1999 sunfire problems need help bad

ok here is my prob I have a 1999 Pontiac sunfire 2.2L ohv. The check engine light has been on and now flashes. I had fuel Fuel Injector service done at walmart and the check engine light went off for about 2 days then it came back on. Changed fuel filter,map sensor, plugs and wires,Oxygen Sensor. It will run fine and then I will have my foot all the way down to the floor on the gas and it takes for ever to pickup speed. Now and then you can smell fuel. also the odometer bounce from the mileage to trip. Someone said it could be the PCM but before I go and replace that I would like some other advice. I thought maybe bad fuel injector. I thought maybe someone out there can help with this

Have you tried removing and tightening gas cap, as this is known if loose to turn ligh on/off as well on newer models.

As for no power, verify sparkl plugs gapped properly, verify wires on proper spart plug as well and verify fuel filter installed in proper direction ( not sure if sifferent fittings, but i accidently did thsi on one vehicle i had :( )


How does rpm gauge looke when you press foot to floor?

As well verify emergency break not on.

Just thinking aloud.

Worse comes to worse you may need to get codes read from car.

I had thought about the gas cap too and I went and got a new one thinking that the old one was no good and that did not help either. I guess I will take it to auto zone to see if I can get the codes. As far as the fuel fiter I had to have a friend help me and i know its on there right. We had to cut the old one off. The rpms will jump up to 4 or 5 real quick and I have to let off gas real fast when it finals kicks in and starts getting speed

I have a feeling you will get a misfire code when you have the computer scanned. This sounds like you may have a bad coil or ignition module. The other possible reason is that you have a blocked cat that is causing the issue. Especially since you state that the car does not want to pick up speed. Finally you could have bad injectors but if you have less than 100K I seriously doubt it. Hope this helps.

Big question, did the car have the accelerate problem before you took to walmart?

Have you done a feul pressure reading as well?

How does engine sound in idle and does it idle erratically? If you rev to 2 or 3000 rpm and hold foot does it drop and jump back up?

The codes that came up where P0300 and P0420. So yes I did get a misfire code. I have had these problem before I took it to walmart. I have not had the feul pressure check yet.

The P0300 is random multiple misfires which can be caused by a lot of things. Bad wires, ignition module, plugs and etc. The P0420 is cat efficiency and relates to the cat and the oxygen sensor (rear). If the cat is partially clogged it could cause the misfire code but at this point I would start with the plugs and wires, then coils also you may want to check the cat to see if it is still in good shape.

A misfire can cause the cat code as the additional o2 in the exhaust stream causes the post cat sensor to assume the cat is inefficient, as the normal amount of o2 in the xhaust is now excessive, based on the comparison to the pre cat sensor.

The codes that came up where P0300 and P0420. So yes I did get a misfire code. I have had these problem before I took it to walmart. I have not had the feul pressure check yet.
Your first mistake was taking your vehicle to Wal-mart..thats like going to McDonalds and asking for a Nachos Belle Grande.
The P0300 code is a misfire.
You will have to do some diagnosis, but look at the coil towers where the plug wire slips on..is there a corroded build up? If so, replace the coil and wires..do the same thing at the spark plug..look for the corrosion where the wire attaches.
That is one of the most common areas on that engine to look at.
Or since you say you have a lack of power and a P0420, you may have a clogged converter (this will give you both codes)
Either way DO NOT take your car to Wal-mart or any chain auto repair store (Goodyear, Pep-boys)..they only do service work and do not have the training or tools to properly diagnose an engine performance concern.

A misfire can cause the cat code as the additional o2 in the exhaust stream causes the post cat sensor to assume the cat is inefficient, as the normal amount of o2 in the xhaust is now excessive, based on the comparison to the pre cat sensor.

Not entirely true!
A three-way catalytic (TWC) converter is used in order to control the exhaust emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction which oxidizes the HC and the CO that is present in the exhaust gas. This will convert the HC and the CO into a harmless water vapor and a carbon dioxide, and reduces the NOx, converting the NOx into nitrogen. The catalytic converter also has the ability to store oxygen. The Powertrain Control Module (PCM) has the capability to monitor this process by using a heated oxygen sensor (HO2S) which is in the exhaust stream past the three-way catalytic converter. The HO2S produces an output signal which indicates the oxygen storage capacity of the catalyst. This in turn indicates the catalysts ability to convert the exhaust emissions effectively. The PCM monitors the catalyst efficiency by first allowing the catalyst to heat up, waiting for a stabilization period while the engine is idling. Then, the PCM adds and removes the fuel while monitoring the reaction of the HO2S. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the O2S 1. When the HO2S 2 response is close to that of the O2S 1, the oxygen storage capability or efficiency of the catalyst is considered to be bad and the MIL will illuminate.
These conditions will cause converter failure

- Engine misfire

- High engine oil or coolant consumption

- Retarded spark timing

- Weak spark

Not entirely of course, but could be a consideration, as listed ,misfire can under some conditions ,cause 0420 with all other parameters normal, I know we both have seen this. I just suggested chase the misfire first.

Easiest way to check plug wires and coil is to start car at night in darkness and pop hood open and look at wire and coil area and see if you can see andy blue spark if you do, shine a light on area and seee what needs replacing.

This test is jsut good for checking if cables are weak, etc. As inside boots can be bad but not seen easily.

I had a spark that was about 1 inch long and could be seen in daylight by one of the modules. Then to check the wires in daylight, you could start the car and start to place your hand next the the wires where they attach to the modules. The tingling on my hand gave me a clue to bad wires.

Homerr