Possible VX problem..
 

so I bought a 92 VX hatchback yesterday, on the test drive i felt nothing strange. once I purchased the car, i drove it 45 miles home, the last 25 miles of interstate i noticed that while maintaining speeds on roads and highway(35, 40, 45, 55, 65, 70mph) the car would feel as if it lost power for a second then the power would kick back in. this isnt while accelerating, this is foot in the same position on gas pedal, and suddenly lose power for a second, then catches again and i resume my cruising, usually in that second of power loss, the RPMs would stay the same, and the car would gradually slow, as if just drifting. anybody have any clues to this? the car is supposedly only getting low to mid 40mpg's, so im thinking this may have something to do with it.

any help would be greatly appreciated!

Nick

if you have over 200,000 miles it might be your o2 sensor, sadly, at least this is the exact problem I was having, and after replacing a whole bunch of other parts, and taking it to the dealer, I spent the money on an o2 sensor, and instantly it was gone, and this is one of the few problems that the computer doesn't pick up on, so the check engine light will not come on, or have a code for.

i have 92,000 miles, did you push your mpg back upto 50s after replacing that 02 sensor?

I didn't notice a big jump in mpg, what I did notice what that drivability increased greatly, that I was able to focus less on keeping the car going a single speed.
when I removed my bad o2 sensor, I found it was soot covered (like a rich burning spark plug, black soot) and it had a bit of a rattle, like something was busted off inside, I latter read that driping oil on the outside can damage an o2 sensor as well, so the design of having it right next to the dip stick is maybe not the best.

It's an ignition issue. Check that all your plug wires are fully seated on the plugs. If your valve cover gaskets (the ones that seal the spark plug tubes) are bad, oil can seep into the tubes and actually force the wire off the plug, but before it does that, you get a faulty connection.

If your wires are properly seated, check your plugs, wires, cap, and rotor button for wear. Look at your wires closely....there could be a date printed on them. If it is 1992, these are the same wires that came with the car and are 14+ years old. OEM wires have the date of manufacture on them. If they are this old, I would recommend spending the $50 and getting a set of NGK plug wires - they're the best. If all checks out, it's possibly your coil. It could be your ignitor, but the tachometer would be going nuts if that were the case.

As a last resort, I have had one incident where the problem described was from a bad ignition switch (the electric component that bolts to the back of the key cylinder).

thanks for that, pretty informative. i was going through the stacks of paperwork that came with the car, and last tuneup was done 2 years ago, but they didnt use the ZFR4F-11 plug, they used ZFR5F-11, is that a big deal? im going to try and find a set of the right plugs today, and while im at it do a nice big tuneup

with the amount of miles on the car i am going to agree with dax. but i have a feeling its more severe than just the plugs and wires.

fyi nopi.com always has a good price on ngk blue wires.

That is a one heat range cooler plug , ,perhaps they had a pinging problem and tried to fix it with a cooler plug.
An uneccesary cooler plug can be fouled and lead to a missfire.

Yep, NOPI has the best prices on the wires. I used to live about 5 miles from there. :D

Change to the NGK V-Power plugs that are supposed to be in there. I don't think the 5-range plugs are causing your problem, but it's always best to go with MFG recommended items.

Isn't it possible that this is just the "lean burn" kicking in?

Either way, after buying a used car it's ALWAYS best to perform a full tune-up on it. Plugs, wires, distributor cap, oil filter, air filter, fuel filter, etc. If you have another $170, get a new O2 sensor on ebay too.

Lastly, enjoy that car... I still wish I had one :)

I don't either...but only change plug heat ranges if necessary.

I wondered that too. I remember Dan (krousdb) describing it kicking in, and if I'm not mistaken, he described it as a noticable loss of power, and that he had to respond by pushing the accelerator more to maintain speed.

If you push too much, maybe it kicks back out of lean burn. (But what do I know about lean burn - I drive a gas guzzling Firefly with the antiquated technology of a farm implement :o.)

I had the same problem in my VX when I bought it, but the mileage was way worse. the car did have nearly 290K miles on it though.

The spark plugs that were in there were the ZFR5F as well, they don't like Lean Burn, get the right ones in right away! Get the motor de-carbonized by going to Honda dealer or a Chevrolet dealer and getting the top engine cleaner and following this procedure: The easiest way: go to a Fleet Farm or Lowes or any home and garden store and get a small (handheld, about one liter) pumping container (commonly used for spreading insecticides or liquid fertilizer). take the intake hose off of the car at the throttle body. Idle the motor and spray the liquid into the motor until the entire can is gone. Make sure not to kill the motor yet. Once the fluid is gone, let the motor die, or kill it yourself. Wait 15 minutes. Then start the car and drive it somewhat hard until all the smoke stops coming out of the exhaust. It stops smoking faster the harder you drive it.

