Something I forgot to mention/ask:

I used my air hose to spray out the afm part of the intake hose. I assumed there was nothing wrong with that. I had to unplug the afm to get the wire harness out of the way, but I was careful about taping the connector part so that no dirt could get in it. Any chance a bad afm would cause these conditions?

Could be the loping is due to the ECU cutting fuel to the injectors from time to time due the high idle speed. The unplugging/plugging in the TPS would point to this, as with TPS unplugged, there is no idle indication as there is when it is plugged in. Not sure why the idle is set so high.

When I first got my 22RE running after installing a new cam, it was a somewhat loping and fast idle. Spent hours looking at things and one day a buddy came over as I was working on it. He asked me why I was missing a bolt on the back of the EGR where it attaches to the intake. I guess with the rough initial idle that bolt had backed itself out and was now causing the sort of loping idle. But in the mean time, I had been going through every sensor and device with the assumption it was bad and then I proved to myself that the device was working properly.

I took the throttle body off this morning and thoroughly cleaned it, taking the TPS and IAC valve off as well. I made sure everything was clean and the the IAC valve was working by putting it in some boiling water. All vacuum and air passages were blown out. Put everything back together and fired up the engine. There is no change.

I verified that indeed there is no miss in the cylinders when I unplug the TPS. Unplugging the ECTS did absolutely nothing, whether the engine was cold or hot.

And once again, the idle kicked up to 1500 on startup. After a minute or two the O2 sensor started oscillating. That's normal behavior. But as soon as the thermostat opened, the surging idle started while at the same time the O2 sensor quite oscillating. I don't understand why the O2 sensor does that. It only oscillates again after I depress the throttle.

I haven't checked the AFM yet, and I will do that. I'm wondering if my next step should be to check signal voltages to the ECU. In particular from the ECTS, TPS.

Oh, and I did check the EGR valve. No bolts are loose. <img src="/forums/images/graemlins/lol.gif" alt="" />

Ok, after swapping a bunch of parts out, it's running normally. Now the question is what was the culprit, as I methodically work my way backwards while re-installing those original parts. I'll update later...

>>>* "To be continued,".. huh?...*LOL**...Glad she is working, it pays to be stubborn and never ever give up...

Post as soon as you know, I am curious myself...*EB

I've been following this thread anxious for a solution, too. I've got somewhat similar situation but at a lower idle. Maybe the solution to your problem will help others.

I had to hang it up last night as the time was pushing midnight, and I hadn't completed the "search" yet.

I'll reveal what I've found so far. I have a spare throttle body with TPS and IAC valve attached to it. So, I swapped that out, after carefully setting that TPS first. I also swapped out the old spark plugs.

Interesting thing on the plugs, if someone can comment. The old ones were NGK's (I think), but they most definitely had "Denso" written on them. They had the flat center electrode. These new plugs I got from NAPA. They are NGK's, but not Denso. Most importantly, they have a v-shaped center electrode.

I haven't totally confirmed it yet, but I think the v-shaped ones cause slightly more of a miss. Now, I had mentioned earlier that there was a lot of "missing" in my testing. Keep in mind that I havn't driven this pickup since January, and it's been since early November since it was running properly. Plus, it's not a daily driver. I've only put 5000 miles on it in the last 1.5 years. Bottom line is that I do think I remember a miss being there before this head swap. Pretty sure of it actually. What I don't exactly remember was how severe it was. I've read from time to time that people have a miss like I do and can never quite figure it out. Well, I guess I'm one of them.

Now, after swapping the other TB out, along with the old Denso plugs, the engine ran like it's supposed to. Cold idle was around 1300, slowly tapering down to 1000 or so after warm-up. I can't get that idle down anymore for some reason, but at least it got that far.

So, I put the new plugs and TB back on, and she runs like crap again. I then swapped out the IAC valve only, and that's where I sit right now. It's about ready to fire up when I get back out there. I'm thinking it has to be in that IAC or the TPS, even though I thoroughly tested those TPS's and could find no fault in either one of them. The TB that I've been running is bored out (58mm), and it hasn't given me any trouble, so I'm skeptical that it is somehow the problem. However, I guess nothing will surprise me at this point.

