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Hello Folks,
I've been struggling with this issue and I hope y'all can lead me towards a solution.
The passenger's side tips become very sooty after a few 100 miles. Originally I thought I may be suffering from bore scoring, but I had the blocked scooped and the shop concluded it was not oil on the tips and the rest checked out.
Long story short, bank 1 runs rich. The shop stated the car had two stored o2 sensor faults. I replaced them myself and it reduced it, however, the exhaust soot still builds up.
Things I've addressed:
-Cleaned the Mass air flow sensor
-replaced the plugs
-replaced the o2 sensors
There is no check engine light but I have a feeling I should replace the coils.
I believe a few folks on here have talked about injectors failing and causing too much fuel; they specifically mentioned it bore washing and leading to scoring but this might be an early symptom?
I believe a few folks on here have talked about injectors failing and causing too much fuel; they specifically mentioned it bore washing and leading to scoring but this might be an early symptom?
Rather than throwing money, labor and parts at it, spend some money to have it tested for fuel trims, cold and hot air fuel ratios...generally speaking an emissions test on the tailpipe (both tailpipes for comparison of Bank 1 and Bank 2) . Since it is not throwing a CEL and thus a code you can look up, I would do some diagnostic work first. And, do you live in a cold climate? Short trips? The soot and condensation is most prevalent when engine is cold start, the air/fuel ratio is rich for running a cold engine, and the cats have not warmed up so condensation is produced. That is why in cold climates you always see steam coming from the exhaust of all cars. Condensation is a product of combustion, but the warmer the car engine becomes, the air/fuel ratio drops, and the hot cats burn it off. The O2 sensors are very sensitive pre and post cat and will throw a CEL if something is wrong. Since it is not throwing a CEL, you need to diagnose the way the engine is running.
I believe a few folks on here have talked about injectors failing and causing too much fuel; they specifically mentioned it bore washing and leading to scoring but this might be an early symptom?
Originally Posted by dporto
+1^^^
+2, injectors for bank 1 won't be a crazy amount of $$. Does the DME pick up injectors that are stuck open? I've read on here it's a somewhat common issue.
Rather than throwing money, labor and parts at it, spend some money to have it tested for fuel trims, cold and hot air fuel ratios...generally speaking an emissions test on the tailpipe (both tailpipes for comparison of Bank 1 and Bank 2) . Since it is not throwing a CEL and thus a code you can look up, I would do some diagnostic work first. And, do you live in a cold climate? Short trips? The soot and condensation is most prevalent when engine is cold start, the air/fuel ratio is rich for running a cold engine, and the cats have not warmed up so condensation is produced. That is why in cold climates you always see steam coming from the exhaust of all cars. Condensation is a product of combustion, but the warmer the car engine becomes, the air/fuel ratio drops, and the hot cats burn it off. The O2 sensors are very sensitive pre and post cat and will throw a CEL if something is wrong. Since it is not throwing a CEL, you need to diagnose the way the engine is running.
San Jose Ca is certainly not a "cold climate"... Regardless, the recommendation for diagnostic work is a good one. Throwing parts at these cars is NEVER a good idea, and as you've experienced gets very expensive very quickly
Replacing bank 1 fuel injectors on a car that has too much fuel hitting bank 1 is hardly "throwing parts at a problem." Even with diagnostics, you're going to need to sack up at some point and eliminate the most likely variable and retest.
My suggestions were based on CA having strict emissions testing, so just about any decent auto repair shop should have a air/fuel ratio tester. Stick it in the tailpipe and get a reading. Okay, so Bank 1 is running rich...then figure out if it needs a bottle of Techron and a good hot high RPM run (the ole Ferrari tuneup to blow out the carbon)...or replacing fuel injectors at $250 a pop (that's Bosch rebuilt green injectors/Pelican Parts). He said the plugs were replaced...were they replaced with the correct ones? Things that come to mind...bad spark plug(s), a sticking fuel injector(s), weak coil pack(s)...and so on. My wife's Mini Cooper exhaust gets sooty because mainly she drives it 15 minutes to work. When it starts to look really sooty, clean it up, bottle of Techron in the gas tank, and then I go drive it for 30 minutes in Sport mode using the paddle shifters. Cleans that crap right up and stays that way for weeks. Repeat as necessary....
Hello Folks,
I've been struggling with this issue and I hope y'all can lead me towards a solution.
The passenger's side tips become very sooty after a few 100 miles. Originally I thought I may be suffering from bore scoring, but I had the blocked scooped and the shop concluded it was not oil on the tips and the rest checked out.
Long story short, bank 1 runs rich. The shop stated the car had two stored o2 sensor faults. I replaced them myself and it reduced it, however, the exhaust soot still builds up.
Things I've addressed:
-Cleaned the Mass air flow sensor
-replaced the plugs
-replaced the o2 sensors
There is no check engine light but I have a feeling I should replace the coils.
Thought?
Perhaps it is normal. My car does the same through all 4 exhaust tips. Due to the soot buildup, I thought the plugs would be fouled pretty badly. Hence I did a plug/coil change. The plugs I pulled out were in very good condition. Apart from a slight grayish color, the plugs looks like new and this was after 50K miles. That black spits you saw collected on the floor were just condensation due to cold starts and the catalytic converter doing its job. I would worry about it.
Warehouse 33-new Bosch injectors $34 ea (996 606 122 00) and Rennlist 10% discount (RM Euro about same price)...cheaper than testing and refurbishing. +1 on check trims and injectors. If pre- and post-cat sensors check out, injectors are a suspect. CEL won’t trip below 30 or 33% miss-trim IIRC. You can try to reset the fuel trims as outlined in other posts. Ahsai has helped lots of us with O2 sensor function questions, so research his replies for more help. The Knowledge Gruppe has a Technical Bulletin addressing injectors in RND engines. Charles graciously posted it in another thread. Go to RNDengines.com for that TB. Those symptoms can happen below 50F. Does one bank do this exclusively on every cold start, or do both banks spit water/soot at different intervals during the approximately 2 minute SAI cycles? You might get some fuel smell and smoke puffs during start. The water drops start after about a minute or more? 3-4 minutes after car started, everything except your heart running at idle? Ask me how I know.
Couple of more questions. Does the SAI pump run when you start it up? Since you did the MAF cleaning, plugs and O2 sensors, have you done a reset of the DME by disconnecting the negative lead on the battery for a few minutes? That returns the DME to default values and by driving it after that, the DME re-maps based on current values being supplied by the various sensors.
IF you determine that your injectors are at fault - check into having them rebuilt. I honestly don't know what the options are for the 996 - but I had all the injectors from my RX-7 rebuilt and it was fairly reasonable. This was probably 12 years ago - but I used Witch Hunter Performance - https://witchhunter.com/ - they provided before/after flow test results and turned them around very quickly at a reasonable price.
#1 shop:
the plugs pulled were in good condition and replaced with oem recommendation. I was told not to change the coils unless they went bad. I wish I would have just changed them in the process.
#2 shop - - they stated that is was normal. : /
#3 shop - they concluded the o2 sensors on bank 1 might be causing the sooty. I opted to replaced them myself and I purchased them from Pelican.
I did not disconnect the battery after but I will try it this weekend. Is there a specific procedure to doing it?
Soot only builds on the passenger tip.
I have a short 10 mile commute, but drive it hard and changed my route to ensure I get the tempretures up.
Again, is there an shop in San Jose, CA that can address such needs?
03-22-2018, 08:53 PM
Sooty Exhaust
