92 Civic VX stumbling/hesitation

[bcfromfl]

Thanks so much again, benfrogg! I really appreciate everything you've offered! I'll try p-ming you for those pdfs.

I went outside and checked again on that throttle body. You're right, I was looking at the wrong spot for the yellow paint -- at the cable attachment point. I looked to the right, and located a nut with yellow paint on it. I don't have a small mirror I could angle inside there to really get a close look. The paint itself is fairly bright, and doesn't have any scrapes or chips on it from a socket or wrench. But the thing that makes this tricky to evaluate is the "hump" of the piece of the throttle body the threads go into, and the nut tightens against. The paint blob doesn't match up exactly between the part of the glob on the throttle body, and the glob on the nut, by perhaps 1/8" or so. Now, I can imagine some Japanese assembly line worker getting paid piece-rate, quickly dabbing it with a paint brush or something and not getting the brush aligned quite right when doing it. Having never seen others to compare this against, I have nothing to go on. Is what I described enough of a change to indicate that it has been turned, or, stated otherwise, is this enough of a change to significantly alter operation?

So, if I'm following correctly, if I adjust the idle downward, it's possible that the idle will actually run more smoothly...given the other components are clean? Going back to what you were suggesting previously, is the idle screw also impacting the throttle plate somehow, instead of simply adjusting RPMs? I'm trying to wrap my head around all this!

I don't know if this is true or not, but the mechanic said that this VX model was an "experiment" by Honda, and the idea was ditched after 1995. It had so many sensors/controls, and required such precise tuning, that it didn't have the kind of long-term reliability they wanted from their cars. Our car has certainly run well these 20 years, but I wonder if we're paying for it now!

I checked out cartalk.com, but couldn't find a shop that looked like it did imports, or find clues about Honda repairs in the reviews. Didn't even recognize any of the shops here locally! It seems to be a good resource, though. I tried plugging in some different zipcodes, but the search feature is a little clunky. Thanks for this suggestion.

That's the link, bowtieguy! Thanks! What is the name of this part? I was scanning parts manuals trying to find it, so I could compare the cost of it new vs. the labor to clean and re-tap it. All I can find is the EGR valve itself.

Thanks again for all the expert help!

-Bruce

[bcfromfl]

OK...hope I'm not being a pain here. I figured out that the part in the EGR cleaning how-to is kit and kaboodle part of the intake manifold. I located a used manifold out of a 1995 VX, complete with throttle body, egr, and some other attached parts that I can't identify because my trusted parts catalog site is down.

Would this be the same part for the 1992 VX? The description I'm looking at says "Y#01", but in the photo there's a tag that says "Y95 Civic VX 01". I'm sure this is junkyard code.

The price for this unit, plus shipping, is worth about two hours of labor. What do you all think?

Thanks!

-Bruce

[benfrogg]

Bruce-
What you are really looking for when looking at the yellow paint is to see if the threads coming out of the nut still have their paint lined up with the paint on the nut. It sounds probable that the nut/threaded rod has been adjusted, but without seeing it/ maybe seeing a direct photo of it, it's difficult to be certain. Usually, if it has been adjusted, the threads will have been threaded down into the nut (thus opening the throttle body to some degree) and would no longer line up with the yellow on the nut. The fact that the paint on the housing itself doesn't line up with the nut face makes it probable that it has been shifted because re-tightening that nut would have altered it's position relative to the housing.
If it has been changed, the intake manifold used would be a good deal because you'd need an un-altered throttle body (hereinafter TB) screw. Now, is there any guarantee the new one would be unaltered, no. More to the point, the new used intake would require just as much cleaning as the old one now needs including EGR ports, etc. However, it would be uber easy for you to do some learning about how to clean them yourself, on the bench, without risk of damaging vital components to your car which would be sitting in pieces. You'd need a few gaskets, notably the intake gasket (to the block) and the throttle body gasket. That may be it. You can re-use the injector gaskets that were installed with your new injectors. After cleaning/testing, you could pay a mechanic to swap in the better intake manifold (IM hereinafter) for not much bread.

