Issue with Exhaust - It STINKS Ė Literally - Defender Source
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  #1  
Old December 15th, 2006, 10:08 PM
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Question Issue with Exhaust - It STINKS Ė Literally

The fumes are so bad that if Iím in the truck for more than 5 minutes I stink of what seems to be unburnt gas and/or carbon. I have a surrey top. It really only smells when Iím on the road. At idle it isnít that bad at all. My clothes smell like Iíve been mowing lawns all day with a push mower. It happens immediately after I made some changes to the truck:

Before Changes:
1995 D90 ST
Stock engine
Stock exhaust and cats (except for a flowmaster muffler)
bosch plugs
1 Bad O2 sensor throwing lambda code on OBD
Did not smell bad at all!

What I did:
Replaced both O2 sensors
Replaced the plugs with Champion RN12YC4
Replaced Rotor
Completely hollowed out Cats
Replaced ECU relays with genuine
Everyone around me notices the stink on my clothes...!


As soon as I made those changes it began to stink of these fumes. Here is what I know:
  • The truck is, from an EPA perspective, burning clean. I had a buddy with an emissions kit and it is putting out almost no carbon monoxide.
  • I had a friend of a friend who works for a LR dealership bring his computer over. The ECU is functioning fine and no adjustments need to be made according to him. (It does not appear to be running extra rich.)
  • I pulled some plugs: The plugs, after 2 tanks of gas, do have a decent amount of carbon, but nothing *too* serious(?) (I think). They are black with carbon near the electrode tip. The threads are pretty much black and the washer is definitely wet. (Does this sound like they are not burning enough gas?)
As far as I know, my options are:
  • Replace the champions with bosch like I had before
  • Try hotter plugs (does anyone know a model number hotter than RN12YC4? I couldnít find a "RN13YC4" which I would assume would be the next step up?)
  • Put the cats back on
What is going on? Any ideas? Itís worse when Iím on the road, not at idle. When Iím going along at 50mph then come to a stoplight the fumes are SO bad when I stop as they blow forward.

If the truck is burning clean, then I donít see how putting the cats back on should help. They are meant to take pollutants out and according to the sniffer I put in the tailpipe the truck is clean Ė but something stinks. Can it technically be burning ďcleanĒ but still letting out bad smelling exhaust/carbon/etc? I feel like Iím driving a diesel. I would think if I had a bad injector or so I wouldnít pass the emission test.

I'd like to try swapping the plugs. That would be the easiest next step. If someone could advise me on what plugs I'd appreciate it.

Let me know if I can provide any more info. I can post some pics of plugs if need be.

Hutch
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  #2  
Old December 15th, 2006, 11:35 PM
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Check and see if you are blowing dark smoke when you really push on the gas. The valve seals may have cracked allowing oil to seep past the valve stems and into the cylinders. I had this happen on an older vehicle that had sat for awhile.
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  #3  
Old December 16th, 2006, 12:02 AM
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If I had to guess Id say the thing that stands out the most is the "Completely hollowed out Cats"

You may be running perfectly fine but the cats are there to clean more than just nox and CO2. Just an educated guess but if you had another set of Y pipes Id bet the smell goes away. Everything else you did to the truck shouldn't cause the smell
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  #4  
Old December 16th, 2006, 02:30 PM
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Scott - No I can't see any visible emissions when accelerating. I keep thinking it must be from one of the things I did because it smelled as soon as I finished the work. At the same time, I'm open to ideas and coincidences certainly do happen....

Tim - Yes and I have no problem putting them back in. I'm just under the impression that they are there for pollutants that are tested for during emission tests (namely carbon monoxide) and I don't detect any of these emissions, but you could be right. If that's the case, I'm hoping that I don't fry the cats by working them too hard (then again, if they've always been doing it but I didn't realize it I guess no harm...)

Thanks for the input.

Anyone have an idea of a Champion plug that is 1 or 2 steps hotter than the RN12YC4 that I have in now? I can also try the bosch again.

Thanks,

Hutch
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  #5  
Old December 18th, 2006, 07:00 AM
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Tim is right on w/ the "hollowed out cat" thing. It'll run great, but rich. If you don't re-tune the ecu (tune resist diode/ european non -cat tune) you'll have a carboned up mess eventually.

