90 accord sedan four banger stick-shift...

Car accelerates well and sometimes drives steady just fine but usually after driving steady for a little bit, it begins to lurch badly. My daughter can get on the gas harder and it pulls fine then goes back to lurching at steady speed. Sometimes it will clear up after a few pull/steady cycles and will be fine until she shuts it down.. Other times it will not clear up at all.

Car has new ignition and tune up parts. Fresh fuel filter. Timing belt and all related to that and water pump replace.

She says it has had this issue for longer than other repairs and this was not affected either way by any of the other work.

What is most common cause?

TIA,
Brent

 

Brent,

Obviously it could be a lot of things. Common causes in the fuel system would be the Main Relay under the driver's dash that controls the signal to the fuel pump. The fuel pump itself. It could also be the throttle body needs cleaning (long shot, but only requires a can of carb cleaner so why not?)

On the electrical side it could be an ignitor going bad, breaking current to the the spark plugs. But this usually causes a quiet stall condition rather than lurching.

Is the check engine light coming on? (does it come on when the key is turned on at start?) You can use any piece of wire to 'jump' the two port connector under the glove box (far right.) to check the codes. That would help knowing if and what the codes are. A long light is a ten value. A short light is a one. Long short would be an 11. There may be multiple codes. Let them cycle for until they repeat. If there is a code, then get back to us and that will help.

 

You might want to check the TPS. If it only does it at a certain throttle angle, then it may be that there is a intermittent connection on the TPS. You can check this with a DVM, back probe the sensor and watch the voltage change, if there is a dead spot or erratic voltage reading rather than a smooth .5-4.5V change then you have found your problem.

Same with the MAP sensor, you will need a hand held vacuum pump to control the amount of vacuum, again you are looking for a smooth transition of voltage. Any spikes, dips, or dead spots indicate an issue with the component.

Check them both hot and cold, as the issue may not present itself if done when cold.

 

What is the rpm range in which this happens?

 

It will begin at about any steady throttle position in fifth gear usually so 55-65 mph.

Brent

 

Which if I'm about right, that would be in the 1800~2000 rpm range.....almost right for egr ports being clogged. On this gen there are "plugs" on the intake runners that have to be removed.

The clogged cat theory (other site) doesn't play out in my mind, you stated she can accel thru the issue. So under hard accel the issue is not there.....

 

Could also point to the 02 sensor as a possible culprit.

Are you getting a Check Engine Light at all?

A bad 02 sensor will cause the car to stumble, idle poorly,hesitate, be hard to accelerate etc.

I think an 02 sensor is code 12 or 14.