S13 SR20 makes boost, lacks ALOT of power

[lazyeyes13]

I have a 90 s13 with a s13 sr20 blacktop. The car ran fine when I got it, pulled the motor and when I dropped it back in it's not running right. All I did while it was out was had the turbo rebuilt (gt2871r) and got a fmic and that is ALL! It has factory sr harness and uprgraded fuel pump as well.
What the car is doing...
Idle is fine, it's not missing but when driving the car is stuuupid slow! Feels like it's being restricted. Right now I'm running open downpipe but with the full exhaust on it feels more restricted (sounds worse than the raspiest honda you could imagine x10).
At wot my boost gauge shows 10 psi (have it tee'd off the Fpr) which I thought was weird because it's got the stock wastegate and I thought it should be 7 psi?? This car ran fine before I pulled it out and I'm stumped... Any ideas??

[kikcaffine]

Boost leak?
Also dont tee stuff off your FPR and your WG should only be connected to a non-boost source, IE the nipple under your throttle body

[lazyeyes13]

I don't believe it is a boost leak... I have all new intercooler piping and couplers. I have the WG line running to the bottom port under throttle body. And could i tee the boost gauge off the bov vacuum port then?

[Croustibat]

boost leak + possibly retarded timing

[240sx_fanboy]

OP don't be lazy and check for boost leaks, just because its new it doesn't mean it doesn't have a loose or broken coupler. do a visual check on it all and grab the pipes move the around to see if a coupler is loose it will only take you 10 minutes.

for the vaccum set up, never, ill repeat that NEVER T into the fpr.
my set up as fallows
FPR -> port under manifold
BOV -> T -> boost gauge and manifold
waste gate -> port on turbo housing.

Now i know someone will come here telling me its okay to t off FPR, on an almost stock step up maybe, but its good to get it into your head not to T into the FPR. You want fpr to always have a very accurate reading on the vacuum.

dont mind the username this isnt main account

[lazyeyes13]

i have went through and checked for loose or broken couplers... they are all good. The vac line setup i had was bottom nipple under throttle body to waste gate. right side nipple above throttle body to fpr. and left side nipple above throttle body to bov. I had my boost gauge tee'd off the fpr line so I switched it to the bov line. My wiring harness was hacked together and i feel like its just a bunch of wiring bugs...
I just ordered a harness from wiring specialties because i was planning on getting one anyways so we'll see if it fixes it!

[ultimateirving]

Also make sure you didn't inject a bolt in the turbo... I had a similar experience and found a misplaced bolt in the turbo inlet.. ������

[cotbu]

OP don't be lazy and check for boost leaks, just because its new it doesn't mean it doesn't have a loose or broken coupler. do a visual check on it all and grab the pipes move the around to see if a coupler is loose it will only take you 10 minutes.

for the vaccum set up, never, ill repeat that NEVER T into the fpr.
my set up as fallows
FPR -> port under manifold
BOV -> T -> boost gauge and manifold
waste gate -> port on turbo housing.

Now i know someone will come here telling me its okay to t off FPR, on an almost stock step up maybe, but its good to get it into your head not to T into the FPR. You want fpr to always have a very accurate reading on the vacuum.

dont mind the username this isnt main account

I wasn't going to explain how you are stupid, but I'll point out a few things just because you wanted to regurgitate something you've read or heard. Mafs cars... boost leaks reek real havoc. Pretty true statement right. OK disconnect your fpr vacuum line, your waste gate vacuum line or bov vacuum line. What happens? (Or means 1 or the other)
This is a test if you truly know what happens post it if you don't do the test. Then post, if you are sure try to drive the car.
If you have a bov line pop off the fpr and waste gate all feel the same about that line coming off, the fpr isn't going to get more vacuum or boost.
Same with a small leak, large leak medium sized leak.

Maybe stupid id too strong of a word, so replace it with drinking too much fluoride
And not every turbo has a nipple on the compressor housing, you could add a vacuum block, but that a big T.

i have went through and checked for loose or broken couplers... they are all good. The vac line setup i had was bottom nipple under throttle body to waste gate. right side nipple above throttle body to fpr. and left side nipple above throttle body to bov. I had my boost gauge tee'd off the fpr line so I switched it to the bov line.
You're not going to find leaks by looking at clamps or couplers, I'f the hole is in the piping.

That's because that vac routing didn't really matter, but you should always have a way to do a boost leak test, with compressed air or smoke, and check timing with a light.

My wiring harness was hacked together and i feel like its just a bunch of wiring bugs...
I just ordered a harness from wiring specialties because i was planning on getting one anyways so we'll see if it fixes it!
The wiring is an important part.

Sent from a Highly Tuned Note 4.5!!!

[zombiewolf513]

Secondly to what corny said,

What's the gap on your plugs set to? Perhaps you're blowing out your spark

if you had a boost leak while boosting 10psi your motor would probably sound like a lawn mower.

Maybe your injectors are weak?

[Dima1127]

I wasn't going to explain how you are stupid, but I'll point out a few things just because you wanted to regurgitate something you've read or heard. Mafs cars... boost leaks reek real havoc. Pretty true statement right. OK disconnect your fpr vacuum line, your waste gate vacuum line or bov vacuum line. What happens? (Or means 1 or the other)
This is a test if you truly know what happens post it if you don't do the test. Then post, if you are sure try to drive the car.
If you have a bov line pop off the fpr and waste gate all feel the same about that line coming off, the fpr isn't going to get more vacuum or boost.
Same with a small leak, large leak medium sized leak.

Maybe stupid id too strong of a word, so replace it with drinking too much fluoride
And not every turbo has a nipple on the compressor housing, you could add a vacuum block, but that a big T.

Cotbu you seem to have very strong opinions. About things but we won't get into that. Why would I open up vaccum leaks?
On a almost complet stock set up its okay to T into it. But is not recommended, I'm not going to argue with you on this matter.
But I will explain my point of view, people will make habits of T'ing into vaccum lines, what would happen if you ran a line to the fpr and T'eed all the other crap into it? I don't feel the need to go on because I see that your not an idiot. But just an entitled asshole.

[cotbu]

Yes I am, To answer your question, with a question. have you ever seen the stock vacuum line routing for an S13 sr20? The stock setup has T's, 3's and B's all over it. A simple setup removes at least 2 of the metal T's
So I usually suggest that you t the Boost and vac sources together for convenience. Its usually 2 things t'd together. You could t the bov and boost gauge if you prefer. The waste gate doesn't need a vacuum source so the bottom nipple on the throttle body is fine, if it's not clogged. When you have a turbo or intercooler piping with nipples use them.
I do know that it's taboo,, but it is what it is!
Sorry got side track by another rb25 problem engine that came in.


Sent from a Highly Tuned Note 4.5!!!

[Javi802]

I didn't read through all of the answers, but it could be your knock sensor. 30 minute job at most.

Check for codes on your ecu

[Javi802]

So pretty much what croustibat said about retarded timing, which a bad knock sensor will do