Car doesn't pull hard in high gears.

[JwUoNoG]

I recently ran seafoam through my car, and did an oil change, and replaced the plugs. 1st thru 3rd gear seem fine, and the car pulls the same way (if not harder) through those gears.

However, on the highway, the car doesnt pull very well at all. I remember before I did this, I could floor it in 5th gear, and it would pull pretty good. Now, the boost sits at about 8 psi for a few seconds, then it slowly rises to 15 psi (what im set at right now). It also breaks up when I let off the gas. What could this be?

I didn't check for boost leaks yet, but I don't think I have any.

I know you're thinking "You shouldn't be racing in 5th gear anyway, just downshift, blah blah". and I know that. But I want the car to pull like it used to.

 

[JwUoNoG]

I also found today that my car breaks up under partial throttle. It won't boost past 7 psi on partial throttle, and then it starts to miss. However, If I go WOT, it hits full boost and is fine.

This has been an ongoing problem that was there since before I did the seafoam.

 

[rjgeier]

What kind of plugs did you put in?

 

[BaddAssGst]

your not venting to the atmosphere, are you? i have the same trouble because i am to damn lazy to find a hose.

 

[TalonRcR]

I recently ran seafoam through my car, and did an oil change, and replaced the plugs. 1st thru 3rd gear seem fine, and the car pulls the same way (if not harder) through those gears.

However, on the highway, the car doesnt pull very well at all. I remember before I did this, I could floor it in 5th gear, and it would pull pretty good. Now, the boost sits at about 8 psi for a few seconds, then it slowly rises to 15 psi (what im set at right now). It also breaks up when I let off the gas. What could this be?

I didn't check for boost leaks yet, but I don't think I have any.

I know you're thinking "You shouldn't be racing in 5th gear anyway, just downshift, blah blah". and I know that. But I want the car to pull like it used to.

You have a knock monitor?

Chris

 

[JwUoNoG]

I put in a fresh set of NGK BPR6ES, gapped to .028.

I am unfortunately venting. I bought the car that way, and haven't had time to get a tube yet. However, venting shouldn't affect the car while driving, only in between shifts.

I don't have a knock monitor.

 

[Carlover121]

I just put in the BPR6ES plugs in my sled today and they felt great in the city but tepid on the highway, as do yours. However, I am also having issues with ignition timing so I havent decided the reason for its' lackluster highway performance quite yet. I gapped mine to 0.030.

 

[Myke Coxlong]

those are two ranges colder are they not?.....looking at your profile you don't have any reason for them in my opinion

 

[Carlover121]

True Myke, but I did it for two reasons; one, I'm paranoid about blowin' up my motor (I blew up a '90 laser turbo 5 years ago by being a knucklehead and running 4+ platinums as well as 17+ boost. Man I miss that Laser...) The other reason is that the plugs that were in the car when I bought it were quite white even after I had artificially enriched the mixture by taping off part of the bottom honeycomb on the MAS. I'll gladly lose 1-2 MPG or 5-10 whp over a motor rebuild, I live in an apartment (no garage) and am on quite the budget being in college.

 

[JwUoNoG]

those are two ranges colder are they not?.....looking at your profile you don't have any reason for them in my opinion

No, they're not 2 ranges colder. BPR6ES's are recommended for stock or mildly modded DSMs, and BPR7ES are recommended for ones running more boost, or more heavily modded.

We checked my friend's plugs on his stock 95 GST, they were BPR9ES!

 

[Myke Coxlong]

i stand corrected i couldn't remember if it was the 6 or 7's....check for boost leak's or hell your turbo could be taking a shit that's what mine did at 1st boost like 6-7lbs hold then jump to 15

 

[JwUoNoG]

i stand corrected i couldn't remember if it was the 6 or 7's....check for boost leak's or hell your turbo could be taking a shit that's what mine did at 1st boost like 6-7lbs hold then jump to 15

Yeah, I'll do it as soon as I get an air compressor. If my turbo blows up, oh well, I have another one with no shaft play at all in my trunk.