Plenum? Where and what is it?
New User
Joined: Dec 2000
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Plenum? Where and what is it?
I have a 92 F150 with a 302. I have read a couple posts where it has been said that checking the plenum gasket for leaks may be a fix to a rough idle. Can anyone please tell me where the plenum is on my truck and what it is? How do I check this? I have looked all through this repair manual of mine and I can't find anything about it. Thanks in advance for any help.
Dwight
Dwight
Elder User
Joined: Feb 2000
Posts: 601
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From: South Sioux City, NE USA
Plenum? Where and what is it?
I believe what they mean is the upper half of the intake manifold.
I did replace the gasket on mine awhile back. The gasket came in a kit that had the Plenum gasket and all the little gaskets for the throttle body and EGR valve.
HTH
Roger Lane
Test Analyst
Sr. Automated Test Engineer
IBP, Inc.
I did replace the gasket on mine awhile back. The gasket came in a kit that had the Plenum gasket and all the little gaskets for the throttle body and EGR valve.
HTH
Roger Lane
Test Analyst
Sr. Automated Test Engineer
IBP, Inc.
Junior User
Joined: Jan 2001
Posts: 91
Likes: 0
Plenum? Where and what is it?
The plenum is the big aluminum piece you see sitting on top of the engine. It is the top half of the intake, it has 6 bolts that bolt it down to the intake manifold. You can buy just the plenum gasket without buying the whole set. I just replaced the one on my 92 302 lat week, I got the gasket from NAPA. My truck ran ok around town but it had no power and missed really bad under load especially at highway speeds. I had it put on a scope and all it said was that it was running lean. Everything was working right, it was just running lean. So I figured maybe sucking air somewhere so i took a shot and that was it.
Fleet Mechanic
Joined: Aug 2000
Posts: 1,504
Likes: 1
From: Texas
Plenum? Where and what is it?
Was your truck backfiring at all? Mine is doing that with a vengence! Seems everytime I start it lately (last few days) it starts and dies immediately. I have checked almost everything, I cleaned the egr and checked it last week, re-tightened the headers, and checked almost everythig else. I can't figure it out! It has a new air filter, and a new fuel filter. So I have no other clues as to where to look.
1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.
Can see both below.
[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]
1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.
Can see both below.
[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]
Junior User
Joined: Jan 2001
Posts: 91
Likes: 0
Plenum? Where and what is it?
No, I didn't have any backfiring. Just driving around town you wouldn't even notice it. When it started acting up is when I had my foot into it pretty good. I took it to a shop and had them do an injection cleaning, he called it a "motor-vac". Hesaid that of all the cars and trucks he does that to, the Fords seem to benefit the most. I could tell a big difference in how it started and ran.
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Fleet Mechanic
Joined: Aug 2000
Posts: 1,504
Likes: 1
From: Texas
Plenum? Where and what is it?
I have had that done to mine but it has been almost a year since the last time. I just cannot get over this stupid backfiring, and bad hesitation. The hesitation is so bad it almost acts like the engine is dead, then it picks up power again.
1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.
Can see both below.
[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]
1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.
Can see both below.
[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]
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