light black soot on rear bumper

[motormobile]

Attention mechanics who know and educated guesswork appreciated.
2006 maxima sl with 62k miles. Car is a pearl white color or this might not be noticeable. Every few days, I can detect a very thin layer of black soot like substance on the rear bumper cover. Seems obvious that it is dust mixed with some exhaust. Of course, I am not a mechanic and "obvious" is a subjective term. Car runs smooth with no check engine light. Have not run a check for any codes though it was in the shop a month ago for a 60k check up.
This black soot is a real concern to me. One guy told it means nothing. another said that he thought the car was either running rich or lean and may need a sensor checked.
If anyone knows what it is....or has had the same symptom, I would love to hear from you.
Thanks.

[Nahkapohjola]

Originally Posted by motormobile

Attention mechanics who know and educated guesswork appreciated.
2006 maxima sl with 62k miles. Car is a pearl white color or this might not be noticeable. Every few days, I can detect a very thin layer of black soot like substance on the rear bumper cover. Seems obvious that it is dust mixed with some exhaust. Of course, I am not a mechanic and "obvious" is a subjective term. Car runs smooth with no check engine light. Have not run a check for any codes though it was in the shop a month ago for a 60k check up.
This black soot is a real concern to me. One guy told it means nothing. another said that he thought the car was either running rich or lean and may need a sensor checked.
If anyone knows what it is....or has had the same symptom, I would love to hear from you.
Thanks.

On any car I'd say it means nothin. Having had ol maxima for years, i can tell no other vehicle I've had, has been so 100% clean. So I say this is exceptional in maxima, most others, business as usual.

I'd start from here, check out what happens "Every few days"? Temp change, rain, or what? Meaning issues like condensation or whatever...
If car has had in its history a splash of coolant (glycol), it means that every humid day the clycol residue chrystals hidden in every micro crevisse, suck condensation from air (car parked outside (every few days?).

Glycol splash means temporarily water ... =minor short circuits only "Every few days". After warmup, all water will evaporate, no problems.... Finding the chrystals will be a pain: water wash (terrible choice) may clean up the problem / power factory - if his is the reason behind.

The issue may also be intermittently dying coilpack(s), typically start dying after 100k miles. Only $wapping all will help.
Or whatever. No panic, your maxima has just dropped to a level all other cars stay always

[motormobile]

[quote=If car has had in its history a splash of coolant (glycol), it means that every humid day the clycol residue chrystals hidden in every micro crevisse, suck condensation from air (car parked outside (every few days?).

Glycol splash means temporarily water ... =minor short circuits only "Every few days". After warmup, all water will evaporate, no problems.... Finding the chrystals will be a pain: water wash (terrible choice) may clean up the problem / power factory - if his is the reason behind.

[/QUOTE]

Thanks Nahkapohjola for the reply. However, due to my ignorance, I am not sure that I fully understand what you are trying to say in these two sentences. Could you restate and clarify what process and conditions you are describing. "splash coolant" "glycol residue chrystals hidden in every micro crevisse" "minor short circuits"

Where does this glycol splash come from?

Sorry to ask this. I know it is clear to you. Much appreciation.

And, if Nahkapohjola is not available and another enthusiast can make it simpler and clear for a nonmechanical person.....thanks.

[Nahkapohjola]

Originally Posted by motormobile

Thanks Nahkapohjola for the reply. However, due to my ignorance, I am not sure that I fully understand what you are trying to say in these two sentences. Could you restate and clarify what process and conditions you are describing. "splash coolant" "glycol residue chrystals hidden in every micro crevisse" "minor short circuits"

Where does this glycol splash come from?

Sorry to ask this. I know it is clear to you. Much appreciation.

And, if Nahkapohjola is not available and another enthusiast can make it simpler and clear for a nonmechanical person.....thanks.

As no info about the car history (means anything may have happened), then just figurin out one solution for intermittently misfiring engine:

(For multiple reasons) radiator, coolant system tubing may get ruptured. If this happens, coolant can burst out and spread out splashing around engine compartment. Later water dries out but glycol chrystals stay, car is repaired. Evertyhin seems to be fine... But. These leftover chrystals absorb water from moist air whenever its possible, then loose that water when air is dry. This means water only when conditions are 'right' = short circuit = medium for electrons to jump over anywhere, intermittently

[motormobile]

Thanks for the explanation. Have a great day.

[Nahkapohjola]

Originally Posted by motormobile

Thanks for the explanation. Have a great day.

Youre welcome. I know that issue is a long shot, but still, I've had that problem twice durin lifetime (non maxima). Cleaning - electronic connectors etc - is today the solution to most problems along fixing failing sensor(s). See article on link below.

As said, the issue is on the edge of normal: on some cool humid morning you can see water dripping from many vehicles exhaust pipes. This is water, result from the burning process is condensing on a cold exhaust end. (that vehicle has been driven max. 1 mile). Depending on driving circumstances, this water will whirl and settle in the bumper are near exhaust tip possibly causing your remedy. Exhaust pipe is often not perfectly clean, thus water is normally sooty; the more so when burning process has not been perfect. Light car color makes this dirt more visible.

[motormobile]

Hey Nahkapohjola,
Can you help me find a page cardomain dedicated to problems, fixes, and specially transmission info for the 2006 nissan maxima transmission.

I am not happy with the tran. It is unstable between 35 and 45. RPMs can rise quite a bit before acceleration takes place. I have been told that there is a part (I think it was called the transducer...something like that) in transmission that is often the culprit that can be replaced before doing a whole transmission rebuilt.

Car has 62k miles by the way. Thanks

[Nahkapohjola]

Originally Posted by motormobile

Hey Nahkapohjola,
Can you help me find a page cardomain dedicated to problems, fixes, and specially transmission info for the 2006 nissan maxima transmission.

I am not happy with the tran. It is unstable between 35 and 45. RPMs can rise quite a bit before acceleration takes place. I have been told that there is a part (I think it was called the transducer...something like that) in transmission that is often the culprit that can be replaced before doing a whole transmission rebuilt.

Car has 62k miles by the way. Thanks

- I bet there is none ...

I guess following issues can be checked by you/friend/ avg transmission shop. If not, go to dealer$hip (after you have ensured that there is really an A/T pro available)

- Dunno how -06 model is fixed in regards of oil change - I'd change it anyways every 30k (dino oil) or 60k with high quality (amsoil?) oils.

- check all tranny related wirings/connectors. First of all: Check charge voltage at battery (low charge will definitely cause shift problems. Then Check charge voltage at TCU = at TCU computer pins (verify +12V AND Ground are both healthy). Read through my A/T pages, 75% is still the same in a 'different package'... FYI: my maxima alternator died at 60k, had oxidized connectors. See the alt-page if voltage level is not perfect.

- A/T computer =TCU follows always throttle position sensor TPS. If wiring or sensor is faulty, will cause hesitation etc. tranny problems:
TPS Assembly, its Potentiometer and Switches may be tested in four 4 ways :
Stand-Alone tests for old maxima - I guess all similar features are there:
1. Zero Position Alignment with multimeter at TPS, both TPS connectors disconnected, see below.
2. Resistance tests
3. Circuit/Voltage test with multimeter at TCU; connectors installed, see below .
'System wide Diagnostics':
4. With TCU -Test Program: Utilizing Automatic Transmission Self Diagnostics -procedure, systemwide functionality test. Built-in Diagnostics
See for refernece: http://www.cardomain.com/ride/748507/6