High pitch sound from tbi.

[Big D]

gotta question hopefully someone can answer, I just got my 91 Dually driveable again (new suspension) and I noticed when im sitting at a light it Idles really high, so I popped the hood today pulled the air cleaner and started it up to see if I can find any vacum leaks, I couldnt find a definitive leak, but there was a super high pitch sound coming what seemed to be the TBI. if I grab the top of it behind the injectors, it goes away......any ideas what it is?


first vehicle ive had with a TBI so any info would help.

 

[Dylan1991_1500]

Sounds like some kind of vacuum leak. Perhaps one of the hoses attached to it is disconnected or split. Would explain the high idle.

 

[Justin S]

It might be your engine screaming for a carb swap.... or maybe the IAC is stuck open a little, or like Dylan said, a missing vacuum line. My truck had one coming out the backside of the throttle body between the fuel lines that was wide open, some trucks have that one go to the MAF. Mine was attached to the front.

 

[Justin S]

oooo I missed the part saying you could grab it and make it stop. They sell a carb rebuild kit at advance auto or autozone, might help you out, they're like 27 bucks and super easy to install. Comes with new injector filters, all gaskets, o rings, etc. I just did one on my 350 tbi. BWD part number 10902

 

[Big D]

well I found the high pitch whistling sound, its coming from a tiny machined hole next to the throttle blade on the driver side. I wonder if its partially plugged... the other one doesent make that whistling sound.

I pulled the codes and got code 44, I changed the O2 Sensor and busted the clip on the male end just by looking at it, so it was running for a while without the 02 sensor hooked up, I got a new connector and hooked it up and reset the codes (disconnecting the battery) maybe my High idle will go away...

 

[Big D]

nope High Idle Remains!!!! Gat Damn It!!!!! I have also noticed the truck is running wayyyyyyy cooler since I flushed the radiator and swapped the thermostat, I bought one of those Fail safe thermostats just because the old lady drives the truck and shes famous for not looking at guages. Ive read lately the Fail safe thermostats blow, and fail almost immediately sometimes. I wonder if thats the culprit of my new High Idle problem.