2000 Ranger 4x4, 4.0 L engine, V6. Recently it was suggested I try Seafoam in the fuel tank. I have never tried this or any other fuel cleaner before. Just after using the fuel cleaner, I started having problems on acceleration. Happens especially at 50 mph moving to 60 mph. But it can happen at any time when I try to accelerate hard. Truck seems to 'bump' rapidly, almost like a slip. Changed fuel filter, all fluids good. Have used STP several times with no cure. Any suggestions?

 

I can think of 3 things that could cause 'bumping'. An ignition miss due to plugs/wires wearing out, a miss due to the EGR kicking in more than it should, or a hesitation caused by a dirty or broken MAF which doesn't respond to the throttle opening quickly enough to add enough fuel to make the acceleration smooth. A fourth is a fuel filter plugged slightly so as to restrict fuel flow or a pump that doesn't give full flow when demanded.
tom

 

I like tomw's ideas.

How much/oz-gallon, Seafoam did you use & was it only used in the fuel tank????

Do you have a CEL lit, or any misfire codes stored???? If so, go to those cyl's, pull the ignition wire & plug & have a look see.

Let us know what you find.

 

Gosh you guys are quick...thank you. I used one bottle of Seafoam for approx 17 gal tank. Then I used it again...so two bottles for two tanks. And we have used about 4 bottles STP. These are all regular store shelf bottles. Yes, all went in only the fuel tank. And I neglected to say that husband changed out plugs, wires and ignition coil. And he checked the onboard computer with a hand held model. No codes stored. No engine light. Please tell me what EGR is. I'll have the fuel filter checked. Someone else mentioned fuel pump today. As well as O2 sensor, MAF or trottle position sensor. Sorry about these wordy mesg. I'm just gettin the hang of this.

 

EGR is Exhaust Gas Recirculation. The system uses exhaust gas as 'inert' filler into the mixture being inducted into the engine. The inert gas dilutes the fuel/air mixture in proportion to the volume of the cylinder, and prevents formation of NOx, nitrous oxides, by high temperatures within the combustion chamber.
The system consists of a pipe from the exhaust manifold or down pipe, leading to either a)ports internal to the intake or b) a port into the intake manifold. The flow is regulated by a vacuum operated diaphragm that moves a 'pintle' valve. The flow is supposed to be stopped when the engine is idling, and the computer will apply flow depending on rpm and throttle position and vehicle speed(?).
The TPS or Throttle Position Sensor does what it says. It provides a proportional signal to the computer [ECM] that indicates the position of the throttle by the voltage. Open throttle produces a particular voltage {~1.0v} and closed produces a lower, i think, voltage. The ECM varies fuel input based on TPS, rpm, coolant temperature, air temperature and load. MAF or MAP tell the load, or approximate fuel requirements. A sensor in the exhaust, O2 sensor, tells the ECM if there is excess O2 molecules in the exhaust, thus indicating a lean condition where all the O's were not cosumed in burning the HC's.[fuel]
Hope that helps. Changing the spark plug wires and plugs can sometimes make the vehicle run a lot better. You can test the EGR for excess flow by disconnecting the vacuum line and plugging with a golf tee, and then taking a test drive. They can get carboned up and stick. Then you clean or replace as necessary. My plug wires were a light show in the early AM when it was dark enough to see all the arcing to the block and heads. They were close enough that plugging the EGR made me think the EGR was at fault. The 'bucking' only occurred irregularly with no apparent other condition.
tom

 

Thank you. I will get back with you after I digest this good information!

 

tomw, can you tell me where I should start with my Ranger; is there a logical order in which to rule out the different possibilities? And by the way, the last few days I have not pushed her at all and I get no 'bumping'. So long as I accelerate normally, she seems to run fine. I may even wait until I get a engine light and check it then on a computer. Any thoughts?
jenn

 

Perform 'standard' maintenance first. Such as spark plugs, plug wires if they show arcing when the engine is run in the dark, cap/rotor if so equipped depending on mileage. Most times the cap and rotor are replaced when there is evidence of 'tracking' which indicates that the spark current is going down the inside of the cap rather than going out through the rotor to the spark plugs.
The golf tee test for the EGR is quick and simple, and if you have been having regular instances of misbehavior, a quick disconnect of a vacuum line, and a plug with a golf tee can be accomplished to see if it makes a difference 'right now'. Fuel pressure can be tested with a gauge on the schrader valve mounted on the fuel rail supplying the injectors. It should hold pressure after being shut off for a decent period of time, and should have the proper pressure and flow rates, which can be measured with the gauge.
That's pretty much the order I'd take. Others may, and will, have different paths and this is just off the top of my head.
tom

 

Thank you.

 

Did the miss under high rpm load, come about After hubby replaced the plugs & wires???? Or was the miss the reason you've been using STP & Seafoam fuel treatments????

What brand spark plug & wires did he use????

 

If you're into it, block off the E.G.R. port. That would eliminate any possible problem there.

 

Oh no, the miss has been occurring since I put in the Seafoam, directly after a fuel filter change. The spark plugs and wires and the ignition coil are Motorcraft. The plugs have the correct gap, etc. I used seafoam because I had some problems before the gas filter change, and it was suggested I try Seafoam. I am thinking I will go back to the shop that changed the gas filter.