Sudden misfire..

**Smittro** · 02-14-2010, 04:07 PM

Okay so I had her out today for a little spin. I warmed her up and headed out to the store, she was running good did'nt get on her. Then, about half way to the store she dropped a cylinder.. I let off and there was a miss with no codes @ idle.. I pull into a lot and she levels off and begins to idle just fine. so I put her in gear and pull out. No problems @ all it seemed.. Then I go to WOT out of a light and there it is again.. I let off and this time no miss, but again I go WOT and the miss returns and then only does it @ WOT.. The car is an 01 3800II Camaro. She is maticulasly maintained and NEVER gets beat on.. I changed out the plugs because they were due anyway. I was waiting to change them till spring since she don't move much in the winter.. I cleaned the MAF with the proper CRC and checked over everything.. Not getting any codes or SES light.. If I go easy on the throttle she pull out and goes down the road just fine only @ WOT does she drop a cycle. Plugs had normal deposits across the board identical.. Suggestions on what to look for is greatly appreciated.. She has just over 80k on her clock and the rear 02 and cat are around a couple of months old..

Up for suggestions before she heads to the shop.. The Doc is stumped...

**Smittro** · 02-14-2010, 05:20 PM

Le Bump.........

**pajeff02** · 02-14-2010, 06:27 PM

You should know better than to drive your car in February!

Without a trouble code to get you started, you have your work cut out for you. Are you still running the original ignition wires? Not that there is any similarity but my brother had the same problem with his Subaru and it had a wire crapping out.

**Smittro** · 02-14-2010, 07:45 PM

Originally Posted by pajeff02

You should know better than to drive your car in February!

Without a trouble code to get you started, you have your work cut out for you. Are you still running the original ignition wires? Not that there is any similarity but my brother had the same problem with his Subaru and it had a wire crapping out.

Yeah I know it was stupid to run her I could'nt resist just once.. I guess that's what I get lol.. But I changed plug wires back in like May or June.. I held off on doing the plugs till last evening when the problem arised.. It just misses @ anything other than a slow throttle being applied. As soon as you goose it or go WOT it begins to miss as the engine starts to rev. But if you go easy on the throttle (slowly depress it) for normal driving she goes like normal. It's a head scratcher for sure I'm headed to the shop in the am. So I'll let you guys know what I find ugh.. I'm thinking I may have fuel line freeze up or something to that effect. Fuel pump is new too less than a year old and I replaced the entire assembly.. Thanks for the reply Jeff..

All suggestions are being considered and very much appreciated.. Just a heads up I'm fly by wire, there are no throttle cables (servo driven) it's a sealed unit with rivets holding on the two side covers where a normal linkage and throttle pivot would be..

**Smittro** · 02-14-2010, 07:54 PM

Well the wife and I talked it over just about 2 minutes ago and @ that time I was told if I can't get it ironed out in the next couple of days we are buying a new ride and the Camaro will go into permanent storage till she emerges blown and completely restored..

In the meantime I'd like to get it corrected so that if it turns out to be a sensor I can repair it so that the problem does'nt get added to the new motor..

**Spikito** · 02-14-2010, 08:02 PM

I have no idea....

my first thought was loose plug, but youve checked that.
my second was torque shudder, but yours is a manual.

so i dunno, lol, coil pack is my only idea left, but its the bottom of my list.

**Smittro** · 02-14-2010, 08:20 PM

Originally Posted by Spikito

I have no idea....

my first thought was loose plug, but youve checked that.
my second was torque shudder, but yours is a manual.

so i dunno, lol, coil pack is my only idea left, but its the bottom of my list.

Nah it's a reprogrammed slush box brudda..

lol, But it's definetly a dropped cylinder and goes away @ idle and normal driving it just showed up @ WOT.. No code makes it a search and stab I guess..

**Smittro** · 02-14-2010, 08:23 PM

I replaced the fuel filter when I did the pump but I'm gonna yank it and see if there maybe ice or some sort of blockage.. I'll run a pressure test @ the rails in the am before I take her to the shop..

