1998 Ford ranger bucking issue please help

[1998XLT]

I have a 1998 ford ranger xlt with the 3.0 and its 2wd with 185,000 miles on it. For the past 2 months its been bucking while I drive and its lost performance and sounds like i have a misfire. It only bucks when i accelerate or when i stay at a constant speed over 40. I have checked for low compression but they all have good compression, ive changed plugs and plug wires, ive checked spark and all cylinders have good spark, ive checked for a vacuum leak and there isnt one, ive checked fuel pressure and it was low it was at 40 so we changed the pump just last night, and it had a misfire in cylinder 4 when i bought it a year ago, it had a cylinder 3 misfire and that went away, and now its got a cylinder 5 misfire, it also loses water pretty quick i have to refill my radiator at least every 2 and a half weeks. The only mods on the truck are a set of nitto terra grapplers size 225/75R16 on a set of KMC XD series hoss 795 and a radio from boss audio. Its very annoying and id love for it to be gone.please reply with any info that might help. Im just at a loss of what it might be

 

[adsm08]

Swap the #1 and #5 plug wires on the coil. See if the misfire moves to cylinder one.

 

[1998XLT]

We swapped it and it didnt change. We put a plug in the wire and grounded it out and it sparked fine. its not the plugs or anything like that. weve changed the coil pack also and I just cleaned the PCM but dont know if theres anyway to test if its bad.

 

[Lost Bushman]

You could have an air leak in your inbound fuel line. If it's sucking air, it will buck under a load and throw off your fuel pressure.

No CEL?

 

[adsm08]

You could have an air leak in your inbound fuel line. If it's sucking air, it will buck under a load and throw off your fuel pressure.

Hate to break it to you, but that is a stupid suggestion.

The fuel supply line is under 35 to 50 PSI. It won't suck air in (yes, I am familiar with Venturi, Brunoli, Da Vinci, and even De Caprio), it will spit fuel out.

It also would not confine the misfire to one cylinder. It would be setting random misfire codes.

 

[Lost Bushman]

Hate to break it to you, but that is a stupid suggestion.

Whatever, dude. I'm trying to help.

 

[adsm08]

98, have you tried swapping the injector to another cylinder.

 

[1998XLT]

i replaced all the injectors so they dont even have 100 miles on them.

 

[adsm08]

And the #5 plug doesn't look like it's been steam cleaned?

 

[1998XLT]

no its burning right with no pre-ignition or anything.

 

[transmissions]

Is it worse when you first start the car then gets a little better or no? if so it could be a gasket.

get a squirt bottle and spray a little bit around the intake and head gaskets and see if the motor starts to stall out from the vacuum leak, or just use a smoke machine.

I'd say it could be a plugged exhaust or something but it seems like it's only one one cylinder

 

[HAPPY+RANGER+GUY]

cylinder leak down

Do a good leak down test starting with cylinder number 5. See if you come up with anything there.

 

[1998XLT]

alright ill try the leak down test and tell you how it goes. but no its the same all the time no difference if i just started it or if ive driven it an hour

 

[1998XLT]

Its the same if I just started it or have been driving a couple miles to were its nice and hot. Ill try the leek down test. I just got another read and it was for the ignition pack (coil pack) which I just changed.

 

[bmerr98]

Have you doublechecked your spark plug gaps? Your trouble sounds very similar to what my 1998 4.0 was doing, and it ended up being erratic plug gaps that I had overlooked. Rode around like that for the longest convinced that it must be some mysterious thing that only the noblest and wisest could discern, but it was getting back to the basics that fixed it.