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1985 Toyota Pickup Vacuum Gauge Readings

Tiny
PCMENTOR29
  • MEMBER
  • 1985 TOYOTA PICKUP
  • 75,000 MILES
I hooked a Vac gauge to plenum and saw 17.5 in Hg at hot idle. My question is why would the needle slowly float between 17.5 and 18.0 in Hg and be sort of corresponding to an uneven idle? At 2500 rpm the needle doesn't move or vibrate at all. I am at 2100 ft elevation. Engine is 22RE 4 cyl FI. I have looked at several vac gauge charts but don't see symptom. Thanks for your help.
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Wednesday, July 10th, 2013 AT 9:17 PM

2 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It could be the idle air control valve opening and closing there is nothing wrong with that reading. If you want clean the throttle plate with choke cleaner on both sides an iac hole.
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Thursday, July 11th, 2013 AT 8:42 AM
Tiny
PCMENTOR29
  • MEMBER
  • 177 POSTS
Thanks for your reply, I am going to see if the Aux Air valve is passing vacuum. It is the IAC on the 22re motor. It has one hose on the plenum and one before the throttle plate. I had the emissions tested and it is bad at idle still even though I put a heated O2 sensor on it. The idle is still uneven so I know there is some other issue. I will post when I have an issue to ask. Any ideas you have I will be thankful for. Thanks.
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Friday, July 12th, 2013 AT 8:55 PM

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