The idle screw is called a "Base idle screw." (you can google what it looks like: "vx base idle screw") It does not in anyway mechanically change the position of the throttle plate. The throttle plate is designed to be closed at idle.
The base idle screw (BIS hereinafter) acts as an incoming air metering valve for a small, easily gunked up port through the TB going into the IACV, then into the IM after the TB. So, this channel determines the most air the IACV can get, not the least. The IACV then sets idle based on factors like engine temp, or makes changes based on load events like a/c or headlight usage, etc.
So, if the BIS is set much more open than stock, idle is much higher than normal under all conditions- warm up, fully warm, gear changing, etc. So, I'm guessing your cold engine idles at more like 2k or 2200 until warm, then drops to 1500, is that right?

Will it idle better at first, no way! Not until it's cleaned, then idle should improve a lot. If not, something is causing the idle to suck, so you'll need to address it. At least you'll know the nature of the cruddy idle and be able to monitor improvements as you do work.

There's much debate about why the VX ceased to be. An experiment? I don't think so. It was an extension of the the ultra fuel efficient CRX. It was more complicated, and heavier. But, it could hold 5 adults instead of two. After 1995, hondas still used lean burn, although less aggressively. Much of that is due to more strict N0x restrictions. There's a debate about that subject in the general fuel economy column labeled "why can't we have these?"
It is in fact more complicated than any previous hondas. It's also the most difficult honda to get running just right. However, once it is running correctly, it will keep doing it reliable for many years. That's why I recommended a honda tech who'd be familiar with all it will need.
If 20 years of good performance isn't reliability, I'd like to see what is! So you might have to drop a grand into getting all these little pidly things sorted out..... I doubt it owes you anything right now. It'll run another 20 years if the body is kept up.
How's the rest of the car? Transmission okay? Body okay?
To have a bought from the dealer by you VX about the best you'll ever get. You know the history, you have a car that can get better fuel economy than todays hybrids if you want to put the time into it. It probably costs very little to register, pay excise taxes (if required in your state), and insure since it's 20 years old.

The link to cleaning EGR ports shows photos of a pretty "hack" job in terms of cutting the intake. I did mine with just a drill bit and a tap. The access hole need not be bigger than 5/16" or so. (use the size recommended by the tap) Then teflon tape the threads, buy short (like 1/2" length) bolts or better yet, allen head threaded plugs and it's done. (don't forget to clean the ports!)

Glad to help.
B

[bcfromfl]

Thanks so much, again, benfrogg, for your detailed explanations and suggestions. So much appreciated! And a BIG thank you for those manuals! I'm humbled by your generosity.

I seem to be going down this path of using the idle diagnosis as a means to correct the hesitation/stumbling issue while driving, although, given what you have said, I am wondering if these are two separate issues.

Unfortunately, with the nut facing downwards in a tight spot, I simply can not see the top to evaluate the position of the paint. What I need is one of those dental mirrors!

I was able to get to the parts catalog site this morning, and verified that the 1995 intake manifold is the same part number as the 1992. The photo of the used part I mentioned has a couple of things attached that I can't seem to identify from the parts catalog...one may be the air temp sensor.

About fifteen years ago, the idle jumped from spec to 1500 as a result of the mechanic I described. From that point until this year it was always rock-steady 1500, never higher as you suggested. I don't know if the latest mechanic visit a few weeks ago adjusted it, or if it fell due to the injectors and ECU. But now it's a stumbly 800-1000. I don't have a lot of driving time in the car now since all these repairs, to evaluate all the nuances. I may have noticed a cold operation 1500 RPM idle at one point, but I was concentrating more on the driveability at that point and can't recall.

