Clutch or something else??

[Brandon Anderson]

Good Afternoon everyone. 6 months ago I installed HF cats from random. Shortly after I started smelling a rotten egg smell when driving. I kept driving the car and 300 miles later I still smell it. The left side exhaust is expanding and making contact with the back plastic near the rear tire and slightly melting it.. I’ve added heat shield there. I have the exhaust as far forwards as possible but it keeps expanding and touching. Right side is fine. Now I’m confused is it the melting plastic, the HF cats breaking in still or my clutch. Car doesn’t feel like it’s slipping but the smell only comes after high RPMs above 3k.. im at a loss. If I need to replace the clutch I will. Any ideas??

 

[Old School]

The "rotten egg" smell is the classic complaint with catalytic converters. Been that way since the 70s, always hated it. It's normal, whenever I witness a Toyota (or anything else) go wide open in front of me, I get a whiff.

But, your metal exhaust tips or pipe is actually expanding?

 

[Brandon Anderson]

The smell is very strong. I’ve never smelt anything like this before. Prior to these new HF cats there was no smell at all. Here’s a pic of the tip. I’m not sure what is exactly expanding. The tip or the muffler but you can see a little discoloration. When it’s hot that tip is touching the fender liner and way behind the hole is should be.

 

[Ramtuff]

The exhaust expands 1/2 to 3/4” when hot. You should put the outlet about 1/4” from the front of the opening when cold. You will melt your wheel well liner from the hot exhaust With spirited driving. You may have to tack weld the joints to prevent it slipping.

 

[Steve M]

I would not suspect your clutch based on the information you provided.

As a quick sanity check, you can put the transmission in 5th or 6th gear going up hill and give it a lot of gas - if the clutch is slipping, you should see the RPMs rise without feeling the car accelerating. That might only work on really worn clutches, but it's at least something you can try before you have to resort to heavier labor.

What year is your car? I've been running high flow cats (metallic substrate) for years on my '08, and have never experienced the smell you describe, even when hot lapping the car multiple times at the drag strip.

FWIW, this is where my driver's (left) side exhaust tip sits with the car completely cold:

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Once it is fully warm, it'll sit pretty much dead on center front-to-back. If it expands more than that, you may have something else going on that'll require you to remove the sills and start poking around.

 

[Brandon Anderson]

Mines an 04. JonB wants me to check for spark. He thinks fuel is getting into the exhaust system. That’s my next step.

 

[Brandon Anderson]

Used a spray bottle and Sprayed water on plugs and coils in a pitch black garage with the engine running. No arcing. I don’t think it’s wires.. it’s got new plugs… and if a coil was bad wouldn’t I get a CEL?

 

[Old School]

A couple of things.

If you unplug a plug wire at the plug, you should get CEL almost immediately.

If there is a plug that is not firing (shorted, fouled etc) the upstream O2 sensor will detect the excess unburned oxygen from that cylinder, the engine controller will interpret this as though there was not enough fuel to burn the oxygen available. It will attempt to keep the air/fuel ratio at 14.7 by adding additional fuel. If you have a OBDII code reader that can do live data you can see this. The long term fuel trim (LTFT) will be ~20% (1 out of 5 cylinders) for that bank.

Unburned fuel in a CAT will heat it up and destroy it.

 

[MoparMap]

An interesting thought would be if the one side was running extra right and making the cat do more work and heat more, that could explain why the one side is expanding more than the other and hitting the back. I agree with others though that I would expect it to throw a code by that point.

 

[Goggles Pizano]

Check if your tip/pipe moves to the center or further back of the hole. If it is supposed to move/expand and does not, sounds like the pipe is fixed mounted.

Plus what diameter exhaust?

 

[GTS Dean]

You could pull injector plugs individually to see if there is an expected drop in rpm with each one. Don't run it more than about ~5 seconds unhooked.

Plug into the OBD port and check Long Term Adaptive Fuel Trim on Left vs Right bank. Check O2 sensor running values to see if they are cycling more or less consistently left/right.

 

[Brandon Anderson]

I am going to order an OBD2 from Amazon and check the above. Fuel trims and O2 sensors. See if there’s a change. I’ll also put it in 6th and see if the clutch slips. I’m out of town until August 2nd I’ll report back then. Thanks everyone.