The harder way: Disconnect the Brake Booster vacuum hose while the car is running and let it "sip" the fluid out of the bottle slowly until gone. Then wait 15 minutes then drive the car to get teh smoke (carbon) out.

After all that is said and done. Get a new O2 sensor from Ebay, get the right plugs in, and you should be set.

At least that is what I did to mine. All that made it go from <250 miles per tank (the previous owners claim) to ~475 miles per tank. That was all before I actually started to drive for FE with it as well.

Let me know if you want any more help.

at least around here if you ask the auto parts store for spark plugs for the vx, their computer tells them to sell you the ZFR5F-11 plugs, I'm not sure why, but that is what they are told is the current correct part.

what the dealer told me was causing my loss of power at crusing speed was the weak signal from he o2 sensor was sending the computer in to it's programed loop, I'm not sure if it's the temp sensor in the o2 sensor maybe not telling the computer that it's warmed up enough to be acurite, or what it might be, but in that programed loop it's giving you an air fuil mix based off throttle possition, and that is crude enough that you have to move the throttle quite a bit for the computer to catch on, thus the loss of power, if you can get the o2 sensor out (with only 92,000 miles it might come out) take a look at it, it should be a grey color, if it's dead, then like I said it will be black and sooty

so today i picked up a DVM to check the o2 sensor, and about 180$ worth of tuneup stuff, the usual plugs, wires, dist cap, rotor, air filt, fuel filt, switching to synt. oil(5-30), pcv valve, 2 cans of sea foam (i hear GREAT stuff about it, no idea how to use it however)

anybody care to help me test my o2 sensor by telling me how to check it?

thanks

Nick

NickF829: Let me know if the OEM PCV valve is still in the engine. Apparently the factory PCV is open all the time keeping the crankcase under constant vacuum (to help with FE). I stupidly replaced mine with an aftermarket one that had the innards in it and had to use my OEM one on my wifes car for a quick repair.

To use the sea foam, just follow my instructions in my above post.

Ryland: Many car parts stores have the wrong info for the D15Z1 motor. I've found that Checker/Kragen has the wrong spark plug wires, spark plugs, and timing belt in their computer. And if Nick posts back about the OEM PCV valve (all black and no innards) then they also have the wrong PCV valve.

as far as checking the O2 for proper signal...I've seen people use a butane torch to heat the tip and then remove it alternating doing so while the positive lead is connected to the signal wire and the ground is attached to the metal body of the O2. Not sure how if this is good for the O2 but the people that use them on the single wire O2s are only out $20 if they fry it.

Best way to test the O2 is by looking at the signal it sends to the ECU through data logging.

To test the 02 just hook up the dvm while driving and watch the voltage output and report back to us. Especially watch it during those times when you experience cruising power loss.

where do i hook the dvm to though while driving? the o2 sensor has 5 wires coming off it at the exhaust manifold, where does that wire run to the pcu and is the pcu in the passenger floorboard, if so which wire do i hook the DVM to

the PCV i pulled out was blue and looked to be replaced somewhat recently. should i goto honda and get a different one?

also, should i use a whole can of the seafoam if im doing the brakebooster vacuum deal?

Use www.honda-tech.com to find a pinout for the p07 (your ecu) and find the signal wire for the 02. Then tap that for the DVM.

krousdb told me which pins to attach the DMM to in order to test the Civic VX. It's in a post here somewhere...

a Haynes manual will proove to be invaulable for all sorts of truble shooting and testing, and what that book does not cover, the factory shop manual covers, o2 sensor testing is better covered in the Haynes manual.

At some point I should have my copy of the factory shop manual edited in to chaptors, and posted for everyone to look at, as it is, it's a 35minute down load with a fast connection.
and I tried scaning in a page from my haynes manual, and couldn't get it to work, then I realised that as an owner of a car that the younger people at the dealer are going to tell you they "don't work on anything that old" (ask for the old crusty guy) you really need to spend $20 on your very own copy of a haynes manual.

You don't really need to. I didn't notice any drop in FE having a regular PCV valve in mine after I swapped it.

I do 1/3 can of seafoam in the crank case, 1/3 can in a very low tank of gas, and 1/3 can sucked up through the brake booster, then drive hard and change the oil in a few days.

The VX does the same thing to me. Very noticable sometimes too. May be hunting down a problem that isn't there, just characteristic of the vehicle. Lean Burn Lag :)

Well, there is a certain amount of lean burn lag. That would best be determined by hooking up the DVM to watch the O2. But I know for sure that having the colder spark plugs in the VX causes more power lose than just lean-burn lag alone.

Ok add me to the list too. Mine does the exact same thing. Now that I hear everyone else's is doing the same think I am begining to think it is normal. Some where on here I have listed everything I have done to fix it all to no avail it still does it.

