Pinging/Detonation-94 Civic EX 1.6L

I have been fighting excessive pinging/detonation for over a year now. Had
dealer clean throttle body and change plugs but the only thing that works is
high octane fuel. According to owner's manual minimum octane is 86 but it
even pings with midgrade 89 octane with low humidity.

Could it be carbon buildup in the cylinders? - my wife drove this car for
four years 2 miles to/from her work.

Thanks for any suggestions!

Mike S.

 

Did you have any work done on the car prior to this problem? Timing belt
change, ignition timing adjustment etc.? I am not asking because I can
provide any particular insight, but I am curious as my '94 Civic with
the same D16Z6 engine as yours has been doing the same thing since about
March of last year, particularly in warmer weather.

 

Mike S. wrote:
-> I have been fighting excessive pinging/detonation for over a year now. Had

===============

What's the mileage, are you at high altitude, when was the timing belt
last changed, what plugs did the dealer put in, does it always start
well, have you checked your dash lights to be sure that some of the
imprortant ones aren't burnt out? Does it ping when cold or only when it
indicates normal temperature? Is your idle stable when cold and hot?
When was the distributor cap changed last? Does it ever backfire thru
the intake or exhaust? When did you last adjust the valves?

'Curly'

============

 

I have the exact same problem on my 91 Si. I'm the second owner. The first
owner drove it to and from work for about 8 years..less than 5 miles each
way.

It's very likely that carbon built up from the short drives, that's what I
suspect on my car. I have to use premium on mine as well.. 89 is just not
good enough. I don't mine paying the extra 10-20 cents though. I still get
36 mpg combined city/hwy, and about 39 hwy.

 

Randolph - the short answer is no. It has been pinging since I met my wife
in 1999 (she bought the car new in 1994) although not nearly as bad as it
does now. We had the timing belt changed about two years ago around 90,000
miles.

It is worse during hot days and very dry air but that is simply the physics
of when a piston engine is more likely to detonate. I drive the car
typically shifting around 3000-3500 rpm and it will ping throughout the
whole range.

 

Great questions -
current mileage - around 118,000
elevation - 200 feet amsl (Richmond VA)
timing belt - 90,291
standard plugs per the owner's manual - I questioned them on whether hotter
or colder plugs would help
starts very quickly unless it sits for several days but then only a couple
seconds more of cranking
all dash lights appear to work when ignition first turned to on
does not ping when cold, only when at full temperature
idle is fine hot and cold
distributor cap and rotor at 90,291
never backfires, ever
valves adjusted at 90,291

Several dealers and other mechanics have tried fuel injector cleaner and
throttle body cleaned twice. I really believe it is excessive deposits in
the cylinders as my wife is a short shifter (I try to run it harder when I
drive it) and for the first five years she only commuted two miles each way
to her work. The last dealer did not have a borescope and could not look
inside the cylinders.

 

Pailyn - I wish I could say the same about the fuel costs. While we average
about 35 MPG the extra 10 (89 octane) or 20 (92 octane) cents per gallon
amounts to $40-$80 a year for us at 14,000 miles/year. That money could be
better spent on lunch and beer! It just bugs me that the car should run
fine on as low as 86 octane (per the manual) and it does not.

 

If you find something that works or cure your problem please let me know.
You can email me directly. I have used a bottle of that GM ..$30/bottle
fuel injection cleaner before in an effort to clean it out with no luck. If
could get it down to not ping with regular unleaded I would be happier as
well...

 

It could be carbon build-up and the non-tear-down "solutions" are sometimes
efective: e.g. a mechanic's decoke... IOW an extended hard blast down a
freeway. Maybe this, with one of the fuel additives which claim to clean
combustion chambers could help.

Another thing to consider is oxygenated fuel. If the oxygenate is ethanol
and there is some water present in the fuel tank, you can get a significant
reduction in effective octane of the gasoline. Ethanol, at 10%
concentration in gasoline, has an effective octane blending number of 111
so it contributes greatly to the gasoline's octane. Any separated water
will pull the ethanol out of the gasoline and therefore reduce its octane
number. In that case, try a bottle of isopropyl alcohol gas line
"antifreeze". Do *not* use rubbing alcohol.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

Pailyn - I will certainly contact you if I find the "cure". I have tried
Chevron's Techron and Amsoil's fuel injector cleaner also but to no avail.

 

George - thanks for the advice on the water "dissolver". While looking back
at my 90,000-mile maintenance invoice I noticed the Honda dealer used and
charged me for a bottle also.

Mike

me??

 

There are many different causes. But yes, too much stop and
go or short trips may cause carbon deposits in the combustion
chambers that could result in preignition. Some fuel system
additives and an occasional high rev may help with carbon
deposits if you must continue with your habits.

When too much carbon buildup inside the cylinders and on the
pistons, it can reduce the size of the cylinders, increasing the
compression and temperature of the cylinder, and retain
excessive heat which ignites fuel early.

Run some engine deposit removing fuel additive using higher rev
or at times higher, which sounds like you're already doing.

 

Additional thoughts.

Pinging not only can be damaging to the engine but may also
produce excessive amounts of nitric oxide, a colorless poisonous
gas (NO) which each state requires a certain allowable limit.

 

Milo - I used the Amsoil Foam Engine Cleaner, you shoot the whole can into
the throttle body intake under high RPM, turn the engine off and let it sit
for ten minutes, and then "run" it out on the highway to blow out the
carbon.

I never noticed a difference unfortunately.

Mike