 

[Brandon Anderson]

Okay… I’m back and I’ve got a problem. The clutch is fine. No slipping but both of my LTFT are -20. Here are some pictures of the problems. Any ideas?

 

[daveg]

LTFT is definitely negative. Sounds like your running too rich. Leaking Injectors, both banks? Not enough air entering? Engine running at steady speed, you want to see as close to 0 as possible.. Older engines wont be as close as newer / less mile engines..
Surprised your not popping a code.

There could be a few things that's causing your trims to be that negative, MAF etc...

PS, where these reading taking during Open or closed loop?

PSS https://www.youtube.com/watch?v=5WnM_NsOtd8&t=651s
When I was first learning troubleshooting, I learned from this.

 

[GTS Dean]

My DRB-III has a nice bar graph function to watch the O2s on either side of the cats for each bank - all 4 stacked together. If you can display something like that, you could see if the sensors are reacting at the same rate by position, and whether the oxidation/reduction process thru the cats are similar by bank. Some O2 sensors act "lazy" compared to others and can lead to bank-bank variance.

I'm probably going to jinx myself right now, but I'm still running the OEM downstream O2's that came with the car for 27 years. I put new upstreams in after the engine rebuild 3 years ago and one of them failed after 18 months.

 

[daveg]

Very important to have a Scanner that does graphing!!!! I went out and bought a an XTool X9 pro with a Borescope. Already paid for it in troubleshooting. As you say Dean, you need to graph, very important.
I had to go to the extent of driving my buddy's Acura MDX and record the drive for 20 minutes to figure out what his very intermittent issue was. After recording, I played it back and determined it was his Wide Band on B1.

I only go Factory or Denso's on O2's.

PS, if you watch the video, there is an assumption that the OS is upstream but he doesn't say it is I believe. Been a bit since I watched it. Upstream reacts very different than down stream and plays a different role.

 

[Brandon Anderson]

Yeah I mean there’s no check engine light and the car appears to be running fine although there’s a smell above 3k. O2 sensors appear to be working normally going from .1-.9 on the OBD but both of my LTFT are -20 I reset the battery and checked again, same thing.

 

[daveg]

You never answered my question about the readings.. Was it in Open loop or closed loop.. Hugh difference. Open loop might explain -20% on both banks.

 

[Brandon Anderson]

Sorry about that. I believe I was in closed loop. I checked it after driving it for ten minutes and the car was up to normal operating temperature. I couldn’t find an indication if the loop was closed or not. Is there a way to verify? Thanks for all the help.

 

[Old School]

Since it's the same on both banks, it's unlikely to be a plug, wire or injector. Clogged air filters, restricted exhaust (CATs) or MAP sensor could make it go rich and be the culprit.

 

[Brandon Anderson]

Since it's the same on both banks, it's unlikely to be a plug, wire or injector. Clogged air filters, restricted exhaust (CATs) or MAP sensor could make it go rich and be the culprit.

Air filters are brand new and I took them off today to verify nothing could be blocking. Cats only have 300 miles on them. I removed the MAP sensor. I’ll spray some MAF cleaner in there I guess but it looks completely clean to the ***** eye.

 

[daveg]

If the car was at running temp, it should be in closed loop.
You can clean the MAF but "typically" if its dirty, LTFT would show positive.. But clean it anyways.

Things I typically do to a car with some miles is clean the MAF AND throttle body(s) / blade(s). You would be surprised how a dirty blade / body can change values. Clean both with some Throttle body cleaner on a lint free rag. Clean both side of blades good especially leading and trailing edges.

Assuming no Exhaust leak, look at MAF values.
Remember, the LTFT is a calculated value and not an actual reading of anything. Because of this, if you have no Check Engine light, drive it and see if you eventually get a CEL. If not, drive it.. LOL...

Did you mention year and if you have any other mods beside cats?

PS, I have been using MAF and MAP interchangeably but they work differently but the ECU uses both to determine fuel amount.

PSS, did you look at LTFT at higher RPM's This is where recording and graphing various components and trims during a drive helps

 

[Steve M]

Unless I’m mistaken, his ‘04 does not have a MAF sensor.

 

[daveg]

Unless I’m mistaken, his ‘04 does not have a MAF sensor.

Correct, has a MAP mounted on the intake where as a MAF would be before the throttle body. still can be cleaned.

