2G Hesitation Problems

[c2joe]

I have a problem that has begun in the last 2 weeks with the car hesitating. It happens when the car is fully warmed up, and the outside temperature is around
or above 90 degrees.
When out driving (normal conditions, no WOT runs) in 3rd, 4th or 5th gear around 3000 rpm the car starts acting up. I can feel the car surge (almost like your in
a rocking chair), in steady pulses about a second apart. While this is happening the rpms stay the same, resistance on the gas pedal does get a little lighter. The problems do not occur when I go to slow down or stop. I've changed plugs (bpr6es .028 gap, and wires which didn't help, anyone have any ideas, had the similar thing happen? Car is a 99 GST, stock everything.

 

[RedTurboEclipse]

i had that problem wen i had my 98 GS-T.. still never knew why.. some said it was phantom knock.. and just timing being pulled for some reason..

does this happen:

u feel the hesitation.. u let off the gas.. then punch it again and everything is fine?

 

[c2joe]

Originally posted by RedTurboEclipse

does this happen:
u feel the hesitation.. u let off the gas.. then punch it again and everything is fine?

No, when I let off, and get on the gas again, it starts right back up, the only time this doesn't happen is when the engine has has time to cool down, or about the first 10 minutes of driving in the morning.

 

[DarkendSoul]

Is the humidity terrible there? I have had that problem with other cars. The humidity along with above 90 degree temps can some times cause certain cars to occasually knock due to preignition from the high engine temperatures. Ones of the causes of phantom knock knock along with time belt exspansion due to age and heat. This only happens with boosted and high compression cars. Make sure you are not slightly overboosting and that your boost control solinoid (BCS) is working properly. Also, where plugs damaged or severly worn? If they where and they didnt have many miles on them then you probily have preignition. If you find you have bad preignition then you need to fix it because it can severly damage your engine.

 

[c2joe]

Originally posted by DarkendSoul
Is the humidity terrible there? I have had that problem with other cars. The humidity along with above 90 degree temps can some times cause certain cars to occasually knock due to preignition from the high engine temperatures. Ones of the causes of phantom knock knock along with time belt exspansion due to age and heat. This only happens with boosted and high compression cars. Make sure you are not slightly overboosting and that your boost control solinoid (BCS) is working properly. Also, where plugs damaged or severly worn? If they where and they didnt have many miles on them then you probily have preignition. If you find you have bad preignition then you need to fix it because it can severly damage your engine.

Humidity isn't bad here, usually it's under 30%. The plugs wern't damaged, just a little black when I pulled them out, they only had about 10k on them. Timing belt is new, it was replaced in January when the water pump took a dive.