mostly truck requires what i consider a lot of pedal push to accelerate from a stop and maintain speed. occasionally it drives "perfect". the amount of throttle to accel and cruise is normal to me.
I considered closed/open loop issues but the issue occurs at any time cold/hot or otherwise I incorrectly identified the map sensor as being bad (didn't account for altitude) and so replaced. After getting tired of researching egr valve as a possiblity I swapped it with a new one. I've done a vacuum check and fuel pressure check. fuel pressure was at 56/58 for [on not running]/[idling] all checked out.
possible related issues
engine does a single "shake" occasionally
also when cruise is set and truck reaches 5th gear it will refuse to down shift unless speed drops by 5 at which point it down shifts 2 gears. Cruise responds normal as long as it doesn't reach 5th gear and TC lockup. Took voltmeter to throttle controller and noticed wide open throttle yet still no down shift
My car has 160000 miles.
My car has an automatic transmission.
Hi there. The issue seems to be with the downshift solenoid in the transmission. As the throttle is demanded by the gas pedal, the downshift solenoid overrides the line pressure in the transmission to the lower gears to allow the transmission to downshift. I recommend replacing the downshift solenoid. If you need further assistance with your vehicle not downshifting, then seek out a professional, such as one from Your Mechanic, to help you.
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