Sputtering problem driving me crazy
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2nd Gear
Joined: Jun 2024
Posts: 2
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Sputtering problem driving me crazy
Hey guys, this for um has helped me a lot tinkering with this truck over the years but I just can't find an answer to this question.
It's a '94 f150 5.8 4x4
Truck takes off fine. Maybe slight rough idle and drives fine until warms up to operating temperature. Then around 30 mph it sputters and wants to stall I can keep her running by fluttering the gas and after I get up to speed about 40 it takes off like nothing's wrong.
So far I replaced the O2 sensor The EGR control solenoid and checked for vacuum leaks with a smoker and using carb cleaner and didn't find any
The only clue that I have is that the green hose going to the EGR? Only ever gets maybe 2 lb of vacuum and the EGR opens but only slightly for a second and then closes. A YouTube video I watched when the guy was accelerating the idle. His vac gauge showed around 5 lb of vacuum and it would stay open until he let the accelerator cable back.
The truck does have an exhaust leak coming from the manifold but I think that's unrelated
I tested the EGR position sensor and it has proper resistance. I'm not sure where else to look. If anyone has any idea, I appreciate it.
It's a '94 f150 5.8 4x4
Truck takes off fine. Maybe slight rough idle and drives fine until warms up to operating temperature. Then around 30 mph it sputters and wants to stall I can keep her running by fluttering the gas and after I get up to speed about 40 it takes off like nothing's wrong.
So far I replaced the O2 sensor The EGR control solenoid and checked for vacuum leaks with a smoker and using carb cleaner and didn't find any
The only clue that I have is that the green hose going to the EGR? Only ever gets maybe 2 lb of vacuum and the EGR opens but only slightly for a second and then closes. A YouTube video I watched when the guy was accelerating the idle. His vac gauge showed around 5 lb of vacuum and it would stay open until he let the accelerator cable back.
The truck does have an exhaust leak coming from the manifold but I think that's unrelated
I tested the EGR position sensor and it has proper resistance. I'm not sure where else to look. If anyone has any idea, I appreciate it.
Last edited by 99bk99; Jun 21, 2024 at 10:44 AM.
Fleet Mechanic
Joined: Nov 2022
Posts: 1,697
Likes: 416
That makes me wonder if the PCM doesn't match the truck, pulling it out and inspecting for corrosion would be worth your time as well.
5th Wheeling
Joined: Dec 2013
Posts: 37
Likes: 4
From: Williston, FL
The EVR controls the vac to the EGR thru that green vac line. At Idle there should be no vac to maybe 1 -2 in. The 1-2 inch will not open the EGR and that vac is because the EVR alway has a little bit of vac due to it's design. It has a felt disc in it and some vac pull can get thru. Maybe check the TPS as it will cause weird idle and engine rpm's to be unsteady. It controls fuel flow thru the cpu acorrding to how much you press the gas pedal. ie how much the throttle plate is open.
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