5.0 rough idle.
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From: Wingo, Ky
5.0 rough idle.
Trying to straighten out a 1992 f150 with 302 I just bought for my fiancé. I hang around the 73-79 crowd. The newer trucks are a different ball game for me.
Today I just did a tune up. Wires, plugs, cap, rotor, fuel filter. All motorcraft parts. Idle is still a little rough, you can feel it shake a little. Starts easy. Accelerates great with plenty of power. Can feel it miss a little while just cruising. Revs up good and returns to idle good. No codes showing. Should I get a code reader? I was thinking maybe problem with iac or map. Thanks for any help.
Today I just did a tune up. Wires, plugs, cap, rotor, fuel filter. All motorcraft parts. Idle is still a little rough, you can feel it shake a little. Starts easy. Accelerates great with plenty of power. Can feel it miss a little while just cruising. Revs up good and returns to idle good. No codes showing. Should I get a code reader? I was thinking maybe problem with iac or map. Thanks for any help.
Fleet Mechanic
Joined: Feb 2007
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From: Mandan, ND
You can test both the IAC and the MAP using procedures in the service manual.
Two basic things to check is look over all your vacuum lines. Especially where they go from hard to soft.
Also make sure plug wires 7&8 do not run near each other. That will cause a misfire. Route them separately so they do not run parallel or touch at any point.
Start with the basics. Don't replace anything without testing it first.
Two basic things to check is look over all your vacuum lines. Especially where they go from hard to soft.
Also make sure plug wires 7&8 do not run near each other. That will cause a misfire. Route them separately so they do not run parallel or touch at any point.
Start with the basics. Don't replace anything without testing it first.
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From: Wingo, Ky
Ok I'll check all the vacuum lines. I was going to make sure I routed the plug wires and separated them good with zip ties yesterday but started getting late. Ill get that done soon as possible.
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From: Wingo, Ky
Checked for vac leaks didn't have any luck finding any. Also routed wires 7 & 8 away from each other. Still sounds the same, slight miss and shake at idle. Doesn't sound like it misses while being revved up and it doesn't miss under hard acceleration. Not lacking any power when you step on the throttle, it accelerates very quickly.
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From: Wingo, Ky
Yes it does miss while cruising just slightly. When not going very fast and lugging up a hill is when it's most noticeable and at idle.
It does make a weird noise every time I turn it off and I'm not sure where its coming from. Every time you turn the truck off it goes "shhh" for a second like air is escaping or being released from somewhere under the good.
It does make a weird noise every time I turn it off and I'm not sure where its coming from. Every time you turn the truck off it goes "shhh" for a second like air is escaping or being released from somewhere under the good.
Logistics Pro
Joined: Mar 2005
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From: Mexico, Missouri
When you say, "no codes showing. Is that just saying there isn't a CEL on or have you tried to pull codes and there weren't none? I would be inclined to try plugging/capping the vacuum line running to the EVP sensor and perhaps the EGR valve. If either is malfunctioning or worst case, both are, then it can cause a miss at idle. This age of truck could just need to clean the EGR and make sure it isn't sucking in exhaust gases at idle. If the EVP is erratic, it too can pull a slight vacuum on the EGR valve, masking the problem from itself, and the EGR not really be at fault.
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From: Wingo, Ky
I unplugged the EVP sensor but forgot to take off the vac line. I removed vac line from EGR and plugged it and noticed no change. I didn't actually take it off and make sure it was closed and I don't have anything to see if it will hold a vacuum. Should I actually take it off and inspect it and what to clean it with? It got dark on me fast today.
Would the PCV valve have anything to do with it? I forgot to check it. Also would the air pump not being functional cause it? I noticed the pulley on it has been removed so it won't turn. It doesn't have a converter anymore, it has true dual exhaust with flowmasters.
I haven't checked for codes but the CEL isn't on. Thanks for any help.
Would the PCV valve have anything to do with it? I forgot to check it. Also would the air pump not being functional cause it? I noticed the pulley on it has been removed so it won't turn. It doesn't have a converter anymore, it has true dual exhaust with flowmasters.
I haven't checked for codes but the CEL isn't on. Thanks for any help.
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From: Wingo, Ky
What is the best way to clean egr valve? I haven't got around to it yet. Still been getting it caught up on general maintenance and cleaning.
Noticed something else. Truck doesn't hold fuel pressure in the lines very long, not even a day. Have to turn key on and let pump cycle then starts right up.
Also noticed gas leaking from the front tank. I haven't put gas in front tank since I bought it and the fuel gauge on front tank doesn't work, it just pegs out the gauge. Taping on the tank it sounds almost empty. The gas looks like it's coming from around the top.
No fuel leaks around fuel filter connections. What do I need to start looking at first? Thanks.
Noticed something else. Truck doesn't hold fuel pressure in the lines very long, not even a day. Have to turn key on and let pump cycle then starts right up.
Also noticed gas leaking from the front tank. I haven't put gas in front tank since I bought it and the fuel gauge on front tank doesn't work, it just pegs out the gauge. Taping on the tank it sounds almost empty. The gas looks like it's coming from around the top.
No fuel leaks around fuel filter connections. What do I need to start looking at first? Thanks.
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