I have an 02 Pontiac Grand Am with the 2.2L Ecotec motor. I have problems with a hesitation coming off idle. I have a code P0171. I have changed the upstream O2 sensor, put new spark plugs in, cleaned the throttle body, and had the injectors cleaned. It is running a little better but still has the hesitation. The hesitation is worse with cold.
Unfortunately, I have the same problem with my 2003 Pontiac Grand Am. Regarding the emissions, it is just a matter of elimination. So far, I've replaced the sensors related to the fuel system but my car's hesistation stills exists. Midas did a smoke test and revealed no leaks. Checked the cylinder heads. Had the tranny replaced. New fuel pump & filter.I suspect that it could either be my computer or a loose wire somewhere. Anyways, I share your frustration. Good luck
Check that your cats are not clogged.
Vacuum leak...bad air inlet hose at throttle body...underside...may also have bad motor mount
SOURCE: 1993 pontiac grand prix 3.1 liter
the 3.1 had some EGR problems, EGR valve stuck open, blown diaphrams, Plugged passages Im not saying that is all your problems and I believe yours has whats called a linear EGR about $350.00 from the dealer (and that is the only place you ever consider buying such a critical part for the emissions system regardless of the cost)
That car is so antiquated as far as computers go that relying on the codes is nearly pointless! Map code can set because of low engine vacuum which you will have with a poor running engine, Check for 5 volt reference voltage at the TPS and MAP with the key on and engine off if no 5 volt reference I suspect a Computer. Computer Ground is on the Thermostat housing and needs to be clean and secure.
There is a legit test in the GM factory manual called the TAP TEST take the ECM (computer) and slap it with an open hand, if the symptoms change the ECM is bad it's very common in the early-mid 90s for the computers to go bad in one way or another the circuit boards come loose and suffer also from cold solder joints.
Make sure the wires are on the correct plugs and hopefuly you used factory plugs and wires and No split fire or bosch plugs only AC delco
Make sure you have good spark on all 6 cylinders.
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SOURCE: can I clean my Maf sensor and throttle body myself
Yes it will help car run better. Take off any hose that goes to card so that you can see down throttle bore. Start car. Grab throttle linkage and figure out how to move it so that you can make the engine go faster. Begine to spray inside throttle body using little red hose that came with carb cleaner. While you are spraying the engine will try to cut out move the throttle linkage to speed up the engine so it won't cut out. Keep spraying all around inside and outside throttle bore.
SOURCE: cylinder 3 misfire
Make sure you're using the recommended spark plugs. When my car did that, I had put Bosch Platinum Plus-4 plugs in and got that same problem. Turns out the plugs are too hot and cause it to fire prematurely and kick the misfire code.
SOURCE: 1992 Pontiac Grand PrixPower loss,erratic idle
spark plug gaps are very critical on computerised cars!! [some wont even start!]
distributor module may be breeaking down as temp rises they fail!
otherwise do compression check as it may have valve problems
also check plug leads & injectors aswell as the fuel pump pressure [ could bestarving for fuel]
SOURCE: 1999 pontiac grand am 4 cylinder rough idle, rpms fluxuates
Most likely your throttle position sensor is faulty. You could have a vacuum leak as well. Most probable cause is a bad sensor. Is your check engine light on? Have you checked your engine codes? You can go to autozone.com and register for full free online repair manual.
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