Hi everybody, I have a strange problem now and I'm not sure where to begin. While driving my check engine light popped on and I went to AZ to get the code pulled and found out there was no power. That was a blown fuse and no problem, but the light came back now. There are two problems that I have noticed and I was wondering what could cause these.

1: My boost gauge gets no reading. I have two, bout it used with both. The pilar gauge reads 0 at all times while the one in the DIC usualy has no reading but occassionaly gets a reading that will just sit there, even when I'm idling.

2: Sometimes the car won't shift. This has happened twice and the problem is that the car will not shift to the next gear until I let off the gas. I have taken the RPM up to 5700 with no shift. Though once I went a bit higher than that and shifted so I think it might be getting an odd reading that is causing my PCM to think I'm accelerating harder than I am and taking me up to the 100% throtle shift point.

I am going to check some electrical stuff after work today but I am curious to know if anybody knows what could be causing this. I moved the auxilary fuse box under the hood and unbolted the alternator to fix my coolant elbow leak earlier so I think that might have caused a loose connection or something. Any ideas?

Edit: Outside of those two issues the car runs completely fine and the no shift issue has only happened when I was driving on city streets for short distances so I don't know if it corrects itself or resets when I turn of the vehicle.

When working on the alternator you may have cracked/ripped/broken or pulled off the vaccuum line completely that runs from the LIM underneath the blower snout to the MAP sensor behind the s/c.

That would be a large vac leak though and you would notice it.

Don't go by the DIC boost gauge, use your other one. Is it mechanical or electrical boost gauge?

How is it connected? check these lines first.

As for your shifting issue, what year is your car? 97's are affected by vacuum so the 2 problems may be connected if you do have a 97.

OR it may have just been in your head or a 1 time thing.

Car is a 2000 GTP. Didn't realize that I forgot to put that in my sig so I'm going to have to fix that. I'm not sure about the gauge but if I had to guess I would assume it is an electric gauge since it is paired with an LED style A/F gauge. I'll make sure there is no issue with the MAP vaccuum line first thing.

I don't think the shifting is in my head but since it only happened twice and letting off the gas fixes it I'm not too worried. It may only happen when I have performance shift enabled as well but I have not been able to verify this yet.

Have these problems only happened once you did this? ...or did this issue happen prior also.

Check right under the MAP sensor, it connects to the vac. line you put your boost gauge into, Its an L shape at the connection, you can see it, but you can feel it.

x2 on checking at the LIM

Both of thes issues have only occured since the work I did fixing my coolant leak. Going to be checking that vaccuum line since that seems to make sense. Especially since I forgot to mention that the shifting problem only seems to happen when the DIC reports a boost value which helps my theory that the problem is a confused PCM I think.

How the gauge looks has nothing to do with it, sorry, I should have been more clear.

An electronic boost gauge would have it's own sending unit. Idk why anyone would want an electronic one but that's besides the point.

Does a vacuum line run to the back of the boost gauge? if it does, it's mechanical. This is likely.

It seems to me there is a vac leak somewhere. I guess if you know someone around you that can tune, they could hook the equipment up and see if they get any readings on the boost.

Some boost gauges have the vacuum also. If you have something like this, you should at least be getting a vacuum reading, if your not you def have a vac leak in that line.

Haven't checked the gauges though I was guessing that they were electric. I believe the A/F gauge is the digital AutoMeter kind found in the GP store and I'm assuming the person who got that would get both as electrical gauges out of lazyness. I still need to find out how the person turned off the DRLs because they stopped the auto-on functionality as well, which is another reason I think they might be lazy since my old 97 kept the functionality while disabling the DRLs with minimal effort.

Edit: Well, time to head home and fix this.

The gauge itself may have a digital readout but that doesn't mean it's electronic. Forget about what I said, you more than likely have a mechanical boost gauge.

Yeah its a mechanical boost and surprisingly enough the problem was that the vaccuum tube was unplugged on the opposite side of my alternator. Thanks for all the help everybody.