MS6 Vacuum Pressure Issue

[Speed_Demon]

I recently installed a test pipe to replace my factory cat. The first day installed I didn't notice any changes in the car's performance. Second day on my way home from work I noticed the car was more audible. When I got home I noticed my vacuum pressure was significantly low(10psi). Normally it's at a solid 22psi during idle. The next morning the vacuum pressure was back to 22psi. When I got to work it was down to 15psi. When I left work it was at 10 psi and has remained at that since. The car does not feel any different while it drives. Everything feels good, not like its running to rich or anything abnormal. I would like to know if this is normal behavior with the test pipe installed. Has anyone else experienced this and how did you correct the problem? Does this have any negative effects on the vehicle?

 

[bova80]

its possible you have a exhaust leak although i am not sure how that would have an effect on the vacuum. also vacuum is measured in inHg not psi did you touch anything in the engine bay? it may also be something like a small hole in a hose somewhere that when cold its tight and sealed but as it warms up it spreads a bit. does it hold boost alright?

 

[FORZDA 1]

I recently installed a test pipe to replace my factory cat. The first day installed I didn't notice any changes in the car's performance. Second day on my way home from work I noticed the car was more audible. When I got home I noticed my vacuum pressure was significantly low(10psi). Normally it's at a solid 22psi during idle. The next morning the vacuum pressure was back to 22psi. When I got to work it was down to 15psi. When I left work it was at 10 psi and has remained at that since. The car does not feel any different while it drives. Everything feels good, not like its running to rich or anything abnormal. I would like to know if this is normal behavior with the test pipe installed. Has anyone else experienced this and how did you correct the problem? Does this have any negative effects on the vehicle?

Are you reading the boost/vacuum on the Scangauge or that ProCrap gauge? Sounds like you're reading it from the ProCrap and it has crapped on you.

 

[bova80]

ha that could be the other possibility, if its an electronic gauge it might be malfunctioning.

 

[coyfish]

The test pipe isn't the culprit. You have some other problem.

Could be your gauge malfunctioning or a wire (such as a ground wire) might be coming loose.

Some gauges, such as my digital, show vacuum pressure in psi. But if you are using the same gauge then thats obviously not the issue.

 

[Speed_Demon]

its possible you have a exhaust leak although i am not sure how that would have an effect on the vacuum. also vacuum is measured in inHg not psi did you touch anything in the engine bay? it may also be something like a small hole in a hose somewhere that when cold its tight and sealed but as it warms up it spreads a bit. does it hold boost alright?

I didn't do anything under the hood when I did the test pipe. I will have to inspect my vacuum hose and all my connections tommorow since I'll have time in the morning. The boost holds just fine. Didn't see a change in that. Thanks for the heads up on the Hg not psi, I learned something, lol

 

[Speed_Demon]

Are you reading the boost/vacuum on the Scangauge or that ProCrap gauge? Sounds like you're reading it from the ProCrap and it has crapped on you.

Yes, I'm reading it from the Prosport. It's been reading differently all day today as well so I think your on to something with the guage being shot.

 

[Speed_Demon]

The test pipe isn't the culprit. You have some other problem.

Could be your gauge malfunctioning or a wire (such as a ground wire) might be coming loose.

Some gauges, such as my digital, show vacuum pressure in psi. But if you are using the same gauge then thats obviously not the issue.

Well while I have it parked tommorow I'll check the connections on the prosport while I'm checking my vacuum hose. Thanks

 

[FORZDA 1]

Yes, I'm reading it from the Prosport. It's been reading differently all day today as well so I think your on to something with the guage being shot.

Yeah, the reason I call it the ProCrap is there have been "lots" of reports of erroneous indications and sensor problems. Hopefully yours will be as simple as a loose/dirty wire connection.

 

[bova80]

I used to have a prosport and one day the sender quit working and the gauge would just peg it self. learned my lesson and now i have an stri x-line mechanical gauge.

 

[FORZDA 1]

I used to have a prosport and one day the sender quit working and the gauge would just peg it self. learned my lesson and now i have an stri x-line mechanical gauge.

Yep, I run Autometer mechanical. Everything else on the car is electronic, so I want a backup sanity check and the mechanical gauges are the only way to go IMO.

 

[Speed_Demon]

I have figured out my problem. I checked all of my gauge connections(ground wire, power supply, etc) and checked all my vaccum line connections and inspected the vacuum hose. Everything checks out all right. The gauge started to jump around on its own giving off different readings even while idleing so I know now its the gauge. Today it didn't even want to register a reading. The gauge itself seems to work but it cannot give a proper reading. Is it possible to just replace the sender?