HommeDeBois

For those who have seen my incessant posting, I've fixed the 21 and 22 cel codes (had to run wires through the firewall, always fun...), so now I have no ecu codes, however I still have the bouncy idle (anywhere from 1300-2000, and sometimes settles at around 2000).
I pulled off the intake and covered the FITV hole (cold) suction; (warm) no suction- check.
Covered the IACV hole (cold and warm) lots of suction, and made the idle calm down. From reading the other threads this is no good... right?
Unplugged IACV (with car running)- calmed down the idle, but settled at around 1300.
Turned off car, unplugged iacv- idles at around 1500. I tried adjusting the idle screw on the TB (it was all the way in), didn't do much, eventually pulled it all the way out, only made idle bounce/jerky a little.
I once caught it with the idle settled (around 2K) and banged on the iacv with my screwdriver handle- that only made it bouncy again.
I checked the resistance across the posts on the iacv (just to see if the connection was open) i got about 33 ohms. I don't know if that's good or bad, but at least it's not an open circuit.
I just changed my radiator (hooray for junkyard day!), in case the little seeping leak in it was causing air bubbles in the system, and I bled the air from the system.
I've also sprayed around all the vacuum hoses to see if that made a difference, but it didn't.
I'm guessing that my iacv is stuck in the open position, creating a HUGE "vacuum leak", would you fine folks agree? Is there anything that I've missed and should do before I buy a new IACV and start throwing money at the problem?
Please advise.

HommeDeBois

Before anyone tells me about it, I also cleaned the IACV and FITV before I did anything else.

that_boy_sammy

Take IACV off and clean its bypass hole. Take fitv off and make sure its screwed all the way down. Also a bad throttle body gasket can cause a high idle if it is letting air in. While the car is on put your fingers around the cracks between the throttle body and intake mani and see if its sucking in air. Drain and refill coolant forget about the bleeding process. I don't think your iacv is bad.

HommeDeBois

I've sprayed carb cleaner all over that intake (especially where gaskets could have gone bad) looking for leaks and nothing seems to make a difference up or down. Just putting my finger over the IACV port on the throat of the tb (felt like it was going to suck my finger in). I did notice that I have an intake off of a D15b engine, rather than the z6- everywhere I've read says that this *shouldn't* make a difference, but does anyone know for sure?

Former User

The resistance should be 8-15 Ohms, so the IACV may be bad.

HommeDeBois

That's exactly the kind of thing I needed to know. If I take my multimeter to the junkyard and look for an IACV that reads 8-15 ohms, could we have a winner? The junkyard near here has TONS of civics and I saw quite a few IACV's but wasn't sure what the criteria was for a good one- of course all of them were dirty, so I couldn't go by looks alone, and I wasn't sure it was an IACV issue- so I didn't want to waste money on a part I didn't need and could possibly be busted anyway.

Former User

Yes, bring your multimeter.

Did you calibrate the TPS?

HommeDeBois

I have not calibrated the TPS- I'm not sure how to do that, I'll have to look that one up.

HommeDeBois

is it listed as the throttle angle sensor in the service manual?

HommeDeBois

So I went and checked the low on the tps- .55 was the highest reading I got. I tried to adjust the tps, but the screws were stripped to hell, so I couldn't mess with that tonight.

Former User

Use a Dremel tool to etch a groove in the screws and then loosen them with a flat head screwdriver. With the key in ON(II) and the throttle fully closed, turn the TPS until the output voltage is 0.5V.

HommeDeBois

You know it's funny that star screws look and feel a whole lot like stripped phillips screws when you can't get a good look at them... anyway, got 2 IACV's from the junkyard today- put one on right in the parking lot just to see, and it didn't make a difference. Anyway, I got home, started messing with stuff (discovered that they are star screws, not stripped phillips screws), tried to adjust that just by sound. I got the idle to settle down- it doesn't bounce, but I still can't get it to calm down lower than 1500 rpm. The next time I mess with it, I'm going to scrub the crap out of the tb throat around the throttle plate just to make sure there's nothing there holding it open, clean up the 'new' iacv's, poke around with the multimeter some more, and hopefully get somewhere.
One other thing that was *new*- while driving home from some errands, turned the AC on, the idle kicked all the way up to 2100 rpm, but then driving around and messing with the AC, turned it off, turned it back on, the idle stayed around 1500. Experimented- turned it off again, on again, idle came back up to 2100. Messed around with it, got it to settle back at 1500 with the A/C on. I know the IACV is supposed to open/close according to additional loads put on the engine from the alternator, but jacking the idle up to 2100 seems excessive. I'm really pulling my hair out on this one.

Former User

Stop deviating from the proper procedures. The only proper way to adjust the TPS is by setting its output voltage to approximately 0.5V at closed throttle. When this is done, test the voltage output at wide open throttle. It should be about 4.5V. When this is done, reset the ECU so that it can learn the new TPS voltages.

What resistances did the junkyard IACVs have? What cars did they come from? After installing them, did you reset the ECU?

that_boy_sammy

Why use a dremel for the screws on the tps? its just a torque screw. You can buy the torque screw attachment tips at any hardware store for 1.99. You sure its not sucking in air on the under side of the TB and intake mani?its hard to spray cleaner around that area. And have you flushed, refilled, and burped the cooling system? On older motors its almost mandatory to drain the coolant before opening up any lines.

