'94 Civic VX stumbles/hesitates in limp mode only when hot

[vxmike]

Hello everyone,

I'm the longtime owner of a '94 Civic VX that I purchased with 118K miles in 2003 now sitting at 218K as my daily driver. Best car I've ever owned as I've hypermiled to 60+mpg routinely on the freeway (best tank ever 73). Up until last week I've only had to perform basic routine maintenance and never had a "problem". Since I've moved to Detroit with uneven roads, bad ethanol fuel, and cold temps it's been difficult to keep a handle on the mpg but I've been doing an average of 45mpg with 80% highway driving. I can't even lean burn 1/3 the year in the sub-freezing temps since my commute is only 15 minutes.

Last week suddenly the VX began stumbling and hesitating badly especially on acceleration. I know there's a million threads about the VX stumbling and hesitating when the O2 sensor fails, and I don't want to be that idiot who doesn't search. Thus far I've performed the follow diagnoses and experiments:

1) Unplugged O2 and EGR sensors and reset ECU to rule out a problem with lean burn. While in limp mode it drives OK while cold but once the car reaches full temp the stumbling and hesitation returns on acceleration. It's particularly bad if I drive for a while, stop somewhere then go somewhere else. On acceleration it just feels "stuck" until something finally "gives" and lets me go.

2) I checked the PCV valve and grommet and both appear pristine.

3) I did a Seafoam treatment (fuel and vaccuum feed) with no noted effects yet. No Seafoam in the oil though, since I don't want to potentially dislodge things that could be helping me after twenty years

4) There was a horrible rattle coming from underneath the car when I idle that has mostly gone away. Bad Cat? I don't worry too much with exhaust maintenance since everything rusts here anyways.

5) I've had the common jumpy idle syndrome for a couple years that has suddenly resolved itself without intervention. It never bothered me too much since I rarely idle on my commute.

Can anyone help with ideas for other areas to look at? I'll buy a wideband O2 sensor if necessary but it seems there is another problem. This issue developed suddenly without warning, but I've driven ~100 miles in limp mode so far without it getting better or worse. This VX is 100% stock, and the engine and trans are otherwise strong. I'd like to take this VX to its 25th birthday.

Thanks in advance if anyone can provide suggestions. Not really interested in taking this car to a mechanic who likely won't understand the lean burn system anyways.

[Baltothewolf]

I'm not sure if that gen had it, but it could be clogged EGR passages or a bad EGR valve.

[Edit]: Duh I didn't read you said you already unplugged the EGR. I had this same exact problem on my HX (the loss of power and then it just gives up and gives me my power back). I never found out why before I sold it. Cleaning EGR plate, replacing air filter, spark plugs, wires and changing oil did help a lot. Not sure which one help, or a combo of all of them but Yea.

[dirtydave]

Sounds like its due for a full tuneup.

[user removed]

Clogged egr passageways.
Bad distributor.
Low compression.
Timing off, camshaft or distributor or both.
Plug wires.
Distributor cap, bad distributor.
Bad-plugged cat.
Low compression.
Valves not adjusted in ages.
Partially plugged injector.
Bad fuel pressure regulator.
Manifold gasket leak.
Cracked exhaust manifold, plugged exhaust.
Crap fuel.
Blown head gasket.

Many more possibilites or combinations of separate problems that could cumulatively result in the driveability problem. Without absolutely accurate service history and knowing all service was performed competently, this is a mechanics nightmare. Look on the net for a truly knowledgeable Honda specialist who might be willing to take on a diagnosis and if you find one, don't expect him to drop everything to take on your problems, because if he-she is competent and a successful business person, then he-she will have a serious backlog of work in line ahead of you.

While you may not like my answer, there really is no starting point without much more information.

regards
mech

[user removed]

Best Auto Repair in the Detroit area - Detroit A-List

might get lucky here

regards
mech

[Chrysler kid]

Originally Posted by dirtydave

Sounds like its due for a full tuneup.

