preignition "rattle"/"ping"

[45acp]

I'm being plagued with pre ingition rattle when the engine is warm and I accelerate or put any load on the engine when it's in a higher gear. This is a 1999 3.0 with an auto 4sp. ( multi fuel) with only 38K on the clock ( bought it from an old guy that died while I was buying it). I have pulled the MAS and cleaned it ( looked fine) and also ran a tankfull of fuel with BG cleaner in it. with no inprovement. No noticable vacum leaks & temp gauge is in the middle/normal range. As the MAS for this model is over $100 ( while the one for my 94 4.0 was only $49.00 ????) I hate to replace it just to find out. No "check engine" codes or any other problems noted. Suggestions appriciated! P.S. are the gauges in this truck functional, or are they the 2 position -idiot light type gauges?
Thanks.

 

[Big Jim M]

Your gauges will tell you if you have enough oil pressure, if the battery is being charged, if you have enough fuel or if the temperature is normal. That's all we need to know! Knowing the exact poundage of pressure or the exact degree of temperature will only serve to excite most of us unnecessarily!
Having only an average of 3,000 miles a year my guess about the pinging is carbon'd-up compression chamber. I think a good hundred mile or more drive would be really good for it. After the drive you may have cleaned up the chamber some.
short of that you may have a vac leak that is leaning out the mixture.
Big Jim

 

[Froggmann]

If it's Flex Fuel and you have access to E-85, run a couple tanks through it. It's the best fuel injector cleaner there is, it also cleans the combustion chambers a bit as well.

 

[45acp]

well, I ran a tankfull of gas through it with the (highly recommended) BG44 (@$22 a can! ) with no appriciable difference ?

 

[kimcrwbr1]

pour about 3 1/2 ounces of acetone in your tank with every fill up for 15 gallons add subtract however big your tank is. Better fuel mileage and it will dissolve any varnish is in the whole system. When the idiot lights come on dont ignore them that will make you one also. When you turn the key on before you start it does the oil light come on or do you have guages that dont register. Did you have a diagnostic done or are you using the on board system, take it to a part store and have them pull codes for you. Pinging is normally the timing is too far advanced and the computer controls it.

 

[McCormack]

A 180* t-stat and disconnecting the hot water feed to your intake manifold are effective ways to reduce pinging. If it still pings after doing those mods then buying a tuner and retarding your timing a degree or two will completely eliminate the problem.

 

[bcost882]

he says it pings before it is warm though, usually pinging comes from cylinders running too hot or running lean, or crappy gas. you can try replacing your fuel filter. or put a tank of gas though from a relativly good gas station and not a cheapo place. I had that problem when i got gas from am/pm. then i got gas on base and it seems to be mostly gone except when flooring it at 1500 rpm or something retarded like that.

 

[BRUTUS_T_HOG]

well, I ran a tankfull of gas through it with the (highly recommended) BG44 (@$22 a can! ) with no appriciable difference ?

44k isn't a cleaner, it KEEPS the fuel system clean after you have run BG's other intake and carbon cleaners through the engine

after determining no other cause for pinging we run the engine on the cleaner and then spray carbon cleaner through the intake for 10-20 minutes. it works very very good. there is usually no pinging afterwards.

i would recommend finding a shop that does BG fuel injection/induction cleaning and getting it done.

seafoam does the same thing but not as much

 

[45acp]

Well, I filled it up with premium (93), put a bottle of Lucas intake/cylinder cleaner in it & ran it 70mph + for about 70-80- miles, and the pre-ignition rattle/ping.... stopped. Now the question is what will happen whenI go back to regular gas. This being a "multi fuel engine", it just should not be this bitchy about the octane. Got to be a problem in there somewhere with either the data sent from a sensor to the computer, or with the the way the computer is responding ??? But I guess that at least rules out a vacuum leak.

 

[stmitch]

There may not be a mechanical issue. The 3.0 has always been a carbon building whore. The 3.0 cumbustion chambers have a reputation for being rough castings which traps carbon, and pings. So it may be more of an engine design/manufacturing issue.
Keeping your fuel system clean is key. I have the same engine/trans as you, and if I run pump gas extensively, I will get pinging. I have switched to running e-85 almost exclusivley, and have ZERO detonation/pinging now. As others have suggested, if its available near you, I'd try a tank or two and see how you like it. If you want to continue with the unleaded, I've had great sucess with the Lucas fuel system cleaner you used. But you're going to have to put some in every few tanks to keep things clean and avoid the pinging.
The best fix would be to take the heads off and smooth out the casting on the cumbustion chambers, but that's a pretty extensive job.

 

[45acp]

anyone else live in my area (Atlanta, Ga.) and know what stations sell E-85? There is a Sunoco down the street, and I run a tankfull of their super premium through my Harley twincam every few tankfulls, but havn't seen the E-85 anywhere ???

 

[stmitch]

Enter your city/state here: http://www.neare85.com/neare85/mapper.php

If you haven't used it before, I'd suggest phasing it in slowly by mixing it with gasoline. Start with about a 50/50 mix. The e-85 will clean out your entire fuel system. Too much at once can clog your injectors or fuel filter with the grime that has accumulated in your fuel system.