Speedmonster185

How much of a chance is there that the MAP sensor itself is going bad? I stopped in to the store and they said they don't carry the connector and that I might have to go to the dealer or something to get it o_O, but they had the sensor, so I picked that up. I would rather not have to use it if it's just going to end up being the connector anyway. Should I be able to see any signs of it going bad? It looks perfectly fine to me. No cracks or anything like that, and the plastic color isn't even really faded or anything, so I can't see any problems with it at all.

Injuneer

The MAP sensor has a thin metal diaphragm in it, and measures the variations in resistance as the diaphragm flexes in response to pressure changes - in effect, a "strain gauge". You can't tell what condition the sensor is in by looking at the outside of it. They are extremely reliable. But they can fail.

The connector should be available anywhere. GM uses the same 1 bar MAP sensor on just about everything it makes. Shoebox has the part #'s for AC/Delco and GM on his parts page.

If you are getting DTC 34, something is causing the MAP sensor to send the PCM a signal lower than 0.24 Volts. Since the engine can't pull the vacuum required to reach that voltage, that would logically indicate that the black ground wire is somehow shorting to the light green signal wire. That could be a short in the connector or a short in the sensor. Simply measuring or scanning the sensor voltage should tell you when that condition is occuring.

Speedmonster185

Ok, I can give that a try when I head home again this weekend. As far as being able to tell visually if it was bad, I was referring the the connector. It looks fine to me in every way.

So if I use the volt meter on the sensor, between where the black and light green wires should be connected, while the car is running and get the correct voltages it should be the connector that is bad right? Then if the voltages are wrong, then it is the MAP sensor itself? I think I've got it now. I'm not 100% sure, but it sounds right. I'm sorry this is taking so long and I have so many questions. I'm new to this electrical stuff and apparently it isn't my thing :P.

Speedmonster185

Ok, now I have to bring up an old topic, but this thing just popped up again after I thought I had fixed it o_O. Here is what i did.

I looked at the AIR fuse (#7 I believe?) and it was blown. So I replaced it and it blew again. Because of that I unplugged the AIR pump, taped up the plug, and put a new fuse in. That one didn't blow and it didn't show the light anymore either. Now, I haven't driven it a whole lot since that time, but it was fine the whole time since then. Until the other day. I took it out for a drive and on my way back that stupid DTC 26 came back on again. I haven;t looked yet, but I'll bet that fuse is blown again. How could that be possible if it isn't even plugged in? Any other ideas?

The other DTC code is fixed now too btw. I replaced the MAP sensor and that seemed to do it. I did notice the rubber seal was slightly twisted on the old one, so I suppose that could have been the problem (letting some air in maybe?), but either way it's fine now.

shoebox

Look, first. You have the cart before the horse.

Injuneer

Remember.... since you have a 93, DTC 26 comes on for the AIR pump, EGR solenoid and EVAP solenoid. It can also be a faulty quad driver module.

EDIT - ADD A SIGNATURE!!! People are going to pick up on the tail end of the thread, an not realize you have a 93. You are hurting your chances of getting good answers, by not posting a "signature".

Speedmonster185

Good point... I'm assuming it's that fuse again only because it went away when the fuse wasn't blown, but I don't know that yet. I'll have to check later though because I had to leave and go back to school again.... Maybe this weekend.

Yeah... I just assumed that I had found the problem because of that ^^^^. I suppose this could be something different though. Or it was just random that it stopped showing the light when I replaced the fuse and pulled the plug so it wouldn't blow it again...

Ok, I put a signature in there . Thanks. It's simple... but it works I suppose :P

Edit: Except it doesn't appear to be showing up out here... I don't see any option to turn that on anywhere or anything. Am I missing it somewhere?

shoebox

User CP>edit options> Thread Display Options>Visible Post Elements>Show Signatures

Speedmonster185

Hmm... I checked that one before, and again just now, and it's checked already.

Edit: And now it's there... weird.... lol. I didn't even click anything. Just went and saw that it was checked and hit back and responded :P.

Speedmonster185

Sorry to bring this back from the dead, but I never did figure it out, and I'm trying to this weekend... So anyway, I checked my AIR fuse (#7) again and it was blown, so I did what was suggested here:

"Yes, the AIR pumps sieze up due to rust. Simply unplug the AIR pump harness connector, and then replace your fuse. The pump will not run, but the ECM will also not set the code. The pump only runs for a couple minutes at startup to help the cat heat up faster."

After I unplugged it and replaced the fuse, I unplugged the battery for a while, and plugged it back in and started thecar. The code got thrown after about 5 or 10 seconds. lol. I checked the fuse again though and it's fine.

So I have this so far. I know it isn't the EVAP Solenoid, I ruled that out last time I did this. The AIR pump when connected blows the fuse, but when unplugged the code still is thrown.

Any more ideas?

LaredoZ28

If you want an air pump to put back in i have 2 of them that i'm not using.

Speedmonster185

Really? I might be willing to try that. It just seems to me like unplugging the pump would make it look the same to the computer as a blown fuse... No circuit. SO putting a working one in might be worth a shot. Do you know that they're both good for sure?

LaredoZ28

Yes. I had no problems with either of them b4 they were pulled out. I had one on my 96Z28 and the other on my brothers 99TA. they are the same and worked perfectly.

Speedmonster185

Hmm... that makes me wonder... if both your '96 and his '99 are the same, what year did they change them? I pulled mine out of my '00 TA and it's completely different than the one in the '93.... hmm...

LaredoZ28

i'm not sure what year they changed. the pump on my 94 was the same as my 96 and my bro's 99. let me look at my 93 real quick and see if its the same. if its not i'll take it out since i dont use them.