I have kind of a cheap code reader from Walmart [be kind, please]. It does have a "freeze frame" function and some other stuff. Would any of that be meaningful?

Other than that, it just seems to be throwing the P0102 code, whether the MAF sensor is plugged in or unplugged.

Thanks for staying with me on this stuff, guys. Its probably tedious. I figure this weekend is probably not optimal to take into a shop. This time of year everyone is waiting for the New Year to get back to work, so I'm just doing my best.

I believe I will actually try to clean the MAF sensor once I look at the video and learn what tools to use. Maybe that will do it.

BTW, I do not believe I am running any type of oiled filter, although I did not install the last time.

Thanks again for taking an interest in this.

Best always,

 

Here are pics of what’s on the code reader.

 

OK, whatever is going on is WAY WAY worse when the gas tank is full. It’s happened repeatedly now. It bucks, basically, shaking forward and back. I had the fuel pump replaced awhile ago and the gas gauge has been reading weird since.

Not sure what to think about this but I know the shuddering/ stuttering./ lurching / whatever is significantly worse after filling the gas tank. Like to the point where I don’t know if I should drive it.

Maybe this will make sense to you guys. I hope so.


Best,

fastertransam

 

Start with cleaning the MAF with the CRC cleaner, super easy. As far as the clamps on the intake tube, they are phillips head/flat blade screws (and one is facing down so youre looking at the end of the screw)..so can use either a flat blade or phillips screw driver. You dont have to take both clamps off, just one is sufficient..and pull the air lid off with the MAF attached, spray it off, blow it out with some compressed air (carefully) and reassemble.

 

Recall from what we know about the P0102:

Common Problems That Trigger the P0102 Code

• The MAF Sensor is unplugged or the wiring is damaged
• Loose or corroded electrical terminals in the MAF Sensor circuit
• Faulty MAF Sensor

All of those band clamps are combo and will take a Phillips or Flathead screw driver. I think you'll find that you'll have better control on these with a flat head.

The one clamp you are having issues with is just rotated so you can't see the screw head. You may need to carefully twist the whole thing around or use a stubby flat head screw driver to undo that clamp. Once it's undone, you can rotate it around to have better access in the future.



^ These corroded terminals are definitely a problem, if not "the" problem. You'll need to clean all that blue oxidization out of there, along with any corrosion on the plug. If you get some 400 or 600 grit sandpaper, you can rub small strips around there with some pick tools or dental tools and get it all out. (Be sure to disconnect the car's battery first!)

When you put it back together, you'll wan to make sure you have a good water seal around the plug. It should be a colorful rubber piece, with flaps, that fits inside MAF cavity between the socket and the plug.

 

You got good eyes wssix99. Yep replace that maf !!!

 

Replacing the MAF won't do it. If there is corrosion like that in the socket - it will also be in the plug. Even a new MAF could have the same issue if the plug is still left corroded.

While at cleaning the plug; might as well clean the MAF, too.

 

Hmm. The oxidation could have happened since the MAF sensor was unplugged, with the socket exposed, or it could have been there awhile. Its been raining constantly. Who knows? I have a lot of experience with electronic equipment as a recording studio owner, and in that setting oxidation generally has to be pretty bad before it starts causing any significant signal loss. I haven't looked at the plug, but what is in the pictures may be enough to be causing issues.

In any event, as I understand it, none of this really explains why the car is acting the way it is with the sensor unplugged, and why it is so much worse when the gas tank is filled. Not saying that the plug and socket shouldn't be cleaned, obviously. I just think there appears to be more to it.

Does any of that data from the code checker mean anything?

btw, are you guys sure you're looking at the MAF sensor band clamps, and not the ones for the Intake hose? I see that one appears to be turned around, but the other one does not look like a combination Phillips/flathead. I will look at it again though.


Thanks,

fastertransam

 

No, this code you are chasing is pretty simple. Once you have the code, you need to probe for voltages. https://www.obd-codes.com/p0102

The code just means that the voltage getting back to the PCM is low. This could be due to a contaminated sensor, high resistance in the circuit, or lack of power supply to the sensor.


The oxydiation is certainly causing degradation in the "signal" but this problem is more about voltage. If that oxydation adds resistance to the circuit (assuming it hasn't cut off the electrical flow completely), the voltage will drop, and the car will read that very little air is coming into the engine. (The code is thrown, when the car is reading a voltage outside of possible values.)

^ If the car "reads" low air flow into the engine when you are hitting the gas, then it will cut fuel and cause the engine to be very lean and stumble.

Here's a really good article on how the MAF works. (We have a hot wire design.) https://wellsve.com/sft503/counterp_v3_i2_1999.pdf


From what I've seen on the car and many of it's other corroded connectors, that oxidation looks very old and like it has been there a long time.


