Knocking and pinging

[Mpetronek]

I have a 91 xlt 4.0l v6...when I put my foot to the floor it makes a knocking/pinging noise...I was wondering what I can do to fix this? I am filling it with regular from chevron so its good gas...can my intake have any input on this? lack of octane? Thanks!

 

[sledgehammer1990]

Sorry I cannot help with this, but I am actually having the exact issue. I was considering changing out the spark plugs and wires, but I haven't gotten to do that yet.

 

[Mpetronek]

I thought about changing my plugs too, they are right around the mileage where they need to be changed again. Ive tried octane booster and that seems to help a little bit, but its still there.

 

[sledgehammer1990]

I have sea foamed my engine, but that was it. How many miles do you have on yours? I am coming up on 125,000.

 

[rileyrs]

i would suggest you run an injector cleaner, in your gas, i use lucas oil injector cleaner.
then maybe seafoam in vacuum line to clean it out, and after that new spark plugs.
then switch to a cooler thermostat to lower temps.

if none of this works, then remove upper and lower intake manifolds and clean everything out well. then replace the manifold gaskets with rubber ones rather than cardboard, and this should reduce carbon/oil buildup in the future, and hopefully fix your problem.

good luck.

btw, anyone have other thoughts on this issue?

 

[Mpetronek]

Thanks for the help! that all sounds good!

 

[Mpetronek]

I have about 137k right now...I have run the injector cleaner through a full tank also.

 

[boggs1227]

rileyrs is kinda right about the intake system ....

mine had a bad ping and after looking at the lower intake manifold i discovered that almost all the bolts were finger loose ( common problem with these engines.

wrenched them back down and no more ping .

 

[rileyrs]

yai forgot to mention check the bolts first.

but either way, cleanin it all out and then using a rubber gasket should help in the future.

dont forget to regurlary run injector cleaner.

i do every other tank, and it seems to help.

 

[Mpetronek]

Awesome, thanks guys!

 

[rayford2]

Egr

Don't forget that EGR valve. When they get dirty they can cause a lot of headaches. On a '94 you can use the "check engine light" to extract trouble codes. If you get 335, 336, or 337 in KOEO or continuous memory a good cleaning or replacement of the EGR valve and/or EGR vacuum solenoid should be considered. Ray S. in PA

 

[rayford2]

Awesome, thanks guys!

Concerning injector cleaners: Some pintle seats on fuel injectors don't particularly like cleaners that contain methanol due to their composition...Watch yourself. Ray S. in PA

 

[celly]

Be careful with your plugs when you Seafoam. I swear by Seafoam, but a recent performance issue I had with my Ex was related to Seafoam. My almost brand new Motorcraft Platinum plugs were pretty fouled and the issue can only be related to Seafoam. They were fouled by all the carbon and other gunk freed up after a recent cleaning. I just had to swap out all the plugs as a result.

 

[Rhett]

if none of this works, then remove upper and lower intake manifolds and clean everything out well. then replace the manifold gaskets with rubber ones rather than cardboard, and this should reduce carbon/oil buildup in the future, and hopefully fix your problem.

Where can I get rubber intake manifold gaskets?
Are there any drawbacks to using rubber gaskets vs. traditional cardboard? Heat issues?