: MAF Housing R&R

07-24-11, 12:39 AM
I'm getting the P0101 - MAF Performance Sensor

Its been happening the past few nights, engine RPM will bounce up and down by about 300 when trying to hold a speed of 58mph or so on an incline then after that it gives the car a nice "push" when its shifting. I can reset the code and the car will drive fine til I reach an incline again, when the SES light isn't on b/c of it the car is smooth (just had full tuneup done and wow its like night and day)

Quickly inspected the area and everything is connected, haven't removed the intake hose to fully inspect it yet but I felt around and didn't feel cracks or anything. I suspect the sensor is just going bad with 162k on it. There is a parts store called City Auto Supply and they have both Delco and Cardone housing, checked on RA for prices and of course the Delco is more expensive, will the Cardone work fine? Trying to save where I can. I'm not too good with cars and usually have a shop do the work but after spending $370 on a new rear right hub then 2 days later $600 on a full tuneup I need to save and do it myself plus it seems easy.

So, for the job, I just remove the 2 sensors (one on intake, one on housing), then remove the 2 metal straps on the intake, then remove and replace the housing. Correct? I'll probably clean the TB too since I'll have the housing off, which leads me to the next thing, when I cleaned the TB last year with my friend we lost one of the bolts for the MAF housing, its not lose or anything but would be nice to get a new one in there also in case I lose another bolt doing this.

TIA I really don't want to mess anything up

07-24-11, 09:18 AM
I believe that your engine has the MAF bolted directly to the throttlebody casting............

Your last paragraph - the missing MAF bolt. ANY air leak at that flange and you'll get codes.

Take one of the remaining bolts to a Fastenal or hardware store and match it.

I also believe that the sensor in the side of the intake ducting is the IAT (Intake Air Temp)

If you just had a tuneup, then first check the MAF and harness electrical connector for integrity and cleanliness of the pins and socket.

(The 2000+ Northstars have a divorced MAF/IAT - clamped into the intake ducting, and any leaks at the MAF or in the ducting will set codes and provide a lousy idle and/or set fuel mixture codes.)

Here's your MAF and then mine..............those honeycomb screens are about 1/4" thick and act as flow straighteners - same principle as used in a wind tunnel.

07-24-11, 02:13 PM
I've been missing that bolt for over a year and this is the first time I'm getting the code, its super tight with just the 2 in there

I'll see if I can get it off today while at work

Here is the picture I took yesterday:


07-24-11, 02:46 PM
The PCV system on the pre-2000 tends to really gum up the TB with oil vapor deposits. Maybe the MAF guts are oil coated - either clean it with TB cleaner or look at new guts from Chris ar Rippy Cadillac or RockAuto.

07-24-11, 03:30 PM
There's a store in my city called City Auto Supply and they specialize in AC Delco parts but also have Cardone Select which is what I'm thinking about going with b/c it seems to be cheaper on RockAuto. I'm gonna go ahead and replace the MAF housing tomorrow. The did replace the PCV valve so I wouldn't doubt it wasn't gumming it up bad, will clean the TB too before I connect the new MAF.

At freeway speeds my gas mileage is fine but as soon as I get onto the streets its starts going down, avg mpg on dash when starting up the car went from 16.0 to 15.9 as soon as I started the car then driving about a mile down hill it went to 15.2 then driving on the freeway after 25miles it was at 18.0mpg then after stopping at the gas station it was down to 17.8 and shifting was getting a bit rough. All this and the SES isn't even lit.

Thanks for all the help, this seems like a pretty easy job, I'm thinking 30min at the most?

07-24-11, 09:07 PM
Indicated gas mileage will vary all over the place with speed vs. miles traveled. Idling at a stop light the gas mileage is ZERO - depending on time/miles since reset that factors mightily into long term averages.

1999 STS - long term average...........good mechanical condition.............

12 - 15 mpg city.
15 - 18 mpg suburban
24 - 25 mpg highway.

07-24-11, 11:53 PM
I never have paid attention to the avg mpg while street driving so I could just be freaking myself out but it seemed to be going from 15-18 just from very little street driving.

Thing that happened last night, I reset code while down the hill at walgreens since it popped up while on the freeway, the hill up to my house is 35mph, I tried doing 35-37mph but the car was surging so I brought it up to 40mph (3k RPM) and it shifted and drove fine. The day I got my car back I drove up the hill with no issue, so I know it has to be related to this code, but will my car still drive funny with the air issue even if the code isn't set?

johnny kannapo
07-25-11, 02:47 AM
I would pull out the IAC rub the carbon off the pintle & seat them generously spray out that port with TB/carb spray.
It would be a more consistant high idle if it had a unmetered air leak.

The throttle plate may have so much build up arund it it doesn't close completely every time.
The surging Idle tells me the IAC is correcting trying to find steady idle air flow.

The IAC could be defective but I think it would send code data.
You don't want to get carb cleaner up into the IAC coil.


07-25-11, 05:50 PM
No my idle is fine. City Auto Supply didn't have an AC Delco MAF so I just went to my shop, he got a Delco for $158 and charged me $45 for labor. He told me not to reset the code and just drive it and see if the SES goes off by itself. Cars drive beautifully on flat land, once again trying to climb the hill by my house I had it at 38mph and it was at 3k rpm and the RPMs stayed put but the car felt like it was struggling a bit, brought it up to about 32/3300 so 40mph and it shifted into 3rd and was fine. Does it sound like a symptom of my cat? He said he could replace it for $300 at the most. My car usually would shift at about 35/37 mph and now it doesn't shift until 40mph

I could smell fumes while driving on the freeway last night with the windows down. I talked to him before heading to work and I'll be replacing the cat some time next week since that's when I will have money and his son will be back from vacation so somebody can watch the shop will he takes it for a test drive on some hills.

07-28-11, 04:30 AM
Just want to update this since I updated my thread in the Seville section. My fix to the P0101 code was to change my catalytic converter, got it done today and instant power gain and no more code. The muffler guy said my cat was really clogged up. I forgot how powerful this car was! I can pass a car going up a hill at 35mph with ease, simply amazing.