BNew

Hey guys i've been having some problems with my truck and i'm finally sick of it. My truck sometimes will idle ruff fluctuating in rpms it does this pretty randomly but it seems to act up more when it's lugged down or I hot rod it but it'll do it other times usually it just idles rough but sometimes it'll get bad enough it will actually die. I did replace the Idle air control valve but it hasn't fixed it. I don't wanna through parts at it things i'm thinking are Mass air flow sensor ( manifold pressure sensor), Throttle position sensor, or maybe the ignition control module but idk what to look for or if there's another explanation any help or ideas are highly appreciated.

Steve83

If you want help, we have to know what you're talking about. Pre-'97 5.0 isn't enough info. Click this, read the caption, study your truck, and fill in your signature:


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Don't post it - put it in your signature.

BNew

It's a 1989 5.0L 302 all stock

Steve83

Re-read that caption, and finish describing the truck in your signature. Miles, maintenance, each factory option... "Stock" tells us nothing because there were so many options, and many could be deleted from the various trim packages.

Do you have a Haynes manual?


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What about a digital multimeter? Basic tools? An all-weather workspace?


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What's the gap on the spark plugs? What brand & PN are they? How old (time/miles) are they? Have you followed the maintenance schedule? Has it ever been wrecked, or abandoned for more than 2 months? Put your location in your profile because it matters what climate you're in - snowy mountains, Death Valley, Southern humidity & insects...

The more info you give us, the more likely we can help you.

BNew

I have a haynes and chillition manuel, I have a digital multimeter and I have more than just your basics tools. The truck had been sitting for ruffly 4 years before i got it wich was about 3 years ago Its always had routine maintenance every 3 thousand miles never been wrecked or had any serious work done to it. I put on new champion plugs and wires about 2 years ago anong with distributor cap and rotor.

Steve83

That's still not much info in your sig. And I have to wonder how you know it's 155Kmi - that truck has a 5-digit odometer, so it would be really difficult to tell the difference between 155Kmi, 255Kmi, and 555Kmi.

Are you saying you don't know what the current spark plug gap is? Pull a few and check them. This took barely more than a year:


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Read your spark plugs according to the link in that caption, and the inside back cover of Haynes. Have you ever checked the timing chain slop?


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What about the base ignition timing, according to the VECI label? Does it have any vacuum or exhaust leaks? Are all the sensors & actuators in-spec?


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Is the engine bay clean enough for you to notice fluid leaks, insect nests, & rodent activity?


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The only part I recommend swapping for diagnosis is the MAP, and I collect them in JYs because they're cheap & usually still good. I test them in the parking lot before leaving, in case they're bad (refund).


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