gregroselli

The subject says it all, my Check Engine Light went on over the weekend and the only code im getting on my Actron is P1128. Any thoughts are appreciated while I go look this up. Thanks

99firehawk

before this turns into a arguement

you need to get fra/rkat (fuel trim) numbers to know which direction to go in.
that fault does not mean replace the maf sensor regarless of what anyone says.
It could be a maf but not 100%

gregroselli

Could you dumb that down a hair and tell me what the MAF sensor is?

1999Porsche911

The code is generated when the O2 sensor for bank 1 drops out of it's voltage range, indicating that the bank is running to lean. The most common cause of this code is an air leak in the untake system or the exhaust. Often a P1130 (bank 2) will follow eventually. There can be other causes, but the above are the most common.

Check vacuum lines, intake tubing and throttlebody bolts. Make sure you have a good oil filler cap seal. If you have a 99 C2, remove and clean with carb cleaner, the idle control valve. Remove and clean the MAF with electronic spray cleaner.

The MAF sensor is the device inline with the air intake system that measures the amount of air passing into the engine and from that reading, the computer will add the appropriate amount of fuel. Often, if it is dirty, it reads less air than there actually is and the computer adds too little fuel.

viper501

I'd also take a look at the oil / air separator bellows for cracking. Replacing it cured all of my codes (as it cured a massive vacuum leak).

1999Porsche911 has offered good advice as well.

gota911

MAF = Mass Air Flow sensor. It does what 1999Porsche911 stated in the 3rd paragraph in post #4.

Ramp

[/quote] If you have a 99 C2, remove and clean with carb cleaner, the idle control valve. [/QUOTE]


I have a CEL problem as well - usually cleaning the MAF solves the problem - but lately it comes back on much sooner - sometimes the same day. I thought a next good step would be to clean the idele control valve - but as a newbie would appreciate some help with description, location, any special issues with removal/replacement.

TIA - Would be a good project on a rainy day like today.

rountreed

I did not think you were supposed to use carb cleaner on the MAF but electronic cleaner????

1999Porsche911

If you have a 99 C2, remove and clean with carb cleaner, the idle control valve. [/QUOTE]


I have a CEL problem as well - usually cleaning the MAF solves the problem - but lately it comes back on much sooner - sometimes the same day. I thought a next good step would be to clean the idele control valve - but as a newbie would appreciate some help with description, location, any special issues with removal/replacement.

TIA - Would be a good project on a rainy day like today.[/QUOTE]


In the picture below, the larger device (with the visable sticker) screwed into the left side of the throttlebidy is the ICV. Remove the cable and 2 screws to remove. Be careful with gasket as you will reuse it. Spray liberally with carb cleaner and make sure that the window inside it pivots freely.

Jim

Ramp

I do have a '99 C2 - Thanks -

Looks like you removed the air box completely. While I'm in their, I may change some vac hoses - I saw some nice red ones at pep boys and thought it would ad a nice touch in addition to ensuring no air leaks.

99firehawk

your not going to be able to get to any vacum lines easily and on a 99 ID be very worry of them breakign when you tocuh them

Ramp

How else do you determine if there is a vac leak setting off the CEL ?

1999Porsche911

There are various ways to test them using smoke, propane, etc, but I would simply visually check them out first. Most of the lines are easily accesable on the 99. The lines going to the vaccum canister above bank 1 can be easily tested by blowing into the line and making sure that it holds pressure. Make sure that the vaccum line from the first intake crossover tube is connected to the fuel pressure regulator on bank 2. Check 2 connections to electric changeover valve located above alternator. Check bolts on throttlebody and related tubing.

It is unlikely that you have a large leak as one would throw more CEL codes and performance would be greatly affected. I would also throw in a bottle of injector cleaner to the gas, clean the throttlebody and intake with carb cleaner.

Then reset the computer and give it another try.

Ramp

"I would also throw in a bottle of injector cleaner to the gas, clean the throttlebody and intake with carb cleaner."

Thanks - Any preferences on the injector cleaner ? or are they all the same ?

1999Porsche911

They're all pretty much the same.