When you unplug the MAF, the PCM goes into Open Loop mode: https://www.enginebasics.com/EFI%20T...Loop%20o2.html

In this mode, the engine's computer ignores the MAF input, ignores the Oxygen Sensor input, and may other sensors. In this "fail safe" mode, the car reverts to a rich gas mixture because there are very few sensors the computer can draw upon to make an accurate air/fuel calculation. The car is also not going to run efficiently and may behave generally "unhappy."

^ So, running like this is going to waste a lot of gas! (It takes all the key sensors that control fuel economy out of play.)


yep. This is the combo head that will take a flathead or a #2 philips. All the other are regular worm-drive band clamps. The MAF itself is held together by 4 allen bolts that run parallel ot the hose. (You DO NOT want to remove these as you could easily damage the MAF by disassembling the case.)

 

The one you have pictured in your post is not for the MAF sensor. Its for the air intake hose that is behind the MAF sensor.



Best,

fastertransam

 

I read recently that running without an MAF sensor for a while can foul the plugs or harm the catalytic converters, contrary to what someone indicated earlier in another thread. Again, its acting up with the sensor unplugged now, where at first it ran good like that.


Best,

fastertransam

 

Not too sure its ever behaved that way. Seems to have been running rich the whole time.


Best,

fastertransam

 

^^^ I still wonder about this.


Best,

fastertransam

 

Actually, I think those are the only pics of the car I have posted, other than the new air intake hose in another thread. But, yeah, the oxidation may have been there for a while. How about using MAF sensor cleaner to clean it?


Best,

fastertransam

 

Same thing [voltage and signal].


Best always,

fastertransam

 

It's not a magic spray.




The MAF cleaner will just dissolve the build-up on the sensor wires, but it won't be able to get the oxides off the plug and socket. Those have to come off with mechanical means. (Like anything else that is rusted.)

 

That's probably related to running rich over a long time. Running without a MAF is not going to be good for the car long term, unless the engine is tuned for it.


In the end, it's basic chemistry around the air/fuel ratio. https://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio

When the MAF doesn't work right, the air side of the equation is not accurate and the air/fuel mixture is off. The minute the MAF comes out of the equation, the car is even more hobbled. Any change in the ambient conditions (temperature, air pressure/weather, etc.) is going to change the air and will also have a profound impact on how the car behaves day-to-day. (When the MAF is plugged in, the car also uses the IAT and MAP sensors to calculate for weather and ambient effects.)

 

The saga continues, alas.

So I had the MAF sensor replaced and that code is gone. I also had the starter replaced, and the car starts now.

HOWEVER, it still runs like crap and gets about 7-10 mpg. So I had a couple of people say that there is a vacuum leak in connection with the intake manifold gasket. One guy sprayed brake cleaner on in and, although he said it was idling up when he did it before, it did nothing when he tried to show it to me. Another guy [the guy who replaced the starter] sprayed it at various places around the manifold and it was causing the car to miss. I actually saw that happen.

Its throwing codes including, but not necessarily limited to, "O2 Sensor, Bank 1, Sensor 1', "system to lean" [although its running rich], 'multiple / random cylinder misfires', and some other P1133 "manufacter specific' code. I doesn't always throw them all. Once or twice the SES light has been flashing, usually its just on steady.

Could it be the Intake Manifold gasket causing all this stuff? I already bought an O2 sensor so I guess I will just have that installed along with whatever else gets done. Or should I wait, or what?

Any advice on the gasket replacement job? I've been told a few different things by different mechanics, as usual. I thought the gasket set was just one pre-cut piece, but one guy says there are actually an upper and a lower piece and that I need to do both. He also says I need to have the coils replaced or something to that effect.

I'm in an area where its tough to find a reliable, honest shop for some reason. Another problem seems to be that they see a guy coming with what they consider a "special" car, and they figure I'll do anything, at any price, to get it fixed.

I'm running low on funds, but need to get this car running right because I can't afford to put gas in it the way it is running, and I am afraid that its bad for the car. It doesn't stall or anything, and it actually still has plenty of power, but the exhaust smells and its definitely running rough.


As always, thanks for helping with this. I feel like we've made some progress with the issues, but I guess there is more stuff to straighten out.


Best always,

fastertransam

 

Yes, air entering the system from behind the MAF sensor would lean out the mix and could throw the code. (The Oxygen sensor could be sensing a condition different than the other sensors, including the MAF, would expect.)

If you are low on funds, I would hold back on the new O2 sensor. Change one thing at a time.

 

Please put your area in your profile.