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anselv
05-06-2005, 04:22 AM
Hey guys . I did some research on this topic but I can't seem to get a straight answer on it . Here is the problem :

When driving normally (not flooring the accelerator ) the car acts normally , but when accelerating hard there is a semi loud "popping" sound that comes from the engine bay and the car feels like it is being held back from accelerating . Also when accelerating hard and getting over 100 km/hr . the service engine soon light starts to flash . (only for a little bit then shuts off ) . I brought it into the dealership to have it scanned and it was showing misfires on cyclinder 2 and 6 , so they thought it was a tune up issue and replaced the spark plugs , fuel filter , ect. But it did not help because it did it again on my way back home , but again only when accelerating hard . The tech guy said it could be a clogged cat , but I don't think it can be that because I have a full custom 2.5 inch exhaust (TOG headers in the front) with a magnaflow high flow cat on there which was installed about two years ago . Could a high flow cat clog ? Also I have 8.5mm Magnecore spark plug wires so I think the wires are still pretty good (I had them put on two years ago also ) . I had checked the coil packs to see if there was corrision but there was not any , so I am pretty much stumped . I also have a weird temperature gauge that keeps dropping from normal operating temperature to 40 degrees then jump up to 130 degrees(in the red) then back to 90 degrees(normal operating temperature) . I have a(hyper-tech) 180 degree thremostat on the engine but I don't think it is causing the problem since I am still getting hot and cold air through the vents .

Any suggestions on solutions to these problems would be helpful , since I can't seem to get a straight answer out of the dealership about these problems . Plus I need to resolve these issues before I put any type of force induction on the car (which I plan to do ) . Thanks.

EASTERBUNNY
05-06-2005, 05:55 AM
A Back Fire Problem Is Usually From A Couple Of Things Usually Secondary Ignition System Did The Dealership Look At The Wires To See If There Was Any Signs Of Carbon Tracking On The Out Side Of The Old Plugs Or On Any Part Of The Plug Wires ? It's Also Possible To Have A Coil Pack Thats Breaking Down But Usually If Thats The Case It Would Be The Two Cylinders On The Same Coil Which You Dont Have An Dit Could Possibly Be The Ignition Module Going Down But Not Likely They Are Usually Good Or Bad ,i Have Had A Pcm That Vwas Breaking Down On Individual Cylinder Circuits That Caused The Engine To Miss On One Cylinder And Only At Times , I Would Take It To A Shop That Has An Ingnition Lab Scope They Can Hook It To Your Ignition System And Road Test It And Watch What Your Ignition System Is Doing While Your Driving, This Takes Alot Of Guess Work Out . There Is Another Poss You Could Have A Weak Valve Spring That Could Be Weak Enough To Let The Valve Not Seat Good While At High Rpm And And Cause A Back Fireit Would Have To Be And Intake Valve .

anselv
05-06-2005, 07:20 AM
No the dealer did not check for carbon tracking on the plugs(what does that indicate?) . Also I don't think it is a weak valve spring problem since I recently had the engine's UIM , LIM , and heads ported and polished and had the valve springs replaced with LS1 valve springs , with new seals . How common is the ignition module failure ?

iceman
05-06-2005, 07:30 AM
Blinking SES = severe misfires. Sound from the engine bay.. knocking maybe? What octane gas are you running?

Anyways try NOT to cause this to occur .. i.e. no heavy acceleration.. flashing SES, bad, it's there for a reason.. I wouldn't rule out clogged cat either seems to be a TOG common thing, mine did as well..

temp gauge... air bubble in the system?

anselv
05-06-2005, 08:20 AM
I am running 91 octane . As for a clogged cat , could that really happen with an aftermarket high folw cat(magnaflow) ? As for the temp. gauge I heard it could be something to do with the coolant temperature sensor ? Anyway I am taking it back to the dealership on Monday see if they can figure it out . But I would still like to hear your guys' suggestion on what could be causing this . Thanks .

