bogging under boost

[TsiJohn333]

I have a problem with my girlfriends 1998 gst sypder (automatic).
Mods: upper hard piping w/ 1g bov recirculating
2 1/2 inch apexi N1 turbo back exhaust system with a cat eliminator
greddy turbo timer
auto meter boost gauge

the problem i am having is that i'm bogging under half boost probably about 80 percent of the time. ill be at 3k rpms on the highway just cruising and when i go to spool up it will start bogging and i cant accelerate from 3-9psi. Any higher than that it works fine. it will hold boost fine while its bogging but it wont accelerate unless i gas it harder. It doesn't hesitate at all at WOT either. i just replaced the tps, the upstream o2 sensor as well. I've been having a little trouble though with the position of the tps sensor. could this cause me to bog under half boost. I'm not throwing any codes either. It bogs really bad when i first start it up and drive. ill be at 5 psi and be going no where. it feels like a rev limiter kicking in and feels like something is holding the car back when it does that.

things i have checked:
i checked all my intercooler piping clamps and such and no leaks
checked all vaccumm lines and no leaks
changed the coil packs
changed all the sparks plugs (ngks)/spark plug wires
changed out the MAF
changed the upstream o2 sensor
changed tps (having trouble with the position)

Thank you guys for your help i also can make a video if i wasn't to clear on what it does.

 

[magik95]

Could have a boost leak. Maybe a crack in the lower ic hoses,or couplers. Start by doing a boost leak test as most will tell you.

 

[TsiJohn333]

i did a boost leak test but didnt find any leaks. i dunno where to begin now.

 

[dexterholland04]

How are your plugs gapped? Are your wires on their way out? I would start with those things.

 

[TsiJohn333]

i changed the wires and put fresh new ngks gapped to .28.

 

[jmye86]

I had a similar problem in my gst. I ended up throwing two CEL's one for the tps and the other for the fpr replaced both and not longer had a problem.

 

[TsiJohn333]

cool, ill try replacing the fpr tomorrow i have an extra one laying around

 

[DSMfreestyling]

test your ECU, actually just by looking at it if its possibly fried. But you can always test too.

 

[miguelmcv]

It happens to me as well, and ended up being a bad TPS.
Changed it and that was it.

 

[dexterholland04]

TPS can be a sono###un...I am 99% sure mine is why my car won't run correctly right now.

 

[TsiJohn333]

TPS can be a sono###un...I am 99% sure mine is why my car won't run correctly right now.

im gonna try to fix the tps sensor soon..... what type of upstream o2 sensors are the best for our cars.? i think when i replaced mine, i might of used the wrong brand. The reason i'm saying this is because when i was throwing the the code for o2 sensor the car was doing the same exact thing and changed it it went away for a little bit and now its doing the same thing. i think its a combination of the tps sensor and o2 sensor but which o2 sensors are the best for our cars? i believe i used bosch.

 

[dsmarmy777gst]

I had that problem before, I changed the fuel filter and it went away. The filter was clogged.

 

[dexterholland04]

im gonna try to fix the tps sensor soon..... what type of upstream o2 sensors are the best for our cars.? i think when i replaced mine, i might of used the wrong brand. The reason i'm saying this is because when i was throwing the the code for o2 sensor the car was doing the same exact thing and changed it it went away for a little bit and now its doing the same thing. i think its a combination of the tps sensor and o2 sensor but which o2 sensors are the best for our cars? i believe i used bosch.

I would (and do) use a Bosch o2 sensor. Also, adjusting my TPS (with the help of DSMLink) got my car running rather well. Good luck and let us know how it turns out!

 

[TsiJohn333]

I would (and do) use a Bosch o2 sensor. Also, adjusting my TPS (with the help of DSMLink) got my car running rather well. Good luck and let us know how it turns out!

well i adjusted the tps sensor and its runs a little bit better than before but i know i have more adjusting to do because it is still doing the same thing. so all i do to adjust the tps sensor is measure the volts between the pins 3 and 4,..... and 2 and 4?