Seirra 2500 - ping problem

[steel_stubby]

Hey there,

 

New to the form, and the interent - curious to know if I could ask for some advice on my 1994 GMC Seirra. It has a 350 throttle body fuel injection with auto transmission.

 

Recently I started to notice a ping. I have been around the engine and tried everything, wanted to see if there was anything else that I could do before replacing the entire d**n engine.

 

I have - checked timing chain and gears

- O2 sensor changed

- EGR valve changed

- new plugs and wires

- knock sensor changed

- tried a new computer

- tried a new distributor

 

 

Thanks very much for reading my post, looking forward to your response.

[Haulin' 8.1]

If by ping you mean the noise generated with load from like bad gas? Make sure it's internal engine and not a loose bracket or such.

 

It's caused by excessive combustion chamber heat, anything that will cause that can cause ping. Lean fuel mixtures burn hotter, check fuel pressure under load and for vacuum leaks after the throttle body. Is EGR opening under part throttle cruise? Carbon build up in the chamber retains heat and acts like a glow plug, run a decarbonizing chemical in your fuel for several tanks or have it professionally treated. Speaking of which if you're not using a top tier gasoline you're getting what you asked for. A restircted exhaust system will overheat the cylinders have a trustworthy exhaust shop check for excessove back pressure. Weak coolant or radiator caps cause localized overheating around the chambers. Make sure your coolant is strong and the system holds rated pressure. Check for a restricted intake, filter etc. Are you getting cool air or hot into the filter? Is your MAP sensor functioning properly and getting a good manifold vacuum signal to read? Sometimes the ports for the hoses get carbon clogged and need to be cleaned out.

 

Vernon

[builderpaul]

If by ping you mean the sound when you are cruising and then accelerate I have never had a 350, with higher milage, that didn't ping . They get carbon in the cylinders, this raises the compression slightly but also can create a hot spot which leads to predetenation (knock or ping as you say).

Easy fix, never seen anything come close as steam cleaning the cylinders. Any old timer will know this trick. I have used it many times works better/faster than any chemical I have tried.

Start and warm engine, fill up a 16oz bottle with water, slighly accelerate truck and dump the water into the throttle body slow enough to maintain the engine speed. You will be amazed at how fast you can dump it in. Instant steam cleaning of the cylinders. You will see the carbon on the garage floor. You will no longer hear the ping.

[99Silver6.0]

If by ping you mean the sound when you are cruising and then accelerate I have never had a 350, with higher milage, that didn't ping . They get carbon in the cylinders, this raises the compression slightly but also can create a hot spot which leads to predetenation (knock or ping as you say).

Easy fix, never seen anything come close as steam cleaning the cylinders. Any old timer will know this trick. I have used it many times works better/faster than any chemical I have tried.

Start and warm engine, fill up a 16oz bottle with water, slighly accelerate truck and dump the water into the throttle body slow enough to maintain the engine speed. You will be amazed at how fast you can dump it in. Instant steam cleaning of the cylinders. You will see the carbon on the garage floor. You will no longer hear the ping.

 

<{POST_SNAPBACK}>

 

 

 

Oh god. be careful doing that s**t. Washing down the dylinders is BAD. Use of SeaFoam would be a MUCH better idea IMO.

[mmmikkke]

If by ping you mean the noise generated with load from like bad gas?  Make sure it's internal engine and not a loose bracket or such. 

 

It's caused by excessive combustion chamber heat, anything that will cause that can cause ping.  Lean fuel mixtures burn hotter, check fuel pressure under load and for vacuum leaks after the throttle body.  Is EGR opening under part throttle cruise?  Carbon build up in the chamber retains heat and acts like a glow plug, run a decarbonizing chemical in your fuel for several tanks or have it professionally treated.  Speaking of which if you're not using a top tier gasoline you're getting what you asked for.  A restircted exhaust system will overheat the cylinders have a trustworthy exhaust shop check for excessove back pressure.  Weak coolant or radiator caps cause localized overheating around the chambers.  Make sure your coolant is strong and the system holds rated pressure.  Check for a restricted intake, filter etc.  Are you getting cool air or hot into the filter?  Is your MAP sensor functioning properly and getting a good manifold vacuum signal to read?  Sometimes the ports for the hoses get carbon clogged and need to be cleaned out.

 

Vernon

 

<{POST_SNAPBACK}>

 

 

Haulin' 8.1 has it right.

 

I had a ping problem on my 95 k3500, turned out to be one cylinder was running lean due to a manifold leak. Take out your spark plugs, making sure to mark which one came from which cylinder. Evaluate the deposits. They can clue you in to the problem cylinder. Lots of web pages give plug deposit evaluation pictures. Find one on google. Then fix the intake leak / MAP sensor / plug wire / etc.