motor not working right

[purple_fluffer]

I have a '99 ranger 4cyl, runs great, haven't done anything to it lately to make it do this so I don't know why it's doing this.

drove to a 7-11 no problems. started it to go home, that's when the problems started.

starts fine, idles fine, but anything to do with the gas pedal being pushed down, it has no power at all, except it revs by itself over and over up to where the gas pedal is. by the way it sounds, people think I'm doing that. but I'm not doing that, it's doing it itself. I'm just holding down the gas pedal.

push it down halfway: mmrRrmmrRrmmrRrrmmmm
push it down all the way: mMRRARRMmmMRRARRMmmMRRARRMmm

that's all how the gas pedal functions, nothing else. I can't get it to do anything different. either that or idle.

so when I actually put it in gear, I can't barely get going in 1st I have to work the clutch to keep it from dying, I have to floor it and work the clutch to get the truck moving anywhere, when it's fully engaged the whole truck keeps bucking like I'm trying to break the driveshaft. same for all gears.

I figured out once I get past 2nd, I can dump it in the next gear and just floor it while massively short-shifting (20mph for 3d, 30mph for 4th, 45mph for 5th) because it has little power, so it gets up to a few rpm's before it starts bucking again, and then on to the next gear and do the same thing.

put it in neutral and let it idle while coasting, the motor purrs like a kitten.

got it to the auto parts store, they connected a diagnostics thing to it, shows no error code. that sort of rules out electrical problems or a broken sensor. checked the fuses, all good.

I'm leaning towards some kind of mechanical problem that wouldn't make an error code, but I don't know what. gas cap wasn't making a vapor lock.

right now it's sitting in the driveway, may be able to make it to a mechanic but not going to try anywhere else. I'm stuck.

it was running beautiful, like always, right up to when this started. so it wasn't a gradual problem.

I just don't know. anybody know?

 

[dangerranger83]

It sounds like a vacuum leak. Check your hoses for cracks, broken hoses, or could be an intake gasket. Spray carb. cleaner around the hoses, etc... If the engine idles up then thats the problem. Same thing that happened to my dads truck, it blew a vacuum plug off the vacuum tree on strat up and ran like crap and wouldn't idle for s***.

 

[Earl43P]

Take a look at your timing belt.

These symptoms sound like it jumped a few teeth to me.

Next, I'd suspect an ignition problem. Use an old spark plug and see if all of the plug wires are good. Pull the wire off each plug one at a time and put the wire on the old plug, set it on the engine and watch for spark. If they all look good, I suspect timing even more. How old is the belt? Ever been changed?

If it were bogging down with rpm, I'd go after fuel pressure, BUCKING as rpm increases sounds like a timing problem to me.

 

[purple_fluffer]

timing belt never has been changed. about 90,000 mi. hoses look ok, didn't find any vacuum leaks. spark plugs all have spark. now it doesn't idle good like it did yesterday, surges a few times and conks out. slight popping every once in a while, I'd assume it's a backfire.

sounds like a timing belt to me, but strangely, the Haynes manual doesn't mention timing belt anywhere in any part of the troubleshooting section. it shows how to replace a timing belt later on but that's it.

anything else to look at? I got all day, no mechanic to take it to on sunday.

 

[Earl43P]

If it were me, i'd already be disassembling the front serpentine, timing cover etc. to see of the timing marks line up. It's due for a belt anyway, so it's not a wasted effort.

Could throw a timing light on it beforehand, I couldn't tell you what degrees to look for. If you post degrees at idle and revved, somebody will be able to decipher it.

For it to have spark yet it happened so suddenly, I'm convinced timing belt jumped when you shut it off at the store. I was also thinking maybe clogged cat/exhaust, but that wouldn't happen all of a sudden.

 

[purple_fluffer]

I don't have a timing light. I think I'm going to take a whack at changing the belt myself.

 

[Earl43P]

Busy work, not really hard.

If you pull the plugs, it cranks over easier, plus you can verify TDC.

See how it was lined up before you pull the belt, sanity check.

 

[purple_fluffer]

just to get back to yall, I replaced the timing belt, that wasn't it.

took it to the mechanic, it was the mass airflow sensor. which was puzzling, because there were no error codes.