I follow and understand your description if the idle is actually higher than operating RPMs, and how it would affect operation in that way. But if the idle is set below operating RPMs, even when it was at 1500 (now 800-1000), I'm still fuzzy how it could impact driveability. I guess this comes back to this used intake manifold I found. This latest set of repairs I've described is a little over $2,000, and if I add in some others done over the last 12 months, I'm at $3,000. Granted, when compared with the other stuff I've done, $160 (plus gaskets) or so isn't much, but I want to make sure I'm chasing the right ghost. I can live with a stumbly idle for now, if it's probable that it's not impacting the driveability. And, as you say, I can clean the used one myself, and save some labor costs that way...but it's still going to require a mechanic to install.

If, however, the idle and the driveability issues are likely connected, then I will continue in this direction. I'm re-reading your earlier post about how a higher idle could affect values from the MAP sensor. This is causing some head-scratching, though, because the car ran fine with this higher idle for fifteen years or so.

The car looks gorgeous right now. We had it repainted last August (in the original teal green), but I just don't have time to wet sand and buff it. There is one small rust spot in the rear of the roof panel, next to the right channel just before the hatch. The shop that painted it said they'd fix it no charge, after it bubbled through soon after the paint. Transmission is nice and tight. I know the struts are shot, but since the car is so light, I don't mind, and we don't have any rough roads around here. Struts would be another $1,200 or so. There is an annoying water leak somewhere in the driver's side cowl area, but only is an issue when there is a heavy rain, which doesn't happen too often. Makes the carpeting wet.

My wife and I are both meticulous about records, and we have all the receipts since she purchased the car.

Currently we live outside Panama City, FL, in the land of the Redneck Riviera and pickup trucks. There is a local Honda dealership, with I'm sure trained Honda techs, but they're trained to work with digital equipment that auto-diagnoses issues on newer models, and probably not older ones. I think their labor rate is about 25% higher than local shops. This latest mechanic I've been using is the best I've been able to find, but after all these latest repairs, which amount to throwing parts at it, doesn't inspire much confidence. The shop is conscientious, though, like how I mentioned they didn't charge for the MAP sensor. The most expensive of these repairs, the injectors, didn't make the impact expected on operation. Yes, two of the injectors were "squirting" instead of "misting", but I'm actually surprised how little this affected operation.

So, this is where I'm at. We don't have a lot of money, but I know that this car is "paying us" at this point. So, I'm willing to go down this road a little further, as long as I'm sure I'm heading in the direction of the driveability problem.

Thanks so much!

-Bruce

[bcfromfl]

I was getting closer to ordering the part, until I began looking closer at it, comparing against mine, and realized that it's not the same...even though it claims to be. I probably can't link to eBay, but you can take a look by plugging in "VX Y#01". It's missing the plate to the left of the injectors for mounting the EGR. Must be from another model Civic.

Back to square one...

-Bruce

[benfrogg]

Bummer on the part not being the same! Good catch though.

I think the idle and driveability problems are linked. Yes, one happened long before the other, but often poor idle is a symptom of a larger problem, perhaps one that hasn't coalesced just yet. An example is: EGR ports being somewhat clogged (lets say one port of 3 was totally blocked) would produce idle issues. It wouldn't likely provide much in the way of driveabilty problems, however as only one cylinder would be affected.
Later, as the other passageways began to block off with carbon/exhaust deposits, idle would likely worsen (but you wouldn't notice because you aren't technically "idling" as you are at 1500rpm) and driveabilty would begin to be affected.
The throttle position sensor and the engine coolant temp sensor are more specific to the current problem. Those can both be tested by you or the shop with a multi-meter or volt/ohm meter. They need not be replaced unless there are discrepancies are found.

One thing we haven't touched on is fuel. You mentioned that the vehicle isn't driven but 3-4k a year, which tells me (in conjunction with the fact that the car sips fuel) its possible it sits a while between going through tanks of fuel. Is that right? A fuel conditioning treatment like sta-bil (better in the blue version) or a fuel drying product like iso heat (with isopropyl alcohol, not sure if it's the red or yellow bottle) might be all you need. Fuel starts to degrade in less than 3 weeks these days due to a number of factors.