Or just put the cats back in, use performance cats if you think they are slowing you down.
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  #6  
Old December 19th, 2006, 09:16 AM
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Matt-

Thanks for the follow up. So I guess I'm to assume that the cats put back-pressure, heat, or something else that affects the ECUs ability to measure oxygen properly? I guess that makes sense. Honestly hollowing out the cats was just something I had done without thinking about any repercussions

The only thing that worries me is that my plugs seem wet (But I realize this could be purely cat-related - just ensuring there aren't other issues). Can you take a look at the 2 photos? The photo of all the plugs gives you an idea of what I mean. It looks like most are too-rich. But take a look at the single plug photo. My concern is that this plug, along with one other, doesn't have ANY carbon on the ceramic portion of the plug which makes me think it isn't firing (or isn't firing enough?). Certainly I'd notice if 2 cylinders weren't functioning(?)!

The next thing I do, before replacing the cats, is to ensure that the O2 sensors are correct. I'm nearly certain they are - just going through the right motions.

Thanks for the input and any advice on the plugs.

Hutch
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  #7  
Old December 19th, 2006, 01:30 PM
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" If you don't re-tune the ecu (tune resist diode/ european non -cat tune) you'll have a carboned up mess eventually."

Do the ECU retune. It is cheap as it is either removing or adding a resistor.

From RPI:

And for the more Technically minded.

Tune resistor info (for those that want to know)



Please note that although the information below is still correct it has been updated here.

All Efi 'Hot wire' systems will incorporate a Tune resistor. Its function is to make sure the vehicle runs the correct Fuel map in the ECU for Cat or Non cat vehicles. If you cannot locate yours the following may be relevant.

There were definitely some EFi looms made after 1990 with the tune resistor taped inside. From 1990 onwards (14CUX systems) they all have to have one, but you've got to find it first!

If there is no tune resistor, then the vehicle will run on the default 'Limp Home' map. Where the resistor is fitted externally, it will be where the relays sprout out of the loom, not by the ECU. PRC9060 is a normal ECU with the regular set of maps in it.

A Green tune resistor (green referring to the color of the wires) will always give a non-cat tune, and White is always a cat tune. By the way, the default (Limp Home) tune is a cat map, so this usually makes a non-cat car run very rich.

You need to run the correct tune resistor to get the correct fuelling from your ECU and you need to re-chip all Hot wire ECUs if you have upgraded your engine spec. in any way. Especially if increasing capacity or changing cam, and even for stock engines, the Optimax chip will refine your efficiency, economy and performance.

For those 'Even More' technical. A tune resistor should be connected between pins 5 and 27. The wire colors are Black/White and Black/Grey (where the first color is the primary color, and the second is the trace). The Green tune resistor value is 470 Ohms, and White tune is 3900 Ohms. Ordinary 1/2 Watt resistors are just fine, although the original is a Metal Oxide 2% item (which I always use anyway). In this location I sometimes use a 1 Watt resistor, because the larger physical size makes them easier to handle.
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  #8  
Old December 19th, 2006, 08:09 PM
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Yeah....the plugs look fine to me although I'm sick as a fawkin dawg right now and cant see shite.

How long have they been used for?

I wouldn't worry that they are clean....and I'd hope that you'd notice if they weren't working..

I've re-tuned some ECU's including mine (headers and largish bore) and it works ok but next time I'll probably just run high flow cats and quit dodging the man. Don't really need all that flow for a trail riggy.


Edit;....cummon Tim, tell us what you know
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  #9  
Old December 19th, 2006, 09:53 PM
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Thanks Matt and Ron-

The plugs were only used for about 1 1/2 tanks of gas - about 200 miles or so. To me that's not much for them to look like that but I do know these trucks run rich.

I'll definitely look into both solutions. Like I said - I have no problem putting cats (high flow even) back on - my only concern is that there was/is something else wrong and I'm going to cause damage by putting on cats with all sorts of crap flowing out the exhaust... Once I ensure that these O2 sensors are definitely the right ones I'll weigh the options...

Thanks again - off to the inlaws for the holidays. Oh joy!

Hutch
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  #10  
Old December 20th, 2006, 06:17 AM
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Hutch,

generally speaking when everything is working right these trucks do not run rich....in fact they tend to run lean.