 

[GTS Dean]

I don't know for sure, but I'm going to assume that the Gen 3 has a Speed-Density ECU just like the Gen 1 & 2. For those models, air density is determined by MAP (engine load vacuum) and IAT. The OE tune is set up for multiple discrete block values of RPM vs MAP-IAT. There are hard-coded blocks for Open Loop operations include Startup/warmup, WOT, and closed-throttle decel. Closed Loop rpm blocks from idle to ~2700rpm adjust based on ECT/IAT/MAP. STFT adjust fuel pulse based on upstream O2 output readings vs expected (base tune). If fuel has to consistently be added, or cut from the base map, this becomes your Long Term Fuel Trim per RPM block. Finally, there's an overall weighted average of LTFT by bank.

All the downstream O2s do is monitor oxygen level in the post-cat exhaust to determine if the rich/lean ST fuel trims are keeping the cats cycling oxidation/reduction within range as programmed. If you smell sulfur from one side, my guess is the rear O2 is only seeing the cat working in one direction.

 

[Old School]

From Chrysler tech training manual (the complete manual is too large to attach).

 

[GTS Dean]

Looks like the Gen 3 includes purge vapor as a substitute for fuel pulse width. Nice touch. Purge flow is fixed by block in Gen 1 and Gen 2.

 

[Brandon Anderson]

Last update. I removed the cats and verified they looked normal.. check. I cleaned O2 sensors.. check. I cleaned MAP and AIT.. check. I checked for vacuum leaks… check. I am replacing spark plug wires and verified spark plugs all gapped and cleaned… check. Then I drove it hard today with the side sills removed. I’m still getting negative LTFT at idle.. -18 or so. At high power it fluctuates between -5/-10 LTFT. STFT is +5 to -5. I didn’t smell the rotten eggs as bad. I’m kind of thinking I just need to drive this thing a little harder. I keep the RPMS under 3k almost always except brief sprints above. Today I kept it higher RPMs and the smell wasn’t as noticeable. Thanks everyone for the help I think the answer is to just drive it a bit harder and if it throws a code then I’ll have a better reason to dig deeper.

 

[MoparMap]

Do you have a tune on the car by any chance? I know when I put my cam in and was building the tune with Dan Lesser I would basically just drive the car around and send him the DRB III fuel trim tables every so often so he could balance the base map based off of the fuel trims to try to get them close to zero in normal operating conditions. They can only go so far though, hence why you need to redo the base map. I guess you have the other issue of smell and possible excessive heat on the one side though, so seems to point more towards some kind of fault. As someone else said earlier, O2 sensors can sometimes be a little funny and read opposite of what you'd think. A cylinder that is so rich that it doesn't even fire lets all the oxygen through as well, which is what the sensor reads so it thinks it's running lean and adds even more fuel, only compounding the issue. You might try pulling the battery cables to reset the fuel trims after all the other work you've done. Let it start from zero again instead of trying to work backwards from -20. If it goes all the way back to -20 I would keep looking for some kind of fault somewhere.

 

[Brandon Anderson]

Do you have a tune on the car by any chance? I know when I put my cam in and was building the tune with Dan Lesser I would basically just drive the car around and send him the DRB III fuel trim tables every so often so he could balance the base map based off of the fuel trims to try to get them close to zero in normal operating conditions. They can only go so far though, hence why you need to redo the base map. I guess you have the other issue of smell and possible excessive heat on the one side though, so seems to point more towards some kind of fault. As someone else said earlier, O2 sensors can sometimes be a little funny and read opposite of what you'd think. A cylinder that is so rich that it doesn't even fire lets all the oxygen through as well, which is what the sensor reads so it thinks it's running lean and adds even more fuel, only compounding the issue. You might try pulling the battery cables to reset the fuel trims after all the other work you've done. Let it start from zero again instead of trying to work backwards from -20. If it goes all the way back to -20 I would keep looking for some kind of fault somewhere.

It doesn’t have a tune that I know of.. I haven’t seen any electronics on the car that isn’t OEM. The extra heat has been disproven. I drove is with the side sills off and used my laser thermometer. The temps are within 30-40 degrees of each other. Both cats are running 500 degree after hard driving at the center so I dont think they’re truly getting hot enough to damage themselves.