Bad Boost Pressure Sender?

[RichB]

I have a Prosport Electronic Boost gauge and something weird stared happening today. When I down shift to accelerate my gauge pins to -30 inHg for about 5 seconds then goes to the true pressure reading. Then when I let go of the gas it pins again at -30 inHg. Normally it goes to -25inHg when I let go of the gas.

Another scenario is when I am stopped and idling, I blip the gas and it again pins at -30 inHg for about 5 seconds then goes to the idle pressure reading.

I have checked all of my hoses and wiring and have found nothing. Could it be a bad Pressure Sender?

 

[CosmicArkie]

Yup. Dun there. Been that. Those sending units are touchy. Mine lasted less than a month. Gave up on the electric, went mechanical over 2 years ago. No problems since.

J

 

[RichB]

Ok, so how did you run the vacuum hose in the car? I got electronic because I thought it would be easier to run.

 

[coyfish]

Could be the sender. Make sure your grounding is secure.

 

[RichB]

Could be the sender. Make sure your grounding is secure.

Wouldn't the gauge completely shut off if grounding was an issue? My sender and gauge are grounded at the same place. I guess it could be my splicing point.

 

[CosmicArkie]

"Ok, so how did you run the vacuum hose in the car? I got electronic because I thought it would be easier to run."

You had to run the wire thru the firewall? Tie/tape the hose to the wire you already have installed and pull it thru. Gently. You already have half the hose run. Trust me, when the sender gets stupid it doesn't improve.

 

[RichB]

How thick is the Vacuum hose? I ran my wire through the hood latch. Do you think it would still fit there?

 

[coyfish]

Wouldn't the gauge completely shut off if grounding was an issue? My sender and gauge are grounded at the same place. I guess it could be my splicing point.

I had a similar issue. My boost gauge was periodically going out of wack and showing goofy numbers. Turns out My ground wire was slipping off a little bit. Just something to check for if you haven't.

 

[abovie3]

I have the same gauge and experienced similar problems. its been a while since ive looked at the wiring but im pretty sure these are the wire colors to check: Make sure the green wire from behind the gauge is connected securely to the white wire on the boost sender. After verifying that I would suspect the sender unit itself. I have had to replace it.

 

[RichB]

Yea I just re-did my ground to make sure. The green wire is a little buried but I remember putting a connector at the spot I had to splice it. So I doubt it is that spot. Since the weird readings aren't random and I can predict when it will happen, the sender has to be the culprit.

How much does the sender cost to replace?

 

[RichB]

How much does the sender cost to replace?

Never mind. I found it on their site. $20.50 if anyone was wondering.

 

[abovie3]

email prosport. if yours fails all you have to do is send in yours and they send you a new one. just pay shipping.

 

[RichB]

1 year warranty is up. I'm guessing i still have to buy one.

 

[RichB]

I drove home from work yesterday and my guage was pinned at -30 inHg basically the whole way except for the first 5 minutes. When I got home, my replacement pressure sender was waiting for me so I installed it. On my drive in to work this morning the same thing happened, pinned at -30 inHg.

My next step is to gut the wiring and re-do it. I'm guessing the wires in the engine bay came apart. It has been 2 years. Hopefully this fixes the problem.

 

[RichB]

I did some more troubleshooting with the three wires that run to the pressure sender last night and cut wires while it was on to see what happens. Here is what I found.

When I cut:

Red Wire - Gauge pins at -30inHg
Black Wire - Gauge pins at 30 psi
White wire- Gauge slowly moves to 30 psi and stays once reached

I checked all of my wiring in the car and it all looks good. I replaced the wires going to the engine bay and everything seems to be all good now. FINALLY!