Bogging Down!

[aleckz]

My little 91 Civic w/an integra engine has trouble between 1 - 2k RPM. I think it is missing some cylinders between those areas, the car shudders and I can hear it having trouble. I wanted to make sure that it's nothing too major before I spend any money.

I was thinking it just needs a set of plugs and maybe new wires.

Also, the car spikes from 500-2000 rpm on start, is this normal?

-198k on body
-100k on engine *92 integra LS engine

cliffs:
spuddering/shuddering between 1k-2k rpm

spiking rpm when warming it up.

Any help is appreciated!

 

[bruceb]

First thing to check would be the Throttle Position Sensor. It is mounted on the
throttle body and usually has 3 wires .. basically all it is is a potentiometer that
tells the engine computer how much the throttle is opened .... that way the computer
knows how much fuel to put in and how to set the timing.

Next thing would be to check the Mass Air Sensor .. located in the Air Intake Duct
usually near or at the throttle body. I would also see if the Service or Check Engine
light has come on. Even if it hasn't try to get a scanner hooked up to see if any
trouble codes are in the computer. Your car should have ODB II on it. Most Autozone
stores will scan it for you at no charge.

 

[M2008S]

throttle position sensor, mass air flow sensor, bad/stuck injector, temp sensor.. dump some good fuel system cleaner in it like lucas or gunk brands. use google.

also about scanning, if theres not check eng lite on then its not throwing codes (error codes made by cpu) then nothing will come up. try it anyways though in case the light is messed up.

 

[DivideBYZero]

"spuddering"

lol!

 

[Zenmervolt]

As others have said, check the TPS and the MAF sensor.

Also, pull the spark plugs and look at them to see what they look like. They will give you a clue about whether the engine is running too rich or too lean or they may just be out of spec on the gap.

ZV

 

[jagec]

Originally posted by: DivideBYZero
"spuddering"

lol!

Maybe he installed a Harley-Davidson engine.

 

[alpineranger]

your car does not have a MAF sensor, but a MAP sensor that is attached to the firewall and has a small vacuum line runnning to it. Because of the age of the car it won't be ODB2 and you can't use a common scantool. You shouldn't need one though, as hondas of this vintage have an LED on the engine computer that blinks to indicate specific codes.

Please give us more information on what the symptoms are. Do you have a surging idle (surges from low to medium rpms repeatedly), and if so, is it when the car is cold or warmed up? Does it shudder only when you punch the gas, or even when driving gently? Is the check engine light on?

Provided you don't have an engine light on, with the little information you've provided, this is what the symptoms seem to indicate:
-surging idle could be from a leak in the intake tract, or a bad IAC valve, coupled with a faulty coolant reading that tells the car it's warmed up before the fact. The engine computer programming that causes surging only goes into effect after things have been warmed up.
-shuddering at low rpms seems to indicate a lean condition, which is also consistent with unintentionally metered air. What this is unlikely to be is a problem with the fuel delivery system (fuel pump, injectors), or you'd see effects at higher rpm, and higher load as well.

From that, this is my short list of problem spots.
Throttle/throttle body. There are several adjustment screws. One for idle speed, another which is a throttle stop which should never be adjusted, but some people do.
IAC valve.
Vacuum system leaks.
Intake system and all associated gaskets.

 

[aleckz]

It shudders when I punch the gas and when I drive it gently.

The check engine light is not on and it does work.

It surges from low RPM to medium RPM on warm up, but then it still surges about 200rpm plus/minus. Also the lights in the car surge a little (fades in and out)

I recently replaced the battery cables, that helped the surging and I will check the plugs and mess with the TPS when it gets a little warmer. I'll also look at the MAP.\

edit: and thanks for all your help!

 

[Zenmervolt]

Originally posted by: aleckz
It shudders when I punch the gas and when I drive it gently.

The check engine light is not on and it does work.

It surges from low RPM to medium RPM on warm up, but then it still surges about 200rpm plus/minus. Also the lights in the car surge a little (fades in and out)

I recently replaced the battery cables, that helped the surging and I will check the plugs and mess with the TPS when it gets a little warmer. I'll also look at the MAP.

edit: and thanks for all your help!

Surging might be a dirty idle air control valve. That's reasonably common in older Honda engines and I ought to have thought of it earlier.

ZV

 

[aleckz]

Thanks ZV, Ill look into it.