Thought I had an octane issue, Lower Intake bolts are ok, Cleaned MAS sensor, TPS replaced, IAC replaced, CPS replaced, ICM replaced, fuel filter replaced, air filter replaced, Temperture sensor replaced, No more pinging in Drive=3rd gear as I understand it, Pinging in OD=4th gear as I understand it, only when i step on it or am in speeds over 55 mph, when I let off the gas, it stops, and I can cruise at that speed with no pinging, only if I'm going up hill or into a head wind will it ping, if I let off gas, it stops, until I try to accelerate again or put a load on engine, tranny was totally rebuit with all updates about 9000 miles ago, any ideas on sensors for tranny? I heard about a torque converter sensor? Hard to replace and how? cost? And also a shift sensor? Once again cost, and is it hard to replace? And where do I ge these? Dealer only? Any ideas or suggestions appreciated, love this forum, good luck with your Explorers also, I have a love/hate relationship with mine, too much time and $$$ invested to quit now, kind of a challenge now, and by the way, I'm having her painted this week, and hopefully this will be the last sensor I have to deal with for awhile, and also replaced the radio in her last week, needed the tunes.....Help!

 

If your truck is an automatic a4ld, you will have 2 solenoids on the transmission. One is for the lock up torque convertor and the other is the overdrive solenoid. There are no sensors other than the neutral/park/reverse light switch. There is the speed sensor on the transfer case, but the transmission will not shift into overdrive or lock up the convertor if this is shot, let alone your cruise control wont work either. I have been pinging for a while, and on another forum, i heard that the IAT intake air temp. sensor could be fouled. I have yet to check this on my truck, but desparately need a solution to getting rid of a bad ping while going up hill.

 

Thanks Hoppy, I can't beleive with all the people on this site, you were the only with a suggestion, I will try that sensor, I talked to the transmisson people that worked on my tranny, and he thinks I still have an octane problem, cruise control does work, I am shifting into OD, just get the pinging in OD, as soon as I fgure this one out, I should be home free for awhile, how much is an IAC sensor? And where is it located? Hard to replace? Thanks again, and come on guys, any suggestions would be appreciated....

 

Couple of ideas to go along with what Hoppy said.
When you say the lower intake bolts are OK, I assume you mean that you've tightened them. I've heard in some cases the gasket is so far gone that tightening the bolts won't solve the problem. Maybe need a new lower intake gasket.
When you replaced the temperature sensor, did you inspect the wiring? On my '92, the wires going into the connector at the sensor are bare. If they ever cross, the computer thinks the engine is running hot and leans out the mixture causing a ping.
I've also heard that dirty injectors can cause a ping. Try running some injector cleaner through, or maybe even pull them out and have them cleaned good.
Finally, Did you decarbonize the cylinders? Dirty cylinders can also cause a ping.

 

Well,

It could be your lower intake that has gone beyond tightening and needs replacing. It could be your MAF (mass air flow) sensor that is dirty and needs a cleaning as well. I have done both of these things, but haven't replaced the lower intake, just tightened it. Maybe mine is gone, but before going through the hassle of replacing it, I am going to do the easy checks first. The IAT sensor is located on the upper intake, You should be able to see it on the drivers side of the intake and it just threads in. I haven't had mine out yet to clean or test it, but this could be the problem I may try tonight to see if it makes a difference for tomorrows drive into work. If I do, I will repost to this message and let you know. As for price of the sensor? I don't know, I never usually buy sensors, Typically, I just go to the wrecking yard and salvage one of every sensor, bench test them and sometimes try them on my truck to see if there are any differences in performance, then put them into my stock pile of spare sensors, just incase I need one while performing work on my truck at home.

Hoppy

 

Thanks MrShorty and Hoppy, I just rebuilt the whole engine 8000 miles ago, new heads and a complete lower end to the tune of $2000 plus for all, lower intake has a new gasket and torgued to specs, have tried injector cleaners, any ideas on a specific brand? And what do you suggest to cleaning cylinders? I have heard about running water thru engine and letting the steam clean engine, is this safe and does it work? And how would you do that? Thanks again for all the help, as soon as something works, I will post the fix, mostly pings in OD, but occasionally in D also......hmmmmm

 

Well, I tested a few sensors on the truck and to no avail. Still pinging. I had a hunch a year ago that the timing chain is getting stretched and the valve timing is going out on me. I don't want to put any money into this engine, so I have a possible solution that you may try that I tried once before when I had a ping issue. The crankshaft sensor is not adjustable on these engines, so you cannot adjust the timing, unless you modify your crank sensor. I have done this once before and just moved the sensor slightly. I retarded the ignition timing, maybe 1 to 2 degrees and this solved the problem. I am going to do this again as I don't want this pinging to ruin my engine.

 

Changing the fuel pressure regulator. Some of these are known to wear the seat only on one side because of a spring that isn't always centered. This is what I found when I cut mine open. After enough wear, it creates a consistant small leak that lowers the fuel pressure. Lean creates knocking. It would ping on hill and high load situations. OD is a low rpm high load. Be sure to disconnect the battery to reset the computer after one is changed.

 

thanks opera house......what is involved in changing the fuel pressure regulator? not much of a mechanic....any special tools? time involved? thanks