Guess what?

If there is stuff coming out of your exhaust did you consider that your cats are breaking up and pieces of them are blowing out? Could be most of your problem if pieces are blocking exhaust flow.

 

You are correct, most of the time it looks like chunks of stuff not hairs, but then I don't know how high flow cats are made. I am struggling with how the exhaust manifolds could "suck" in air as they should always exhibit positive pressure which would always push material out. At any rate, if I think of anything else I'll post, good luck...

 

That is not true. They are "mostly" positive pressure.

Look at the 328 exhaust. It has a fresh air passive injection system that "sucks" in fresh air from the airfilter using just vaccum on the exhaust. There is a one-way valve in the air injection stream such that air flows in when there is exhaust vaccum. This system does not work as well as an active air injection system, but it does work.

 

1) why bother...you are just going to do it your way while I sit back and eat chicken wings.

2) actually, what are you doing Friday afternoon or this weekend?


What condition is the car in now? Does it run? If yes do not take it apart. You need to diagnose where the miss is coming from. Do you really have a miss or do you think you have a miss? All you said was headers. You got a crack, burn hole, leaky gasket? What? And you will be screwed with CARB 100% guarantee. Do they look like burnt 355 headers? If not I can fix them 99% of the time. I got MIG, TIG and just about every flavor of welding wire.

 

I love these diagnostic threads. Always learn something.

 

Ernie,

You've been the essence of the Brotherhood ever since I can remember, always first in line to help novice 348 diy'ers diagnose, fix and lend support for their problems. It's rare to see you bummed out... I hope big-D and FB can help you work through this.

 

""why bother...you are just going to do it your way while I sit back and eat chicken wings""

The wise old fat man speaks the truth! My concern is there are new owners or potential owners reading this and thinking this is how it really is. There is always a way to prove a convoluted theory as long as facts don't get in the way.

Do you HEAR an exhaust leak? If a deaf old turd like me can hear a slightly cracked header on a 14:1 race engine with a 330+ degree cam running straight pipes... you can damn well HEAR it on a stock muffled engine. If they are broken, by all means fix them but do not expect that to fix a flat tire.

Unplug the O2 sensors and go for a drive. That will either confirm or blow a hole in this WAG. Unplugging two connectors putting the engine into open loop beats the hell out of pulling a pair of headers in my book but hey... I'm new at this. Is the miss gone? No? Then that doesn't even come close to proving your theory correct but it does give clues to a direction, none of which involves removing headers! Are your multi values HIGH or LOW? Don't know? Why would you go through the PITA to remove headers until you know? Is it a lean miss or a rich miss? What bank is the miss? What cylinder or is it random and floating on one bank?

MECHANICS 101! Identify, diagnosis (!), confirm and game plan, repair, verify and final check.

No where is the afore mentioned logic path is "WAG involving fuzzy things". Fix the car properly based on facts and logic and THEN while your relaxing after a rewarding, fun drive build a new Space Age harness and redesign headers if that still trips your trigger. It is very easy to get into the mental rut you are in, we spoke about this. This is the point where you step back, take a breath (of FRESH air), gather facts and move forward with a plan based on those facts.
I am in exactly the same rut working on a serious problem with the Bosch engineers regarding the 355 out your way. Four weeks of notes and research was put in a file and a fresh new legal pad pulled out after an hour long conversation last evening with some pretty smart folks. Some times its the only way to pull open the blinders... I'm there myself. Your problem? That is simple stuff, you can HEAR and FEAL it... I wish that was the case with mine! In my case we both have hard facts proving two opposite theories. You want to talk about "Bull Headed"? I'm the only one NOT getting paid to figure this out, that goes well beyond bull headed and firmly planted in "Dumb Ass" territory. After 40 yrs you would think I would know better!

You cant work on these cars with blinders on. That is the cause (based on what I have read only) of many of your follow up problems. Work on a system, fix it properly and completely ONCE and then move on to the next.

 

Or is your problem that you can always remember how good it is on the days when everything is actually working as it should and consider that worth the perseverance?

Hope you're back on the road again soon, Ernie.

All the best,
Andrew.

 

Q: How can insulation from the headers make it through the cats?

I agree, more diagnosis is needed. Has the compression been tested? A misfire can be caused by a leaky valve. Or by a bad injector, or a plug with a cracked insulator, even by oil usage in that cylinder, where the oil residue short circuits the spark. Not immediately and not always but still with a degree of regularity. It should be easy to find which cylinder it is, unplug the injectors one by one checking for the popping noise changing - if the misfire gets worse then the cylinder you unplugged is not the culprit. Then diagnose further by checking out the injectors or swap them to another cylinder.

 

Buying these cars is easy. What truly sets the bonafide Ferrari owner apart from the rest is his/her ability to perform the hardcore maintenance. Not the plugs and oil but the real heavy lifting ****. I'm certainly no where close to expert but I do know from other facets of life that the art of good diagnosis falls within the 'heavy lifting' category.

I think you are on the cusp of achieving that next level and this is your final test.

Hoard in the intellectual capital to be gained from this last hurdle.

Wish I could help. Perseverance baby!

 

I can't get up there today. I think you should put the old injectors back in so that you can diagnose the problem today. If you send them out you could get lucky and they need to be cleaned anyway but if that does not work you just delay the diagnosis another 2 weeks. Taking the headers out today will only open a new can of worms. You will do something like brake off a header bolt to the level of the head casting and then moan about how to take that out without ever confirming the header theory. Why cause more problems. The 348 headers are pretty stout and can take some significant vibration. Besides your car does not run enough to damage them anyway. Now that was a kick below the belt!

 

I'm bettin' the o-ring problem in 8 is a bigger one. The cracked tip is rather routine and can be replaced with $1.50. What's the plug in 8 look like? Is it lean?

 

Now *that* looks like a problem and adds up (at least to me) why Eric's fuel rails with gold connectors only partially solved the issue.

 

Attention to the seemingly small details, the difference between drivable and running Correctly.

I'm with Bruce, the cap isn't much of a concern but a vacuum leak sure could make a difference. Unless there is one heck of an ugly injector.... you are only part way to the fix. I would bet you are dealing with no less than 4 small problems that add up to what you can hear and trip the CEL.

As long as you are working on the injectors, check the WHOLE fuel system and put that to bed. Remove the fuel filters, shake them up real good while holding the ends capped and pour them out backwards onto a white paper towel. Still perfectly clean from the pump over haul procedure? Any debris showing? Debris from what source? Freshly serviced injectors require this double check so they are not put in jeopardy once running again. Rest assured, those filters do not catch all the debris, you need only pour a dirty filter out on a clean paper towel the direction of flow to prove that fact!

Fabricated fill neck and vent tubes still completely intact? New orings should go on the vent pipe connections..... Cover every Fuel System component now and then put any question to its integrity to rest for good.

Assumptions lead to oversights and missed opportunity in diagnosis.

 

Previous fuel pump gasket failure augurs toward Dave's recommendation.

 

Nice to see the brotherhood working together.

 

+1

I really like the concept of working thought a complete 'system' before moving on. In this case Ernie is putting the whole fuel system to rest via working on it's individual parts.

Dave is handing out gold bars for free here....

Ernie, let me know if you need someone to take any sort of baseline values on a stock, good running 348.

This is a good thread.

 

ERNIE ---

Have you tried swapping the entire car with a 360 !!!

 

Any garbage in the filter baskets of the injectors? How bout a plug read on all 8? Been wondering how to check lamda values without SD. Any way to check additive/subtractive values?