SilverGAGT04
05-06-2005, 06:16 PM
Well, if it was me, I'd hook up my back pressure gauge first, cause my guess would be clogged cat. I have had these symptoms on a few customer cars (all were GP's) but they were all clogged cats.

eric99gt
10-10-2005, 06:38 PM
ughhh....bringing this back. Just bought a used car. Everything seemed fine until on my way home. Car starts hesitating and I get the flashing SES. What I was wondering is if anyone knows if this means the same thing in a 2001 Chevy Lumina. I'm guessing so since they probably both use OBD2 but i'm not positive. Any insight?

iceman
10-10-2005, 06:42 PM
Flashing SES = severe misfire

MetaGTP1
10-10-2005, 07:58 PM
Hey guys . I did some research on this topic but I can't seem to get a straight answer on it . Here is the problem :

When driving normally (not flooring the accelerator ) the car acts normally , but when accelerating hard there is a semi loud "popping" sound that comes from the engine bay and the car feels like it is being held back from accelerating . Also when accelerating hard and getting over 100 km/hr . the service engine soon light starts to flash . (only for a little bit then shuts off ) . I brought it into the dealership to have it scanned and it was showing misfires on cyclinder 2 and 6 , so they thought it was a tune up issue and replaced the spark plugs , fuel filter , ect. But it did not help because it did it again on my way back home , but again only when accelerating hard . The tech guy said it could be a clogged cat , but I don't think it can be that because I have a full custom 2.5 inch exhaust (TOG headers in the front) with a magnaflow high flow cat on there which was installed about two years ago . Could a high flow cat clog ? Also I have 8.5mm Magnecore spark plug wires so I think the wires are still pretty good (I had them put on two years ago also ) . I had checked the coil packs to see if there was corrision but there was not any , so I am pretty much stumped . I also have a weird temperature gauge that keeps dropping from normal operating temperature to 40 degrees then jump up to 130 degrees(in the red) then back to 90 degrees(normal operating temperature) . I have a(hyper-tech) 180 degree thremostat on the engine but I don't think it is causing the problem since I am still getting hot and cold air through the vents .

Any suggestions on solutions to these problems would be helpful , since I can't seem to get a straight answer out of the dealership about these problems . Plus I need to resolve these issues before I put any type of force induction on the car (which I plan to do ) . Thanks.TOG did have a problem with their headers not too long ago. The coating was flaking off and causing the converter to clog.

matt shauf
10-11-2005, 04:57 PM
my car is doing the EXACT same thing! I replaced the cat, and it did not help at all. I am showing missfires too on the computer. I changed the MAF sensor and that didn't help either. Mine does this alot worse when the car is warmed up. I also have MSD 8.5mm plug wires. I'm gonna change the plugs and see if that helps any, but I'm kinda doubting it will. I have no idea what is causing this, but it is annoying as hell. Anyone have any ideas?

Panacea
10-11-2005, 05:04 PM
my car is doing the EXACT same thing! I replaced the cat, and it did not help at all. I am showing missfires too on the computer. I changed the MAF sensor and that didn't help either. Mine does this alot worse when the car is warmed up. I also have MSD 8.5mm plug wires. I'm gonna change the plugs and see if that helps any, but I'm kinda doubting it will. I have no idea what is causing this, but it is annoying as hell. Anyone have any ideas?

Bad/clogged fuel injectors.

mr_eh
10-11-2005, 05:28 PM
kek. yeah dont race your car at the track while you have a misfire either, it really hurts the e/t.... :)

eric99gt
10-11-2005, 07:24 PM
Mine turned out to be #6 plug wire. It was completely off. They must have forgot to put it back on at the dealership after changing the plugs or something.

Coop
10-12-2005, 02:48 PM
Like already stated the flasing SES light means there's a misfire, should say in your owners manual as well.

Yes, I have seen an ignition module be intermittent so it could be the problem but I'd look more at plugs/wires (which you said have been replaced and assumed to be good), coil packs, crank sensor/connection, and all ignition module connections. Sounds like it almost has to be ignition related though.