lean and misfire

[LETZRIDE]

OK, I'm pretty sure I might have figured out my voltage problem (loose negative battery cable, the bolt was stripped somehow?)

But here is a whole new issue...maybe related who knows? Was trying to get home last night, started the car is it was bucking and misfiring all over the place. Since it usually kinda hesitates on first startup when cold, I started driving. When it didn't clear up after a minute or so I pulled off, called the flatbed. While I was waiting I found my neg battery cable was loose...fixed that and the car rann soo smooth. I cancelled the flat and drove hom about 18 miles.

Today I start the car and the misfire is back, just as bad. I made sure everything was tight and it was.

So I've spent the last few hours looking everything over. Found 2 plug wires that were cracked (replaced them) and one of the spark plugs that was totally white where the boot would go over it (replaced that to)

STILL have a bad misfire. I have zero codes showing/pending...I notice the car seems to go lean when it starts misfiring. It will go up and idle at 18afr rather than 14.7-15.3ish that it normally idles at....under light throttle when missing it sits ar about 16-17afr instead of 14.4ish where it normally sits.

I'm totally stumped? The no codes when running this rough is throwing me wayyy off. Hp tuners and the aeroforce gauge aren't picking up anything...

[LETZRIDE]

Re: lean and misfire

The other thing that throws me off to is how it will misfire as your try to get it going all day, then out of the blue it will be totally fine for like 5-8 minutes...then be on the extreme of misfire again....

[LETZRIDE]

Re: lean and misfire

to add to this, Ive pulled off all the vacuum hoses I can see, without fuel leaking from them?

[bigbrian442]

Re: lean and misfire

Check your O2's voltage on the scanner. If they look fine and your wide band says lean I would say one or both are bad.

[LETZRIDE]

Re: lean and misfire

Check your O2's voltage on the scanner. If they look fine and your wide band says lean I would say one or both are bad.

I have a mini saved scan here that I took. What type of voltage am I looking for?

The narrow bands seem to coincide with the wideband. Seems like when I hit 17-18afr one bank will go lean, then richen up and the opposite bank will go lean. But to me they look like they are reading right.

Plus, if the wideband were bad, it still wouldn't explain the misfire as the tune was good.

So here is where I stand at the moment, it's piss pouring rain. Yesterday I found 2 plug wires that were totally cracked and falling apart. I replaced them with old msd wires that visually looked good that were lying around. I had no luck with this, other than it seemed that I was able to drive a little more with the car totally fine before it went to total misfire mode.

My thoughts right now...I'm hoping maybe one or more of the wires are bad internally and I just can't see it. I'm thinking that maybe the vibration of the car causes the wire to make a connection at one point and the car runs totally smooth, while at another point it totally misfires through the entire rpm range including idle.

Since I can't leave mixed wires on the car, I bought a set of new wires just now. Since plugs were only 20$ for the entire set, I bought new plugs and I'll take those out of the picture to.

To me it HAS to be something that is phasing in and out. How else could the car be totally fine and run smooth one minute, and the next moment it won't even idle smooth let alone rev up or drive without coughing all over the place.

so, the wires that were cracked were cracked bad, multiple deterioration right through the wires (oddly enough when I swapped them it the car wasn't any less violent)
So again, hoping many of the other wires were also cracked underneath the rubbers where you can't see it

[bigbrian442]

Re: lean and misfire

Try tapping on the MAF with a screwdriver handle. Or even just unpluging it. It may be going south.

[LETZRIDE]

Re: lean and misfire

Try tapping on the MAF with a screwdriver handle. Or even just unpluging it. It may be going south.

I'm VE tuned, so the MAF is set to fail (and that code is in the background) I just didn't mention that because I didn't want to start confusing other people...sorry about that

I did have a low voltage map code but I deleted it and it never came back...not sure what to make of that.

[bigbrian442]

Re: lean and misfire

I would still try unpluging it.

[LETZRIDE]

Re: lean and misfire

I would still try unpluging it.

New plugs and wires didn't fix it, I tried unplugging the maf, and still nothing.

Still no codes either...when I started it up she was rich (as usual with first start and was missing with about 12-13afr) then it went lean 16-17 afr and continued to mis, can't catch a smooth idle, it's all choppy.

The only other thing I can think of that throws me off, is that cylinder piece that is black that sits behind the alternator...I have no clue what it is, it a thick vacuum line coming from the throttle body to it, and on the left side it has a vaccum line that goes to the fuel line, but then I have a nipple on their that looks like a vacuum line should be attached, but there is nothing.

I looked around and around everywhere and I can't even see any lines that could or should attach to it?

[bigbrian442]

Re: lean and misfire

IF you cover the end does the idle smooth out?

[LETZRIDE]

Re: lean and misfire

IF you cover the end does the idle smooth out?

No difference when I cover the end of it...

[ssms5411]

Re: lean and misfire

Maybe a bad or going bad fuel injector that would be on my list.

[LETZRIDE]

Re: lean and misfire

Injector duty in the scan seems to be steady at a few percent...maybe a timing issue? How about a clogged cat? (Although I can feel quiet a bit of pressure coming out of the pipes...

[LETZRIDE]

Re: lean and misfire

Waiting on the flat bed now :(

[2.8 Bird]

Re: lean and misfire

Usually if it's lean and misfiring and it's not injectors it's usually the MAF that's the culprit.

If it's the cat your car would stumble in accelaration and no power at all to claim up.

I'm taking a wild guess by saying crank/cam sensor. I wonder too if you're losing compression.

What kind of scanner are you using? You might want to take it to a shop and have their scanner go over it.