Pinging on highway.

[pitbulldell]

I have a 95 Explorer 4.0 .In city driving the truck runs fine stop light to stop light rumps it pulls hard and does not miss a beat and it idles great.I took apart and cleaned the MAF after reading about that on here.the problem went away but now it is back and worse.I have since replaced the MAF with no luck.If I stump on it from a stop ,It will accelerate great up to 90 and above ,but once I let off the gas and get back down to cruising speed and try to stay at 70-80 mph it will start to vibrate and seem to loose power and if I try to accelerate the valves will rattle.Since I have replaced the MAF and giving it a good tune-up where do I look next to fix this problem.

 

[MazdaGreg]

What do you mean by Vibrate? Do you think it could be misfiring?

Pinging is a common problem on 4.0L, but you can sometimes reduce that by running Fuel Injector cleaner though or using SeaFoam. There are many threads on how to do a Injector / Intake cleaning with the stuff.

But, I want to know what you mean by Vibrate.

 

[marragtop]

Try a higher octane gas. Also, how long has it been since you've replaced the plugs and wires?

 

[Crizz]

Can be caused by a bad O2-Sensor or a bad camshaft-position sensor, too. First I would check sparks and cables. If you run the recommended fuel class, check wht happens after you plugged of the batt for 30 min´s. ( Resets the EEC, the Explorer´s EEC automatically detects higher octane fuel - but, if you run lower octane again, it doesn´t switch back ).

 

[rookieshooter]

Try a higher octane gas. Also, how long has it been since you've replaced the plugs and wires?

My 97 would lose power like that untill I checked the OHM's in the stock plug wires and found thay were no where near what the book called for. Made a big differance. Changed plugs with knew wires also. If you pull the plugs look at the condition of them. This can tell you a few things. Ususally in the back of a good auto manual they will have pics.

 

[pitbulldell]

What do you mean by Vibrate? Do you think it could be misfiring?

Pinging is a common problem on 4.0L, but you can sometimes reduce that by running Fuel Injector cleaner though or using SeaFoam. There are many threads on how to do a Injector / Intake cleaning with the stuff.

But, I want to know what you mean by Vibrate.

It feel like I have a tire out of balance,but I know it is coming from the motor,because it goes away when I take my foot off the gas.I did a complete tune up,I even changed the coil pack.

 

[pitbulldell]

Can be caused by a bad O2-Sensor or a bad camshaft-position sensor, too. First I would check sparks and cables. If you run the recommended fuel class, check wht happens after you plugged of the batt for 30 min´s. ( Resets the EEC, the Explorer´s EEC automatically detects higher octane fuel - but, if you run lower octane again, it doesn´t switch back ).

wouln't the check engine light be on if bad 02 sensor or cam-shaft sensor.

 

[pitbulldell]

you can rev the motor to the moon and it sounds great ,you can stomp on it and squeel the tires.It will idle smoothly all day. its just once you are up to cruising speed on the highway it has this problem.If I set the cruise control at 75 and it is going along smooth once I start to go up a long hill the problem will show up.I put a fuel pump and filter on about 6 months ago.

 

[Crizz]

wouln't the check engine light be on if bad 02 sensor or cam-shaft sensor.

you´re right ( if the MIL works )

 

[MazdaGreg]

I say you still have a Misfire. Normally, the OBDII Explorers are good about catching misfires, but maybe this one only occurs under a slight load. I read through the thread again, but want to make sure. You have changed plugs and wires on this truck?

 

[Runnin'OnEmpty]

PitBull, I think you're getting lean misfires. The OBD II won't pick this up, because the plugs are still firing, it's just that the mixture is too lean. Mixture at cruise is (largely) determined by the MAF and TPS signals. Since you've already replaced the MAF, try checking the TPS with an ohmmeter. Look for a steady 1-4v meter movement on the signal wire when the throttle is advanced. If you see spikes or dropping voltage, then the TPS is at fault.

TPS potentiometers tend to wear out in the 'cruise' areas, because that's where the most movement is, most of the time. OBD won't pick this up, because a signal is still being generated; it's just a lean idle signal when it should be a richer cruise signal.

This may not be your problem, but it only takes a few minutes to check the TPS, and dosen't cost anything to rule it out......

 

[Rhett]

.If I set the cruise control at 75 and it is going along smooth once I start to go up a long hill the problem will show up.I put a fuel pump and filter on about 6 months ago.

Stop throwing $$ at it and do something cheap and easy first. I think you need to run some Seafoam through it, and then come back and tell us if that solved your problem.

 

[pitbulldell]

Stop throwing $$ at it and do something cheap and easy first. I think you need to run some Seafoam through it, and then come back and tell us if that solved your problem.

Can you post a How to link please.

 

[pitbulldell]

I say you still have a Misfire. Normally, the OBDII Explorers are good about catching misfires, but maybe this one only occurs under a slight load. I read through the thread again, but want to make sure. You have changed plugs and wires on this truck?

Changing the plugs and wires was one of the first things I did.

 

[pitbulldell]

PitBull, I think you're getting lean misfires. The OBD II won't pick this up, because the plugs are still firing, it's just that the mixture is too lean. Mixture at cruise is (largely) determined by the MAF and TPS signals. Since you've already replaced the MAF, try checking the TPS with an ohmmeter. Look for a steady 1-4v meter movement on the signal wire when the throttle is advanced. If you see spikes or dropping voltage, then the TPS is at fault.

TPS potentiometers tend to wear out in the 'cruise' areas, because that's where the most movement is, most of the time. OBD won't pick this up, because a signal is still being generated; it's just a lean idle signal when it should be a richer cruise signal.

This may not be your problem, but it only takes a few minutes to check the TPS, and dosen't cost anything to rule it out......

Thanks,I will test the TPS at work tomorrow.

 

[pitbulldell]

I just want to say thanks guys for all your help.

 

[pitbulldell]

Still Pinging Along,and Driving Me Crazy.

 

[Crizz]

Did you check the HO2-sensor and can be sure that it is okay ? My 90 XLT kept pinging till I swapped the HO2-sensor, even the MIL hasn´t told me an DTC.

 

[Runnin'OnEmpty]

Pitbull, is your 95 an OBD II diagnostic system?

You must have a vacuum leak somewhere. Check the air tube very carefully for leaks. Even a slight split in the rubber will allow a leak and throw off the mixture. Make sure the clamps are tight. Check the PCV hose.

Also take a good look at the intake manifold(s) for cracks. If all this stuff checks out good, I'd be tempted to change the intake gaskets.....

 

[Rhett]

Can you post a How to link please.

Pitbull before spending all that effort and $$, I would de-carbon the engine.

How-to? There is a thread on this site with pics, I'm sure a thorough search will find it. In short, buy can of sea foam. Put about 1/2 the bottle in a glass container. Then with the engine running, pull any hose off the manifold (brake booster comes to mind) and then, while someone is gently gunning the truck, *gradually* pour in the sea foam, a little at a time, until it's gone. Shut down truck. Let it sit for 15-20 minutes. Then drive it like hell on the interstate for about 10-15 minutes.

Read MrShorty in this thread: He has great advice for you.

http://www.explorerforum.com/forums/showthread.php?t=156991&highlight=sea+foam