There's a sticky in Electrical on installing the boost gauge, but I'm having some performance issues after installing it and I know people here know their stuff...

Used a "T" joint to tap into the vacuum line as per instructions, reconnected everything. Started car.

Engine raced to 4K then settled down to a very erratic idle. Boost gauge showed vacuum (about -10). Drove off, thinking that maybe the system needed to repressurize and got about 100 yds before the trottle began "bucking" a bit. Gave the engine gas but could not accelerate properly. Had to turn off car and restart to get power. Even when under power, the gauge barely showed any boost and decel was very rough. "Check Engine Soon" light is on.

Returned home and disconnected my new fitting, reconnecting the OEM "L" fitting to the regulator. Engine started fine and drives perfectly, however "Check Engine" is still on (assuming because the ECU detected a bad mixture?). Car runs fine withb the boost gauge line disconnected.

Any idea what I did wrong?

 

go to autozone have them read the codes. Write them down and come back.

 

The only time my engine has had idle problems my IC boots were loose. I'm guessing when you put everything back to normal they got tight. You can check the code, always recomended. But through normal driving it may shut itself off.

 

You have a vacuum leak. Check your lines, es[ecially at the fuel pressure regulator. Your vacuum should read closer to 15in.

 

Your boost gauge doesn't have enough LEDs built into it. Nano doesn't like it. Get a different one with more LEDs and all should be fine.

 

I KNEW it!

So sounds like I might not have reinstalled the IC correctly the first time out... I can put it back on and see if that was it - I know the second time I reinstalled it it was easier. I'll see if that helps - thanks.

If I need to have the code read, what do I ask them - just to hook some sort of scanner or something to the ECU?

 

If the setup introduced a leak, the regulator would not have seen proper boost or vacuum, causing high fuel pressure at part throttle and insufficient pressure during boost. The most likely set a too rich and/or too lean code. The bucking was due most likely to lean fuel mixture when accelerating.

 

The fitting on the bottom of the regulator isn't that tight - just pulls on and off, and I know the NEW connections are tight - so my money's on the loose IC. Insufficient pressure during boost sounds like exactly what was happening - could a loose IC boot do that though?

 

Yes. You will lose quite a bit of boost of the boot is not installed properly (it usually gets flipped over on the IC or horn lip) or the clamps get assembled wrong. Each clamp has an upper and lower piece that look the same, but only the lower piece has the threads in it. If you swap bottom for top, you end up being able to run the screws in tight and things look about right, but the clamp will not 'close' properly. If you try to make boost, the pressure pushes the boot from the IC and you have an outrageous leak. If there is a leak at part throttle, the ECU plays hell at trying to modulate the throttle and will set a code.

 

Recheck the lines and the IC horns. When I installed my OCC I did everything very quick, and ended up putting one of my boots on the IC backwards, which turned into a boost leak and through my car into "limp-mode."

Recheck the lines to make sure everything is on correctly, and make sure the IC is seated correctly, then you should be fine.

-Cody

 

Lots of great suggestions in here. I would start with:
1-Re install the boost gauge. Use a very small siptie to hold the lines on the bottom of the pressure regulator. Helped me out several times.
2-Make sure the IC boots, as suggested above are all installed properly.
3-See how it runs, if good, disconnect the battery for 30 minutes and then reconnect. Should clear your soft code for a vac leak. If it is still bucking get the codes read rather than erasing them.

FYI idle boost should be around 16-18mm mercury. Depends slightly on your IC and your pulley size, but 10 is too low.