If those products seem to help, I'd try to run the tank close to empty and refuel and see if things improve.

I'm still voting for having EGR ports cleaned though. In the interest of full disclosure, I have cleaned two VX EGR ports and one CRX. Both VX's had a few less miles than yours and weren't really all that dirty. The valve was crusty (which absolutely needed cleaning) but the ports were only slightly restricted. The CRX without the same mileage as yours, however, was completely clogged. It took drilling into the sides of the rail of the EGR system to run a length of flexible wire in there to agitate the junk! It improved the car's driveabilty. The car still suffers from a different but similar issue, but it made things better for sure. I'll ask the guy (he's a user on here) what the status of that is for you.
Cleaning the valve itself is pretty quick, generally speaking and can be done yourself with sockets and spray cleaner and rags. Or, pay the shop and it shouldn't cost too much. That might give you an idea of the condition of the system overall. The EGR valve and ports can be tested. The easiest way is to open the valve fully with your finger while the car is idling. The car should stall. If it doesn't, either the valve or the ports are clogged.

I have an extra IM for a vx lying around. I have to look and see if I have a TB that hasn't been messed with or if I can get the precision possible to get it adjusted right. If so, I'll clean both of them for you and sell you mine.
I have at least one I can remember.... I got a steal on a parts car once and snagged TONS of parts from it.

It sounds like you have a real sweetheart of a car. I think you'll get the issues resolved for a little more bread and then stop having to dump money into it for several years. Once you get this stuff out of the way, it'll once again be reliable.
B

[bcfromfl]

Wow, more great points! On the gas situation, you're right -- sometimes it takes me two or three months to go through a tank...when I'm getting 600 to 700 miles per 14 gallons or so. (Gotta love it!) Because of my concern about the 10% ethanol, and its potential impact on gaskets, rubber parts, etc., I began filling with ethanol-free gas a little over a year ago. I've also always been nerdy about adding Regane about every 2-3 tankfuls, but after my experience with the injectors, I'm beginning to doubt the value of this. The car does run better with Regane, but I've avoided doing this recently because I'm trying to diagnose issues, and don't want the additive to mask anything.

I also always, always, drive each tank as far as I dare before refilling. There are times that it only gets driven once per week, and that amounts to perhaps 75 miles of driving. But the car has also been taken on long trips within the past few months. Do you think the products you mentioned would work better than what I've been using?

By the way, I made a discovery years ago about the gas tank, that directly impacts mpg calculations. The sheet metal used in the construction of the tank is a relatively thin grade, and will flex as you fill it. By spec, it's supposed to hold 10 gallons, but I've put as much as 14.7 gallons into it. The last 3-4 gallons have to be dribbled in, but you HAVE to do this if you keep track of the mileage like I do. You simply can't estimate where the gas tank is in terms of flexing if you stop when the filler valve in the nozzle shuts off.

Wow, that's a great diagnosis tip about the EGR and ports! Seems simple and straightforward! I just went outside and looked the EGR over, up, down, and sideways, and don't see how to open it with my finger while the car is idling. I see two wire "flippy arms" that attach at the top where there's undoubtedly some circuitry, and catch under the cap maybe three inches below. What am I not seeing?

Also, by chance is there a good cleaning how-to with pics somewhere? I'm assuming I need to get a gasket first. I found this one: http://www.civinfo.com/forum/how/256...-ctdi-fk3.html Is this close enough for what I need to know?

I really, really appreciate the time you've been spending to help me out. That would be awesome if you had some parts you'd be willing to sell. You da man! ;-)

-Bruce

[benfrogg]

After looking up the specs on regane, it should do what both products I suggested do. The ones I suggested stabilize the fuel over time. (which this product doesn't specifically address... it only says it fixes the ethanol "problem"... but you aren't using ethanol gas anyway, it seems) I don't know if the red stabil or the blue stabil are any better at this than regane would be. Worth a shot? Besides, you can use the stabil in all of your other engines or gas that sit for any length of time. It's very concentrated.
The iso heet product is a water remover, which this product claims to be, so I think that base is covered.
I doubt very much that ANY fuel system cleaner that you put into the tank does very much, but I have no data but empirical evidence to back that up.

