Performance Issues 99'GT

[s2h_GSXR]

Hi, i own a 99 Sunfire GT and fuel/performance problems. Warm, cold, sunny, snow, rain, full tank, 1/8-tank, it doesnt matter, but every so often the RPM's in my car will just drop. It usually happens in 2nd gear but has also happened in 1st and 3rd.

Typical bad day: Pull the car out in reverse. Shift to 1st, shift to second at approx 4500rpm. Accelerate hard in 2nd and dies when the tac hits 35-4000rpm. When I put the clutch in, I can hit the gas a few times before the tac begins to respond. After this happens once, the car is usually ok through its entire performance range for the rest of the day.

The Car has 63K, fuel filter was replaced @ around 50K. Running K&N air filter and Bosh platnium 4 plugs.

I would like to try other options before I have a $500-$1000 fuel pump replacement. Any suggestions or similar problems.

[Overtime]

How long did this start after you replaced the fuel filter? After the plugs?

[s2h_GSXR]

Not exactly sure, but the fuel filter was replaced about 1-2 months after the plugs, and issue began not more than 6 months after that.

Also, I know I shouldnt have, but I did run one of those E-bay resistors in the temp sensor during that 6-8 month period.

[Overtime]

Originally Posted by s2h_GSXR

Not exactly sure, but the fuel filter was replaced about 1-2 months after the plugs, and issue began not more than 6 months after that.

Also, I know I shouldnt have, but I did run one of those E-bay resistors in the temp sensor during that 6-8 month period.

While I understand what the eBay chip/resistors do, I don't THINK it would have caused this issue, but it sounds like you may have a slow leak in your fuel line. It wouldn't be something you'd easily notice if it is. If this is the case, it may have happened when you changed the filter (the connections didn't get on tight enough), when you changed the plugs (accidentally bumped a fitting loose) or a fuel line fitting somewhere is deteriorating. It truely sounds from your description that you are getting air in your fuel line.

Disconnect the fuel filter and re install it, insuring a good, tight connection and not crossthreaded. You can also use this opportunity to check the flow from the fuel pump. If you have a slow leak here, then the fuel pump may have to completely build up pressure in the line again.

Afterthought, have you been having problems with your security light when starting your car?

[s2h_GSXR]

I dont know if it would be a leak cause it generally only happens once after the car sits awhile. For instance this morning:

1. unpluged the block heater
2. Started the car and revved a few times to 5000rpm (I usually find this helps?)
3. Pulled on the street everything seemed fine.
4. Then after about 100feet, I make a right hand turn uphill (45deg slope) in 1st
5. RPM hit 4000 and drop (in 1st gear).
6. depress clutch and break, and rev engine.
7. Delayed response from gas peddle with a boggy sound (however she did not stall) - Sounded kind of like she was getting too much or not enough gas??
8 Tried it again in 2nd - same thing.
9. After about 3min of this (by the time we creeped to the top of the hill) she was fine all the way to work.
10. This evening the same thing may happen again.

I know with a motorcycle, spark plugs are heat rated, perhaps this could be the issue? (I did buy the ones listed in the catalogue though - Bosh platinum 4).

Also my drive way is fairly level?....

Dont know if any of this helps but I need to find the issue. She is a great car, but this performance has me seriously thinking of selling.

I think I will replace the plugs and see what happens??

[4dr92cavi4cyl]

I have one of those, but I didn't get mine from E-bay (still wasn't worth it, but it does make a little difference) it's called a G-box, it's never caused any problems for me.

I've heard that those Bosch Platnum-4 are not a good idea, I'm not sure but I think I saw it here. Good idea to change them. Either AC Delco or NGK V-power (I use NGK)

It sounds to me like your getting air in the fuel lines and when you finally get it running smooth the air is gone, but when it sits for awhile it's pulling air back into the lines. It might not be a big enough leak for fuel to come out but just big enough for air to go back in. Try tightening the connections on the filter.

[whitenbluesX]

replace the THROTTLE POSITIONING SENSOR on ur TB.. it's located on the drivers side of the TB.. it's a $5 part at autozone.. buy it- look at it- find it- replace it. same damn thing happened to my 99 GT.. it seems to be a 99 problem..