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Boost Dropping Off

Destijl

By Destijl,
in Engines & Forced Induction

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Destijl Apprentice

Destijl

Posted
Posted

Hey everyone

I realise this is a skylines forum but no one else has been able to provide me with an solution to my problem. I currently drive a S13 silvia with a 1998 Sr20det out of a 1998 180sx type x

The current modifcations to the car are:

Cat back exhaust

ARC side mount intercooler

040 fuel pump

K and N airfilter

For the first 15-20 minutes when i drive my car, i am getting 10 psi(BTW i had it dynoed when it was running 10psi and it wasnt leaning out at all), but after this it drops down to 8 psi and feels sluggish. However if i pull over and turn the car off and turn the car back on literally 10 seconds later i get 10 psi again. What could be causing this problem and how could i solve it?

Thanks alot! :(

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Destijl Apprentice

Destijl

Posted
  • Author
Posted

Im not running a boost controller, just the standard solenoid, however it is pretty common for SRs to run at 10 PSi with a intercooler, exhaust and air filter. Ah on Srs im pretty sure the actuator signal comes off the intercooler piping on the "cool" side just after the intercooler.

Im reading 10 psi off the vacuum hose going to the fuel pressure regulator on my boost/vacuum gauge.

Cheers!!

what boost controller?

where is the actuator signal coming from?

where are you reading 10psi from?

BHDave Grand Master

BHDave

Posted
Posted

The fact that you can solve the problem by turning the car off and back on again points squarely at the factory solenoid or the wiring to it as it is the only component in the system that can directly effect boost that is also electrical.

But that said, the solenoid is controlled by the ecu so that may be doing something silly.

As a first step i'd unplug the factory solenoid and see if the car still gets doughy after 15-20 minutes. It'll probably only make 8psi with the solenoid disconnected but you will see if the boost drop is only part of the problem or the ecu is doing something else aswell like pull timing/richen up mixtures.

Adriano Grand Master

Adriano

Posted
Posted

I would check for trouble codes, could be going into limp mode, as 2 psi less shouldn't make it feel doughy and unresponsive. If its like a 300zx computer, after it detects knock a certain number of times it locks into a low-octane map with less boost, more fuel and less timing until it gets turned off and restarted.

mad082 Grand Master

mad082

Posted
Posted

well i know early model sr20's had no boost protection. i was running 15psi on my stock computer, and so were most of my mates with them. the stock wastegate is 7psi. i wasn't aware of them using a solenoid.

i would be checking the ecu for error codes. could be a faulty AFM.

Destijl Apprentice

Destijl

Posted
  • Author
Posted

How do i get the timing checked? can i take it to a workshop and get it checked?

I had this exact same problem with my R34 GTT. It turned out the timing was too far advanced and was going into Rich and Retard. I have no knowledge of the SR20's so this is purley for your information.

Good Luck with it.

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