Car is lurching


#1

I own a 1997 Volvo 850 stationwagon wit 134,000 miles on it. When driving at higher speeds and after about 15 minutes of driving, the cars lurches forward as if it had a hickup, or is starved for fuel. The rpms increase for a second and drop back to normal, as the car resumes its regular speed. I had it tune up and the problems persists. Any idea what might cause it?


#2

It sure could be your fuel system from what you have mentioned. RPM’s rising for e second could indicate a leaner mixture causing this. Has the fuel pressure been checked and the fuel filter repalced?


#3

i own a 2001 v70xc with 70k miles and it does the same thing. it’s been doing it for the last 10k miles and no one seems to be able to fix it, yet i spend an average of $600 everytime i visit the dealer. not only that, but at 65,000 i replaced the front and rear suspension, and when driving, the “check engine” “abs” and stabilitrak lights come on at random intervals. dealer can’t find anything that corrects these problems. i’m so disappointed in this car. looking for a new car right now – will avoid all brands made by ford.


#4

Your first step should be getting any codes pulled since this could be an ignition coil breakdown or any one of a hundred or so other things, including a failing fuel pump.

AutoZone, Advance Auto, Checkers, etc. will do this for you free. Post any results back here for discussion.

Also; any Check Engine Light on? When was the last time the fuel filter was changed?


#5

I just changed the fuel filter, air filter, ignition rotor, distributor cap, ignition wire and new spark plugs. The computer scan comes up with the PO172 code, which is the O2 sensor, not sure fixing that will fix the lurching, any other thoughts?


#6

The RPM’s increasing while cruising at speed when this happens might be an indication that the lock-up torque converter might be unlocking and locking back up.

The next time this happens, try shifting into the next lower gear and see if this hickup continues. If not, then somethings going on with the torque converter clutch.

Tester


#7

My DTC (Digital Trouble Code) guide shows P0172 as; “System Too Rich”. Check a third source, online or elsewhere, for a third opinion. It’s time to do some checks and measurements: fuel pressure at about 1500 rpm with transmission in DRIVE to check for fuel pump function (stamina), actual spark test from the end of one, or more, spark plugs. Erase trouble code, drive, and check the codes, again.


#8

This does sound similar to an O2 Sensor problem that I am familiar with. The codes aren’t always wrong. O2 sensors are engine candy, they get chewed and should get spat out when they do.