`92 VX idleing problem
 

mt del sol had the same problem everybody told me it was a vacuum leak, but after i changed my o2 sensor it want away. odd???

I'm going to try cleaning up the IACV tomorrow AM, see if that helps. The black smoke belching out of the exhaust kind of freaked me out, though...

I'm also wondering if the idle adjustment is right, since the wrong PCV valve was installed. I understand it can be rather touchy, especially on the VX.

I would order the OEM PCV valve for the VX. It has a much smaller diameter inside of it, and that should help slow down the air going through it. I don't think ripping apart a normal PCV will give you the same results.

That being said, you probably should clean the IACV since that will almost always give you a surging idle it it's clogged or bad.

Also make sure you have the correct plugs for the VX since they are specific for the motor. And don't go with platinums. Buy the NGK v-power or irridiums.

how did it idle befor the PCV valve was installed? I'm having the same issue and I bought the correct PCV elbo from honda and still have the idle bounce.
I haven't tride pulling the "back up" fuse that clears the computer to see how that affects it, I did however have some luck with useing some carburator cleaner in the intake to clear the crud out, of course that stuff doesn't burn so it stalls the engine if used while it's running.
Also when I ordered parts from honda I ordered part number 2 and number 5 and they sent me two parts that looked like number 5, a bent elbo, one was empty and one had a spring loaded valve in it, when I installed the empty one the idle still bounced so I'm currently running with a PCV valve, in the same confused boat as you are in.

I ordered the "right" PCV valve, after arguing with the parts store guy for a while...he insisted "the PCV valve HAS to have the spring/plunger in it". I had read the VX PCV has a smaller orfice, as Danronian says to restrict the air flow. Should have it Friday or Monday, one of the joys of living out in the sticks...waiting on parts.

I'll update with results as I go along.

OK took an hour this AM to install a different IACV (from my spare VX engine) after I cleaned it thoroughly. Started it up, while in cold idle (around 1200rpm) it runs OK. After it warms up, same scenario....surging about 100-200rpm. I disconnected the sensor on the IACV and attempted to adjust the idle adjustment screw, per the Haynes manual. When I disconnected the IACV, it ran smoother (still surged though), adjustments to the screw had no effect on RPM. I went out 3 turns, back in all the way, no effect on RPM. Left it at 1 turn out, reconnected the IACV sensor, pulled the backup fuse for 30 sec., plugged back in, started car. Now it does idle slower....900 RPM or so, still surging.

Have noticed it's smoking, too...white smoke. What do you think....O2 sensor, or maybe ECU? Prior owner was a wannabe tuner, he may have screwed up the ECU.....guess I could just put in the "wrong" PCV valve, but I want it to run right!

Ok, I am going to tell you what my experience was with the IACV and idle bouncing, similar to what your describing. Take it for what it's worth, since this is not on a VX.

What I discovered, finally, was that I could plug the hose from the air filter, going into the IACV/intake manifold and when I did so, the idle settled right down. What I discovered was that the IACV had a broken tip, so it was not able to seal tightly. With the IACV unable to shut off air flow, their was to much airflow. In turn, the ecu uses the Oxygen sensor to try to maintain the idle mixture on the engine. When their is to much air, it apparently does some sort of a hunt on the time interval the injectors are turned on, trying to get a match between the fuel and air flow. However, it isn't able to do so with the extra air being allowed by the broken IACV valve, in my case, so the engine rpm modulates.

On my car, if I plug off the IACV, the car idle speed can be set to where the car will idle fine, when it's warmed up. It can be a little tricky to get it started. After I replaced the IACV valve, I readjusted the idle and it runs fine.

From what your describing, I would try blocking off the pcv valve and see if the idle will settle down. It sounds to me like excess air is getting into the intake from somewhere it shouldn't be.

I find it kind of odd that honda changed the PCV parts, the two different honda dealers that I delt with said that it has the spring loaded valve, and it does run smoother with it, and I don't think that two of us (anyone else out there?) could randomly have the same problem.
Is anyone besides 4bfox and me having this problem? and 4bfox, anything else you can tell us about your car? number of miles and so on.

Does it idle smoothly when it has the PCV valve with the spring loaded valve in it?

I have heard of the VX PCV valve problem, but I think your guestions have merit.

If it can be adjusted to idle correctly, with the spring loaded valve, that's what I'd go for.

This is the new(er) VX engine/trans we just put in my car about a month ago. Supposedly came out of another car with 30-40,000 miles on it. I replaced it because the old engine had over 230,000 miles on it, and the trans was going out on it.

