4.0 SOHC cruise issues

[gw33gp]

On a recent trip my 4.0 SOHC started doing some strange things when trying to maintain a constant speed. If I let up to slow a little it was like shutting off the engine. Then when I stepped on the gas pedal to gain speed it would not do anything until I stepped a little harder and it would surge forward. Once, I floored it to make a pass and the engine just booged down. I had been driving for a long distance when this happened. I needed to get gas, so I pulled off to fill up. It was difficult to drive on the streets. When I pulled up to the pump I pushed in on the clutch and the engine died. I filled up and checked under the hood to see if any vacuum hoses were loose or the PCV valve was secure. I disconnected the MAF connector and reconnected to make sure it was getting good contact. When I went to start it, it fired right up and had no further issues until about another 600 miles it started doing it again and went away on its own.

I considered the IAC but thought that would just create an idle issue. Could it be causing throttle control issues at higher rpm?

I had an issue after another fill up where the rpm hung a little high while shifting and when I stepped on the gas pedal to accelerate after shifting it would not go until I stepped down a little more, it surged forward again. It cleared again after that, and I had no more issues for the rest of the trip home.

Is there anything else that could be causing it? I plan to use dielectric grease on the MAF connector to reduce any corrosion on the contact pins that may cause a bad contact.

 

[franklin2]

How old are the sparkplugs? How old is the fuel filter? Any serious sensor issue should turn the check engine light on. Did you happen to get a batch of bad fuel at the station?

 

[SenorNoob]

600 miles? Sure you weren't just out of gas? LOL

Seriously tho. It does sound like an intermittent vacuum leak or bad gas.

 

[Uncle Gump]

The intermittent nature of this will make it tough to diagnose. But there could be clues...

Does it start acting up only after getting near empty?

Have you checked fuel pressure when it starts acting up?

You might want to connect a scan tool and monitor some live data as you drive.

I know this is a high mile rig... has it ever had the fuel pump replaced?

 

[Roert42]

I agree with the others.

First thought was a vacuum leak. I’ve had similar issues before that were caused by a crack in the upper intake manifold (plastic)

I’ve also had similar issues caused by a weak fuel pump, clogged fuel filter, and bad wiring going to the pump.


I have a fuel pressure gauge, so I would probably check that first.


I’m leaning more towards a vacuum issue.

 

[sgtsandman]

I haven't worked on a Ranger cruise control but on the Honda CR-V, they were sensitive to vaccum leaks and throttle cable adjustment. They had their own, dedicated vacuum reservoir and an in line check valve to prevent robbing the rest of the system of vacuum if something in the cruise control system failed.

So, see if your system has a check valve and if so, is it functioning correctly. Check the reservoir for cracks, if it has one. The actual actuator may have a vacuum issue as well. The diaphram inside may be failing.

 

[gw33gp]

How old are the sparkplugs? How old is the fuel filter? Any serious sensor issue should turn the check engine light on. Did you happen to get a batch of bad fuel at the station?

The spark plugs and wires were changed less than 10K miles ago. Fuel filter has around 15K miles on it. No check engine light. This happened with several tank fills on a 15,000-mile trip.

Fuel filter change is a good idea.

 

[gw33gp]

The intermittent nature of this will make it tough to diagnose. But there could be clues...

Does it start acting up only after getting near empty?

Have you checked fuel pressure when it starts acting up?

You might want to connect a scan tool and monitor some live data as you drive.

I know this is a high mile rig... has it ever had the fuel pump replaced?

It did occur once at about 1/4 tank left. It also occurred at 1/2 tank. It did not happen once when I was pushing the gas limit with about 1/2 gallon left. I carry extra gas when on long trips.

A scan tool is a good idea, but it seems to only happen after driving a long time (3-4 hrs). The fuel pump was replaced once.

 

[gw33gp]

I agree with the others.

First thought was a vacuum leak. I’ve had similar issues before that were caused by a crack in the upper intake manifold (plastic)

I’ve also had similar issues caused by a weak fuel pump, clogged fuel filter, and bad wiring going to the pump.


I have a fuel pressure gauge, so I would probably check that first.


I’m leaning more towards a vacuum issue.

I will be checking fuel pressure. As I said before, it only happens on a long trip. Fuel pressure could still be low on a short trip.

 

[gw33gp]

I haven't worked on a Ranger cruise control but on the Honda CR-V, they were sensitive to vaccum leaks and throttle cable adjustment. They had their own, dedicated vacuum reservoir and an in line check valve to prevent robbing the rest of the system of vacuum if something in the cruise control system failed.

So, see if your system has a check valve and if so, is it functioning correctly. Check the reservoir for cracks, if it has one. The actual actuator may have a vacuum issue as well. The diaphram inside may be failing.

It never actually happened when using cruise control, only when trying to maintain a certain speed manually.

 

[gw33gp]

Thanks for all the suggestions. I have some new ideas to work with. I may not ever have the problem again because I most likely will not use it on long trips again. However, problems like this usually get worse with time and start happening more frequently or all the time.

 

[sgtsandman]

It never actually happened when using cruise control, only when trying to maintain a certain speed manually.

I misunderstood the context then.

What about the throttle position sensor? Perhaps the engine bay heat is getting to it in certain conditions?

Meaning that it might have some developing dead spots being exacerbated by getting hot.

 

[Uncle Gump]

It did occur once at about 1/4 tank left. It also occurred at 1/2 tank. It did not happen once when I was pushing the gas limit with about 1/2 gallon left. I carry extra gas when on long trips.

A scan tool is a good idea, but it seems to only happen after driving a long time (3-4 hrs). The fuel pump was replaced once.

Like I said... gonna be rough to figure out. Maybe you deserve another road trip?

I figured you could monitor some engine data to have a base line on "normal" data values... and when/if it acts up... you might find some way out of the norm.

It sounds like fuel delivery to me. I'd be prepared to check fuel pressure any time its out on the road.