99 Alero Hesitation

[Z 99 Olds]

Hi

I have had a problem with my 99 Alero for some time. It is a 4 cyl 2 door
and there is a hesitation that comes and gos I have changed the plugs,
fuel fiter and air clener and will still do it from time to time. I have also tryed diffrent grades of gas and enjector cleaner. It seems to do it most
when we are going up an incline just befor it shifts when the moter is geting the most load on it but it will also do it when I start it up like it has a miss. As I said this comes and gos and no lights have come on so I'm not sure if it has stored codes. Recently I have tryed Outlaw super concentrated fuel enjector cleaner and I have not had the problem for
the last week or so but I would like to know if anyone has had this problem befor and might know what it is.

Thanks

[Ridenour]

Could be your MAF - try cleaning your MAF. Or try buying a new one / borrowing one to see if it fixes the problem.

Or it may be something tranny related.

[peswierc]

Having the exact same problem you had. Had entire fuel system cleaned/flushed and still same hesitation. inclines are worst. Had couple different people look at car, but no one seems to be able to find problem. If you have any more info. it would help

[peswierc]

Originally Posted by Ridenour

Could be your MAF - try cleaning your MAF. Or try buying a new one / borrowing one to see if it fixes the problem.

Or it may be something tranny related.

What my MAF??

[BNaylor]

Originally Posted by peswierc

What my MAF??

One sysmptom of a defective MAF sensor (Mass Airflow Sensor) is a "chug" effect going up an incline or hill. Or a hesitation or miss when accelerating. Since your engine is under load it is an ECM/PCM open loop mode problem. When conditions are "ideal" the ECM operates in closed loop mode. A lot of times the miss occurs right about at torque convertor lockup making one to believe it is tranny related. You may or may not have a SES light or DTC error codes when checked with an OBD-II code reader/scanner.

A simple test is to disconnect the MAF sensor electrical connector. Test it again on the hill/incline and see if it improves or problem goes away.
You may get a SES light during the test. The ECM/PCM will use pre-programmed RPM values instead of the signal from the MAF sensor.
When disconnected the initial idle may be errratic until the car warms up.

The MAF sensor is located on the throttle body intake side. It is a black ring with a standard GM quick disconnect electrical plug. Cleaning it is not recommended because you may break the air flow wires, etc. Cost may range from $40 (used) to $140.00 (new).

I have a 2002 Alero GL2 (38K miles) and we replaced ours with a high performance Granatelli racing MAF for $250.00.

At least you will be able to rule it out because other issues could cause your problem too. Good luck!

[shermo_6]

Also have the same problem for about a year now. Intermittent. Tried premium gas and several times used Techron or Gumount fuel injector cleaner. Thought I saw better performance for short time after Techron. Tried dry gas. Car accelerates until it needs to shift to next gear and then it just doesn't shift but sputters. Have to lay off gas and feather or wait a little and then it slowly will accelerate and shift into next gear.

Have next on my list to change the trans fluid & filter.

I have the 99 6 cylinder, and have about 50k and drive it rather hard.

Will look into the MAF suggestion, thanks.

[vamc]

Originally Posted by shermo_6

Also have the same problem for about a year now. Intermittent. Tried premium gas and several times used Techron or Gumount fuel injector cleaner. Thought I saw better performance for short time after Techron. Tried dry gas. Car accelerates until it needs to shift to next gear and then it just doesn't shift but sputters. Have to lay off gas and feather or wait a little and then it slowly will accelerate and shift into next gear.

Have next on my list to change the trans fluid & filter.

I have the 99 6 cylinder, and have about 50k and drive it rather hard.

Will look into the MAF suggestion, thanks.

Alot of it has to do with the PCM. Getting a jet chip or anyother chip will not help because it is a programable PCM. if you get it reprogramed, it will lean out the fuel mix. and could get better take off. Just a thought.

[shermo_6]

Thanks for the tip.

Have been noticing lately that the hesitation occurs usually after car has been running and engine is warm, and when I drive on a downhill incline. Something as small as a driveway apron or a swell in a street, and I noticed the hesitation occurs. After about a minute, the hesitation gowes away. Gas level seems to be irrelevant. Hesitation occurs in drive as well as neutral.

[MirandaSal]

I just read all of this - seems like this is pretty common - I put a posting up the other day "Transmission Issues" I will look into this MAF thing - I hope to figure this all out - it is so frustrating! anyother suggestions out there???? Help me please! Thanks all!
Miranda

[choice.musicians]

I own a 99 alero 4 cyl. the car would hesitate unless i slowly worked the gas pedal...turns out the problem was a vaccum leak, on the front of the motor there was a short 2 inch hose that was cracked. the hose was formed like a C so i could only see half of it, however the crack was on the inside of the C shape...its right on the intake manifold and super easy to miss. It should be secured by a clap, check that...after changing my plugs, cleaning the IAC and intake, changing the air filter, changing the tranny fluid, and ALOT of injector cleaner, it was a .95 cent hose causing a vaccum leak. Well at least everything is done and my alero runs great!