Another WTF is Wrong with My Car Thread

[|Chaz|]

Alright boys and girls, my 1992 Civic Sedan with a JDM D15b VTEC (not the three stage VTEC) has been driving... oddly. At the behest of Matts96HB, I changed my fuel filter because in the 205k miles of the chassis, it has never been changed as far as I know. I changed that because my car had been stumbling and hesitating while driving.

That change seemed to help a little... but now it is back to feeling the same. Around town under 40 mph it feels a little less unsorted, but still down on power. Once on the freeway, it makes me worry if the car is even going to make it to work 10 miles away. It's not a dramatic hesitation or stumbling, but going downhill, pressing lightly on the gas pedal, I can feel the car hesitate and resume and hesitate and resume.

I checked the spark plugs, they seem to be within the appropriate appearance according to the spark plug thread.

The wires are slightly dirty looking and actually look like they have some wear to them so I think they could definitely be replaced at this point. I don't know however if this would cause my symptoms to the extent that I'm feeling.

I have seen that a bad ignition coil could cause my symptoms or a bad rotor/cap/distributor.

Any other ideas? Ask me questions and I'll do my best to answer them. This is my only means of transportation. My girlfriend and I carpool in this car everyday to work so we're pretty dependent on this stupid thing.

Thanks in advance for your help.
Chad

 

[SlushboxTeggy]

It's going to sound weird, but check your coolant level. If you have a leak/air in the system, it can cause the hesitation similar to what you're talking about.

 

[|Chaz|]

Alright, I will. Now that you mention it, every now and then I'll pop the hood and there will a little puddle of coolant on the radiator... could be cracked.

Would this also cause my car to feel down on power?

 

[SlushboxTeggy]

The way you described it it seems spot on. I'm actually in the midst of dealing with this issue with the 2nd radiator in my Teg. Yesterday, it was a scorcher and after a 20 minute drive air/vapor was actually hissing out of the radiator. I'll drive around with coolant in the trunk until I get around to fixing it.

 

[reckedracing]

1. compression test to rule out motor weakness/failure.
then move onto spark and timing
low coolant usually first manifests itself with bouncing idle, if iac equipped

check your inlets and outlets
clogged air filter, or cat
my money is on cat if it OE equipment

edit1: put vice grips on fuel return to rule out a weak/smoked fuel pump

any CEL? other symptoms?
visually inspect cap and rotor for burn to a crispness

heat related issues include bad distributor and potential main relay problems, but the main relay is usually a go or no go, wont even start the car

 

[92stoccord]

I was going to also suggest checking your fuel pressure. Since changing the fuel filter seemed to help, perhaps it was that the fuel pump is weak and couldn't push through all the garbage blocking the filter. Other's suggestions seem to be a bit easier though, I'd check those first. What's supposed to happen if you clamp the return line?

Edit: My second guess is also the cat if it's old/never been changed. I just drilled a 1 inch hole in my girlfriend's aunt's Taurus's cat. It went from barely climbing a hill to having considerable power with full A/C on. It's surprising how much it can effect it.

 

[Dual-500]

What is the gas mileage. I would be tempted to clean the injectors. Check for exhaust backpressure in front of the cat too. Many time when fuel injectors get dirty, they won't flow correctly and will not seal - i.e. leak and make the engine run rich.

 

[|Chaz|]

What is the gas mileage. I would be tempted to clean the injectors. Check for exhaust backpressure in front of the cat too. Many time when fuel injectors get dirty, they won't flow correctly and will not seal - i.e. leak and make the engine run rich.

I'm getting about 32-35 mpg. How do I check for exhaust back pressure in front of the cat?

 

[92stoccord]

Is your CEL on?

 

[|Chaz|]

Sorry, no check engine lights (CEL). Put that in case some noob comes along and reads this thread. Took me forever to figure out what CEL meant when I was a noob, I was a dumb noob.

 

[CAFROG]

Shot in the dark......but TPS can start to fail and have similar symptoms.

In terms of catalytic converters.....you can take you cat out and look though it (at the sun...like a scope) if you can't see any light....cat is clogged.

 

[92stoccord]

If its bad enough, beat it a little with a hammer, stand behind the car and have someone rev it, and put your hand behind the muffler. If you get flakes on your hand its time for a change.

 

[Dual-500]

I'm getting about 32-35 mpg. How do I check for exhaust back pressure in front of the cat?

That's good mileage - probably not dirty injectors or the cat. TPS would be next on my list as CAFROG suggested.

 

[dc4dude]

real quick question, does the hesitation get worse at low rpms, and go away at higher rpms? do you get a POP under acceleration at low rpms? might be a coil going out. check the cap for any carbon tracking, check the coil for any cracks or carbon tracks... and when any of this happens, it usually wont trigger a cel.. tps will set off a cel (usually)

 

[dc4dude]

also, with the engine running, LIGHTLY spray water over the wires to see if they are arcing... listen for a arcing wire, watch for the spark...

 

[Matts96HB]

does it vary based upon how much gas is in the tank?

 

[thsancho86]

When I changed out the header on my 97 ex I knicked the O2 sensor wire and had to cut and reconnect them, several moths later mine was kind of doing the same thing. It would do okay in the city but wouldn't go over 50 without bogging down. I properly reconnected the wire and it ran perfectly fine after that. So that might be a connection to check.

 

[Dual-500]

^ Did it throw a CEL code?

 

[thsancho86]

^ Did it throw a CEL code?

Oddly enough it didn't. I had changed plugs wire and my fuel filter all before hand and when that didn't do it I did the wire repair as a shot in the dark.

 

[Dual-500]

^ I've had TPS sensors with rough spots in them that didn't trip the CEL threshold.