I have heard of squeezing 14.7 gallons into these tanks before... I have never been able to get more than 10.9 or so. That's both before with my old stock tank and later with my new aftermarket one. I've never really tried to run it really slowly until it does though, either. If I get 10 gallons on a fill up, I don't fill the tank again (during summer) for 700 miles... I don't really need to go 1000 between fillups, unless I start getting 100mpg. The extra weight doesn't help mpg either.
To your point about fillups and accuracy- So long as you average your fill ups over time and always use the same method (regardless of wether you top all the way off or just go to the first click), you'll get as close to an accurrate reading as possible. The only real way to measure consumption is to have a removable fuel cell with shut-offs that you weigh before and after. Compare that with the weight of refined fuel before and after, and voilla.

The EGR valve has a rubber diaphragm pushed downward (when installed it pushes towards the ground) by spring pressure. In the center of this diaphragm is a large needle valve. When the diaphragm is opened by vacuum pressure from the running engine, the needle valve opens and allows exhaust gases to pass into the IM via the EGR ports. The vacuum is controlled by a solenoid (I think) that is electronically controlled by the ECU. To manually operate this valve, reach under the mushroom's cap to where the threaded studs and nuts protrude from the IM. Your fingernails should be touching these nuts as you give a "hows your father" motion underneath the mushroom's cap. You should feel the rubber diaphragm. Push all the way up at idle. If the idle doesn't change at all, the ports are clogged. If the diaphragm doesn't move the needle may be seized to the valve body. If the diaphragm moves but doesn't return with tension, the spring has failed/is worn badly.

If the car stalls, there's another test you can perform on the EGR to determine a fault. Shut off the car. Unhook the vacuum line from the IM that feeds the EGR valve. That'll require first spinning the hose with a pair of plyers where it meets the IM as it will likely be seized onto the aluminum. Don't worry if it's brittle and cracks off... it's worth replacing with new hose if that happens. You can always shorten it too, if there's enough length in it. Most auto stores carry that hose by the foot... the ID is the only number that matters.
Anyway, get that line off at the IM so you can then put vacuum pressure on just the EGRV itself (yes, with your mouth... clean the end of the hose first for the faint of heart). When sucking, you should hear and feel the EGRV open. It won't take much pressure. Once it's open, hold the pressure there (breathe through your nose at this point) and see if it doesn't need to be "recharged" with more suction after 30 seconds or so. If it loses pressure, the EGRV's diaphragm is shot and the whole assembly needs replacing.

The only other thing that can go wrong is the electrical solenoid (I think it's called) failure. There's a test for this in the service manual, but I don't remember it at this moment. It's either grounding a wire, unplugging it, or providing 12v to one of the wires when running to see if the car stalls. That's a much less common failure, though.

The link wasn't bad, but this EGR is simpler than that one. Only two nuts to remove instead of 4 or more. The gasket isn't a bad idea, although I have re-used this gasket (it's a metal gasket with gray paste on it) 3 times now with no leaks. I would have replaced it be the auto stores have the wrong listing, at least in my case. Not a bad idea if you can find it. Not the end of the world if you cant.
The only tricky part to getting it off is that the nuts are hard to get to. One of the two (I think the one closest to the drivers side) comes off most easily with a 1/4" drive extension and socket of the same species. This is because the extension fits right up against the body of the valve itself and the larger, more common 3/8" drive makes your socket land at an angle on the bolt face... thus increasing the likelyhood you'll strip it. So, 1/4" drive extension and socket, you are golden. Remove the vacuum line and plug before unbolting and it should come right off.

