8.1 L Vortec misfire & Ping Solution (non plug wire issue)

garyspang · 02-02-2012, 10:47 AM

(2003 GM 8.1L Vortec) Backfire though intake manifold preceeded with ping ( pre-ignition).
Replaced all known sensors to no avail

. Culprit were deposits left behind on valves, plugs and cylinder walls. Inspect your plugs for any deposits. Problem surfaced about 30,000 miles after ethanol was added to the gas (101,000 mi at present

).
My solution was not instant. It took over two years of experimenting. I will tell you my process.
0. Increased fuel rail pressure by 10 psi for 0% injector boost, as per lap-top display, at 60 mph: no improvement. Setting retained.
0.5 Replaced all sensors. No improvement.
1. Used 3 cans of aerosol SEAFOAM at throttle plate. Partial cure
2. Continued use of SEAFOAM fuel additive: no further improvement.
3. Used OTC 7448 www.otctools.com fuel rail injector with professional fuel injector cleaner: no improvement.
4. Used MARVEL MYSTERY OIL as a gas additive: Problem got worse, re-cleaned with aerosol SEAFOAM.
5. Used Z MAX gas additive in the OTC 7448 fuel rail tool along with gasoline: noticeable improvement.
6. Continued to use Z MAX in gas tank and oil (after oil change): gas mileage went up by 0.5 mpg but no further improvement. Still use it in oil.
7. Used TECHRON CONCENTRATE 20 fluid oz with gasoline in the OTC 7448. Problem solved 99% . Occasional ping occurs, but that is supposed to be normal.
8. Am using 20 oz TECHRON CONCENTRATE in every 80 gallons of fuel as a preventative measure. Engine runs like new

under all load conditions.
Bought two cases of TECHRON CONCENTRATE on sale at half price

. Good bye to pre-ignition and intake manifold backfire.

This was a most frustrating experience, but with about 12,000 gallons of fuel with questionable locally added ethanol passing through the engine something like this is of no surprise.

CoastieSCPO · 02-02-2012, 10:57 AM

Thanks for the report, it's quite a lot of hard work, thought and experimentation. Glad you took care of the problem. So, you used the OTC 7448 to solve the problem with Techron and now, just adding the Techron at fill up maintains the injectors. I will note this in my records for future reference. Again, thanks.

Bob

garyspang · 02-02-2012, 12:38 PM

To CoastieSPCO
This was not an injector issue. It was engine deposits in the combustion chamber and valves. The first treatment was applied through the injectors for the TECHRON to contact the valve stems and combustion chamber directly at maximum strength (50/50 with gasoline).
The issue was never related to injector cleaning or maintaining.

George Schweikle · 02-02-2012, 01:42 PM

Gary,

This is good information. I suspected that Techron was supposed to be good and, several years ago, a friend who worked for Standard Oil related that one of his employees discovered that the Nissan GTP race team was buying Techron on their own initiative for the race car. They had discovered that using Techron maintained engine power during long dynamometer runs. Shortly after I heard this story, a TECHRON sticker appeared on the race car along with the other sponsor decals.

oemtech · 02-02-2012, 07:05 PM

That is the one and only additive other than maybe Stabil I use.

Did your plugs look like these?

garyspang · 02-02-2012, 07:21 PM

Hi George
TECHRON actually dissolves combustion chamber deposits. It is in all TEXACO and CHEVRON gasolines at the pump. Unfortunately these companies are not selling at the east coast where I live. It has no negative effect on anything in the engine or fuel delivery path. A PHD in Chemistry friend that chose to be a high-tech auto mechanic and garage owner told me about it after I unloaded two years of frustration on him. I can now use regular gas again.

garyspang · 02-02-2012, 07:32 PM

Hi OEMTECH
They were actually worse, but colored light brown. The deposits were crusty almost ceramic like. I saved them and showed them to a retired GM engine engineer. He was flabbergasted and remarked that the non-uniform deposits were indicative of an internal combustion chamber flow design issue. I told him it is a Vortec and that means circular air flow which went along with the deposit patterns. He suggested to send the plugs to GM research, but then acknowledged that it may be an exercise in futility since the 8.1 L VORTEC is no longer in production. The mystery is solved and a solution was found.

