Lost some vacuum!

[BoostedSUV]

Re: Lost some vacuum!

Sorry I'm new to this and trying to learn all the terms. What is the "bike tube" test? Is that the same as taking carb and choke cleaner and spraying it over the intake and all vac. lines?

No, a "bike tube" is the modification of a bicycle tube. It utilizes the valve stem of the bike tube to pressurize the intake system to detect a leak. If you do a search for "bike tube test" you can find more information.

 

[The_Bronze]

Re: Lost some vacuum!

The vac is consistant with idle, the idle tends to bounce a little though because the truck goes from lean to rich due some other strange issues.

I can't tell from your descriptions so far: If you are using a vacuum gauge to verify the actual condition, is the gauge steady or does the gauge "bounce" around. A smooth steady gauge is a system-wide failure, while a bounce is usually one or two cylinders. It makes a ton of difference on how you tackle this issue.

 

[BoostedSUV]

Re: Lost some vacuum!

I can't tell from your descriptions so far: If you are using a vacuum gauge to verify the actual condition, is the gauge steady or does the gauge "bounce" around. A smooth steady gauge is a system-wide failure, while a bounce is usually one or two cylinders. It makes a ton of difference on how you tackle this issue.

Vacuum is steady and consistent in relation to rpm and engine load.

 

[WyoSyclone]

Re: Lost some vacuum!

I haven't read the entire thread.... are you sure the vacuum gauge line doesn't have a crack in it?

 

[The_Bronze]

Re: Lost some vacuum!

So independent vacuum gauge mirrors datamaster/scan tool information from MAP? Sorry, I still can't figure out if your readings are the scantool or is an independent gauge. So that everyone understands my reason- the scan tool will NOT show the fluxuations that the gauge does.

 

[BoostedSUV]

Re: Lost some vacuum!

My readings are off of the Autometer boost gauge and I also tried another gauge for verification. I haven't hooked up datamaster yet to confirm the guages readings

 

[EcSy#2671]

Re: Lost some vacuum!

Maybe a bad senser causing a false reading and the computer is pulling timing decreasing your Vacuum. The computer should be pulling ~30 degrees of timing at idle. Just check if that is right.

 

[BoostedSUV]

Re: Lost some vacuum!

Just an update to this thread. When I was putting the engine into my new truck and moved the vacuum line hoses over I noticed a small breeak in the hose right where it plugged into the MAP sensor. It wasn't a vacuum leak so much as it was lack of vacuum to the map sensor causing the timing to be retarded. I have one of the silicone vacuum hose kits from the GP on the board. Seems the vac line running to MAP is a little too small and streching it to fit caused it to break. Just wanted to update my findings...