Intake gaskets and SC VX

I've got a supercharged VX. I've got a check engine light and the idle is high or stumbles, with the car dying out at low speeds or idle. The codes indicate bank 1 and 2 lean. P0171 and P0174 are the codes it keeps throwing. I think the intake gaskets need replacing. Am I on the right track? Anything else I could be missing? Also, how much should the bolts for the intake manifold with supercharger be tightened? Should I stick to Isuzu's 13 lbs of torque? Any tips in for removing the manifold to replace the gaskets?

Any help/ ideas appreciated.

13lbs is correct - did you replace the gaskets when doing the install? Check for other airleaks spraying around connections with carb cleaner or starting spray (I prefer) on a cool engine - if engine changes speed when spraying, there is a leak in that area.

To replace the gaskets once the SC is installed is a little easier than with the stock manifold. Remove fuel rails, disconnect all hoses and electrical connections and unbolt.

The gaskets were replaced, so maybe it is something else. The Isuzu tech thought it was the gasket, but a vacuum line definitly could have come loose (the ISUZU dealer I trusted closed down, so now I'm stuck with a place where the mechanic doesn't seem to know a whole lot). I'm going to take it to Driver's Image, who did the install, (www.driversimage.com) to have it looked at.

Just to let people know, this problem has nothing to do with the SC itself.

I just want to emphasize that the SC is a great product. It's been absolutely a blast to drive, and the issue I'm having right now has nothing to do with the SC itself. I couldn't imagine having the VX without the supercharger. If anybody in Chicago is interested in trying out a VX with a supercharger to see the difference, maybe we can set up a meeting, so you can give it a whirl.

Tone Monday has been nothing but extremely helpful. The only thing I would suggest for him to do is to move to Chicago, so I could have him near by.

Did this just happen out of the blue or has ANY work been done lately?

Also check intake ducting connections, air temp sensor fitting, valve cover vent connection, fuel pressure and regulator.

There hasn't been any work done before this happened, and it's something that's been gradually getting worse. I have a vacuum boost gauge that was working intermitantly for the last month and is now stuck on the highest reading (24). I thought the sending unit or the gauge was bad, since it's an unreliable Cyberdyne unit. Now, I think differently.

When i did mine I didn't think of the throttle body gasket...I bought one recently for about $4.00 just to have on hand in case I start pulling in unmetered air and want to change it out as it is only 4 bolts and disconnecting the throttle/cruise cable as well as unplugging the sensors.

Not having your idling problems but I recently had a check engine light indicating "lean under acceleration" and "bank 2 O2 sensor #2". I replaced the fuel filter first as it had 15k miles on it..didn't help.

Than I pulled my cone filter & cold air intake and reinstalled the factory airbox to choke off some air....didn't help.

Finally, I tried adjusting the fuel regulator by turning the security torx screw about 1/4 turn clockwise to go from lean to rich (as Tone mentioned) and it seemed to do the trick...about a week and no check engine light and I notice a bit better performance.

I bought a new fuel regulator in case I need to swap it out and in the process found out that you can buy a fuel regulator rebuild kit from dealer for about $12.....or buy the entire unit for about $52....as it turned out I have both! I figure I can swap out the original with the entire unit and rebuild the original for later use.

Also check the allan bolt that mounts the EGR bracket to the rear of the SC as if this comes loose you will get a vaccuum leak...mine could be snugged up a hair.

It was the gaskets. Greg and the tech at www.driversimage.com did a great job. I highly recommend them for your VX needs. No more check engine lights or codes. The VX is back to its robust self.

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Originally Posted by MachineVX

It was the gaskets. Greg and the tech at www.driversimage.com did a great job. I highly recommend them for your VX needs. No more check engine lights or codes. The VX is back to its robust self.

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It appeared from your previous post that the intake manifold gaskets were not the problem. Could it be that the manifold bolts were retorqued to the required 18 Ft lbs or more the second time around?

I ask because I am about ready to reinstall my rebuilt SC & new intake gaskets. When I removed the intake bolts & nuts the torque value appeared to be a lot higher than 18 ft lbs, more like as tight as you can get it + 1/2 a turn.

Incidently, my Throttle body had no GASKET installed

You might be right that it originially was over torqued, so I made sure this time that I gave them all the right torque specs, which I should have done in the first place.

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Originally Posted by MachineVX

You might be right that it originially was over torqued, so I made sure this time that I gave them all the right torque specs, which I should have done in the first place.

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Thank you for your quick reply. Perhaps undertorqued (13 ft lbs) The right torque specs being 18 FT lbs (Isuzu manual) & not 13 Ft lbs is that correct?


Bob F

There's a TSB that changed the spec for the manifold bolts to 13lbs.

Thank You 13 ft lbs it is.

Bob F