It ran OK with the traditional PCV valve in it. However, I couldn't get the idle set below 1000RPM, no matter what.

I do have the correct VX PCV valve coming in, hopefully tomorrow. I'm going to try that next and see if it helps. Apparently it has a small orfice to restrict air flow, which may fix my problem.

The surging or bouncing is about 2 seconds apart...may have to do with the fuel injector timing.

Guys,

I've been following this thread because my VX had this same idle bounce problem, and my current '95 DX has a little bounce once in awhile as well. Here's what I read on a honda-tech.com thread aboutthis problem:

"It's unlikely its the Idle Air....that's the f*ckin annoying H-T answer to all idle problems that is rarely the actual issue. What is FAR more commonly the issue is the thermo valve below the throttle body. The valve seat inside screws it's way out and the valve never seats when the motor reaches operating temp allowing constant blow by air...essentially a vacuum leak.
Pull off your intake tube and idle the motor to operating temp. On the inside of the bore of the throttle body there are two holes in the side. With the motor at operating temp put your finger over the lower hole. If it's sucking vacuum at operating temp, that's a problem. You need to take the assembly apart beneath the throttle body, screw the plastic valve seat all the way in, then back it out 2.5 turns. You don't want the valve seated when cold, but as the coolant warms the thermo valve you want it to seat and shut off the bypass air.

That's likely your issue. Check that first, then if that isn't it check the idle air. The Idle Air gets blamed on this site constantly for bad idle just simply because the work "idle" is part of its name I swear. I've done this for years and I've fixed the bouncing idle syndrome more times than I can remember and out of all the times the IAC was bad twice, maybe three times. When they are bad the rubber boot inside is usually cracked or broken down. The IAC's are pretty straightforward to check. Get a two pin plug as a test plug and run some extension wires. Hit the IAC with 12v....if it clicks it's good. It's a simple solenoid...that's why they rarely go bad."

https://honda-tech.com/zerothread?id=...ostid=30429468

Thanks for the info...will check it out tomorrow AM.

D15Z1 motors (VX Motors) don't have FITV (Fast Idle Thermal Valves).


Check to make sure that your coolant system is bled properly and that the coolant level is where it is supposed to be. If an air bubble gets up into the lines for the IACV (Idle Air Control Valve) or the coolant temp. sensor, then it causes some issues as well.

OK..still hoping the correct PCV valve shows up today.

OK, received the new PCV valve, NAPA part #2-9379 (Echlin box) today. Upon inspecting the same, discovered it had a plunger (but no spring). Rattles when you shake it, not like the one I "modified"...it had a spring that kept the plunger shut. Find below blurry, poor quality photo of the PCV valves...black one is what my mechanic had installed, white one is what I installed today.

Installed in my VX, runs great. Going to try and adjust the idle again tomorrow morning...

Damn. I'm sure glad my VX is idling well. I would suspect a vacuum leak if all these things you have tried don't work. I know my engine idles perfect w/the OEM PCV and I cleaned out the IACV lately.

Good luck.

Yeah, going to take another swing at it this morning after running errands. Alternator is making a lot of noise (I think it's days are numbered), so I couldn't hear a vacuum leak if I had to. May try a little carb cleaner, see if I can find a leak that way. Still not convinced the vacuum system is right...I may have to invest some $ and take it to a Honda dealer to see what's missing.

Well! Unplugged the IACV, set the idle to around 400 RPM per the Haynes manual, plugged the IACV back in, shut off the car. Unplugged the "reset" fuse in the engine fuse block for about 20 seconds. Restarted, and it's idling right around 600 RPM!:)

I think a lot of the problem was I wasn't unplugging the "reset" fuse, to reset the ECU after dinking with the idle/IACV. I am gradually learning the ways of the Honda....a lot different than the Detroit iron I'm used to.

Yeah, ECU controlled cars are a whole different story.

You'll hate it at first, but once you get the hang of the obd1 Hondas, you'll never want anything else. Self diagnosing and how they tell you what is wrong is just so convenient.

Glad to hear you got your idle fixed.

This may be a topic for another thread, but here goes....what do you VX guys use for diagnostic devices? I've seen CDs for your laptop, cables, etc. But what actually works? I'd like to be able to monitor RPM while tweaking engine, get diagnostic codes, etc...

Not sure on that. I would just install a small tach under the hood.

For diagnostic codes, you need to "jump" the small connector above the ECU and your CEL will blink telling you the code. Do a search for a picture-explanation.