Newbie here. Have not done intro to forum yet. 1999, 4.6L, Auto Trans. Car is new to me. At heavy acceleration or WOT, it runs great. With light load (going up a long moderate incline) it hesitates as if bogging down and needing more power. It will eventually downshift to a lower gear, accelerate, & upshift to the next gear. I added some injector cleaner & drove about 100 miles. It still does it. It also idles quite rough. (sometimes enough the tachometer shows it) All comments appreciated. Ezre
Drivetrain Hesitation during light acceleration
- Thread starter Ezre
- Start date
SN95_fanx54
Member
Yeah probably some sort of vacuum leak. I fought one for a long time under the throttle body where it mounts to the intake manifold... but yours could be easier. If not a vacuum leak, could be ignition coils or plugs, but you'd likely start getting check engine lights for that.
Mcmahst
5 Year Member
Quickest way to determine if you have a vacuum leak is to test the vacuum at idle. If you don’t have a vacuum gauge, at my Autozone, they have one to loan. I suspect they all do. You can do it in the parting lot. If it’s not more than 15”, take a video of it for like 15 seconds and post it here. Just my 2 cents.
I found a cracked vacuum hose that connects pcv(?) Valve to air intake. Put hose clamps on both ends. Engine ran a lot better. Will get *new" hose. Willl keep chasing leak if new hose does not fix. I'm convinced it's a vac leak. Will report back as things progress. Thanks to all.
The rubber hose section I'm wanting to replace is a short 1/2" x 3" x3" (size questionable) elbow that connects between valve cover and pcv valve hose/tube that runs to air intake. I can't find one online. Has it been replaced with a different type fitting? I feel stupid. Been wrenching a "lot" of years, but can't find a piece of hose.
Overwhelmed with work right now. Will make "more sensible" posts when I have time to focus. Thanks for all help so far.
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