Hey guys, I usually hang out on the '48 to '60 board, but I recently bought an '89 F150 with a 300 6 in it. I love the truck, but I was wondering if it's just me and I'm expecting more than it's able to deliver or if it's got something wrong with it? It has a 5 speed in it, and I've never owned a vehicle with a stick before. I've driven lots of them before, but never owned one. When I got this truck, the trans was stuck in 2 gears, cause the previous owner run it without trans oil (it leaked out the shifter rail) I fixed the leak, and got the trans "unstuck" it does fine, but the 2nd gear synchro is bad.


Anyway, my question is do your trucks feel kind of like they fall off from power around 2200 rpms? I mean if I keep it around 2500 or higher, it pulls pretty good, but when I get it in 4th gear, it just dont have much power? I'm thinking about chaniging gears. It has 3:08's now, I'm thinking about going to 3:55's. The truck is a 2wd long wheelbase. It is EFI, and still has all of it's hippy tree hugging smog junk too. Would I gain anything to take off the convertors and run true duals? I've been told that Ford smogged these engines to death in the early years of EFI.

What do yall think?


Thanks for any help!!

 

Try change spark plugs, air filters, check compressor on those engine, and get sea foam from auto store that should help you notice power better.

Do those have injector? maybe fuel filter is dirty so try change that and see if it work or not then try check gas pressure I think 40 to 60 psi is good.


for manual transmission you would like 4 speed because heavy duty or you can get 5 speed from junkyard but make sure they are work good.

Or rebuilt that transmission.

 

The EFI engines put out the most power of the 300 line, hippie smog stuff and all. Sounds like something is off here, as the engine usually pretty strong and getting stronger at 2200 and falls off after 3500, maybe a little higher for the EFI.

Only if the cats are plugged, and they are not if it runs good over 2500rpm, would you gain.

Some folks have claimed gains getting rid of the stock muffler as it seems to be a cork. Real power or just noise, no one has a dyno in their back yard to prove it either way....

You can find a rebuilt trans or if you want a granny low gear and od switch to a ZF. Rebuild kits are available also. Google "m5od rebuild kit" and find dozens.

 

I wouldn't do true duals. High flow cat and muffler. I did a Y pipe and ran two pipes. I got rid of the muffler and I regret it. I lost power when I did that. People told me I would but I didn't believe them.

3.08's aren't bad but they're highway gears. Slow off the line.
My power band in every day driving is up to about 2,400 rpms, and I'm kind of a heavy foot. I never need to go over that typically. My numbers may be a little off - I'm more tired than a zombie and I can't fully remember what kind of RPM's I run in *normal* driving. However you shouldn't feel the 300 go slack at 2200. There really isn't a whole lot more power past that, but there is *some*. If I were you, I'd go through everything and give it an excelent tuneup.

If it's any consulation, *my* 300 sometimes feels like a dog. Don't know why. Truth be known there's probably something wrong with it but I can't tell. It runs and it runs good, but sometimes it just feels really doggy and slow. Makes a lot of noise but doesn't move like it should.

 

Since it is an EFI you might end up in a world of hurt removing any of the hippie tree hugging smog junk since all that stuff inputs to the computer...it can't handle very much less than all systems operating as they should.

 

Hey guys, I forgot to tell you, when I got it the high pressure fuel pump was bad or going bad. I didn't have much fuel pressure (about 25 psi) I changed the high pressure pump and fuel filter. The previous owner had just tuned it up, but it looks like he used twilight zone parts (auto zone junk) currently it still has EVERYTHING of the smog junk, it's just UGLY!!!!!


I scanned it tonight, and come up with a 32 code and a 51 code. I know the codes are coolant temp sensor and 02 sensor's. The truck runs fine, sounds great! It's just a dog!! I've heard that these things had all kinds of torque till around 2800 rpms, but so far I'm not impressed. I'm not trying to make any of you diehard's mad, but I'd just like to find out what's wrong with my truck?? I do know if I changed the gears, that would help, but I dont know how much? On a side note, I just had the radiator flushed, and the heater core too, and I dont have a heater worth a hoot!! the heater hoses are only getting up to 140 degrees. I have an infrared temp gun that I tested them with also on the thermostat housing. I just replaced the thermostat too with a 195 degree one.??? Any ideas would be appreciated!!