I just got done moving so it's gonna be a few days until I can dig around in the pit that is the garage to find the parts. I'll get back to you on what I've got.

B

[add|ct]

Strong PEA container Fuel System Cleaners can have a 'mild' effect on non-clogged(that is to say still functioning) EGR systems but mainly can help PCV systems long before it even has a shot at EGR cleaning. If some PEA makes it exhaust side it can also help the front 02 sensor as well.

Something like a foam-spray top-end cleaner(a true soak) can soak the EGR system 'some' at the ports along the IM and if any of the foam starts recirculating during ingestion.

I prefer Amsoil's Power Foam for this(no I dont sell Amsoil, yet lol) but I like this one because of all the foam cleaners(they are all really similar) it keeps foaming without as much shaking needed AND is a larger can = more product to use for a decent price. It generally has to be purchased online unless an Amsoil dealer is really close by that stocks the stuff. If you don't want to go that route, you can always try something like Mopar or AC Delco(depending) Combustion Chamber Cleaner, another top-end foam cleaner that may help with soaking at least for carbon removal near the heads AND possibly EGR. Ask your local parts department @ CDJ dealerships.

If the EGR is clogged, those once a year may help prevent re-clogging of the ports after you have done the cleaning yourself.

Back to FSCs, I prefer Red Line's SI-1 complete fuel system cleaner, since it's available locally at O'Reilly Auto stores, it's pretty concentrated around 40% PEA content, depending on variables, etc. Regane labeled Gumout products are the best of their products, they do contain PEA.

If your system is really carbon laden, read up on BITOG regarding Kreen. It's a newer product a lot of guys are using to clean up neglected engines. One can(= 1 quart) has to be purchased online. It's a pretty strong solvent based, so it's best to under-dose and follow the instructions. It'd probably be $20-$30 to ship to you, but that's probably extreme at this point, but I'm going to try that on my VX eventually.

Anyway, ben is offering good advice regarding testing the EGR valve itself and yes it is controlled by an electric solenoid which is mounted along the firewell/center area inside a box that also contains the Constant Vacuum Control solenoid assembly which the VX has, like EGR, and no other Civic's of this gen have. Also, as you may know there is no FIT valve.

Currently, my VX is having issues with IACV sticking. I'm going to remove it, inspect the screen for blockage/mounting area on the IM itself, and then manually clean. Also, good to bleed the cooling system to make sure air isn't in there and to inspect the PCV valve for any crud(good to use a dealer PCV valve IMO).

Lastly, back to FSC, the Red Line SI-1 claims it will clean the PCV system and users of Kreen(it can be used in the oil and in the gas) also note it's benefits of the PCV system. EGR would be helped by top-end foam cleaners, note* not Sea Foam the product which is a liquid.

PS: If one uses a top-foam cleaner for a soak to expel excess carbon, please remove your non-fouled EXPENSIVE front 02 sensor during ingestion/soak/expelling. Re-install post expelling.

[bcfromfl]

Thanks, add/ct for all your product knowledge. I guess one can only "easily" clean the EGR port, and not the other four. What do you put in the O2 sensor hole when you remove it for the cleaning? I think what you're describing is what a couple of shops have offered to do, but I must admit to having some reservations about doing. Having that caustic compound come in contact with gaskets and other rubber parts concerns me, although, certainly, someone with your knowledge and experience has no qualms about doing it!

What I imagine doing is spraying directly into the throttle body while the car is running, with a finger on the accelerator cable to keep it from stalling. Would there be benefit to shutting the car off at some point to let the foam soak for a few minutes, then start again?

I can't seem to locate the PCV valve, and wonder if they stuck it inside the valve cover?

Ben, I printed out your last post, and took the instructions out to my car this afternoon. I was able to locate the EGR diaphragm, and move it with my finger. It had more travel than I was expecting, and there appears to be good spring tension returning it to the null point. I didn't, however, have time to run the diagnostics yet. Does it matter hot or cold idle?

Thanks again so much to all!

-Bruce