Ditto, new cap/rotor/plugs/wires/fuel filter. Clean out the big 3 for the intake to clean up the idle

218k is nothing, 43 mpg city is good but I think you have more left on the table. Do you have a block heater yet?

[OG VX]

I just did a full tune-up on my intake manifold and all EGR/VTEC valves, etc... I posted pics/details in my build thread. After that, the idle was cleaned up a good bit, mpg went up by about 3mpg, and (most notably) I had a huge increase in overall low-end torque/power, especially in gears 3 and 4.

However, while this fixed all of my power and idle issues, my throttle hesitation issue still remained. Still stumbled a good bit here and there. Not as bad as before the intake manifold tune-up, but still not good.

Finally, came across my solution: installed a new fuel filter.

I had run SeaFoam in my take 4 weeks prior. I think it loosened a bunch of crud in my fuel tank. I suspect that my fuel filter then caught all of that, essentially clogging it and reducing adequate fuel flow to the injectors. Once I replaced the filter, I solved the remaining hesitation issues.

Just be mindful: if you are doing a full tune-up on the intake manifold, that VX engines have a completely different IM gasket from any other 92-95 Civic. I ended up ordering mine through CarQuest. Dirt cheap and delivered to my local store within a day. Also, you'll need the CX throttle body gasket. Get BOTH VTEC and the IACV (shaped like an 8) gaskets from Honda. You will need an EGR valve gasket as well. Also look to replace the thermostat, thermostat gasket, and plan for heater hose replacements as well as PCV valve while your back there.

Best solution, in my opinion (in retrospect): order a complete gasket kit off of Ebay (all gaskets for entire car; $50). This is cheaper than a la carte, and a whole lot less headache/time tracking down gaskets. Also, silicone heater hose kits are available off Ebay from China. They take 3-4 weeks to special order, but are a great deal at only $50. They also look great too, which is an added bonus. Plus, again, they are all there, and you don't have to go hunting everywhere around town for each individual fitted heater hose. The smaller hoses attached to the oil filter housing, in particular, were hard to find. I ended up getting hoses made for other cars that were close and cutting them to fit for about half of the heater hoses.

Hope this helps!

[user removed]

Start with the basics, check out all of the relevant systems to establish a basis for any repair strategy. Don't automatically replace anything until you haveestablished reasonable cause for replacement. It costs too much to do it the "maybe I'll get lucky and fix it way".

Compression and valve lash.
Ignition timing and a visual inspection of the cap,rotor and wires, looking for any significant wear on anything that creates spark.
Once you are sure everything ignition and compression wise is in good shape, then you can dig into the fuel delivery system, it get's complicated from that point.

regards
mech

[Baltothewolf]

Originally Posted by Old Mechanic

Start with the basics, check out all of the relevant systems to establish a basis for any repair strategy. Don't automatically replace anything until you haveestablished reasonable cause for replacement. It costs too much to do it the "maybe I'll get lucky and fix it way".

Compression and valve lash.
Ignition timing and a visual inspection of the cap,rotor and wires, looking for any significant wear on anything that creates spark.
Once you are sure everything ignition and compression wise is in good shape, then you can dig into the fuel delivery system, it get's complicated from that point.

regards
mech

I have a bad, bad habit with doing the above.

[user removed]

If it has an igniter (magnetic wave amplifier) in the distributor that would be suspect but it might be better to get a rebuilt distributor. Let's throw a couple hundred at that? Not if you can test it!!!!!!

Wrap a wire around your coil wire and your radio antenna. Might even have a piece laying around. Tune the radio to am and you will get terrible static. If the static changes when the car malfuntions then it's safe to ASS-UME it's the distributor. I would get one with a lifetime guarantee if aftermarket and not OE man, but prefer the greatly lower failure rate of OE when it really counts.

Now the problem becomes whether the car is worth the repair? That really sucks when the repair does not fix the problem.

The whole distributor thing is a GUESS!!!!

regards
mech