EEC!V Fuel Injection Strategy
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Tuned
Joined: Apr 2007
Posts: 372
Likes: 14
From: Central Minnesota
EEC!V Fuel Injection Strategy
I've an "issue" with one of my 460 5 spds on the farm. With a heavy load, as goose neck trailer loaded, when you're revving up to say 4000 to shift, as you put the clutch in, the engine does not return quickly to idle, allowing a quick, smooth shift. Even with double clutching, because of the engine rpm, there's a problem with the throttle hanging up. The last of the carbed engines had a vacuum bleed plunger that slowed the throttle return for a moment to allow the fuel, under the throttle blades due to the sudden high vacuum induced by the throttle closing enriching the mixture, to be burned, ie emission issue, and understood. But I can find nothing in the system of this 97 to cause that, and I'm a bit mystified. I have a '90 and a '95, all F-250s that do not have this issue. Any ideas? The syncros don't like it, nor the owner/operator
Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
Likes: 116
From: Saskatchewan Canada
Obvious question, are there any codes present?
One thought may be a faulty TPS sensor. Grasping at straws here, but I would agree that it would be unlikely to be an inherent problem with the EFI strategy.
One thought may be a faulty TPS sensor. Grasping at straws here, but I would agree that it would be unlikely to be an inherent problem with the EFI strategy.
Fleet Mechanic
Joined: Aug 2015
Posts: 1,829
Likes: 362
From: Candy Mountain
At 4000 rpm the IAC is wide open to prevent a stall when you let your foot off the go pedal and the throttle body slams shut, but as the throttle closes the IAC should close and bring the engine to idle down very quickly. Practically immediately. Sounds like that isn't happening. Does it have any other running problems?
Checking for codes is always a good place to start. Check for mechanical problems like binding of the throttle blades or cable.
If you do not have any other problems or codes I would suspect a faulty IAC (EEC commands closed position but the IAC doesn't respond) or TPS (TPS doesn't report change in throttle position so no change in IAC opening is commanded). The MAP sensor would also bear scrutiny. A more remote possibility would be an incorrect or malfunctioning EEC.
Checking for codes is always a good place to start. Check for mechanical problems like binding of the throttle blades or cable.
If you do not have any other problems or codes I would suspect a faulty IAC (EEC commands closed position but the IAC doesn't respond) or TPS (TPS doesn't report change in throttle position so no change in IAC opening is commanded). The MAP sensor would also bear scrutiny. A more remote possibility would be an incorrect or malfunctioning EEC.
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