>>>*One thing here I see over and over is a TPS problem. But once checked out and set they should work, still, I am guessing somewhere around a dozen cases of "strange stuff" that gets fixed when it is replaced are in my files.

The other interesting thing is a bored out throttle body. That point is not a restriction since the engine is only 2.4L and can only draw so much air, so all that could happen is RPM potential. Adding airflow potential certainly can help, adding too much always hurts.

*Combine a freer flowing intake with a freer flowing head/cam combo, then add a very nice 4 into one header and it all adds up to the ECU going "WTF??" at lower RPM's, unable to compensate for a velocity drop. ...Simplistic there but it can happen.

Then it is possible for the system to start "hunting" to try and find a balance, since once baselined she basically tunes herself..

There is an old saying that bigger is not always better, and when dealing with computers, just right is.....well....just right. Everything else is...just wrong.

Your description is mildly similar to some this old man has heard before except for being WAY more extreme.

Keep digging, this is getting to be worth a sticky....You could be helping a heck of a lot of folks here, including me.

*And yep! The wrong spark plugs will sure skip at different throttle settings...*EB

I don't know that I have the wrong spark plugs, but I am hoping for confirmation from others that may know in particular what these v-shaped electrode plugs do (or not do) to these 22re's.

I know I didn't need the bored out TB or the LC headers, but "I had to try them". Hee! Hee! I've had the headers since 2003 when the stock manifold got a big crack in it. Can't say the LC headers have helped the power, but I can't say they've hurt either. Either way, it's been way to long since I ran a "stock" system to know the difference.
I did notice that the bored out TB gave better throttle responce.

Side note: I don't know if this is normal, since I've never driven any other 22re's: My set-up makes very little added power past 1/2 throttle, and my vacuum gauge confirms that. Anyone care to comment? That's something I've been wondering about for some time.

Okay, here's what calmed the idle down. Now, I did a lot of reading in the archives to figure out what causes a surging idle, and it almost always came down to the TPS not set right, a bad IAC valve (or blockage in that area), a bad ECTS (or usually an air pocket in front of the ECTS needing to be burped and/or more coolant added), or the idle adjusting screw being set too far out.

I probably swapped the TB out at least 6-7 times to figure out what was going on. End result is that the IAC valve must have been letting too much air through even after it was hot and the piston was extended. This particular IAC valve I got off another vehicle when I purchased the TB as a whole unit. I did that because my original IAC valve wasn't allowing any air to pass through on cold starts.

Fortunately, the original valve still works after I cleaned it up and got the metal shavings out of it. I have a feeling it's still slightly short of fully functional, however, because I'm having a hard time bringing the idle way down like I should with the screw turned all the way in.

Now, another problem, and maybe one that people forget to check. As I already stated, I'm running a bored out TB. When the machine shop fitted a new throttle plate, they did "okay" but there were some gaps around the edges letting a little too much air through. Funny thing is I've been running this set-up for over a year with no trouble. For some reason it now wants to rear it's ugly head.

So, I filed down the spots that were too far extruded and not allowing it to fully close. I now have it to where it's as sealed as the other TB is that I have on hand. I then realized that in my case the linkage that connects the TB to the throttle parephenalia on the side of the intake plenum needed to be shortened slightly to allow the throttle plate to fully close. I noticed that the idle would stay in the 1400-1500 range unless I put pressure on the external throttle linkage, forcing it closed. Easy fix, and now the idle stays around 1000, which is plenty acceptable to me. But I wish I wasn't maxed out on the low side of the idle adjustment screw.

I consider myself fortunate that I had that extra TB with accessories handy. Otherwise, this could have been much longer and more painful. I did most of the usual stuff before trying this, such as making sure the ECTS, TPS, AFM were all working. I even pulled the ECTS out to make sure there wasn't some fluke piece of something blocking the sensor.

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Back to EB's comments above:

All this free-flowing stuff could very well be why I have that miss in one of more of the cylinders. I haven't verified it yet to be sure but I think I detected that the miss would subside quite a bit at higher rpms (3000 plus).


*Much thanks to EB and the others who helped me figure this out.

How low of an idle?