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Does the 89 model have an extra intake part they later deleted?; Intake sensor delete on the throttle body
Topic Started: Feb 8 2015, 02:27 PM (904 Views)
chapelhilldave
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My boy has an 89 metro, and I have a 1990. Lately his has been acting a bit odd, occasionally conking out on the highway, or struggling to get up a hill, stuff that makes me think fuel starvation or vacuum leak issues. I was poking around his vacuum lines and realized he has a module with a sensor wire and hoses coming from the air filter housing and the lower throttle body that I don't have. the two inlets it uses are caped on mine, either from the factory or by a previous owner doing nice quality work. Did they just get rid of this part on all the later models?
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In my 1990 you can see they are capped.
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You can also see my awesome paperclip bypass on the IAC. I disconnected the hoses to his and got a big engine rev from one. Then I reconnected and unhooked the electric connector on the back and saw/heard no difference at idle? Should I just delete and cap this feature on his 89 to eliminate one more possible issue in the future?


MMM was here, now photos are better...
Edited by Metromightymouse, Feb 8 2015, 11:55 PM.
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Highwayman
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Im not even going to comment on the coming destruction I forsee in those photos with the necessary systems disconnected and the dirty air getting into the engine.
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Metromightymouse
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Powdercoat Wizard

Highwayman
Feb 9 2015, 01:40 AM
Im not even going to comment on the coming destruction I forsee in those photos with the necessary systems disconnected and the dirty air getting into the engine.
He didn't say anything that would lead to dirty air in the engine.

"Should I just delete and cap this feature"
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Highwayman
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Back when I worked in some one elses machine shop, we would send out vehicles to the local mechanic shop to have the engine R and Rd. I would over haul the engines then when we got the vehicles back every vacuum item would be disconnected; then I would get to spend a week reattaching the vacuum operated heat risers or waste gates or choke pull offs, Etc. They didnt understand that some vacuum operated items are required to be hooked up for the engine to run at all. Such as that air bypass solenoid for increasing engine speed in relation to engine accessory load.

The idle speed control is usually on vehicles with air conditioning. But it also can compensate for other loads such as when the heater blower is turned on. That is also the item ( held to the back of the throttle body with two screws) that I replaced on my 92 and 93 to make the engine stop surging while driving at constant speed in town and the several surges I used to get when I stopped at a stop light. When the hose falls off the bottom of the air cleaner it will be open to the environment. I just went out and looked at the engine I pulled out of a 1991 and a 89 with brass serial number tags and they both look the same as his. My 96 and 99 engines have a different throttle body setup.
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myredvert
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myredvert

The component in the first picture on the firewall is the Air Conditioning Solenoid Valve (AC SV), that activates only when the air conditioning is on to further raise the idle in addition to the Idle Air Control (IAC) function. The IAC is the component on the back of the intake on all standard emissions vehicles.

It is the component you have "bypassed" with the binder clips. It raises the idle speed when any of the five specific idle up components are activated (headlights, blower fan, coolant fan, stop lights, rear defogger). Do not plug, disable, or do any other weirdness to it for no apparent reason. The fact that the idle increased when a vacuum hose was disconnected points towards an IAC that is (at least in part0 doing what it is supposed to do. Depending on the specific conditions, the fact that there was no idle change when disconnected could be an indication that it is working, but you still haven't determined whether it is working properly or not.

The IAC also performs several other functions besides the idle up function mentioned above.

You aren't really "preventing future issues" by disabling normal systems - you are just avoiding repairing them now and may make diagnosing other issues in the future more difficult or unnecessarily create compounded drievability issues.

I vote no on molesting a system by default before determining if it is or isn't working, and if not working, when simple repairs may be possible.
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Hanuman
"The Almighty Grounds Cleaner"

myredvert
Feb 9 2015, 02:36 AM
The component in the first picture on the firewall is the Air Conditioning Solenoid Valve (AC SV), that activates only when the air conditioning is on to further raise the idle in addition to the Idle Air Control (IAC) function. The IAC is the component on the back of the intake on all standard emissions vehicles.

It is the component you have "bypassed" with the binder clips. It raises the idle speed when any of the five specific idle up components are activated (headlights, blower fan, coolant fan, stop lights, rear defogger). Do not plug, disable, or do any other weirdness to it for no apparent reason. The fact that the idle increased when a vacuum hose was disconnected points towards an IAC that is (at least in part0 doing what it is supposed to do. Depending on the specific conditions, the fact that there was no idle change when disconnected could be an indication that it is working, but you still haven't determined whether it is working properly or not.

The IAC also performs several other functions besides the idle up function mentioned above.

You aren't really "preventing future issues" by disabling normal systems - you are just avoiding repairing them now and may make diagnosing other issues in the future more difficult or unnecessarily create compounded drievability issues.

I vote no on molesting a system by default before determining if it is or isn't working, and if not working, when simple repairs may be possible.
:gp
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