Odd hesitation in Honda Civic
 

My 91 Civic Si has about 127k miles, and for quite some time it has had an odd hesitation under certain circumstances. It happens on hot days (85 or higher) when I first start it up. It starts and runs fine, as it always has, but for the first few miles, under mild acceleration and steady cruising, it will intermittently hestiate. It happens at even intervals of about 5-7 seconds, and it acts like the throttle is briefly closed - just a quick drop in power - for a brief moment, then back to normal. This will continue for the first five minutes or so, then it runs perfect after that. It does this to a much lesser degree after subsequent startups with the engine still warm, but mostly after the first start of the day when it's hot outside.

I recently replaced the fuel filter (not due to this problem, just because it was time) but the car has been doing this for several summers prior to that. It acts like it might be a fuel supply problem, but I'm guessing it could also be igntion related. It's never enough to cause drivability problems, it's just annoying.

Any idea of a fix?

You might want to try running the engine at full throttle up to (near) redline a few times. Sometimes that helps cleans out the system. It's fun too :).

hmm to me it sounds like you might have an o2 problem.. just do to the fact that it seems like your car is not accelling, your o2 might not sence enough exhaust and stop pushing as much fule into you engine.. either that, or you could have a vac leak in one of your lines, OR possibly you are not getting enough air into your engine, in which case take apart the intake, start the car and test the butterfly valve and play with it. or better yet, have someone step on the throttle and you watch to see whats going on..

thats my ideas,
-trev

Have you ever changed your plugs and wires? and if you have a distributor how does the cap look?

The plugs have ~ 10k miles on them. It's been doing that since before I put the current plugs in. Original wires. I'll check the cap up close, but no problems are apparent there. I actually thought it might be the plug wires - is this the kind of thing they might do if they're going bad? How long do wires last?

Usually wires last around 100k....that can cause it to be a little sluggish....

Since you have already checked the plugs, move on to the wires, then distributer cap and router. My guess is that the cap and router are misfiring.

I had a similar problem but mine was car was fine on cold days but in heat it did that or wouldnt start at all ended up being my arc not hitting my cap even though it looked fine to me. They only cost 17 bux and 9 for the rotor.

Yeah, if it hasn't had a tuneup in a while that would be a good place to start. Does your car have a tach? If so, does it jump and down when it is hesitating? If so that pretty much eliminates fuel problems.

Also a bad oxygen sensor can do this. Not many people think to change them, and they do go bad after 80k miles or so.

Check the o2 sensor

I have the exact same problem with my carburettor Nissan.

giver a full tuneup.

plugs, wires, dist cap, rotor, air filter.

then see if the problem is stil there.

if you keep having problems, the boys on www.honda-tech.com may be able to help, if its a honda-specific problem. but BE SURE TO SEARCH THE ARCHIVES FIRST!