Good morning. My question regards a 1993 Civic LX 1.5 liter, 5-speed manual. ~120,000 miles. Timing belt changed at ~80,000.

Firstly, let me say that I did look in the “already solved, FAQ” section and did see what I thought would be a relevant posting to my problem, but I did not see the definitive fix included in the string.

My Civic bogged down yesterday, when giving it any throttle over just a touch. That is, at a very light acceleration it ran fine, but giving it any more than that would result in a severe bogging down. It stumbled and actually stalled a couple of times, but restarted. The ambient temp yesterday was 96º F with the heat index at 104º. I had just exited the freeway and made a turn when the bogging started. I made it to a gas station, removed the fuel filler cap, heard the requisite whoosh, and then filled up the tank. It was at about ¼ capacity before the fill up. The car recovered, and has not exhibited a problem since yesterday. I also added a bottle of Techron Fuel Injector cleaner with the tank of gas. No check engine light illuminated.

I believe that this problem will be back soon, and possibly will not recover allowing my to get to a destination. Therefore, I am looking for any similar stories, problems found and fixes.

Ed Fisher
Dallas, Texas

 

i would check the timing on the car...... my old car was stumbling and then picked up fine and it was the timing... when i swaped the belt i had the one or two tooths off the timing belt.... fixed it and then reset the timing to correct and it ran like a champ...

 

Addiction2Bass:

Thank you for the response, I will check the timing. My posting title may have been a little misleading though, it should have read, "bog, stumble, stall, recover". It was immediately after exiting a freeway, stopping at a light, and then taking off from a stop. If the timing had jumped, as in from missing teeth on the belt, I cannot imagine it recovering after a brief stop. It would seem that the cam/crank being off-synch would stay off. It certainly is worth a look though, and I do thank you for your response.

There is a posting with my exact symptoms on Wikipedia, so there may be a documented fix that shows up there. If so, I will post my findings here.

It almost seems as though there is a switching valve, or similarly actuated sensor, that is open/closed at freeway speeds, that didn’t like the sudden stop from those speeds/vacuums/signals, and then asked to move into a off-freeway state. A lazy slide on a valve? Perhaps carboned up on a 1993 with 125,000 miles? A vacuum line that collapsed just a little in this high-temp and demanding scenario? There has to be a logical explanation, and I am pouring over the manual now trying to understand the diagnostics a little better.

Thanks again for the posting, and any and all help from others is certainly appreciated.

 

And what is that documented fix? Or is there only a question with no responses yet?

 

"And what is that documented fix? Or is there only a question with no responses yet?"

It is simply a question with no responses yet. When I do find the root cause problem I will certainly post it to this list. Actually, I had hoped that someone here would have seen this/fixed it, but apparently it is not as common as I originally thought.

 

Making the exit ramp and sharp turn might have led to pulling a slug of water out of the gas tank. Purely a guess.

The controls are very simple. There aren't many valves, etc. to go wrong. Just a few sensors and a computer. There isn't any part specificially dedicated to high speeds versus low speed.

 

Rare intermittent problems are typically the most difficult to solve, leaving you to consider common causes for the symptoms. Low fuel pressure would fit into this category. When was the fuel filter last replaced? If it's been a while, this is a relatively straightforward maintenance item that would be worth doing and may even prevent the problem in the future.

 

Ron J wrote: "Rare intermittent problems are typically the most difficult to solve, leaving you to consider common causes for the symptoms. Low fuel pressure would fit into this category. When was the fuel filter last replaced? If it's been a while, this is a relatively straightforward maintenance item that would be worth doing and may even prevent the problem in the future."

I agree with intermittent problems being the hardest to pin down, and also with the fuel filter replacement being a smart move. I was just looking at the diagram for the fuel pump and it says (loosely quoted) 'if the fuel is obstructed on the discharge side, the relief valve will open to prevent over-pressure'. A intermittent clog inthefuel filter would certainly cause that condition, whereby the relief valve prevents full fuel pressure resulting in a starving/bogging condition.

mk378 wrote: "Making the exit ramp and sharp turn might have led to pulling a slug of water out of the gas tank. Purely a guess.

The controls are very simple. There aren't many valves, etc. to go wrong. Just a few sensors and a computer. There isn't any part specificially dedicated to high speeds versus low speed."

This is a good guess, since water and fuel can certainly separate. I was thinking of something like the fuel pressure regulator, perhaps getting an indication that the manifold pressure and the fuel pressure differed by enought to open the diaphram and feed the excess fuel back through the return line. Not likely I admit, but just a thought.

I really appreciate the comments and thoughts that I am receiving. Thanks for taking the time.

Ed

 

Fuel filter has been replaced, and the problem started to replicate when the fuel tank reached the 1/4 mark. This is the same symptom as last time, that is, exit freeway, come to a stop, car bogs way down with acceleration, recovers when the accelerator is released, stumbles, and tries to stall. This time, I filled the tank right away and the problem has not duplicated, again. Before the hard failure I notice that when shifting into 3rd gear there is a stumble, which may or may not be related. Any other ideas? Incidentally, the idle is going very low when the ambient temp is 90+ and the AC is on. Will cleaning the IACV screen remedy this?

Thanks,

Ed Fisher

 

I think cleaning the EACV/IACV is a good idea.

The main relay that controls power to the fuel pump is well known to fail in hot temperatures, so you might also consider soldering it:

http://techauto.awardspace.com/mainrelay.html