Full-Timers · 02-02-2012, 07:34 PM

I have used Chevron fuel since my first car (63 ford falcon). Being my first car I knew nothing about fuel but noticed a “seat of the pants” difference with Chevron. I have found since then that Chevron is what is known as a “tear 1 fuel” meaning it is the best you can buy. Chevron has Techron already in it, no need for the additive if this is the only fuel used. Texaco is owned by Chevron and also has Techron in their fuels.
I was always a stickler about using Chevron and my old Hyundai’s carburetor always looked as clean as new until I gave the car to my daughter. She used Arco. She brought me the car one day because it was running bad. I removed the air cleaner and the carburetor was black with crud.

dieselclacker · 02-03-2012, 08:55 AM

Not to be controversial, but I have 42000 miles on my 8.1, and am still running the original plugs that came in it. I have never heard a ping from the engine in the over eight years I have owned it since new. I do not choose a specific brand of gasoline to use in my motorhome, but rather use the lowest priced per gallon that is available. I did experience a noticeable drop in fuel mileage and engine power, while traveling in the midwest and using fuel with a high content of ethanol. I have kept track of fuel mileage on my rig since new, and it still averages 7.5 to 8 mpg consistantly.

I do plan on changing the spark plugs and fuel filter come spring as part of preventive maintenance on the motorhome.

Concerning Arco gasoline, I used to live on the west coast, and used Arco gasoline in my vehicles for years and experienced no problems from doing so. I still use it in my motorhome and toad when I visit there.

I too have heard good things about TECHRON additive as a combustion chamber deposit remover. I have never had the need to use it in my rig.

edgray · 02-03-2012, 09:15 AM

Quote:

Originally Posted by dieselclacker

Not to be controversial, but I have 42000 miles on my 8.1, and am still running the original plugs that came in it. I have never heard a ping from the engine in the over eight years I have owned it since new. I do not choose a specific brand of gasoline to use in my motorhome, but rather use the lowest priced per gallon that is available. I did experience a noticeable drop in fuel mileage and engine power, while traveling in the midwest and using fuel with a high content of ethanol. I have kept track of fuel mileage on my rig since new, and it still averages 7.5 to 8 mpg consistantly.

I do plan on changing the spark plugs and fuel filter come spring as part of preventive maintenance on the motorhome.

Concerning Arco gasoline, I used to live on the west coast, and used Arco gasoline in my vehicles for years and experienced no problems from doing so. I still use it in my motorhome and toad when I visit there.

DC: This post is to remind everyone to NEVER use E-85 fuel in their Workhorse chassis motorhome. Workhorse issued a specific bulletin warning against this "mostly alcohol" blend, say ing it WILL cause problems. In fact, the National Service Director is opposed to any increase above the 10% ethanol we see today. I understand the current administration is pushing for a change to 15% alcohol, but I get better MPG when I pay the extra price for non-ethanol "100% gasoline". Around here the increase is $.05-.10/gallon

wa8yxm · 02-03-2012, 09:36 AM

Sounds like you got it.. I will tell you a short true story.. This is not as much of a problem today as it was back then.. But as a ham radio operator I was listening to the local 2MTR (VHF) Repeater and a couple of hams were chatting.. one had car trouble and the other was updating the tow service for him....We will concentrate on the one with trouble.. NOTE: WINTER TIME well below freezing. his car would start and run, for about half a mile, then die,, after a few minutes it would do it again, and again, This was before all the modern Emmissions sensors and such.

So I am chatting with the ham in the nice warm house... I mention that the symptoms sound a lot like when I had an issue with Gas Line Freezup.. (The Standard Gas (remember when BP was Standard Oil) commercials back then were "My Advice Sir, Get De-Icer" don't you know.

The ham ask how I fixed it.. I put in a can of gas line antifreeze and then switched to standard (Which by the way really did contain a de-icing chemical.. HEET brand gas line antifreeze to be specific)

Where do you get it:

Any gas station or hardward store, It's just shellac thinner (From hardware) if they don't have Gas Line antifreeze.

As I was saying this the ham with car trouble was coasting to a stop.... In front of a hardware store.

He made it home no problem on the next re-try (After visiting the store) and returned the next day to buy a case of the stuff.

Some days...... You get lucky.

dieselclacker · 02-03-2012, 11:02 AM

Quote:

Originally Posted by edgray

DC: This post is to remind everyone to NEVER use E-85 fuel in their Workhorse chassis motorhome. Workhorse issued a specific bulletin warning against this "mostly alcohol" blend, say ing it WILL cause problems. In fact, the National Service Director is opposed to any increase above the 10% ethanol we see today. I understand the current administration is pushing for a change to 15% alcohol, but I get better MPG when I pay the extra price for non-ethanol "100% gasoline". Around here the increase is $.05-.10/gallon

Ed, it wasn't E-85, but good old Iowa corn ethanol added to the gasoline. This was in 2005 in Iowa. I believe the concentration was supposed to be 10%. I have my doubts about that.