99 Malibu 2.4L 4 cyl., Surging/hesitation

I have a 99 Malibu with the 2.4L 4 cyl with 185,000 miles. It has starting surging/hesitating at highway speeds. It's usually not enough to make the RPM's dance, but you can feel it. Also hesitates a little sometimes when pulling away from a dead stop.

Before this problem it has not been shifting into overdrive correctly and downshifts prematurely when going up a hill. It's been doing this form almost 2 years. Had it to several shops and no one could find anything wrong with it. Tranny specialist ran a scan & charged me $70.00 with no solution. :banghead:

Any help would be appreciated for either or both problems.

Thanks-

Jason K.

I have a 200 Malibu and my car also surges , mainly around the 45-50 mph range. It also surges whenever it is first started. I asked around and was told that it could mainly be a vaccuum problem.

Did you ever figure out your problem? Mine has been doin that for years and finally last night the check engine light came on and now its barely running! Any Info would be helpful!

Haven't Figured it out yet.

Did you ever figure out your problem? Mine has been doin that for years and finally last night the check engine light came on and now its barely running! Any Info would be helpful!

Hallelujiah, maybe now you can get a solution. Get the codes read immediately..

I took it to the garage to have it tested and was a Misfire on cylinder 1, mechanic told could be one of several things, fuel injector, coil pack, plug or plug wire. Ill Keep yinz posted on the findings.

Sorry, no plug wire just a plug.

I've seen the coil cover go bad and cause misfires and idling problems. With as many miles as your car has, that might be worth looking into. Also check the spark plug extensions (between the coil cover and plugs) and be sure to use AC-Delco plugs. These engines are very particular about the kind of plugs you use.

Well I put AC delco platinum plugs in(like you suggested) and that seems to be the problem. It also solved that hesitation problem when you first pulled out, its running alot better with the ac pltnums, so thanks for the info jonnik!

Glad to help. Aftermarket parts are OK, but some things (ignition parts and fuel pumps especially) are best replaced with OEM parts.

Wanted to update everyone with the surging/hesitation I had.

Put in new AC Plugs and no improvement. Installed a new Throttle Position Sensor as I suspected first and this did the trick. Hesitation is gone at all speeds. Now if I could just get the slow shift into overdrive fixed

@jaybo80 Could you elaborate on if you tried any other fixes before changing the TPS?
Also, did you notice any pattern to the hesitation on acceleration from a stop? I seem to have very similar problem with '00 Malibu (though it is a 3.1L): Hesitation/lack of acceleration from stop, lacks some power at highway speeds and intermittent surging (100-300 RPMs) at highway speeds usually. I seem to notice both problems appear mostly after the car is warmed up and less when cool, though this could simply be coincidence. Did you notice a pattern? Otherwise runs and idles well. EDIT: I'll add that sometimes when acceleration is sluggish letting off the accelerator a little improves the engine response and acceleration.

btw: I've done spark plug wires a year ago (a squirrel chewed every last one off!), all new plugs the other day, tested all three coil packs primary and secondary resistances all within specs (cold at least - I may go back and test warm when I have a chance).
I checked the TPS a little - removed and cleaned a bit... but didn't have back probes to test output voltage on the vehicle. I did measure the variable resistance from the 5v power lead to the return signal lead while rotating the TPS... I seemed to get a pretty smooth variation in resistances... but I know this is not necessarily the same as smooth voltage signal and range being produced..

I'm also considering Catalytic converter, Tranny filter/fluid change, Fuel filter.

Any thoughts would be appreciated!!
Thanks!

The only other thing I tried was the new AC spark plugs. When I popped open the old TPS you could see a very noticeable spot that was worn. Appeared to be around the location it would be at when running at highway speeds.