SR20DET Extremely high Rev after start.

[cparsons0331]

So I am new to the forums here, and have searched for an existing thread on this issue for the better part of 2 days, along with looking over the car for something I did wrong and I'm pretty much lost looking for help.

Engine Mods (All of these mods where done before I bought the car so I dont have much information on them):
JDM 1989 Silvia with a SR20DET Redtop swap from a CA18DET
Stock Turbo.
FMIC
HKS turbo Timer
Some aftermarket BOV
KOYO Radiator
750cc Injectors

I Installed an after market Intake.

So onto the problem, before I installed the intake the only issue with the car was a flat spot in acceleration around 3500RPM usually at cruising speeds. It wouldn't do it if I got on the throttle a little heavy.
After I installed the intake I tried to start the car, it didn't want to at first then I gave it a little gas and it started, idled a little rough for about 5 seconds and then the car would bang off the rev limiter until I shut it off. I double checked all my electrical connectors, the throttle cable and plate, and the vacuum lines. Everything seems to be good.
While I was in the process of installing the intake (about 90% complete) I started it up without the intake hose hooked up to the throttle body. The engine idled a little rough but I figured it was because the intercooler piping wasn't hooked up. This gave me the idea to take it bake off with the intake fully installed, and it did exactly the same as when I tested it, idled a little rough but didn't rev high. While it was running with the piping disconnected I moved it back over the throttle body and immediately the car started to increase the revs.
This sounds like my wastegate may have taking a crap, I'm not too sure as this is my first turbo car. Any help would be appreciated thanks.

[Mikester]

Not a wastegate issue.

If it's an aftermarket intake, there are 1/8 NPT ports all over it that need to be capped off. Check it really well to make sure whatever small holes are there are closed.

[ultimateirving]

Mikester is correct, check for vacuum leaks.
Also if the TPS voltage is off its possible that is what caused your flat spot before so check the tps voltage.
I dont know if the Silvia came with the shorter throttle cable like the s13's had here in the states, but make sure with the new manifold its not pulling the cable at all.

[cparsons0331]

Originally Posted by Mikester

Not a wastegate issue.

If it's an aftermarket intake, there are 1/8 NPT ports all over it that need to be capped off. Check it really well to make sure whatever small holes are there are closed.

Thanks Mikester, I located some of those sneaky little NPT port on the bottom side of the intake in the middle of it. I put some plugs in them and it idles 100% better. Still seems to have another leak though as its not down where it used to be, I will continue my search for leaks with some carb cleaner and watch my fuel trims to see fluctuations.

Originally Posted by ultimateirving

Mikester is correct, check for vacuum leaks.
Also if the TPS voltage is off its possible that is what caused your flat spot before so check the tps voltage.
I dont know if the Silvia came with the shorter throttle cable like the s13's had here in the states, but make sure with the new manifold its not pulling the cable at all.

I'll have to look into this as soon as I get the car to idle normal again, which hopefully will be tomorrow.

Thanks for the help.

[Mikester]

There are 2 ports on the back, usually for Brake booster & PCV...



3 ports on the bottom about midway... Extra places for gauges, FPR etc. (mine has 4)





... and 2 ports underneath your throttle body.



Make sure whichever of those you aren't using are plugged with 1/8 NPT plugs and you'll be golden. The plugs are only a couple bucks apiece at www.verociousmotorsports.com . Note also that I use thread tape for these things- Very effective stuff

[KoukiMonsta]

Damn, mike you must be feeling nice.

Very informative post.

OP build yourself a boost leak tester. Must have for these setups.

[shift_down]

Check throttle cable, it may be opened up and you have to adjust it.
Also, check to make sure tour cruise control cable isn't opened up. I had the saw issue, I accidentally pulled on my cruise control cable and it for stuck open.

[Mikester]

Originally Posted by KoukiMonsta

Damn, mike you must be feeling nice.

Very informative post.

LOL thanks.

- Dude posed his questions intelligently

- He lives in Kaiserslautern (used to live there by the stadium back in the day- fricken awesome place!)

- Given he's in Kaiserslautern, he is most likely a brother in arms

[AWahl]

Did you keep the stock maf when you installed the aftermarket intake? I remember I made the mistake of installing a z32 maf when I did my swap and the same exact thing happened it would idle real rough then the rpms would redline because of the ecu getting the incorrect a/f signal