**Smittro** · 02-15-2010, 02:16 AM

Update: the misfire only starts to happen after it warms up. When it's cold the misfire is'nt present..

**pajeff02** · 02-15-2010, 03:48 AM

Originally Posted by Smittro

Update: the misfire only starts to happen after it warms up. When it's cold the misfire is'nt present..

That's interesting. Faulty coil aggravated by engine heat?

**Spikito** · 02-15-2010, 05:34 AM

Originally Posted by pajeff02

That's interesting. Faulty coil aggravated by engine heat?

thatd be my guess

**Spikito** · 02-15-2010, 05:36 AM

oh and when I had a misfire, I didnt always get a light, its gotta miss more than X number of times in a certain time period to get a light.

A lot of shops can hook up their computer, and itll show misfires individually for each cylinder, help you locate then.

Id swap around the coils, see if the misfire moves, if so, youve found your bad coil.

If not, well, you know.....

**pajeff02** · 02-15-2010, 08:35 AM

That blows. Is it most likely the intake gasket? I thought I read on here somewhere that they have had their share of problems.

**35th-ANV-SS** · 02-15-2010, 08:47 AM

I think you have bad luck. My 3800-II has 209K miles and still kicks...and has been beaten on plenty. I got her when I was 21...

**Smittro** · 02-15-2010, 11:06 AM

Originally Posted by pajeff02

That blows. Is it most likely the intake gasket? I thought I read on here somewhere that they have had their share of problems.

I hope... I'm going to rip it down in the am. and then I'll have a better look @ the issue.. Yeah they are known for gasket issues, but usually it's in puller cars with the plastic intake. I thought I was safe with the aluminum set up.. Guess not.. Could have been an under lying issue that the previous owner just left alone.. Who knows really.

Originally Posted by 35th-ANV-SS

I think you have bad luck. My 3800-II has 209K miles and still kicks...and has been beaten on plenty. I got her when I was 21...

Maybe you're right bro, some have great luck with the 3800 and some not so much.. Oh well obviously it was something that could'nt be helped who knows. Just aggrivating is all.. I spent hours upon hours taking care of everything that has arrisen with her I leave no stone unturned on my rides and then this.. Kinda get the feeling it was all for not... All in all one thing is for sure she will not be sold or traded far too clean to be sold for book.. She stays no matter what her troubles..

**35th-ANV-SS** · 02-15-2010, 11:44 AM

Yeah I hear ya. You know my luck with my SS. 12K on her and the transmission shits. It sucks to say the least.

**cammed goat** · 02-15-2010, 01:24 PM

Imagine if you had an import. All the wiring, tubing and covers and NO room to work. You would be saying "FML" right about now. Good thing it's a GM.

**Spikito** · 02-15-2010, 01:37 PM

those intake gaskets are notorious for going out.

theres that, EGR, and coils, all are bad on the 3800....the bottom end itself is well built, just none of the shit on top.

**Smittro** · 02-15-2010, 01:59 PM

Originally Posted by cammed goat

Imagine if you had an import. All the wiring, tubing and covers and NO room to work. You would be saying "FML" right about now. Good thing it's a GM.

Originally Posted by Spikito

those intake gaskets are notorious for going out.

theres that, EGR, and coils, all are bad on the 3800....the bottom end itself is well built, just none of the shit on top.

Well there's mixed reviews on the bottom end, and powder forged rods ehh..
Give me a 60* and I'm all over it, no ballance shaft, no goofy oil pump set up, real forged factory rods, a million cross ref parts.. Just plain better imho. There's a video of a single spool TDC pushing 400+hp on all stock internals and 9.25/9.50:1 CR. with 4 stock cams and a -6/+6 degrees of timing. Spin a 3800 to 7200 on stock bottom end and watch the chunks fly!

But the 3800 can be built to sling asphalt too, even wheel stands, so the potential is there with the newer castings. The newer 3800's (from the late 90's to early 2000's) have lower deck height and slightly shorter stroke, less mass = quicker responsiveness.