Where's the boost?

[myrodr]

On the way to work this morning, I stepped down on the gas. Noticed boost only went to 6 lbs. normal - 10. Vacuum is about 13 normally 17-20 at idle. Will do compression test on all cylinders as soon as I get time. Any other ideas at what to look at? Thanks in advance for your help.

[HorneDogg]

hey MYRODR i am having the same issue with my MM right now. it is at the shop as we speak. It started out like that and then eventually went to the car not even wanting to go faster than 30mph and even the slightest pressure on the gas would make any vacuum i had on my gage disappear. I have been doing a fair amount of research and it looks like there was a manufacturing flaw in the heads especially the passenger side one. After talking with a couple of different mechanics on the phone who specialize in MM and High Performance Mustangs they told me to remove the valve cover and check the valve springs on which ever cylinders i showed a low compression on. there is also the way of checking the compressionto determine if it is the valves or piston rings using a tablespoon of 50weight oil. It is weird that someone else is starting to have the same problem that i did and i hope yours is does not get to the point mine has. I dont know if i have helped you out any but maybe this might get you going.

Jamie

[myrodr]

thanks i hope i wont need to pull the heads,but if needed so be it. hope you get yours back soon!

[SC Cheesehead]

Check for vacuum leaks first, guys; sounds like that may be the culprit.

[DOOM]

Check for vacuum leaks first, guys; sounds like that may be the culprit.

That's what I was thinking.

[SC Cheesehead]

That's what I was thinking.

Yeah, that's what the issue turned out to be on Silverback. Pat had Zack give the car the complete once-over, but a vacuum leak at the rear of the boost gauge was the issue.

[myrodr]

Will check that too think

[Local Boy]

Check your blow off valve...the diaphram (sp?) may be shot...

Aloha

[myrodr]

Good news!!! trouble with my MM vac line for boost gauge. Fixed it tonight after work. Thanks for the tips,

[SC Cheesehead]

Good stuff! Glad we could help.

[HorneDogg]

cylinder #1 & #2 are consistently misfiring and the car as absolutly no power. in my cars case, no vacuum leaks have been found, valve cover was removed and springs were visually inspected for any broken or cracked springs and of course we found none. leak test is going to be performed next to see if it is a head gasket. MMR has been contacted in the event that i have to pull the heads they are going to get the Stage 1 Port and Polish, Bronze valve guides and Manley valve springs, if it needs new valves i will more than likely go with some oversized stainless steel. No sense in beating around the bush and doing what needs to be done, just have it all done at one time and get it over with you know.