car problems, detonation

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
hello,

i'm having some detonation issues in my civic. i can't get it to go away. it happens mostly at part-throttle when the engine is warmed up. i put some NGK g-power spark plugs in, ran them for 7000 km and took them out (i now have stock ngk in there) and they look PERFECT. i don't get it.

ok so anyway i've been told that this car has no EGR.. and no knock sensor.. to me this sounds like a pretty stupid setup as the EGR would allow cooling of the combustion and the knock sensor to retard the timing. i've checked the timing and it's right on. also changed fuel filter, air filter and added some fuel system cleaner crap to the gas tank a few times.

the one thing that i will say is that there's a small crack in the radiator at the top where the air intake is bolted on... i've tried to contain it using JB-WELD but it always manages to seep though. since it's at the top it will only make the water level go down to a certain level until it will stop leaking (until the maximum pressure level is right below the crack). the temperature needle always is in the lower half of the gauge (it always points at the bottom of the green square around "D4"). the engine light is not on and there's no codes.

help meeeee

it's a 1991 DX 4-speed auto, dual point injection btw.
 

Rent

Diamond Member
Aug 8, 2000
7,127
1
81
Originally posted by: Pepsi90919
Originally posted by: Radeon
Check your spark gap...

how do you know your car is detonating?

the spark gap is 0.042 inches.

you car hear it.

Detonation kills your car. Quickly.

Perhaps you aren't detonating.
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
Originally posted by: ElFenix
using high octane gas?

it recommends 91 research octane, 86 pump octane and i use 87... i'm not going to use expensive gas in a fricking econobox, and besides that there's an underlying issue that needs to be fixed. having said that, i've changed brands of gas with no effect.
 

What year civic ?

Almost all cars built after 1973 have EGR valves.
Is your civic fuel injected or carburated ?
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
it's a 1991, 1.5L 92 hp, dual point fuel injection.

both Napa and Canadian Tire can't come up with a listing for an EGR valve between 1988-1991. a couple civic groups have also said some 4th-generation cars came without EGR.

i also remember my 92 bonneville (3800) had no EGR.
 

Here's what you do ;

(1)Purchase Chevron Techron fuel injector cleaner, pour it in and fill the tank.(Do not put gas in again until it is at least down to 1/4)
(This will not only clean the injectors but also the combustion chambers)
(2)Check your base ignition timing
(3)Remove distributor cap and inspect the inside carefully, what you are looking for are carbon tracks leading from the terminals to ground or to other terminals.
(4)If none of these help, your next step is to check the camshaft timing (This must be done accurately)

If you need more assistance, PM me.
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
i don't think there's any chevron products for sale here :(

anything that exxon/mobil maybe puts out that i could try? they own all the Esso gas stations here.

as i said i checked the timing several times. i tried retarding it to the max allowable spec, 16 degrees BDTC which barely helped so i put it back to normal, 18.

perhaps i will check the distributor inside...

btw, since the spark plugs are directly above the engine, are there any cleaning products that you can stick through the spark plug holes that land on the piston to clean stuff? hell i should get a flashlight and look down there to see what's up...
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
Originally posted by: lightpants
How are you checking the timing?

using an inductive timing light hooked up to the #1 spark plug with the timing connector shorted underneath the passenger's kick panel.


i noticed when i went for a drive, just now (it's like 5*C out right now) and the heater on full blast it would barely ping, but the temperature stayed at the same level it's always at.
 

JC

Diamond Member
Feb 1, 2000
5,854
72
91
How many miles are on it? Sounds like carbon buildup in the combustion chambers, which raises compression and creates hot-spots for preignition.

JC
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
sh1t, forgot to include that. sorry.

i bought the car when it had 124,000 km (77,500 mi) on it, now it has 130,000 km (81,250 mi) on it.

i looked through the owner's manual and receipts i got bundled with it, and i came to the conclusion that within the first 2 or 3 years, it traveled 60,000 km (37,500 mi). then it took NINE YEARS to go the last 64,000 km (40,000 mi) !! :confused:

if you look thru the oil cap you can notice everything's pretty much black except in a few spots since i've run mobil 1 in it.
 

JC

Diamond Member
Feb 1, 2000
5,854
72
91
Well, if it is carbon buildup in the combustion chambers, you have 3 choices:

1) Have head pulled, clean carbon from piston tops and combustion chambers in head (most expensive, but ultimate fix)
2) Use Techron and hope it eventually starts to clean the carbon (don't know how long/or if this would even work much)
3) Hold engine revs around 3000, slowly trickle a cup of water into the intake. (riskiest, dislodged carbon could stick to a valve seat, stuff blown out also could clog the catalyst- I don't really recommend this procedure, but I have seen it done with immediate results)

Remember, I'm not saying this is definitely the problem, just what I think it is :)

JC
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
Originally posted by: Radeon
Please tell me your not running synthetic in it....

if you'll look at the post above yours it says I'M RUNNING MOBIL 1 5W30 SUPERSYN 100% SYNTHETIC OIL IN IT ;)
 

Rent

Diamond Member
Aug 8, 2000
7,127
1
81
Originally posted by: Pepsi90919
Originally posted by: Radeon
Please tell me your not running synthetic in it....

if you'll look at the post above yours it says I'M RUNNING MOBIL 1 5W30 SUPERSYN 100% SYNTHETIC OIL IN IT ;)

Mobile 1 is attached to more than just synthetic and you didn't specify. /slap

You should NEVER switch from Dino oil to syn in a car like that. Its very possible that the buildup from the older dino oil in the car is now breaking down and causing detriment to your car.
 

Pepsi90919

Lifer
Oct 9, 1999
25,162
1
81
you should 'never' switch? :p people do it every day. you just have to take precautions like changing the oil filter early.
 

MajesticMoose

Diamond Member
Nov 14, 2000
3,030
0
0
Originally posted by: Radeon
Originally posted by: Pepsi90919
Originally posted by: Radeon
Please tell me your not running synthetic in it....

if you'll look at the post above yours it says I'M RUNNING MOBIL 1 5W30 SUPERSYN 100% SYNTHETIC OIL IN IT ;)

Mobile 1 is attached to more than just synthetic and you didn't specify. /slap

You should NEVER switch from Dino oil to syn in a car like that. Its very possible that the buildup from the older dino oil in the car is now breaking down and causing detriment to your car.
Eh, I don't think so. I switched my car after 100k to full synthetic(just assuming it was cream of dead dino before) and my dad switched his explorer after the first 100k. My burns oil either way(needs valve work) and his hasn't had any problems in the last 125k. Would you care to back up your statement. I've heard that same thing a couple times and still not scene any actual research to back it up