Rough idle when oil cap is removed. (1 Viewer)

Joined
May 25, 2014
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35
Hey all,
Like the title states, the truck was cold and I was looking around the engine as it was warming up, decided to pull the oil cap and as soon as it cleared the last thread the idle dropped hard almost stalled. As soon as the cap was threaded back in it came back. Any idea on this? I've searched and found nothing.
Its a 94 1FZFE with 190,XXX miles.
 
Joined
May 25, 2014
Messages
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You introduced a giant vacuum leak. Don't do that and it will be fine.
Lol really. It's that simple? I cant say that I've ever done this on my 80 before but I can go pull the caps off the other 5 cars in my driveway and NONE of them do it.
 
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Yep, no oil cap = no vacuum. I would be more concerned if I didn't get a rough idle with my oil cap off.
 
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Lol really. It's that simple? I cant say that I've ever done this on my 80 before but I can go pull the caps off the other 5 cars in my driveway and NONE of them do it.
Yup. It's that simple.

Really.

Your other cars are shyt.
 
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Couple others I remember:

"There's a whirring noise coming from behind my stereo unit with the key in ON position. How serious of a problem is this? Is it ok to drive till I get it fixed?"

"I was standing near the back of my rig with the truck running and all the doors and windows closed and I could feel air escaping the vehicle from right behind the sliding windows. Where should I start to track down the problem?"
 
Joined
May 25, 2014
Messages
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Couple others I remember:

"There's a whirring noise coming from behind my stereo unit with the key in ON position. How serious of a problem is this? Is it ok to drive till I get it fixed?"

"I was standing near the back of my rig with the truck running and all the doors and windows closed and I could feel air escaping the vehicle from right behind the sliding windows. Where should I start to track down the problem?"
Lol I hate you.
 
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May 13, 2012
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Seattle, WA/ Jacksonville, OR
Lol really. It's that simple? I cant say that I've ever done this on my 80 before but I can go pull the caps off the other 5 cars in my driveway and NONE of them do it.
It depends on what years the other cars are in your driveway and how the ECUs adjust/ compensate for the massive influx of unmetered air being shown to the oxygen sensors. If you were to leave your oil cap off and drove around for a while, eventually you'd see a check engine light for lean mixture or mass air flow sensor plausibility among other things.
 

Dave 2000

Not all Land Rovers are useless!
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The idea behind the system of a closed crankcase system with the vacuum, is to draw combustion gases that get past rings etc into the air intake and burn them off and out of the exhaust, years ago these gases would have been piped out under the car.

Regards

Dave
 

thatcabledude

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Walton Co, FL
One day when my 80 still had a 1fz in it I pulled the cap and added a quart of oil and checked some stuff. Next time I opened the hood (hundreds of miles later) I realized the cap was still off. Truck ran fine the whole time. Hood insulation had a oily spot on it though.
 
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Orangevale (aka, Sacramento)
Couple others I remember:

"There's a whirring noise coming from behind my stereo unit with the key in ON position. How serious of a problem is this? Is it ok to drive till I get it fixed?"

"I was standing near the back of my rig with the truck running and all the doors and windows closed and I could feel air escaping the vehicle from right behind the sliding windows. Where should I start to track down the problem?"
Since we're having fun, I'll add...
The vehicle needs: :wrench:
New muffler bearings:bang:
New upper Dingell arm Bushings (OEM of course):slap:
New head gasket:deadhorse:
 
Last edited:
Joined
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Juneau, Alaska
One day when my 80 still had a 1fz in it I pulled the cap and added a quart of oil and checked some stuff. Next time I opened the hood (hundreds of miles later) I realized the cap was still off. Truck ran fine the whole time. Hood insulation had a oily spot on it though.
I also did this once, maybe just a couple days of driving. No difference in performance, just a 🤦‍♂️
 

Francis K

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May 11, 2005
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732
Location
SE Michigan
When I first got my LX 22 years ago when I was 16 I couldn't figured out why there were spots all over it after I sprayed it down at the DIY car wash, without drying it or course.

That wasn't just car dumb it was dumb dumb.

What do I win?
 

Dave 2000

Not all Land Rovers are useless!
Joined
Jan 24, 2009
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Spain
Clearly you guys are not keeping the fluffer valve clean, and not adjusting the cosmic torque flange converter on a regular basis.

Regards

Dave
 

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