Former User

The stock TPS was not designed to be replaced. The bolts have smooth topped heads that can't be removed with a phillips, flathead, hex, or torx screw driver.

HommeDeBois

You're right, I'll make sure to do it the right way to get consistent results.
The junkyard IACV's measured at 10 and 13 ohms, I got them off of a 94 ex and a 93 lx, I used the one off of the ex (10 ohms) because it looked a bit cleaner. I did reset the ecu after putting on the iacv, and after messing with the tps. Would changing the IACV necessitate an entire coolant system 'burping' all over again? It didn't even spill enough coolant to get the parking lot wet.
I'm not sure it's sucking in air from somewhere else, I'm going to re-check this.
The next time I wrench on the car I'm going to hit everything (clean IACV, FITV, check/adjust tps voltage, snug down vacuum lines, bang my head on the valve cover, etc...) all over again, including looking for vacuum leaks.
By the way, is there a way to check to see if the FITV is toast? Or is the mechanism one of those things that just doesn't go bad? I assume that when it hits operating temp, the FITV hole in the tb is supposed to have little to no suction, and thats how you tell if it's good. Is there any other way?
Thanks all.

HommeDeBois

Ok, I was finally able to get out there on the car this last week. Calibrated the tps to .495 (the next jump up in the adjustment was .52) at idle, but at full throttle it only got as high as 4.3, is this REALLY bad, or just something that's within tolerance but looks weird? Cleaned the junkyard iacv again (the one that I've been riding with). Messed with the throttle cable bracket, so I have actual adjustable slack on it. Scrubbed out the throttle body and throttle plate (got some good crunchy stuff out of there).
Between all of this, I got the idle down to normal speed! Each little thing incrementally brought it down a little lower, and finally adjusting the tps and iacv got it down to a normal level! YES!
But now it idles really rough (like it's missing), and has no response or pick up at all. I'm guessing the timing is off (like the timing was adjusted for the higher idle setting, not for the normal low idle).
So if it's not one thing, it's your mother... I mean another.

Former User

Your TPS voltages are fine. Be sure to reset the ECU to alllow it to learn the new TPS settings.

When was the last tune up? Definitely also check the ignition timing with a timing gun.

strategy400

Not sure what year model car but you may have to jump the service connector to adjust timing. I'll now be accepting my Capt. Obvious award.

Former User

This is true for all 92-00 Civics and Del Sols.

HommeDeBois

I'm not sure what to say about the tune up, as it seems like the guys that put the engine in just slapped a bunch of parts together. I tried to adjust the timing (using the service connector), but lo and behold, the lower timing cover, which I'm missing, has the alignment mark. So, between my neighbor (who is an all around gear head) and I fabbing up an alignment mark, we think we got it lined up and adjusted. And now it's flashing a CEL code 1. O2 sensor. Woo. It doesn't come on right away after turning the car off and back on. After adjusting the timing, we got some guts back in the car, but it still runs like crap.
Can you clean off O2 sensors and get a little life back in them?

HommeDeBois

So I cleaned off the o2 sensor. It smelled like gas- probably from being off timed and running rich. Cleaned it off. Reset the ECU. It seemed to help a little, but it still smells like it's running rich, and it still runs like crap, so I'm thinking that our 'timing mark' is a bit off (or my o2 sensor is totally wrecked, or both). Does anyone have any ideas as to anywhere else we can line up the 16* BTDC mark off of? Another reference point on the engine?

Former User

Buy and install a lower timing belt cover ASAP! You can buy a new one for $10 at Majestic Honda. Or find a used one at a junk yard. Do nothing else until this is done. Then do a tune up and set the ignition timing to spec.

HommeDeBois

Got a junkyard timing cover, we were off by a little, but not much. Timing is set to spec, and it still smells like it's running rich and is bouncing in it's mounts. Why would my o2 sensor suddenly throw code now that I have the idle lowered? Was the ecu running in a loop that didn't include the o2 sensor at that high rpm? Is there a way to check and see if the o2 sensor really is bad or if something else is effecting it and making it code?

HommeDeBois

Ok, so we set the timing to spec. I was at the junkyard looking for something else and I saw it- a civic that had just barely had a tune up (new distributor cap and spark plug wires), the o2 sensor looked dang clean as well. So I snagged all that and did a quick tune up. However, my neighbor was under the hood and I was in the car and he asked me what the order was (referring to the spark plug wires)- I thought he was talking about the order on the head, so I told him 1, 2, 3, 4. I fired it up and it ran horrible. After running like that for a minute or two, I realized that he was talking about the order on the cap! So I hurried and shut the engine off, put the wires in the right order (my neighbor is used to V8's, so I won't hold it against him at all) and fired it back up (after pulling the ecu reset, of course).
So now it runs smoothly again, and I have plenty of power, but now it's doing the bobbing idle again.
What damage could I have caused to the engine, and being that there was a lot of back firing, what sensors could I have messed up?