Welcome! Log In Create A New Profile

P1128 update...

Expect the best, and accept no substitute.

Products for your Boxster, Cayman and Carrera.
P1128 update...
MarcW - 1 year ago
Got the Boxster in for this the other day, last Thursday actually, but then Thursday night at the office the 996 failed to start. I had the car flat bedded to the dealer and I left it there and picked up the Boxster.

Got the 996 fixed: New fuel pump. The old one failed just short of 160K miles if anyone is interested.

Anyhow, picked up the 996 this AM and left the Boxster. Again.

SA emailed me just a few minutes ago: "Tech wants you to stop by and he can show you what is kicking off the CEL."

Talk about the suspense...

Anyhow, earliest I can stop by is Thursday AM before work.
*not* an intake or vacuum hose leak. Tech reports the smoke test was negative for any intake and vacuum hoses. That's a relief.

Tech removed the air filter and found leaves in the intake air box and in the tube that runs from the air box to the MAF and beyond. Loaned me his mirror on a stick and helped me aim it I too was able to see the leaves.

When I changed the air filter I couldn't help but have some leaves/trash from the top of the filter element fall into the air box. The air box/filter is a lousy design -- it does a good job of filtering no question -- but serviceability sucks and if the filter element has any trash on it and it will have this trash fall into the air box.

But this is a known, at least to me, for I've changed the filter a few times in the past.

The last time I didn't have access to a shop vacuum -- doing this at "home" where I am not supposed to work on the car at all let alone run a 100ft extension cord to power a shop vacuum -- but I did use a ball of sticky tape on end of a stick to pick up all the leaves and stuff. After I removed all I could see I used a can of compressed air and as I aimed the air blast around I didn't see any other trash in the air box.

Hard to believe I missed something. But hard to believe the leaves were in there from before. I haven't changed the filter myself for a couple of change cycles so this means a Porsche tech left some leaves in there and I definitely can't believe that happened.

But the leaves didn't grow in there either.

Wait a minute: It just occurred to me possibly because the filter was so loaded with trash some leaves didn't fall down into the air box but got trapped -- temporarily -- up high (and out of sight) only to after the filter was installed and the engine run some then fall down. Still my bad for not checking with a mirror.

So the tech is going to remove the intake tube between the air box and the throttle body and clean it out to make sure there is nothing between the plastic mesh and the MAF and to make sure the throttle body isn't fouled with trash.

Lesson is do it right or do it twice. I screwed up not having a shop vacuum handy and not bothering to use a mirror on a stick to check the inside of the air box for any missed leaves/trash.

Car should be done later today but earliest I can pick it up is Friday AM before work.
I was going to suggest vacuuming it out, but then i opened your post (beyond preview) and actually read it.
You're way ahead of me as usual ...


Grant gee-lenahan-at-vee-eff-email-dot-net
Yes, but in this case they had my help in getting where they didn't belong.

Another reason I miss my Cayman S. The air box was redesigned and the air filter was huge and while I never changed it -- obviously didn't have the car long enough -- the tech when he was removing the baffle at the fitler intake told me the new Cayman air filter was much easier to change.

Anyhow, spent the weekend with the car and no P1128. The engine runs even better than it did after I replaced the dirty air filter and even after I replaced the MAF.

When I visited the car Friday the tech showed me a pic of the throttle body. The butterfly valve was filthy: The bottom edge and up around the portion of the valve on the drive side was caked with black oil. There was even some tiny bits of leaf fragment stuck to the mess.

I was probably remiss in not cleaning the MAF after the last AOS failed. I should have known with the engine smoking as bad as it was the intake was just full of oil vapor and some of this can't help but get on the throttle body. Well, I did know. That last AOS was my 3rd. The engine was running fine after the AOS was replaced though and I really didn't see any reason to clean the throttle body. Things age and while I don't fear a bolt breaking I fear an electrical connector breaking or something. The less an old car's wiring, hoses, fittings, etc. are handled the better.
Not following
Boxsterra - 12 months ago
The MAF and throttle body are both upstream of the AOS.

Yes, the subject is intended to be a double-entendre. You're welcome.
oooh, very clever *NM*
grant - 11 months ago

Grant gee-lenahan-at-vee-eff-email-dot-net
Re: Not following
MarcW - 11 months ago
The MAF and throttle body are both upstream of the AOS.

Yes, the subject is intended to be a double-entendre. You're welcome.

Don't get the double-entendre but that's not important I guess.

The MAF is quite a ways from the AOS and was not affected by the AOS's failure. Might mention the old MAF was not dirty.

The AOS connects to the intake directly after (downstream) of the throttle body. I know from the experience from my Boxster's first AOS failure the throttle body can be affected. When I removed the throttle body it was very oily and in fact there was a drop of black oil hanging from the butterfly valve. This suggests that post engine shut down the some oil vapor fumes manage to deposit some oil on the throttle body.
Sorry, only registered users may post in this forum.

Click here to login