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**Injuneer** · 03-21-2006, 06:56 AM

Many areas of the country mandate "oxygenated" fuels for the winter months. They should not cause misfiring or backfiring problems. They will show a loss of fuel mileage.

"Backfiring" can mean different things to different people. A true backfire is an explosion that occurs in the intake manifold.... the result of incorrect timing or a sticking valve igniting the air fuel mixture in the manifold. Then there is the combustion that occurs in the exhaust pipe when you have excessive misfires, rich condition leaking valves, etc.

Which of those are you experiencing? Or, is it simpy the engine misfiring, stumbling and "coughing" when you hit higher RPM? Or possibly just some "surging" as the power drops off and returns erratically (knock retard)?

**94formulaLT1** · 03-21-2006, 08:11 AM

well it only occurs when the engine has load, when i am moving..if i sit with the car in park/neutral, i can rev all the way up to my rev limiter. But when i am accelerating hard, i hear little "bang bang bang bang" up at the engine. this one has me baffled, i hope this info helped you. if it doesnt, ask some more questions so i can explain my problem even more.

Originally posted by Injuneer

Many areas of the country mandate "oxygenated" fuels for the winter months. They should not cause misfiring or backfiring problems. They will show a loss of fuel mileage.

"Backfiring" can mean different things to different people. A true backfire is an explosion that occurs in the intake manifold.... the result of incorrect timing or a sticking valve igniting the air fuel mixture in the manifold. Then there is the combustion that occurs in the exhaust pipe when you have excessive misfires, rich condition leaking valves, etc.

Which of those are you experiencing? Or, is it simpy the engine misfiring, stumbling and "coughing" when you hit higher RPM? Or possibly just some "surging" as the power drops off and returns erratically (knock retard)?

**Trash man** · 03-21-2006, 08:47 AM

u better hope it aint detonation, or u could have a serious problem

**Johnyd2** · 03-21-2006, 11:44 AM

Mind you im not nearly as experienced as alot of guys on this forum. But it sounds like your car has a misfire. My 97 V6 camaro was missing only under load and while the engine was warmed up. Turned out to be a coil pack. The point that im trying to make is just because your car seems to be missing under load doesnt mean it probably isnt the opti. An engine missing can be be caused by faulty injector, bad coil, bad opti, bad plugs, bad wires, bad fuel pump, bad ICM, etc. And as far as i know the symptom to any of these problems can show up at certain temps or rpm ranges. If it turns out to be the opti put in a new water pump while your in there.

**SteveH95Formula** · 03-21-2006, 11:55 AM

Change your fuel filter too it's cheap and will effect the engine at high RPM's.
I thinks it's a thing most often over looked.

**fastTa** · 03-21-2006, 12:12 PM

I think you already answered your own question....so you might want to try running premium gasoline instead of the 87.

Detonation occurs in almost all motors on a regular basis and is in most cases not harmful to parts especially with a knock sensor system. Audible detonation is the worse kind of detonation and can be caused by many things. Pre-ignition is the part breaker and is what a lot of people confuse with detonation.

Good discussion on pre-ignition and detonation:
http://www.f-body.com/forum/showthread.php?t=13941

**94formulaLT1** · 03-21-2006, 10:33 PM

alright guys, since the car is running just peachy when cruising...even when i get on it a little bit like up to 3500, i will keep driving it. i have to use the full tank of 87 octane i put in it...im such a dumb you know what..it runs perfectly fine right now, only when i clime up the rpm. I cant believe i was doing that to my engine, i would die if i blew my engine, i love my car to much to do that...~obsessive...~ im glad i am going to be ripping apart my top end now, i can now see what damage occured to the valves and pistons if any so heres the deal and i need some back up..

i am replacing the whole top end, heads, valves everything on that...cam, timing chain, opti, injectors...so on

now i will need to look at my fuel pump...just changed my fuel filter not to long ago, im doing my opti...didnt MSD come out with their new optispark?..changing the wires...just replaced the plugs with AC delco last year, might take em out, look em over and sand blast them..i spent 75 bucks on 8 of those, just not going to throw them away

but before i do all of this, i am going to go to school and hook my car up to the scanner and see if i have a miss firefire..i might be able to check for detonation...i use a TechII GM scanner, the best out there... oh oh, and i am also going to switch to premium...that could be my whole problem...or what caused my problem..87...this is why you read your owners manual.. alright guys and gals, post back to tell me more, i need to get this stupid problem fixed before race season.

