HELP - can't go over 45

[powerranger262]

So I was just on my way to get my alternator/battery tested, when my truck decided it only wanted to get up to 45mph. I noticed earlier today that when I turned on my headlights, the engine bogged down a little bit, not enough to kill it or anything, just idled a little lower. So that is why I was heading to get the alt/batt tested. While getting up to speed, I hit about 40 and it starts jerking, bucking like crazy, and when I didn't let off the gas, it let out a small backfire through what sounded like the intake.
Got it back home, put it in park and revved the engine a little, but it wont go over 3K. No CEL, so what the F#*k is it?!

 

[powerranger262]

Just realized the 3K is probably the rev limiter. COuld this be a bad cam synchronizer and where is it located?

 

[Big Jim M]

Ha!

Just realized the 3K is probably the rev limiter. COuld this be a bad cam synchronizer and where is it located?

It takes MORE electricity to go FASTER! If the voltage system is failing the engine may idle or go slow but might NOT go fast.
Big JIm

 

[88_Eddie]

what did they say about the batt/alt?

 

[powerranger262]

Never made it, had to head back home. Hopefully I can get it checked Thurs. at a local shop. Getting a blizzard tomorrow, so everybody will be closed.

 

[powerranger262]

Makes sense to me Jim, I will start there first.

 

[powerranger262]

I've had the bucking problem for about 2 years now. A buddy of mine has a f-150 that does the exact same thing mine does, and he just found out he had a bad coil on one of his plugs. SHould I pick up a new coil pack or just wait until I get the alt/batt tested? Pretty sure coil pack is original, with over 100,000 miles on it.

 

[88_Eddie]

i'd get the alternator tested first, that's easy to do if you have a parts store nearby. deternmine if it is indeed your electrical system or if it's something else. could be fuel, ignition/timing components or even a transmission problem.

my bronco used to do a bucking/jerking thing every now and then, eventually my transmission went out.

 

[powerranger262]

Things I have done/tried. New plugs, wires, IAC, cleaned TB and MAF. Replace my Airhog filter with stock paper one, fuel filter, idler and tensioner pullies replaced. Changed trans fluid and filter, TPS and PCV valve replaced. Cleaned negative battery ground on rad. support, greased slip joint, new u joints, unplugged MAF and drove around, unhooked EGR and drove around, cracked elbow replaced, and probably more, just can't think of it right now.

 

[Earl43P]

If it starts reliably and drives without needing jump-started, it can't be a bad alternator OR battery at this time of year in Wisconsin.

Pretty off the wall, but I'll say it:

The auto trans has a DTRS. I've heard they fail where the engine will not rev past 3k while driving (rev limiter) because DTRS reports to the PCM that the transmission is in neutral, not OD like the selector shows on the dash. That part is also called the Neutral Safety Switch and delivers the reverse lights signal.

So, if you can absolutely say it never revs past 3k while driving, the DTRS is a possibility. Try it in L and 2.

But by all means, get the alt and battery checked. Could be that simple, or could be a bad coil. They'll test the battery and alt for free, right?

 

[powerranger262]

I hope it's free. Advance Auto is too far away to drive there, so I am going to try a local shop.

 

[88_Eddie]

most parts stores do it for free, i know for a fact that advanced and autozone do

 

[powerranger262]

Can't get it to advance, it's too far to go with the problems I'm having.

 

[powerranger262]

Alternator and battery checked out good. 14.4 under load. Took it out for another drive today and there were no problems. Got it up to 65 without anything. I just picked up a coil pack to throw in later tonight. Keeping my fingers crossed. The hood has been open more than closed lately, really sick of it.

 

[powerranger262]

Put the coil in it today, took it for a drive and it did the no go over 45 again. Started leaning towards a possible trans. problem. But, when I pulled over and shut the truck off for a few seconds, then started it back up, it drove fine. I am going to swap out my autolite double plats for some motorcrafts to rule them out. Don't know where to go next. Fuel pressure? Fuel pump? Swap out the computer? I'm just going to have to break down and take it in I guess.