2003 Supercharged Xterra Dropping Boost

2003 Supercharged Xterra dropping boost. No performance mods which include stock intake and exhaust. OBDII code reader says all is clear, but the dropping in boost seems to be ECM controlled. This may explain why most people complain that the truck feels sluggish once warmed up. Problem was caused by an over-sensitive knock sensor that had been replaced with a resistor.

Category:

Autos & Vehicles

Tags:

• Xterra
• Dropping
• Boost

[ISBOOST300]

I installed a boost gauge on my X and sometimes it registers 7lbs but now its will not go over 2lbs. Doin the boost bypass is not a good idea better yet do a smaller pulley so your knock sensor is still active. I am replacing my knock sensor to fix my boost drop.

[Nd4SpdSe]

Although it could be a few things, but the reason why your only getting 2psi is cause the ECU is detecting that something isn't happy so as a safeguard it cuts the boost. The bypass/smaller pulley won't fix the underlying problem and just piss it off more. Knock sensor is highly liklely to be the problem. Check for a KS code in the ECU, it doessn't throw a CEL, but like mine, even if it doesn't, it was still causing problems. Probably was damaged in shipping to the dealership.

[Nd4SpdSe]

Seems to be the symphome of a few conditions. On mine, it's an over-active (new) knock sensor, that I replaced with a 560k ohm resistor.

[Nd4SpdSe]

I'm not sure. I actually re-routed the vacuum lines to bypass the solenoid and the ECM adjust timing too. It works well for about a week until it ECM compensates furter. No codes, with the knock sensor recently replaced. I believe there's a fix for the '02 in getting it reprogrammed, but I've got an '03, so it may not apply, but I doubt it'll fix it anyway. I know the knock sensor is a common problem, but I think this is too, but most don't know about it since there's no boost guage.

[fishman231123]

2 things check all vacuum lines boosted cars do that with vacuum leaks and vacuum clams tie wrap them also if its no that check vacuum lines there may be a cut in line

[aaronthemoose94]

Why does it do that? I have an '02 S/C xterra... I guess I'll find out if mine does that when I get the boost gauge installed.