Misfire issues
#1
Misfire issues
My 2000 Ford Ranger 4.0 OHV is having an issue, I know its not bad gas etc, it cranks a little rough at first but stops idling rough after a few seconds, then when I start down the road and it usually happens when I don't get on the throttle much, it'll start misfiring pretty bad but if I put the throttle to the floor it will stop, its not throwing any codes, I'm thinking its a vacuum leak somewhere but I have no clue, if someone can help thank you.
#3
RF Veteran
iTrader: (1)
Welcome to the forum
Warm up engine
On the front, side, of upper intake is the IAC(idle air control) valve it has 2 wires plugged in to it.
While engine is idling(warm) unplug those wires, RPMs should drop to 500, or engine may even stall, either is GOOD, it means no vacuum leaks.
If idle is above 700 then there is a leak
Start unplugging vacuum hoses from intake and seal port with finger, when RPMs drop you found the hose with the leak.
If all hoses are OK then you will need to check intake gaskets.
Vacuum leak almost always causes a lean code
Warm up engine
On the front, side, of upper intake is the IAC(idle air control) valve it has 2 wires plugged in to it.
While engine is idling(warm) unplug those wires, RPMs should drop to 500, or engine may even stall, either is GOOD, it means no vacuum leaks.
If idle is above 700 then there is a leak
Start unplugging vacuum hoses from intake and seal port with finger, when RPMs drop you found the hose with the leak.
If all hoses are OK then you will need to check intake gaskets.
Vacuum leak almost always causes a lean code
#4
#5
Welcome to the forum
Warm up engine
On the front, side, of upper intake is the IAC(idle air control) valve it has 2 wires plugged in to it.
While engine is idling(warm) unplug those wires, RPMs should drop to 500, or engine may even stall, either is GOOD, it means no vacuum leaks.
If idle is above 700 then there is a leak
Start unplugging vacuum hoses from intake and seal port with finger, when RPMs drop you found the hose with the leak.
If all hoses are OK then you will need to check intake gaskets.
Vacuum leak almost always causes a lean code
Warm up engine
On the front, side, of upper intake is the IAC(idle air control) valve it has 2 wires plugged in to it.
While engine is idling(warm) unplug those wires, RPMs should drop to 500, or engine may even stall, either is GOOD, it means no vacuum leaks.
If idle is above 700 then there is a leak
Start unplugging vacuum hoses from intake and seal port with finger, when RPMs drop you found the hose with the leak.
If all hoses are OK then you will need to check intake gaskets.
Vacuum leak almost always causes a lean code
#6
RF Veteran
iTrader: (1)
4.0l OHV did have a weak spot between valve seats in the heads that could cause a crack if overheated.
But symptoms of that problem would also include a full overflow tank from too much pressure in cooling system and overheating if driven more than 15 minutes.
Misfire would be a secondary symptom
But symptoms of that problem would also include a full overflow tank from too much pressure in cooling system and overheating if driven more than 15 minutes.
Misfire would be a secondary symptom
#8
RF Veteran
iTrader: (1)
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