im not sure i should start another thread in a different spot but this is about my 4.9 and this is the 4.9 section. anyway ill try here, i have a 1990 4X4 with the 4.9. runs great and not bad on gas but when i go up a steep grade with the ac on i can only get up to 50mph. im sure if i hit passing gear i could go faster but i don't think thats a good thing to do. now maybe thats all its got. for weight i have about 300-400 lbs in the bed. motor is tuned and i checked the vacuum, both at idle and reved up, it held good 18hg. where i live i could get rid of the cat if i wanted to but id like to find out if its bad first. the truck has 150,000 miles on it but doesn't use a bit of oil. seems to me that i should be able to go uphill at 70mph not 50mph. maybe my cats clogged. i don't know.
well i havent driven this hill with the ac on for years so i cant remember if thats all it will do or not. i just wondered if these trucks with the 4.9 can go uphill at 70 or is 50-60 max.
Mine will hold speed on most hills, but will not gain speed. My OD and overall gearing allows me to run 65 in 3rd (1:1) and not be overreved, so it may be a gearing thing. Are you too tall in od and too short in direct? It shouldn't be as the od's are that severe in these... (.79 I think)
i cant get into od going uphill. 50mph tops without ac and in third. i checked the vacuum at idle and at 2000 rpm to see if cat is clogged and the vacuum is good.
thats what im tying to find out. is starting out from a dead stop and heading up a steep and only getting up to 55 in third normal, just wondered if i should expect to be able to get up to 70 in a mile uphill.
if you have somthing like 2.73 gears it may be normal to not have any power going up hills. My '94 with 255/70 R15 tires and 2.73 gears tops out at 72 on what i think is a mild hill (actually a hill over a expressway) on a steeper hill, like the ones in norhtern Kentucky, it wont go over 60ish in 4th ( i have the m5od). This is with no A/C or load in the bed.
About a year ago i cut off the exhaust infront of the muffler. Without the muffler the performance did improve. With the muffler, it would top out at 60 on the above mentioned mild hill. W/o the muffler it tops out at 72 on the same mild hill. I also gained 1mpg city by cutting off the muffler. I still have both cats though.
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1994 f150 4x2 reg cab I-6, 5spd
ain't no such thing as too much overkill.
Amazing what a tuneup will do. When I first got mine, I had to keep it in second gear to be able to go up hills, and it was usually around 30mph with my hazard lights on. A 2% grade and I couldn't keep it over 65. It was insane.
Several tuneups and freshening ups later, I can easily increase in speed from 60 - 70 going uphill in third. I have 3.00 gears too.
i should check my gears. i know i have posis in the front and back so i can just jack up the rearend and count the number of turns the driveshaft turns for one complete turn of the tire.
well i switched to my rear tank today and i picked up about 10 mph uphill. but when i checked the fuel pressure on the side tank its 48psi and holds. seems like i may have a flow problem.
well i switched to my rear tank today and i picked up about 10 mph uphill. but when i checked the fuel pressure on the side tank its 48psi and holds. seems like i may have a flow problem.
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