: Random missing, down on power



turbojimmy
06-20-11, 10:42 AM
I started whining about this in my Opti thread, but I figured I'd dedicate a new thread to this issue because it apparently is not Opti related.

When I first put this "new" engine in, I had a solid miss at idle that would occur at random. After watching the engine idle at night, I noticed the #7 plug wire grounding out. A new wire fixed it.

Recently, it started missing again. I put yet another wire on the #7 cylinder, thinking that was the cause. It wasn't.

It will idle pretty decent, but when you drop it in gear the missing starts. Upon acceleration, it stutters and runs like it's down a cylinder or two. When it's not under a load, it's fairly normal. But try to accelerate up an entrance ramp and it will barely pull itself along. It seems electrical, but I replaced the Opti distributor, cap and rotor. I guess it could be another wire, but I don't see any that are bad. I have a new set of wires that I haven't installed yet.

I guess it could be a fueling issue. I've been fooled many times by missing that turned out to be vacuum leaks or a bad injector. I'm not sure where to start diagnosing it, beyond replacing the wires. I don't have any codes.

Curiously, it doesn't seem to care whether I have the MAF plugged in or not. It runs the same with it plugged in as it does unplugged. I also don't get any codes when I unplug the MAF, which is odd. My Buick would get upset immediately when I unplugged the MAF: it would start running rough and the SES light would come on right away.

Ideas?

CadillacPimpinNOLA
06-20-11, 01:00 PM
so many possibilities

fuel filter
plugs
wires
coil
ICM
vacuum leak

hard to diagnose without being there as ive had your same headaches

turbojimmy
06-20-11, 02:08 PM
Okay, I fixed it. And there's a moral to the story: always check the easy stuff first.

I basically replaced the distributor, cap and rotor for no reason. Yeah, the cap was visibly worn inside but who knows how much longer it would have lasted.

What was it? Well, I was looking at the wire holder on the driver's side head trying to figure out how to remove it so I can properly run the new spark plug wires. It was then that I noticed the #5 wire had a funky bend in it and was contacting the exhaust manifold. It was also covered in soot from firing against the manifold. Also, the #7 plug wasn't seated in the new distributor cap properly. I took care of those 2 things and it runs great again.

On a separate note, the exhaust leaks are getting worse every time I get in the car. Both mufflers are rotted through and both intermediate pipes are leaking at the cats (rusted as well). I let the guy at Meineke talk me out of a Flowmaster Force II system. As much as I'd love a hot rod sound, he is right in that the drone will drive me and my passengers nuts, even with the addition of the resonators that come with the Force II system. So I'm having an entirely new stock system put on it this Thursday. They'll put the extra 8 feet of pipe (4 feet for each of the dual mufflers) on it for no additional charge. Cost-wise it's pretty much a wash (stock vs. Flowmaster).

csbuckn
06-20-11, 02:56 PM
Stock? Put a little something on there. Nothing loud, just better flowing.

turbojimmy
06-20-11, 03:13 PM
Stock? Put a little something on there. Nothing loud, just better flowing.

I'll see what he recommends - maybe better flowing mufflers? I'd love to have "off road pipes" made to ditch the cats. I can tune them out with my tuner software, but a big chain shop like that won't make them for me. I don't know where the choke points are otherwise. It's only a 2" system, but they are true duals so don't know if the diameter of the pipe is really a restriction.

jayoldschool
06-20-11, 05:59 PM
You can do those pipes easily yourself. The only hard part with doing pipes is getting the old parts separated, and you don't have to worry about that if you are doing mufflers. I did one of the intermediate pipes on my Caprice wagon this afternoon in about 1/2 an hour. Cut the old pipes behind the flange, torch the bolts out of the flange, cut the pipes in front of the muffler, then behind to drop the muffler. Install new pipes with new flanges, bolt down. Slide extensions over the intermediate pipes. Slide new mufflers over old OTA pipes. Clamp, holding mufflers flat. Slide extensions in mufflers, clamp. Done. You may need a 2 1/4ID slip piece to get the new muffs on the old OTA pipes. My cost today for the one pipe? 30 bucks.

Note that ANY aftermarket passenger intermediate pipe (cat to muffler) will flow better than the stock piece (that is crushed down flat). None of the aftermarket pieces are flat.

I used to say that exhaust is the one job that I refuse to do on a car, and I totally regret that. Now that I have worked on a few different systems, it is very easy to do IF you have the right tools. Sawzall, air, torches are just about mandatory.

thefleetwoodguy
06-20-11, 10:32 PM
my two thoughts
quality ignition wires are a must! with these cars
and my friends 96 gave him fits, he replaced every sensor
opti/dist, plugs wires, 02's etc, and in the end it was a bad cat
he did have a mil lit up

turbojimmy
06-21-11, 09:12 AM
I used to say that exhaust is the one job that I refuse to do on a car, and I totally regret that. Now that I have worked on a few different systems, it is very easy to do IF you have the right tools. Sawzall, air, torches are just about mandatory.

I've done my fair share of exhaust repairs and they're never particularly fun. As I got older (read: lazier), I migrated toward kits. It's just easier to replace everything than to splice in pieces, particularly if you're not really adept with a torch. Plus, I got spoiled - my "marital home" (which I had to sell through my divorce) had a lift. It made just about any work a piece of cake. Now I have to roll around on the blacktop, which sucks.

Aaaannnyyyway....the biggest issue with the pipes on the limo is the intermediate pipes. There's an "extra" crossmember that the coach builder put in for the middle driveshaft bearing. The intermediate pipes bend down around it and back up. It's custom work that I can't do. The coach builder cut the factory system and spliced in 2 44" sections of pipe. Meineke is going to install 2 long pipes so there's no joints until you get to the mufflers.

They quoted me $780 w/ tax, out the door. The Flowmaster Impala SS kit is $650 shipped, plus I'd then have to pay someone to bend the 48" pipes (44" stretch plus the additional 4" the Caddy is vs. the Impala SS). I figure it's pretty much a wash cost-wise. Plus, the $780 included new resonators and tail pipes at $250. Mine look pretty good. My problem is the intermediate pipes and mufflers. I'm hoping to get away with $530 or so. Yeah, it's a lot of coin but they guarantee their work. There's nothing better at making a car sound like a heap of crap than a leaky exhaust. Pet peeve of mine.

turbojimmy
06-24-11, 06:50 PM
So I got the work done at Meineke today. Awesome job. Custom bent intermediate pipes, not flattened like stock. Everything tucked up under there nice and tight. They saved the resonators and tailpipes so it was "only" $500 out the door. The mufflers are stock replacements but are noticeably louder. I'm really happy overall. One less thing to worry about....

Cadillacboy
06-25-11, 11:07 AM
Good to see you fixed that glitch and that was not a big deal . I agree with you on the checking the easy stuff , namely if you have some problems with A/C