 

Before someone volunteers me, I'm out of my league when it comes to EFI's.
All my time is w/ '65-'72 Carb'd versions & all my books are still packed away.
Silver Streak would be a good one for this I believe, as he keeps all that stuff locked away in his head.

 

Hey guys, I've been reading some of the other threads on here and I meant to tell you my truck is getting 15 miles per gallon and if I keep it around 2500 rpms it feels pretty good? It's just different than anything I've ever drove. I'm still wondering if any of you have an '89 with 300 6 and a 5 speed with 3:55 gears do you get bad gas mileage? Thanks again !!!

 

One thing to remember is the 300 has, in your version, about 250-265 lb ft of torque. That comes on just above idle and peaks about 2000 rpm.

That torque curve makes the 300 feel more powerful than it is. A 302 makes more torque and hp, but needs another 1000 rpm to hit the mark at least. While the 302 gasps and bogs, the 300 pulls. So if you are expecting a Keith Black drag motor, you are no doubt disappointed. If you came from a larger V8, you are no doubt disappointed.

That said, it should pull cleanly and in a very linear fashion from right off idle. If you have a flat spot or bog between 1200 and 3000 rpm, something is wrong.

 

If you're getting a code that the temperature sensor is bad then I'd investigate that further since coolant temperature plays a big role in air\fuel ratio. The 300 is a peppy motor. My '79 has a 300 with California emissions and it's pretty quick, and can keep up with highway traffic pretty easily until about 60-65.

 

Thanks guys! That's what I needed to hear. There's nothing wrong with the motor then, just needs a coolant sensor, but still runs well. Yes I did come from big V8's so I'm a little disapointed, but now I know what to expect. I still think I'll change the rear gears to 3:55's anyway.


Thanks again!!

 

3.55 is probably the perfect balance. Although I went to 4.10 and I like it. She's quick off the line now.

Mine doesn't do too bad either. I don't have any idea what kind of emissions are on it. She'll run with the best, and blow away off the line.

 

Definitely fix the O2 and temp sensor, then come back with what has changed.

And as for big V8 vs. 300, they truly are two totally different beasts. I went from a 300 to a 390, back to a 300, and now i'm working back towards a 390 again (long story).

What I tell everyone is the 300 has half the power of the 390 i was running, but is more than twice as smooth and pulls twice as hard right immediately off the line. The 390 is twice as powerful, half as smooth, and passes the 300 about .25 seconds after launch.

In the end I love them both for what they are, but right now my goal is to build a 390 to idle and run just as cleanly as my 300 while making all the power that it did before. Best of both worlds

Justin

 

Change your coolant temp sensor b4 you mess w/ ur O2 sensor, if your coolant temp. is constatnly reading -30F it will be dumping fuel into your engine, causing bad gas milage and the feeling of flooding, it will also cause the O2 sensor to read rich and do everything it can to lean out the mixture once it goes into closed loop. But the cpu may never go into closed loop when the temp sensor is constantly that cold.

I to have 31's and 3.08's and hate em, or rather I hate the T18, 2nd and 3rd I can power through, but 4th I seem to fall outta my powerband, there's to much of a jump, it's great for the interstate doing 75mph where my engine is making it's power, but now back on the highway I hate it. It's better then stock, way better then stock, but it could be better with closer gears. I think the 5spd ZF, 4.10's and 35's would be about right.

 

One thing that jumps out at me, is the engine is only running around 140*F, even though you say you just replaced the t-stat with a new 195*F unit. Perhaps it is a bad t-stat. New does not always mean good.
Getting a temp sensor code does not mean the sensor is bad, it means it is reading "out of range". This issue can be from either a bad sensor, or the engine running too cool/too hot. 140*F is too cool. Your infared gun has backed up the coolant temp sensor reading out of range.
I'd say try another t-stat, as it seems this one is just not doing the right thing.