over it to see if there's vacuum - too bad all of the damn hoses are buried too!

Let's go over the list in the FSM:

• Throttle valve fully closed - you adjusted the accelerator & cruise wires and they should be good
• PCV - difficult to check
• Downstream of throttle valve is free from air leakage - are there any vacuum leaks, loose hose clamps, etc?
• Adjust closed throttle position switch & reset memory - I believe you tried this one without success

No CEL? Is the SES bulb OK?

[CanuckQx4]

Ya throttle fully shuts, PVC is probably 125k old oem, all clamps and hoses are tight in the intake (checked em all, even sprayed quick start on connections to hear for any changes in idle and there were none), and I am sure the throttle position switch is accurate and was reset.

Only CEL is I get is for rear 02 sensor P0138 every tank of gas or so. I believe the FSM says the car needs to be above 159 temp and 12.9V aswell to complete the test (EC58 I believe)

Im stumped. It idles @1300 right now full warmed, but is very loud on a cold start jumping and holding @ 2k for a minute, Im borrowing my girls cavalier, no fun.

[Towncivilian]

I'm clueless, really. I think it might be time to take it to dealer to see what their diagnostics reveal.

[CanuckQx4]

Eff that, they will shotgun a grand in parts in labour into it, when all I need to accomplish is this idle air volume relearn test which I practically have a cheat sheet for hahaha. Dealership is also few and far between in Canada in the sticks where I am aswell, and Im having a good time doing it myself

EDIT: actually not myself at all, this forum is my voice of reason, I just turn the wrenches and probe the wires lol

[Towncivilian]

Okay, that sounds reasonable. I suppose the next viable thing to try is replacement of the PCV valve, because both you and I are out of ideas.

Is any oil consumed over your typical oil change interval? Often, a failed PCV can cause oil consumption.

Is coolant temperature verified within range (167 - 203F)? Do you have an ODBII scan tool?

What does your intake plumbing look like currently?

[CanuckQx4]

I dont burn any oil at all, always stays full, but I dont go more than 5k before changing the oil. The coolant temp is verified I have a ScanGauge 2 permantently installed in the car that gives alot of real time data, came in handy alot of times, and it can read/clear codes etc.

I dont have a pic of my intake but its fairly simple, 90*silicone coupler, about 10" of tube,silicone coupler, MAF, 7"of tube, then my large K&N intake behind the headlight. I have 2 vacuum lines right before the filter, and the IAT sensor at the very tip of the K&N (drilled a hole for it)

[Towncivilian]

Do you have the stock intake components still? It might be worth a try to swap the stock intake back in and attempt the idle air volume relearn procedure.

[CanuckQx4]

Unfortunately I tossed those pieces I guess

[CanuckQx4]

uuuuuugh do I really need to replace this PCV on a whim....

My scangauge II shows that my car is at 5 degrees timing advance. When the fsm says 15 is spec. How would my timing go out?? I dunno if I trust the gauge or if its talking about the same thing

[Towncivilian]

Do you run 91+ octane fuel? Using lower than specified octane can cause timing to retard.

Hell, I replaced my PCV valve on a whim. It's really not that bad if you have a large workspace (which I didn't) and know what you're doing.

[CanuckQx4]

87 octane , always ...

[CanuckQx4]

91 is $1.49 a liter here, like $6/gal I think that works out to

Hurts the wallet

[Towncivilian]

What's the price difference between a liter of 87 and a liter of 91? Here in the US it amounts to ~20 cents per gallon, which only results in a couple extra dollars per fill up, which is well worth the extra cost for the better performance in my opinion.

Try running a tank of 91 octane and see if the timing advances.

[CanuckQx4]

87 to 91 is about 14 cents per liter difference. So almost 60cents per gallon difference

And 94 octane is like 16-17 cents ontop of 91!!

Maybe ill try it for a few fillups and see if it changes what the scangauge is showing. I wonder if its actuallly retarding my timing because of the gasoline though, Im low on gas so I'll throw some 94 into the mix today

[CanuckQx4]

Put $20 worth of 94 octane into a near empty tank and drove to and from work (short drive). Didnt change anything. I'll wait til that goes near empty and then fill with 94 again and hope it changes. Might be pulling a short straw on that try though hoping it advances the timing

Id love to know if the PCV can actually even cause the Idle Air Volume Relearn to not happen

[Towncivilian]

It's listed under possible causes. The engineers who wrote or contributed to the FSM obviously know more about our vehicles than we do, and we've basically ruled out all of the other listed possible causes, so it's logical to assume that a possibly malfunctioning PCV system is the next thing to rule out.

[ARKQX33V6]

Canuck, do me a favour and take a small hammer to your EGR ASSEMBLY AND SEE IF IT IS STUCK while at idle. Also verify the throttle plate is fully closed and feel around the IAC valve for leaks.

Your timing, static needs to be checked and verify it advances properly. Test for air leaks and vacuum leaks.

[CanuckQx4]

EGR assembly? Ill have to fsm that cause I dont know where that is.

The throttle is fully closed, and the IAC isnt leaking. I tested for leaks spraying a can of quick start around connections and listening for changes in idle

As for checking the timing, I do have this gauge that shows it advance to the 22 area while driving part throttle. But at idle my gauge shows 1-3 degrees advanced timing on cold idle, then settles on 5 degrees advanced when warm.

You say static timing, I say advance timing, am I comparing the same thing?? FSM says timing needs to be 15 degrees, plus or minus 5. But is that advanced timing??

[Towncivilian]

The VQ35DE engine on R50s has no EGR circuit.

[CanuckQx4]

i changed out the pcv valve today, what a crappy job that was. Found the source of an oil leak to so thats good.

When i started the car the idle jumped up high still and settled at 1200. so i think i need to do some resets and relearn procedures. is there any i should do that i may be missing??

maybe pull the battery cables off for a while??