P1128 Code Only + Smog Check Details

[HarryC]

I have a 2000 Porsche Boxster S that I recently took to a Smog Test Only place here in California to complete a smog check in order to regsister my car for the next year.

My car failed the test as a gross polluter. I need to fix the problem.

Details:

The "Check Engine" light was not on when I went for the test. Car was/is running fine. Recentlty started to smell odor coming from car when outside the car after driving. Don't smell anything in the car when driving.

Have noticed small occasional oil drops under car under engine.

The only other change in my car is after a repair to my right front fender due to someone hitting me - it is almost impossible to fill up the tank to the "full" level on the guage. The gas pump/handle itself when filling the car clicks off like every 10 seconds - so it takes forever to fill up the tank. I need to find out what is causing this - perhaps something not put back together properly by the body shop???

The test says that I passed these areas:

PCV
Catalytic Converter
Fuel Injection
Vaccuum Line Connection
Fuel Cap Functional
MIL
Pump Air Injection
Ignition Spark Controls
02 Sensors and Connectors
Other Emissions Related
Fuel Evaporative Controls
Fuel Tank Cap Visual
Wiring of Other Sensors or Switches
Liquid Fuel Leaks

The test says that these results are as listed as N/A

Visual EGR
Fuel Evap Test
Thermostatic Air Cleaner
Functional EGR
Fill Pipe Restrictor
Carburetor
Ignition Timing TDC

The ASM Emission Test Results are:

@ 15mph

RPM - 1842
MEAS CO2% - 12.27
MEAS 02% - 0.00
HC (PPM) MAX 56
HC (PPM) GP 274
HC (PPM) MEAS 185
CO% MAX - 0.51
CO% GP - 2.01
CO% MEAS - 4.28
NO (PPM) MAX - 443
NO (PPM) GP - 1930
NO (PPM) MEAS - 15
Result - Gross Polluter

@ 25mph

RPM - 1916
MEAS CO2% - 12.25
MEAS 02% - 0.00
HC (PPM) MAX - 40
HC (PPM) GP - 224
HC (PPM) MEAS - 153
CO% MAX - 0.49
CO% GP - 1.99
CO% MEAS - 4.31
NO (PPM) MAX - 730
NO (PPM) GP - 1730
NO (PPM) MEAS - 15
Result - Gross Polluter

Now my check engine light comes on from time to time and then goes away. The OBD Code that comes up - even with no "Check Engine" light on - is P1128.

I've seen alot of posts for when P1128 comes up along with P1130 - but none yet with only P1128 coming up.

I've read that it's a good idea to check/clean MAP - which I will do this afternoon - but I'm wondering - with all the info/details above - does anyone know or have an opinion if the problem can be zero'ed in to one thing only or possible - or will many things need to be checked tested?

The problem is - and maybe some of you have been in the same situation - I don't have the funds that I had when I bought the car and when I did I'd take it into a qualified shop. But times are tough and don't currently have those kind of funds. I can/will repair whatever is necessary - but I'm trying to avoid buying/trying many parts/labor that is not necessary.

With all the data above - would appreciate any advice/suggestions/opinions!

Thanks,

Harry

[Zeke]

Did you type "p1128" into the search box? There's a bit of info suggesting the MAF (which you can clean) and an 02 sensor problem (although the O2 sensor code should come up if that's the case). One post even suggests you might have a real dirty air filter.

[BYprodriver]

Hi Harry, the fuel tank vent & EVAP canister are in the pass. fender so all of this may be related to your damage/repair there. P1128 is a rich running condition on the pass. side engine bank cylinder 1-3. I would first UNPLUG the MAS & see if the car runs better with it disconnected. If you want to clean it buy the MAS cleaner spray made for this. I have a new MAS in O.C. CA that I would sell you at a great price if you need 1. Your car is running very rich, if you can remove the sparkplugs to see if it is all the cylinders or just 1-3 that would help & good idea to replace unless they are like new. How many miles on your car ? Where in CA are you?

[BYprodriver]

To minimize emissions:
Fresh oil change with highest safe viscosity
Chevron premium fuel
New spark plugs (brand doesn't matter when new)
CRC emissions pass fuel additive used previous tank of gas.
Engine hot from driving on freeway 3500 rpm 10 miles. Go directly to smog check station avoid idling.

[Zeke]

BTW, welcome to the forums. Show us your "new" car!

[Schumi]

p1128 turned out to be a bad MAF for me- I cleaned it using MAF cleaner twice, but it didn't fix it. Replaced the MAF with a new one and car ran much better.

I unplugged the MAF and ran the car with it unplugged, and the car had tons more power from 6-7K RPM than it did with the MAF installed, so that's how I knew it was bad. A new one took care of that power loss, it was night and day. Try unplugging the MAF and running the car for about 10 minutes and see if the car has more power on the top end.

[HarryC]

Thanks to all for the input! Seems like the MAF is the place to start - so I'll check that out and clean or repalce if necessary. I keep reading about related posts and one difference that I find is that my engine is showing not any problems at all - it runs like a champ. No idle problems, no lack of power or perfomance - I don't know if that is an additional "clue" or not - but will disconnect MAF and see if there's any difference.

Thanks again and if anyone has more to add it would be much appreciated.

[faverymi]

Harry.

I had the CEL on with a bad gas cap. Based on the story, check your the way they put your fender, gas filler together, with no leaks or missing gaskets

I got a gas of bad gas once that made the car backfire ruining the MAF easy fix. I would start with the first step. Regards

[turboflyer]

+1 New plug, oil change, fresh tank of gas, clean MAF sensor. You will need a tamper male torx , think #20. I replace both O2 sensor ahead of CAT due to one failing, then found an out of range code which was a dirty MAF sensor which I cleaned. Passed smog two days ago no problem. O1S. Good for two more year. Yep pee!