CA Gross Poluter opinions

[xjbubba]

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My MAP sensor just passed its test. I believe the MAP sensor interfaces with the EGR flow via the ECU so possibly with a bad EGR the ECU is sending bad info.

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MAP sensor and EGR are entirely two different systems/circuits--no interface--. As you already observed, the EGR system is for controlling NOX.
The MAP system tells the ECM how much load is on the engine, and adjusts fuel flow, as needed; problem with MAP system (electrical, vacuum, sensor itself) could easily cause high HC, and probably elevated CO. CO is generally results of incomplete combustion, while high HC is caused by rich mixture, or misfire.

 

[cj5wagomando]

OK, I am working my way through the sensors checking them per my manual. O2 and Coolant Temp sensors will get checked this evening.

I will re-read, but the way my manual describes the MAP sensor is that it controls the EGR flow as well as quite a few other items (spark time, fuel pulse, etc.) -I don't have it with me now.

Since the EGR is known to be bad I will switch it for the new one I picked up at lunch and keep on checking.

thanks.

 

[xjbubba]

Well, ECM control over EGR function would be dependent on the input from the MAP, VSS (if equipped, like my emissions system), CTS, etc. That doesn't mean they are directly connected. Yes, by all means, replace the bad EGR valve; but don't expect a properly operating EGR to be your solution to high HC or CO.

 

[letank]

Check your timing, too much advance can wrech havoc on emissions.... I lowered a friend 2.5L engine from 25 to 18 degrees and the HC went from 140 to 2 ppm.
Basically lower has much as you can to stay within smog specs. Recheck distributor timing, if the advance is somehow stuck on full advance, or.... I forgot how the timing is set... probably the ECU does it all.... But with a timing light you can see where you stand at various speeds....
Will call latter.
Michel

 

[xjbubba]

In my prior post (post#21), I stated CO is due to incomplete combustion, while HC was do to rich mixture. My statement was misleading. CO is normally do to a rich fuel mixture, often caused by high fuel pressure, bad MAP, bad ECT, and bad IAT sensors, while HC is do to rich exhaust gas due to cylinder misfire, caused by ignition, or mechanical issues such as low compression in one cylinder, or intake leaks; however, if HC is high due to misfire, CO will be LOW due to little or no combustion taking place in the misfired cylinder. It's unusual to have high HC and CO at the same time. O2 readings, in conjunction with HC and CO readings help diagnose where the problem lies. Search for causes of a combined high HC and CO.

 

[cj5wagomando]

Bubba,

Thanks for that clarification. I have arranged for a fuel pressure guage to be waiting for me when I get home from work so I can test that this evening.

MAP, 02, coolant temp and MAT sensors check out ok. I did notice that when I went to check the O2 sensor that it did not seem to be plugged in all the way!!?

D

 

[cj5wagomando]

Looks like it is running at 30-31 psi. Book calls for 39 psi.

Dave

 

[oscar.zulu]

HTTP Error 404 - File Not Found

 

[letank]

Looks like it is running at 30-31 psi. Book calls for 39 psi.

Dave

What is your timing? The specs is on the hood sticker!

As said I hope that you find the report for the 02 reading.

Then the Throttle Position Sensor..... . I have some pins made so you can reach the wires easily.

Michel

 

[cj5wagomando]

I will check the timing.

Re-Read and seems the pressure is to be 30 psi.

 

[letank]

I will check the timing.

Re-Read and seems the pressure is to be 30 psi.

Good result, so you are not over, and it depends on the accuracy of the gauge.
M

 

[letank]

found this post, timing is not adjustable....

http://208.101.10.250/~naxjaor1/forum/showthread.php?t=68410

Otherwise all the renix sensors explained

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

Best,

Michel

 

[djgrayxj]

Note from DJ
Smog inspection numbers Lambda calculator web site
Google search for lambda calculator emissions = Free Automotive Calculator =
http://www.smogsite.com/calculators.html
Then scroll down for Lambda Calculator and put in your inspection numbers.

Search the internet for a lambda calculator emissions you plug your emissions numbers into it and it will tell you if you are running rich or lean. If it is ok then your cat may be going bad.

 

[cj5wagomando]

update

I am doing a tune-up- new cap, rotor, plugs - it has been running rich (high HC and CO) - I did notice the o2 sensor was not quite plugged in all the way.

So if all goes well the not quiet plugged in o2 sensor was causing the high CO
and the need for a tune-up that was exaggerated due to the rich condition created by a lack of o2 sensor input.

....off to buy some tune up parts...

Dave.

 

[cj5wagomando]

update:

After new Cap, Rotor, spark Plugs and o2 sensor properly plugged in:

Decided it needs a good freeway run to blow/clear everything out of the system that the rich condition had created. Or that I allowed, but that is another topic.

MPG went from 11mpg to 16mpg on my 60 mile run to BassProShops in Manteca. topped up the fuel on the way out and upon return. I think I may be in good shape. This drive consisted of a 1500 foot elevation ridge to go over twice with a traffic jam on the DOWNHILL side as well...so the mileage may be better)


I will be posting the Smog ReTest results when I get that done....I may need to go back to BPS first.......

Dave

 

[xjbubba]

You ever get re-tested? Results?