3.7 Duratec pinging question

[mbacfp]

In the course of diagnosing a rattle (was a worn out flex pipe) my car made a pinging sound when we had on rack to diagnose flex pipe rattle. My mechanic said (not sure if I understood correctly) that the 3.7 pistons are flat which can lead to preignition causing that pinging sound. Recommended I use 91 vs 87 octane. Book says 87 or higher...does that make any sense? Gas mileage is good and never heard that pinging before. Thanks for all the help and info you all share.

 

[SubieRubyRoo]

Detonation sounds kind of like marbles in a metal coffee can. Not sure if I believe it, but it will only take one tank to find out. A way to help ensure no additional octane is needed would be to run a good fuel system cleaner with PEA to help clean out any carbon deposits. I don't know how big the tank on that thing is, but if it's less than 21 gallons, use one bottle of Techron or Gumout AIO, and if its bigger than 21 gallons, use two bottles. Then make sure you go for a long highway drive after you fill it up.

 

[mbacfp]

Cool...will do. Thanks...usually hear (thought was part of flex pipe rattle) when slow speed up a hill...appreciate the help...Just noticed other thread on pinging as well...same situation. Take care.

 

[john_pifer]

Hearing some light pinging in low-speed, high-load conditions (exactly as you're describing) is perfectly normal in modern engines. IMHO it's just an indicator that your engine is operating at peak efficiency. It's not going to do any harm unless it becomes full-fledged detonation. And your car's ECU will detect any real knocking and immediately retard timing before any damage can be done, anyway.

What's happening is, as you drive up the hill, you're dipping your foot into the accelerator to maintain speed, but you're not pushing the pedal down far enough to trigger a downshift. Therefore, the high-load condition is causing a little spike in cylinder pressures, and that's causing some minor pre-ignition of the fuel/air charge before the spark plug can fully ignite it.

If it bugs you, you can either run hi-test gas, or just dip your foot down a bit more, and allow the transmission to downshift and raise revs, and that situation won't happen.

 

[mbacfp]

Thanks John_Pifer. That is exactly the circumstances I get those noises...very rare I drive like that slow up a hill...thanks for explaining that for me. Thanks again Subie and John.

 

[PimTac]

Some very good points here. Sometimes you end up in a situation where you might not be able to adjust to get rid of the pinging. Just yesterday I had to follow a slower car up a two lane hill. Fortunately I was in manual mode on the transmission and kept it in a lower gear.

I would try moving up one octane grade at first to see how it goes. There was some good discussion on Redline’s S1 fuel treatment and how to use it as maintenance rather trying to correct and clean over at the fuel additive subforum. That would be your choice whether or not to use.

 

[BAJA_05]

Nothing wrong with using a good Fuel System Cleaner like Redline S1 -- Techron -- Regane High Mileage or Gumout All in One. Give it a shot on your next tank of gas and just follow the directions on the bottle. I personally use the Techron Fuel System Cleaner every 3000 miles in my Acura & Subaru. I would do that before I would step up another octane level if it was my car. Possibly just needs a good cleaning -- back to back does of a Fuel System Cleaner would never hurt also.

Dale

 

[Revving2Redline]

Try Gumout All in One full dose and then use another bottle in micro dosage to maintain. Might help to clean throttle body out too. Occasional ping is okay but keep eye on it. You might just need to try gas from another busier station.

 

[mbacfp]

Appreciate it guys. Have been using Archoil 6200...been tracking MPG and is running great on 87...just noticed rare slow uphill conditions which I thought was all from flex pipe issue...will listen going forward and see if I hear it again...have not for over 110+ miles since flex pipe repair. Good day all and thanks.

 

[mbacfp]

Strictly Costco gas fyi which I thought was top tier unless I am wrong.

 

[oilstudent24]

Had this happen in a 4.0 about 18 yrs ago. Cleaned the mass airflow sensor and it solved the problem. It was like an old school lightbulb filament that was dirty. If you are careful it can clean up. If not it could cost a bit to replace. This was on a 94 ford