Make sure the o2 sensors are functioning, as well as all the other sensors and the CEL.
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  #11  
Old December 20th, 2006, 09:22 AM
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Just change the tune resistor. The 3.9 was designed to run with or without cats.

Ron
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  #12  
Old December 20th, 2006, 08:15 PM
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Quote:
Originally Posted by junkyddog11
Make sure the o2 sensors are functioning, as well as all the other sensors and the CEL.
I would assume if the ECU OBD isn't throwing a code out then they are fine. Is this not the case? (If this is not the case, then I think a buddy of mine can help me take a look at them.)

Hutch
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  #13  
Old December 23rd, 2006, 08:49 PM
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Matt/Ron-

I'm still trying to figure out the tune resistor out vs. the chip swap. Is a "re-tune" and a "re-chip" the same thing? It doesn't sound like it. I found this page and it's full of info, but I'm still a bit confused. I have the 14CUX ECU with my 1995 D90.

http://www.v8engines.com/faq-inj.htm#tuneresistor

Dumb Question: If I don't go the re-chip or re-tune route then if I put the cats back on will it just "work" and be back to normal (assuming everything else is fine of course)? I guess the underlying question is what are the cats doing? They can't be filtering all that carbon garbage out right? I'm assuming that by virtue of them being there they slow down the flow which gets the truck out of "limp-home mode" - correct? If they were actively filtering out that much crap they'd be gummed up for sure.

What if I opt for performance-cats that have better flow? Will the ECU be able to function with these higher-performance cats? I'd hate to do that and end up having to re-tune or re-chip anyway.

Thanks in advance,

Hutch
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  #14  
Old December 23rd, 2006, 09:34 PM
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You do not need to change the chip. All you need to do is find the tune resistor in the harness and swap it for the non-cat one. It has to do with the heat caused by the cats, without them the front O2s (the only ones on a 14CUX) do not run correctly. Like I said via PM I never did it on my D90 but I know a couple morgan owners who have and it worked fine after the swap of the tune resistor.

The only unknown is where the tune resistor is on a 95 D90. Anyone????

To answer your question, yes, putting the cats back in should fix it.

Ron
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Old December 23rd, 2006, 10:06 PM
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I'm stuck in Chicago with the In-laws but as soon as I get back home I'm going to see if I can find the tune resistor under the seat or somewhere on the truck. I'm assuming if I can't find it that I can purchase one somewhere online...

Thanks Again,

Hutch
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  #16  
Old December 24th, 2006, 08:04 AM
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The tune resistor on a 95 is in the wiring harness in the engine bay, drivers side, very close to the clutch master cylinder. Looks somewhat like a spade fuse about a 1/2 inch long by 1/4 inch wide. IIRC, it has a black/white wire going to it.
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Old December 24th, 2006, 02:25 PM
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Question Am i just an idoit here

Sorry guys but I am really not understanding how to change from cat to non cat. Do you have to get a new tune resistor? Can you just buy one of the correct ohm's at a place like radio shack and put it in? Or do you just have to switch wires? Or am i just really in left field. I need to do this and am just confused Please help.
Thanks
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Old December 24th, 2006, 07:54 PM
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The tune resistor is a chip that slides into a slot in that wiring harness. I don't know where you buy one, but I would imagine it's going to be a dealer thing or maybe RN. Pull the old out, put the new in, and re-wrap your wires. The biggest issue will be finding the correct one.
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Old December 24th, 2006, 10:23 PM
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Rimmer brothers in the UK has them for about $10 US plus shipping and they list the part numbers. According to RPI it is a simple resistor you should be able to buy at any electrical place (probably not radio shack).

Ron
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Old December 28th, 2006, 07:31 PM
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Quote:
Originally Posted by Andrew Vick
The tune resistor is a chip that slides into a slot in that wiring harness. I don't know where you buy one, but I would imagine it's going to be a dealer thing or maybe RN. Pull the old out, put the new in, and re-wrap your wires. The biggest issue will be finding the correct one.
Based on what everyone said, this is a simple resistor that you can buy at Radioshack..... I'll send one to you for $10 (shipping included)! ;-) The 1/4 Watt resistor is the most common thing ever, the 1 Watt resistor is probably an online buy. Resistors are the most basic (and cheapest) electronic components you can buy.
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