View Full Version : PCV/MAP Issue.


melchoir
01-21-2007, 09:55 PM
I got a Code thrown today, so I scanned it and found code P0108 (Map sensor high voltage)

I clear the code, it comes right back.
The MAP sensor is showing like 92kpa steady, this doesn't change with revs.

I look around under the hood and find that my pcv hose on the driver's side valve cover is torn at it's connection pivot and obviously creating a leak.

#1. Will this leak cause my code issue?
#2. My car is a 98, the hose didn't easily seem to just pop off of whatever it's connected to (I assume the PCV valve?). Is there a simple way to remove it?
#3. Do I need to order a whole new PCV hose, or can I substitute a different line?

brad8266
01-21-2007, 10:02 PM
Your map is stuck or just plain defective. This does not sound like a PCV issue to me. You should fix the pcv issue too.

melchoir
01-21-2007, 10:08 PM
MAP sensor measures vacuum in the intake, and if there's a leak like this (in the intake), wouldn't it screw with vacuum? The sensor is relatively new (2 months or so) so I'm not going to believe it's defective this soon.

brad8266
01-21-2007, 10:17 PM
MAP sensor measures vacuum in the intake, and if there's a leak like this (in the intake), wouldn't it screw with vacuum? The sensor is relatively new (2 months or so) so I'm not going to believe it's defective this soon.
92KpA, thats about what you read at WOT. There is no way a leaking PCV will do all that. Maybe the plug came out or something.

melchoir
01-21-2007, 10:28 PM
If the plug came out it would be a low voltage code =/
It is a bad tear in that hose, not just a small leak. Enough to make the car sputter and even stall. I'm hoping that's what it is still.. Any other ideas? Open to suggestions.

Also, any info on the hose replacement?

brad8266
01-21-2007, 10:29 PM
If the plug came out it would be a low voltage code =/
It is a bad tear in that hose, not just a small leak. Enough to make the car sputter and even stall. I'm hoping that's what it is still.. Any other ideas? Open to suggestions.

Also, any info on the hose replacement?
If its that bad of a tear then yeah that may be it. Id wrap that bitch in some tape and see what happens with that code.

TransAminal
01-21-2007, 10:38 PM
If the plug came out it would be a low voltage code =/
It is a bad tear in that hose, not just a small leak. Enough to make the car sputter and even stall. I'm hoping that's what it is still.. Any other ideas? Open to suggestions.

Also, any info on the hose replacement?

Sounds like that was the issue to be. The PVC hose connects to the intake manifold behind the TB, so if its cracked, it will create a definite vacuum leak. This will cause the MAP sensor to get an improper reading, which tells the ECU that something it wrong with it.

Get a new hose and reset the ECU. It should fix the issue.

melchoir
01-22-2007, 09:07 AM
This morning when I started the car I checked HPTuners and the MAP sensor was reading normally (32-34). After the car heated up the MAP reading went back to 92.

I can only assume that when the car was cold, the hose was closed upon itself and sealed. After the car warmed up the hose expanded allowing the vacuum to leak.
This made a TPS code be thrown (expected as the MAP is reading WOT but the TPS isn't)

I'm 99% convinced that this hose is my problem. Can anyone point me into some instructions for replacing the hose on a 98 model? Or how to disconnect the hose from the driver's side valve cover. It connects to a cylinder that I can only assume is the PCV valve.

Any assistance/pointers would be great.

brad8266
01-22-2007, 04:31 PM
This morning when I started the car I checked HPTuners and the MAP sensor was reading normally (32-34). After the car heated up the MAP reading went back to 92.

I can only assume that when the car was cold, the hose was closed upon itself and sealed. After the car warmed up the hose expanded allowing the vacuum to leak.
This made a TPS code be thrown (expected as the MAP is reading WOT but the TPS isn't)

I'm 99% convinced that this hose is my problem. Can anyone point me into some instructions for replacing the hose on a 98 model? Or how to disconnect the hose from the driver's side valve cover. It connects to a cylinder that I can only assume is the PCV valve.

Any assistance/pointers would be great.

Just pull on it, it will come off, it wraps around to the drivers side valve cover too.

melchoir
01-22-2007, 05:27 PM
Just pull on it, it will come off, it wraps around to the drivers side valve cover too.

I'm trying to remove it from the Drivers side valve cover.

brad8266
01-22-2007, 06:48 PM
I'm trying to remove it from the Drivers side valve cover.
it lifts out, the actual PCV valve is on the passenger side of the intake manifold right where the manifold and throttle body meet.

melchoir
01-24-2007, 08:15 AM
I've replaced the bad section of PCV hose, but the issue still exists.
At a cold start the MAP will usually read 32Kpa and then find it's way back to 92kpa within 5 minutes or so.

Now the car is idling around 400rpm when warm in park.

Any ideas? I'm running out myself.

brad8266
01-24-2007, 08:28 AM
Did you replace the PCV valve?

melchoir
01-24-2007, 09:05 AM
No, just the section of damaged hose that connected at the driver's side valve cover.

BTW, thanks for your efforts you've been all over this thread. lol

I removed the rubber "elbow" that connects the two hard plastic pipes, one connects to the pcv hose, and one connected to the drivers side valve cover. I replaced this hose, yet the high MAP reading continues.

brad8266
01-24-2007, 09:07 AM
Try the PCV valve first, it might be stuck open.

No problem helping out, i dont have shit else to do here at work anyway. :jest:

melchoir
01-24-2007, 01:35 PM
Even if the PCV valve was stuck open, now that the hose is complete again, there would be a vacuum to the engine. Unless I'm wrong about that...

The way I see it the PCV valve open or closed, is now a closed system again. So there should be no loss of vacuum.

Any other ideas? I don't think it's the MAP sensor as it's pretty new, and again, I've seen it read "accurately" with HPTuners on cold starts.

brad8266
01-24-2007, 01:38 PM
Even if the PCV valve was stuck open, now that the hose is complete again, there would be a vacuum to the engine. Unless I'm wrong about that...

The way I see it the PCV valve open or closed, is now a closed system again. So there should be no loss of vacuum.

Any other ideas? I don't think it's the MAP sensor as it's pretty new, and again, I've seen it read "accurately" with HPTuners on cold starts.
Yeah its a weird issue, but a new PCV cant hurt, they are only a few bucks anyway. If it is stuck open its venting into the valve covers.

melchoir
01-24-2007, 01:48 PM
Right, but the valve covers are sealed, thus.. a vacuum..

I don't think that's the source of these problems.

Unfortunately I'm running out of possibilities that I can think of.
I hear no vacuum leaks, when the car ignores the MAP (because of the code) it idles and drives mostly fine.

brad8266
01-24-2007, 02:19 PM
Right, but the valve covers are sealed, thus.. a vacuum..

I don't think that's the source of these problems.

Unfortunately I'm running out of possibilities that I can think of.
I hear no vacuum leaks, when the car ignores the MAP (because of the code) it idles and drives mostly fine.
There is positive pressure that is built up under the valve covers, thats is the whole purpose of the PCV(Positive Crackcase Ventilation). Im not sure if that is your issue but for 5$ id replace it anyway. Next step may be to pull the intake and check out the MAP on the back.

melchoir
01-27-2007, 12:38 PM
I didn't replace the PCV valve, but I did "fiddle" with the map sensor wires (previously had to re-wire it.) and that seems to have resolved the issue.

I let the car warm up and drove around monitoring the map gauge, 102Kpa with engine off, 32-34 idleing, and like normal with more gas.

So far so good.