Just a side note I think that seafoam kills iffy o2 sensors. It killed mine and I saw on Honda Tech a few others that had the same thing happen. I have my old one to put back in if I even want to seafoam it again just in case.

Good luck with it. If you figure it out please let us all know.

As other have stated in this thread, it sounds like lean burn kicking in and out. YOu should be able to hold lean burn up to 75 MPH. If you are driving faster than that, the activity you are explaining would be normal. In that case, it will go away of you slow down. :)

so what causes the lean burn to kick in? because it will do it at speeds as low as 20mph upto 70(i dont drive faster then that). It just seems as if it does it when im just cruising down a flat road, it certainly is much better then before now that ive tuned it up but it still feels unnatural, at least for now.

I'm sure someone can chime in with a better response than me. In my VX I notice the Lean burn happening at a steady speed (for me anywhere between 55-65MPH) and after I've maintained that speed for at least 30 seconds. LBL (lean-burn lag {hmm, maybe a new acronym to add to the glossary?}) can still be felt by the driver of a VX and maybe a passenger if they pay attention enough. It usually takes about 3/4 of a second for it to disappear once you press the accelerator down.

Why doesn't someone with a VX rig up a lean burn LED or something on the dash so that you know when lean burn is kicking in. Then you could tell for sure if it was lean burn that was causing the issues.

See this thread HERE.

I replaced my PCV "valve" (no innerds) with one that had the valve innerds when I got the car, and just thought that someone had done something funny with the whole thing, and then I thought it was a screw up when I got what must have been the right part from the dealer... because the PCV valve they sold me was empty... but I just checked part numbers, and the all modles use the same part number as the VX, except the CX... but the shop manual explanes in great detail how to test it for proper operation... so I'm a little confused why the repair manual tells you to exspect a PCV valve to be there, when it's not there???

Why is the cx different I wonder...mehbe this affects my random idle issue...

I just checked on my Honda E-catalog (the same software the dealer uses) and got different numbers for the VX/CX model as compared to the rest of the models.

VX/CX = PCV 17130-P07-A02 (shown to be used on all CX/VX model civics 92-95) The rest = 171300-PM6-003 (all models except CX/VX)

Usually Honda has the parts grouped by ECU ie VX=P07 and the correct corresponding parts have that in the middle of the part number. So it seems that VX and CX share the same PCV valve.

I'm interested to see the part numbers that were on teh bag that you got from the dealer Ryland.

Side note: Maybe we should change the title of this thread to "General VX/CX discussion"? So we stop thread-jacking, lol. ;)

It wouldn't be too hard to rig up a simple voltage comparator circuit to light up an LED when the signal from the O2 goes higher than the reference signal. hmm, but for me, it's just easier to hook up a DVM. Hmm, Tech edge has a display that can read a LAF as well, in fact the controller kit they used to sell has a heater controller circuit as well. And the cool part...the display shows A/F ratio or voltage depending on how you set it up during assembly.

Wide band display HERE

Tech edge site HERE

This company actually uses the VX L1H1 sensor in it's first version of DIY kit.

I'm not sure if I still have the bag or not, because I didn't end up useing the part that they sold me as it wasn't a pcv valve, and I thought that I needed a pcv valve and now that I think about it, I might not have even accepted the part because it didn't look like something I could use, but I'll take a look around for it.

well i checked the o2 and i think it may be in good working order still. now what? i only got about 41 mpg on the last fillup and thats with 60mph top speed, sub 2000rpm shifts and 40psi in the tires

could it be that the tires the prev. owner put on(non - LRR) would cause that drastic of a decrease in mpg? i've found a place that sells the vredestein quatrac2 LRR tires in the stock tiresize, 4 for 324$ shipped, im tempted just to do it

any other thoughts of things i could check for mpg issues? so far i've tuned it up(plugs, wires, distr. cap and rotor, filters, oil, checked o2 and its ok), any help would be appreciated, thanks

Did you verify that your actual mileage matches that indicated on your odometer? You never know...maybe your getting better FE than you think.

You didn't mention checking valve lash or timing either.

-- Scott

[QUOTE=NickF829]well i checked the o2 and i think it may be in good working order still. now what?

NickF829; what did you do to check the O2 sensor. I agree that you still seem to have something not working properly. However, I don't think it's your tire's. If you want to minimize them, as a source of problem, run the pressure up to 55 lbs. I've been running 55 lbs for about 6 month's and other than a little bumpier ride, the car roll's significantly better.

TomO posted a thread on how to measure the O2 sensor, on the VX. If you follow his direction, you should be able to see if the sensor is working all of the way, in both directions. On a lean burn sensor, they use a reference voltage, which is different for different manufacturers of car's. However the way it's described in the writeup, you are using the reference voltage as the negative lead for the voltmeter, so all of your voltages will be referenced to 0 volt's.:o