**Trash man** · 03-21-2006, 10:56 PM

get a flat peice of metal, take a ball peen hammer and hammer (with the round side) in the middle of the metal. now pretend ur rods are ball peen hammers and the metal is ur bearing, thats what detonation does, and if u have that, i wouldnt drive it much longer if u love ur rods

**fastTa** · 03-21-2006, 11:03 PM

Originally posted by 88bird5spd

get a flat peice of metal, take a ball peen hammer and hammer (with the round side) in the middle of the metal. now pretend ur rods are ball peen hammers and the metal is ur bearing, thats what detonation does, and if u have that, i wouldnt drive it much longer if u love ur rods

That is not accurate information. You really should read the thread that I posted.

**fastTa** · 03-21-2006, 11:18 PM

Originally posted by 94formulaLT1

alright guys, since the car is running just peachy when cruising...even when i get on it a little bit like up to 3500, i will keep driving it. i have to use the full tank of 87 octane i put in it...im such a dumb you know what..it runs perfectly fine right now, only when i clime up the rpm. I cant believe i was doing that to my engine, i would die if i blew my engine, i love my car to much to do that...~obsessive...~ im glad i am going to be ripping apart my top end now, i can now see what damage occured to the valves and pistons if any so heres the deal and i need some back up..

i am replacing the whole top end, heads, valves everything on that...cam, timing chain, opti, injectors...so on

now i will need to look at my fuel pump...just changed my fuel filter not to long ago, im doing my opti...didnt MSD come out with their new optispark?..changing the wires...just replaced the plugs with AC delco last year, might take em out, look em over and sand blast them..i spent 75 bucks on 8 of those, just not going to throw them away

but before i do all of this, i am going to go to school and hook my car up to the scanner and see if i have a miss firefire..i might be able to check for detonation...i use a TechII GM scanner, the best out there... oh oh, and i am also going to switch to premium...that could be my whole problem...or what caused my problem..87...this is why you read your owners manual.. alright guys and gals, post back to tell me more, i need to get this stupid problem fixed before race season.

Switching to premium should show you a significant change. Run some through the system then get it on the scanner. You won't be able to actually see pre-ignition or detonation on the scanner, but you will be able to look at things like your Long Term Fuel Trims(LTFT's), O2 Sensor crossover counts, O2 voltages, knock retard, etc., not to mention any codes present. It will give you an idea of what's going on.

**94formulaLT1** · 03-22-2006, 07:03 AM

Originally posted by fastTA

Switching to premium should show you a significant change. Run some through the system then get it on the scanner. You won't be able to actually see pre-ignition or detonation on the scanner, but you will be able to look at things like your Long Term Fuel Trims(LTFT's), O2 Sensor crossover counts, O2 voltages, knock retard, etc., not to mention any codes present. It will give you an idea of what's going on.

Thanks guys, i will try to get it on scanner today...i guess it just makes me mad..oh well i guess this is what i get when i get a nice car with a nice engine...trouble.

**Trash man** · 03-22-2006, 08:27 AM

Originally posted by fastTA

That is not accurate information. You really should read the thread that I posted.

my bad, was a long day at work

**Joe 1320** · 03-22-2006, 11:36 AM

I have seen instances where the ignition coil driver module was getting an intermittant signal and causes an ignition breakup under load. This can be mis-diagnosed as a plug and wire or optispark problem. It also will appear regardless of fuel quality. It would be worth your time to check the harness connection to the coil driver module located right above the coil on the front of the driver's side head. Spraying an electronic contact cleaner and checking the tightness of the pins and contacts within the connector are the fix. There are also reports of an overheating driver module causing the same symptom that many fix by spacing the coil and module away from the head by using a few washers on the mounting studs.

**scoobydoo** · 03-22-2006, 02:46 PM

UH....HELP!

Has anyone read my post yet? Marked "Backfiring" I need help with my problem as well.
Thanks
Suffering backfires.

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Car is still backfiring...Could it be detonation?

Car is still backfiring...Could it be detonation?

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