Distinct Buzzing Under the UIM
#1
Distinct Buzzing Under the UIM
A while ago I blew one of my stock turbo coolant hoses. Which was a lot of fun to replace, since I have fat stupid hands.
After the fact, my car has developed a distinct buzzing sound under the rear of the UIM, on the side near the turbos.
The buzzing happens intermittently through the rev range. Blipping the throttle and letting off will cause it, and it also seems to happen right around light load cruising at 2500-3000rpm.
And, when I take the ACV line off and listen it seems to coincide. Should the ACV line kindof roar at me coming off throttle?
I've acquired a couple spare ACV's to swap in. Also considered the ISC. Anyone experienced similar symptoms or have any clever ideas before the car goes under surgery?
After the fact, my car has developed a distinct buzzing sound under the rear of the UIM, on the side near the turbos.
The buzzing happens intermittently through the rev range. Blipping the throttle and letting off will cause it, and it also seems to happen right around light load cruising at 2500-3000rpm.
And, when I take the ACV line off and listen it seems to coincide. Should the ACV line kindof roar at me coming off throttle?
I've acquired a couple spare ACV's to swap in. Also considered the ISC. Anyone experienced similar symptoms or have any clever ideas before the car goes under surgery?
#5
Full Member
iTrader: (3)
The ISC is located on the UIM on the firewall side next to the throttle body. If the buzzing is from the turbo area I doubt it's your ISC but its easy enough to check. There is a electrical bung in the back. The ISC solenoid is silver with a black base and has a white connector. Just unplug it. Bazai has a good picture of it on their site under the block off plate instructions. Just make sure the A/C is off.
There are a lot of random bolts and connectors around the stock turbos. Check that you didn't knock any loose during the coolant line repair or that one hasn't worn away. I had a similar problem and it turned out that the worm drive clamp at the y-pipe to cross over connection had worked itself loose and was just rattling around. Another possibility would be your air pump. The air pump engages and disengages depending on the load to prevent it from running at the high rpms. If that is the problem you should be able to pick one up for cheap off the forum. A lot of people remove them. Or just take it off and run a smaller belt and enjoy the extra hp.
There are a lot of random bolts and connectors around the stock turbos. Check that you didn't knock any loose during the coolant line repair or that one hasn't worn away. I had a similar problem and it turned out that the worm drive clamp at the y-pipe to cross over connection had worked itself loose and was just rattling around. Another possibility would be your air pump. The air pump engages and disengages depending on the load to prevent it from running at the high rpms. If that is the problem you should be able to pick one up for cheap off the forum. A lot of people remove them. Or just take it off and run a smaller belt and enjoy the extra hp.
#7
Full Member
iTrader: (3)
Speaking generally, not rx7 specific, over tightened belts can cause noises from the pulleys. But that would be noticeable up front and not under the UIM. The air pump has an internal clutch that allows it to engage/disengage. If that is starting to go it would definitely cause some buzzing that would echo through the piping and be audible around the UIM. I can't say for certain belt tension would affect it's operation.
But a lot of auto parts stores like advanced auto have belt tension gauges for rent/use to get yourself in spec. Just call around and see if any stores near you have one. The FSM has the values for what a belt should be set at. It's a quick check and should be done any time you loosen or remove a belt. An overly tight belt or a loose belt are equally dangerous for an engine. You don't want that snapping on you on the highway.
But a lot of auto parts stores like advanced auto have belt tension gauges for rent/use to get yourself in spec. Just call around and see if any stores near you have one. The FSM has the values for what a belt should be set at. It's a quick check and should be done any time you loosen or remove a belt. An overly tight belt or a loose belt are equally dangerous for an engine. You don't want that snapping on you on the highway.
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RyanFox
New Member RX-7 Technical
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09-18-15 09:09 PM