Lower power under load in higher gears

[Shigun]

So, here is the general scenario:

S14A, 2871r, 555cc, z32 maf.

This is a motor swap, and the particular swap required me to do a little odd work with the exhaust, 3" downpipe to a 2.5" crossover under the transmission tail to 3" back. (Don't *think* this is my problem, but throwing it out just in case).

I did a leak test once, found a few leaks and welded them up. I also found a few (very) small exhaust pinhole leaks and fixed those as well.

The problem comes in the fact that in the higher gears, 4 and 5, when I am in the lower end of the RPM range, if I try to open the throttle up (not even WOT, but say going from 20% throttle to 60% throttle) it will feel like it just struggles to get power. Eventually once the RPMS build, it will get up and go fine. During this period, the boost builds fairly slow as well.

The thing that is confusing me is that this isn't really a scenario of "too high a gear to get on it." This is like, me driving at around 2.75k RPMs or so, I press down on the accelerator and it feels like it's going nowhere fast.

If I drop down a gear, no problem, but from my experience with my old 240, and various other manual vehicles I have driven, this doesn't seem normal.

Now, with all that stated, this is my first boosted vehicle, so I don't know if that has anything in play with this. When I do get on it in the lower gears, it builds boost nice, quick, and gets up and goes. When this problem comes up, it will start to build boost, but it will just be *so slow*. Like, creeps up to 5psi, 10psi, 15psi, whereas in the lower gears it will shoot up through the range.

Any assistance or just thoughts in what I could begin to look at would be incredibly helpful, or even just somebody more experienced telling me if this is normal.

[cotbu]

Not normal, per description.
What's the condition of the clutch?
What's the wideband say?
Have you taking it to the dyno? I'm sure a graph would confirm your concern.
Maybe do a tuneup. Boost leak test.

Sent from my Highly Tuned Galaxy S3.4!!!

[Shigun]

Not normal, per description.
What's the condition of the clutch?
What's the wideband say?
Have you taking it to the dyno? I'm sure a graph would confirm your concern.
Maybe do a tuneup.

Sent from my Highly Tuned Galaxy S3.4!!!

Thanks for responding.

When I got the motor, I checked out the condition of the clutch and, while I know that it will need a new one in the near future, the condition of it was one that it should easily be able to last another year or so with how much I drive. I've only put on about 1000 miles since I've got the swap done, of pretty easy driving.

No wideband as of right now. I got a bung welded on and got the wideband o2 installed in there, but nowhere really to put the gauge (as I already have a 2 pillar pod that has oil pressure and boost) so I'm having to figure out somewhere that I can just toss it in the meantime.

Not taken to dyno yet. As mentioned, it's a new swap and I've been working out all the kinks and bugs.

Recently, in regards to a tuneup, I've installed a new O2, gapped and installed new spark plugs, cleaned the MAF, changed the oil and transmission fluid.

It should also be noted as well that I have a Blitz SS BOV that is currently vented, but I have a greddy RS on the way that I will be using to recirc, as I can tell that the car is generally running a bit rich, and I get some scenarios of things like backfire when changing gears and all.

For a tune, I'm running an Enthalpy ECU. That would generally go along with the running rich aspect, as I heard his tunes are like that sometimes, but I don't see that being the cause of this if everything else is fine.

[Shigun]

Alright, bit of an update. I hooked up the wideband (just have the gauge sort of sitting there right now, lol), and it seems to be fine. Leans out when I let off the accelerator or am at idle, running anywhere from 15-18. Casual driving has me around stoichiometric to slightly lean area, 14-~15.7 range, and getting into boost has me anywhere from 13 to 10, with 10 being the high boost and 13 being lower boost, so that all seems fine.

At this point I'm wondering if I potentially have a leak somewhere, as I notice now that my vacuum is roughly 15in/hg at idle, when it used to be around 20in/hg. Kind of confuses me, however, because I would figure that to affect everything, and not just this one section of the power band.

[cotbu]

Idle is lean. Cruise is good. Boost 13 is lean for anything considered boost. 10 is too rich for just about anything your setup is capable of.

Check ecu for codes. Check tps voltage and timing. BTW what rpm do you idle at? What's your low and hi boost? Starting to feel like timing to me.

Sent from my Highly Tuned Galaxy S3.4!!!

[Shigun]

Idle is lean. Cruise is good. Boost 13 is lean for anything considered boost. 10 is too rich for just about anything your setup is capable of.

Check ecu for codes. Check tps voltage and timing. BTW what rpm do you idle at? What's your low and hi boost? Starting to feel like timing to me.

Sent from my Highly Tuned Galaxy S3.4!!!

I've checked the TPS voltage before, for a separate problem, it's good. I'll have to check timing and ECU codes. I idle roughly around 800rpm.

Boost controller off is about 8PSI, low boost is 15PSI, high boost is 20PSI.

[Shigun]

Also, I guess I should clarify, it was higher end of 10 on high boost (closer to 11), and idle mostly stuck to 15, with the variance being from when I was letting off from a drive and coming to a stop to idle, so that is why I wasn't too worried about the AFR in this case.

[cotbu]

I'm gonna review something's but 20psi and 555cc injectors is cutting it close from a gt2871r 56 trim with my specific values for b.s.f.c and I tune rich. I used a guy with an s14 660cc injectors, z32mafs, 2871r and 3.69 final drive to try and duplicate what I couldn't on my setup and his was slower but nothing like your description. Of course, the lower gears produced desired results.

Sent from my Highly Tuned Galaxy S3.4!!!

[Shigun]

I'm gonna review something's but 20psi and 555cc injectors is cutting it close from a gt2871r 56 trim with my specific values for b.s.f.c and I tune rich. I used a guy with an s14 660cc injectors, z32mafs, 2871r and 3.69 final drive to try and duplicate what I couldn't on my setup and his was slower but nothing like your description. Of course, the lower gears produced desired results.

Sent from my Highly Tuned Galaxy S3.4!!!

I actually haven't been running it at 20psi constantly because, as mentioned, this is my first real boosted car, so I am getting used to boost first. I don't want to get on it and make my car an offroad car, lol. My 2871r is a 64 trim as well, but I don't think that would be making too much of an issue.

[Shigun]

Bit more of an update. I went and did another boost leak test and found that one of my IC pipes was leaking pretty substantially, but only when I would move it a little. Tightened up the coupler and fixed that.

Seems like it helped out a bit with the AFR numbers, putting them back to slightly more normal levels, with less hugely varied ranges. When I idle, I still get the 15-16 range, but getting into it on boost only really puts me in the 12-13 range, high 11 when it's held at peak boost.

The issue still persists, but it *feels* like it's not as bad to me, however this could also just be a placebo effect. I still need to check the ECU for codes, and I need to get a timing light to check timing, which I'll probably do tomorrow.

I know that there is still a (very) minor pinhole leak on the cold pipe. Because this is a motor swap, I had to have the piping fabricated up with a welder that wasn't the greatest at getting penetration, so it's been a little trial an error in finding any leaks and fixing them until I can get proper piping made from my templates. This leak however is incredibly small (when doing the boost leak test, I could barely feel it, and only found it because I was sweating and felt the cool air on my hand). I don't think it would be the cause of this problem.

[zurud]

Sound normal to me. Its call turbo lag

[Shigun]

Sound normal to me. Its call turbo lag

No, this is completely different. This is a scenario of I can be WOT and the rpms and boost just build *so* slowly that it feels like there entire system has no power to get up and go. It's not a scenario that then the boost kicks in and I go, it will just slowly start going faster as the rpms start picking up.