MAP sensor may be bad

**98TransAmWs-6** · 09-23-2010, 07:05 AM

How do you know if your MAP sensor is bad? Is there a way to check it? I just replaced my vacuum line that goes behind the manifold and when I put the car back together I got the code p0108 for the MAP sensor.

**shady milkman** · 09-23-2010, 07:33 AM

Originally Posted by 98TransAmWs-6

How do you know if your MAP sensor is bad? Is there a way to check it? I just replaced my vacuum line that goes behind the manifold and when I put the car back together I got the code p0108 for the MAP sensor.

id make sure it is fully seating in its housing behind the intkae..there is a good chance you bumped it out.

**98TransAmWs-6** · 09-23-2010, 07:35 AM

Originally Posted by shady milkman

id make sure it is fully seating in its housing behind the intkae..there is a good chance you bumped it out.

I pulled the intake last night and the connection that connects to the housing was in fine but the housing for it was loose, is it suppose to be? If it's not how to I push it into the intake or get it tight again.

**shady milkman** · 09-23-2010, 07:36 AM

but more than likely may just need to replace it..it isnt too expensive

**98TransAmWs-6** · 09-23-2010, 07:40 AM

Okay I have another question though, before the code showed up my car would start but immediately shut off unless I kept revving it, would this explain that? The last time I started it without pressing the gas it spiked up to 3k rpm and would go down to almost dead but then go back up(not to 3k but up more) would this faulty sensor cause that or is there some other reason for that? I had my TPS unplugged at this point because I wanted to see if it made a difference, so it might have just been that.

**shady milkman** · 09-23-2010, 07:45 AM

id say there is a vacuum leak somewhere personally ...but to tell you the truth.i dont know exactly how our cars react to that code. go buy a new sensor...plug it in..see if it helps/works...if not take it out..clean it up and return it and tell them you didn't end up needed it

i have done that several times

**98TransAmWs-6** · 09-23-2010, 07:48 AM

There is really no way it could be a vacuum leak, I replaced the vacuum hose and I looked at it too and there is nothing wrong with it. Unless of course it's the hose that plugs into the back of the intake, but nothing looked wrong with that either. I'll give that a shot though, is there anywhere to look on how to remove the sensor since I'd rather not break anything else

?

**shady milkman** · 09-23-2010, 08:03 AM

Originally Posted by 98TransAmWs-6

There is really no way it could be a vacuum leak, I replaced the vacuum hose and I looked at it too and there is nothing wrong with it. Unless of course it's the hose that plugs into the back of the intake, but nothing looked wrong with that either. I'll give that a shot though, is there anywhere to look on how to remove the sensor since I'd rather not break anything else

?

there are tons of spots to introduce a leak..if you didn't torque the bolts tight enough on the intake...if the gasket on the back isnt seated properly..like you said about your intake. if during install you pinched or rolled the intake port gaskets. the list goes on and on

**98TransAmWs-6** · 09-23-2010, 09:35 AM

If I had a vacuum leak wouldn't a code for that come up?

**shady milkman** · 09-23-2010, 09:41 AM

Originally Posted by 98TransAmWs-6

If I had a vacuum leak wouldn't a code for that come up?

no not all the time ..but usually if it is sever enough it will through a code like bank 1 and bank 2 system lean

**35th-ANV-SS** · 09-23-2010, 09:41 AM

Probably yes. But your RPM jumping around like that sounds like a vac leak to me also.

Spray some carb cleaner or something similar at the bottom of your intake and see if the car idles different. If it does, bingo, you have a leak.

**shady milkman** · 09-23-2010, 09:43 AM

i personally dont like the carb cleaner trick...i like to have it smoked to see if there is a problem

**35th-ANV-SS** · 09-23-2010, 09:45 AM

I agree, but most people don't have a smoke machine to test that theory...

**98TransAmWs-6** · 09-23-2010, 10:04 AM

Originally Posted by 35th-ANV-SS

I agree, but most people don't have a smoke machine to test that theory...

This may sound stupid but would any smoke machine work? Like the fog machines you can use for the fog effect on stages and halloween and stuff? Cause I have one of those. If I can use that how exactly do I check for the leak with the smoke machine?

**35th-ANV-SS** · 09-23-2010, 10:07 AM

From the way I understand how it works, you basically just blow smoke into the throttle body (make sure connection is sealed) and if you have a leak you will see smoke coming out from where the leak is.

I believe what you are talking about should work just fine.

**35th-ANV-SS** · 09-23-2010, 10:09 AM

There might be a pressure issue with what you have....

The actual smoke machine may be pressure controlled...

Wait for someone else to chime in on this.

**98TransAmWs-6** · 09-23-2010, 10:19 AM

What do you mean by pressure controlled? Like too much pressure or too little? Cause if it could burst my lines I don't want to use it. I saw on this website this guy did what I am thinking of doing.

**35th-ANV-SS** · 09-23-2010, 11:03 AM

If too much pressure is applied, you could damage things.

**Cutlass** · 09-23-2010, 07:37 PM

I read threads on here with people mentioning smoke machines and I have no idea who uses these things or how it would possiblly even work really. They do make smoke machines for testing Evaporative Emission systems for leaks, but for checking for vacuum leaks...no clue.
98TransAmWs-6, with that code, its possible that maybe you pinched/broke a wire for the MAP sensor during your fuel injector repair.

**shady milkman** · 09-23-2010, 08:00 PM

Originally Posted by Cutlass

I read threads on here with people mentioning smoke machines and I have no idea who uses these things or how it would possiblly even work really. They do make smoke machines for testing Evaporative Emission systems for leaks, but for checking for vacuum leaks...no clue.
98TransAmWs-6, with that code, its possible that maybe you pinched/broke a wire for the MAP sensor during your fuel injector repair.

the hook it up and it pumps smoke into the engine as it is sealed..and will show the area where the leak is happening ..this is all done with the engine not running