I have a 1993 Honda Civic DX, with a 1.5 liter engine and 144k miles on it. Unfortunately because of the year and model, it doesn't have a tachometer, but the engine surges hard enough to make the car twist very slightly when it's sitting still, then it drops back down and does it again. The surge occurs very quickly. Previously the surge would be on and off, it would happen a day here and then stop, then pop up again a few weeks later and it was much softer then. Now the surge is much harder and sounds like the engine is going to about 3k RPM (Just a guess from knowing how the car drives). It does this surge at all times of the year, regardless of weather or how I drive it. It's completely random in how strong it is and when it happens, so I have no pattern to look for. The only time it doesn't do it is when the car is in gear, but once or twice I've noticed that when the car is coasting in 5th gear at lower speeds it has been doing it.


I've tried adjusting the idle, the air flow, opening the engine and cleaning things out. I've only put premium fuel in it, the oil gets changed every other month, sometimes more often than that. I've checked the fuel injectors, the intake manifold appears very clean, I put in an injector cleaner/engine cleaner, 2 to 4 times a year.

Admittedly I do drive the thing pretty hard on a regular basis. Intake and exhaust have been changed to larger applications. And I've been spending the past four days trying to find out what's wrong with this car, this is the worst that it's ever sounded. It was quieter when I didn't have a muffler on it.

The radiator has straight water in it (I live in South Florida, it's always hot here), a friend of mine suggested that perhaps I add some antifreeze in it.

Anyway, thanks for any suggestions that you guys might offer and thanks so much for reading this post.

 

Ok, I talked to a few guys and they said that it might be my throttle sensor or a vacuum leak. So now my question is, if it's a vacuum leak, how would I go about fixing it? Or if it's the throttle sensor, how would I test to see if that's the problem?

 

Ok so, I changed the whole throttle body, sensor and all and it's still doing it. Anyway to find a vacuum leak, if that's even what I'm looking for at this point? I'm really at my wit's end here, if I don't find it by Saturday, I'm installing a whole new engine and I swear, with my luck, it'll probably still keep on happening... I've already got my eye on my friend's 1.6 liter Vtec

 

I have noticed a few other symptoms: The car has lots of trouble idling low, I set the idle to a much lower setting and the idle is for the most part exactly the same, except for when I press on the gas and take my foot off. The idle drops down to a low, very normal pace, briefly, then pulls back up. Also, while pressing on the gas, while the idle was set high or low, it always revs up to about the same spot, which is probably around 3000 - 3500 RPMs. Also the exhaust smells heavily of gas, probably meaning that some valve or sensor is sending too much gas through the line, hell it could even be the gas pump sending too much gas through.

Anyway, I'm looking through the manual trying to find a solution for this insanely annoying problem...

Any help that you guys might offer would be very much appreciated. This problem is killing me.

 

Sounds like you need to adjust your valves.

 

or Check your fuel pressure, just install a cheap fpr, then your will know if your pressure is consistant.

 

I haven't had a chance to try out the FPR suggestion, thanks for that though. At this point anything will help. The car has been unusually torquey lately, not that it's a bad thing, but it at least tells me that it's getting way too much fuel.

But just when I thought that car couldn't get any worse... It gets worse... Tonight I was on my way home, I'm at a light and I pull off. When I go and shift into second gear, suddenly the car gets really laggy, almost barely not moving, as if second gear has gotten only half way in and the engine light comes on. I quickly take it out of gear and put it back in.. it drives fine, but the light is still on. I get to the next red light and I take the car out of gear and let it coast to the light while I slow down (just an old habit), but while it's coasting, instead of the idle going up and down anymore, it is now holding at that high rev... (about 3000) and that damn light is on. I called up my bestfriend, he says I might have broken a valve, I call my father he says he seriously thinks it's my injectors. I didn't realize that injectors weren't supposed to be open by default.. turns out they might all be bad. I'm waiting for the car to cool down a little bit, then I'm going to take off the injectors and see if this is actually the problem. Dad told me to blow through them and see if air comes out the other side. If this is the case, then the ones that allow air to pass through are all bad. I'm hoping that this is the problem, because i can't take this anymore.

 

I checked the injectors and based on his little test, they're all fine. The only thing I can think of is possibly a vacuum leak that just got worse. Do you guys think this might be it and if so where should I start looking?

 

If your MAP or MAF sensors are messing up you might get a simular result, however the high rev seems to me it may be vacume also. Have you checked all of your gaskets, cam seals, timing? Its possible your timing belt might have slipped slightly and your timing could cause the unusual power, then if it slipped again it would likely cause you to rev erraticly or not even start at all. It may also damage your valvetrain, have you double checked for clearance on your valves and rocker arms?

 

It could definatly be a leaky head gasket as well.... thinking of gaskets again. I'm not sure the blow through test is enough to know. The only test I know if is a peak and hold test performed by companies like RC. It might be worth seeing if you can borrow a friends to test the change.

 

Ok, so the high throttle was being caused by the plug into the throttle sensor wasn't secure and it slipped off... I plugged it back in and the car started no problem. And then it continued singing it's annoying song of 1k - 3.5k... 1k - 3.5k... bastard car needs to be shot... I checked all the hoses for any leaks and found nothing. I started unplugging sensors to see if there would be a change in idle and only found two that didn't make a difference. The MAP is fine by the way. There are two sensors located on the back of the intake manifold, one on top of the other. The one on top has a black cylinder on it that can pull off pretty easily. And the second one.. also on the back but lower down has a white plug going into it. I'm not sure what sensors these are, but I'm sure that one of them might be the problem, since the idle didn't change at all when I unplugged it.

I checked all of the injectors a different way this time: Plug them all in, start the car and take a long screwdriver and put the metal tip to the injector and your ear to the handle end... you should hear a VERY rapid clicking if the injector is working. Did that with all of them and all but one seemed to be working... I'm not entirely sure about that one, but it seemed to be clicking.. just not as loud and rapid as the others.

And the gasket seems to be fine. There's no oil outside of the engine and there isn't any smoke of any kind coming out of the exhaust. Other than the gasoline smell coming from the exhaust, there isn't anything else. Is there possibly another way for the gasket to leak other than these situations?

 

Well sounds like that would mark gaskets off the list. It must be sensor related, generally something like this would kick out a code within a few hundred miles at least.

 

Yea, you'd think that it would kick out some kind of error or check engine light after a few hundred miles, but I was pushing the stupid lil thing for at least 120 miles a day and I've been doing that for several months now. *sigh*

The other thing that I noticed is that in the distributor cap, the connectors were highly oxidized after I cleaned them out, they were all different kinds of sizes now. Is it possible that if one or some of them weren't getting a connection from the thing in the middle that spins, that it could cause this problem?

 

thank god, at least some noobs believe in paragraphs

anyway, vacuum lines are typically just little rubber hoses. go down to an auto parts story, buy an array of a bunch of them, and just replace all the ones you can find. it will only help. no telling the last time they were replaced

next, check your injectors (not sure if you said it was carburated or not) to make sure they are not leaking. if they were, they could be dumping fuel into the combustion chamber randomly caushing detonation, or quick revs of the engine.

and the car has a distributor right? no coil packs i mean. i would either replace the distributor (wires too) or at least have it checked out. your timing could just be totally screwed up

 

ya i would guess that as well i have a 92 civic dx with 1.5 does the same damn thing no leaks i checked the timeing ; advanced it set **** tdc did everything the way it should b still running like crap. think might b my sensor clogged ganna check that tom;