I'm haveing this weird Engine problem. Started last night, I think. Driving down the road the truck barely runs at ~600-1000 RPMs, no mater the gear or speed. It will stumble on take off, and it will stumble after and upshift and the RPMs drop. Now its been studdering for a few seconds at first start up in the morning for a while now, not sure if that was an indicator or not. Any thoughts or tips on how I should go about fixing this? Thanks!

 

first off, check your air filter. that is listed in the guide book/repair manual type deal as sputtering start up. how long has it been since your oil was changed? theres a valve, i believe it is called a PCM valve but not sure, it controls something like air or fuel but it can get dirty which can cause symptoms you are having. should be located somewhere around your throttle body.

if not that then check your fuel, it may have water in it. my truck used to have horrible startups and sputtering, shaking, then stalling. when it stalled i pumped the throttle a few times and started her up and she was good to go. been a few months and all ive done is change my oil and airfilter and shes all fine and dandy. dont know if that did it though. hope my first half helped you.

 

Thanks, its the PCV valve your thinking of (Positive Crankcase Ventalation) I havent even thought to check it. Oil is new, ~1000 on it in a month Mobile 1. Air filter may need a cleaning, its dirty but I'v had it quite a bit worse.

Anybody else? I dont care if its totaly stupid or obvious, those things are usually what causes these things.. lol

 

600-1000...isnt that idle speed?? How are you moving enough to even shift [:D]

But really, are there any lights on...O/D flashing? CEL?

Could be the clutch fan...I think that is bad on mine and it is a dog right now
When you do apply the gas does it rev up with not much go and sound like a vacuum? And when you really lay on it (like 4k+) is there any squeaky type noise?

 

One thing to note, I have the OHV engine since its a 99, so it runs at a much lower RPM, I dont even see 4000+ unless I'm in 4low or really passing somebody on it real hard, and on the flip side I can get off the line between 1000~1500 rpm with good power.

Yea idle speed, its bad at idel and just getting off the line, then when it upshifts and drops back down to ~1000 crusing at 30-40

No it doesnt rev up like that. Its almost like there is a dead cylander around that RPM, I can even hear it in the exhaust note, its like a bad miss.

But its not throwing any codes, no CEL and no OD, which I would expect with a miss that bad... thats whats stumping me and why I'm thinking(hoping) its something simple and stupid that I would over look...

 

Might check spark wire boots and make sure they are secure. Check the spark plugs themselves for possible malfunction. (You'll know if that cylinder is dead) Could also be an injector is clogged. Fuel filters? I think that would be more the case on higher RPM problems, unless you have a mechanical fuel pump on that 99.

 

Any whining associated with the rough idle? I had a problem similar to yours a while back... made a real loud ... don't really know how to describe it... maybe howling sound ... turned out to be the idle air control valve... changed it out, and all is well...

 

Nope, electric pump.

That is the plan, pull the all the plugs checking the boots and such and see if there is any signs on them, then clean the throttle body nice and good along with the couple sensors up there. And see if that solves this. Fuel filter is only about 5000miles old, could be an injector... but I have honestly no clue what it could be.

 

Yes and no, I'v had one go before and had it replaced about a year ago. Now this one whas howling for a while, but I could get it to shut up by hitting the gas. It has been a few weeks since it did it, maybe it finally just went... hmmm...

 

Bad fuel
Bad fuel pump/plugged filter/bad fuel pressure regulator
Serious restriction in the intake tract
Smashed exhaust
Melted/plugged catalytic converter
Cam slipped timing or broken

 

All of those would cause problems through out the RPM range wouldnt they? My problem goes away over say ~2500....

 

I thought you were saying it wouldn't rev over 1000 RPM.

So, it has a big bog/hesitation/misfire up to 2500 and then clears out, right?

 

Yes. It idles rough, and hesitates/miss's more so under 1500, but after 2500 its totaly gone and runs like "normal"...

 

You have an IAC that is bad. IAC=Idle air control valve

 

sounds like somethin to do with idle to me. (of course it is lol) but uhhh...check for cable slippage on the throttle body and check your exhaust for crimps or something. have you been exhaust tip deep in mud or water lately? if you werent on the throttle then somethin may have creeped in there. then you may have a valve or lifter sticking that the engine is able to overcome at higher rpms. just because no codes are being thrown doesnt mean nothing is wrong internally. my cats have been off for a month or two and my engine light still has yet to come on (which means it never will for that code)

 

Thats what I suspect too....

 

is there a bannana in your tail pipe???

 

it cant hurt to remove and clean the IAC, as well at the TPS, MAF, and TB itself. make sure to use the correct cleaners

 

Cleaned the MAF with Electric parts cleaner yesterday, cleaned the TB just now, took off the IAC and its full of dirt and grime so I think I found the culprit.. I'm heading to Autozone now to get a replacement and see if that fixed the problem. Thanks for the advice so far...

 

If I find a bananna I'm gonna kick your ***

 

lol

 

Ok.. .UPDATE... now its missing through out the RPM range and threw a code.... now I need to get a reader to figure out what it is...

Oh, and I replaced the IAC and it helped the high idle at first, but then it all went to ****

 

thought about ignition?? coil/s perhaps? how old are the wires? lets see what the code is now and go from there

 

Code is a Cylander 4 Misfire

Wires are about 5000 old, I had a small miss before and replacing them cured it. Coil is the Distributerless Ignition System they all have, so if it goes they should all go, plugs are about 10,000 old and are Autolite Double Platinum.

Soooo... I have the stock wires and a second set of plugs, so I will swap cylander 4's plug and wire and see if it cures the problem.

No the million dollar question, which is cylander 4? Is it numbered

5 6
3 4
1 2

or

3 6
2 5
1 4

??

 

they should have had a printout at autozone to tell you, right now i dont have anything handy to show you. if its not a plug or wire, dont be suprised if its in the ignition. some parts can be tested if removed at autozone if you get someone who knows what they are doing or not to lazy to look in the book