This weekend i put in a NAPA reman 351 with comp cams basic replacement cam in my 92 f-150. On sunday I got it in and drove it around 40 miles and evey thing seemed good, maybe alittle doggy but over all ran good. Then I went back home over the mountians about 250 miles and on the hwy and it did not have any power at all. It ran worse than my old I-6 did and on top of it it only got about 9 mpg allot worse than the 16 mpg i got with the old 200k mile engine. I thought it might be timing and was planning on checking it the next day after work. This morning when going to work it was very cold out and it started fine and ran the same. At noon it started and then died and would not start again. it sounded like it was out of time really bad, would try to start but would not grab hold. Later to day i went back to try and get it going. IT started but I had to keep it going for a min or two then it ran like it has been. I checked the timing and it was at 10 BTC with spout diconnected. When gased it advanced to some where around 30 degrees. One thing that seemed strange is when you let off the throtle it took quite a while for it to return to 10 degrees. other than that i dont know any thing else. All I can say it it has no power, firing order is correct and timming is set at 10 degrees. Any other ideas. This has been a pain, after busting my *** this weekend to get the truck done and all the money and it dose not run good
Really appricate any feed back
Thanks

 

you could increase it up to 14 btdc and do the mountains and thin air have anything to do with the lack of performance. i don't know why it would be weak being a reman. The cam must be worthless. Sounds like another pissed reman customer. good luck

 

Thats odd, is your ignition system new or reman unit? (distributor)

Are you confident in the cam install and break in?

Is your choke working properly?

I know my 351 truck seems to have more torque, initially, when I go from driving the six to the 8. My motor took some time to break in as well, definitely noticed improvement in over all feel as it broke in. Just a thought, later

 

I will try runnignt he timing up to 14 and see what happens. I have ran the truck over the mountians with the old 200k mile engien and it did allot better on power and gas millage. And i am pretty sure the cam was broke in correctly.
ANy other thoughts
Thanks

 

I wrote the above comment wrong sorry, I meant to say when I go from driving my six to the 8, the six feels like it has more torque, even though the 8 is supposed to have more.

Are you sure of your timing marks? Later

 

its possible that your cam is to big for the speed density system to work with. when you ordered the cam did you talk with a person at the company or did you just find one and order it yourself. the computer doesnt like to much change when it comes to cams. also something to think about is the power range that cam operates at . if its to high in the rpm band you will act slugish until you get it wound up.

late

 

the cam is a just comp cams stock replacement cam, and is as mild as you can get. I will keep looking into the timing.
Any more thoughts
Thanks

 

possible clogged fuel filter or injectors. also your cat might be plugged. might also check your fuel pressure. could also have a bad coil to not allowing enough spark. did the check engine light come on at all , should see if there are any codes

late

 

THe old engien had a very dirty fuel filter and idoled rough, looked like mud. But with the new motor i purged the lines and replaced all injectors, along wiht EGR sensor and valve and o2. There are no codes in the truck. ANd some one else suggested a plugged exhaust, so i just got done puttign it on a vac guage. At idol it read 17 in hg snaping the gas gave a reading of around 5 and at 2500 it was about 24 hg, so i dont think it was the exhaust. But the truck still idols rough, and the vac guage jumped around allot any where from 1/2-1 hg at idol. It did move pretty slow and the book said it might be the mixture. Could it be a MAP sensor. If so where is it located and how can i test it.
Thanks

 

There are a couple of ways to test the map sensor, one by tachometer (believe it or not) and the other a voltmeter. The easiest thing for you to do, would be get a haynes manual, it explains either process, and you will end up using it over and over again, or at least I have. Another thing, if you do get the haynes manual, how to test the map sensor (and other sensors as well) is found in the fuel and exhaust systems section, chapter 4. Good luck finding the problem, later

 

Just a note for the Haynes procedure to test the MAP sensor: It says that the MAP wire (the middle wire) should have 5 volts when the harness is plugged to the meter, which is incorrect. It should be 2.5 volts instead. I bought a new sensor thinking that the reading was incorrect, when it was right (per another source). MAP sensors rarely go bad, but it is a possibility. The sensor is near the heater blower on the firewall, with a vacuum line going to it.