Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   General Miata Chat (https://www.miataturbo.net/general-miata-chat-9/)
-   -   Low Vacuum at Idle (https://www.miataturbo.net/general-miata-chat-9/low-vacuum-idle-88988/)

Rshannon81 05-13-2016 05:20 PM

Low Vacuum at Idle
 
At idle, I'm only seeing 14-15 inMg on the boost gauge, and 55kpa in TS. I've set the timing to 20*, AFRs are about 13.8 now. What would be some things to check for the cause of this? There are no vacuum leaks, timing belt is good, stock cams. I'm really lost as to what could be causing thing.

shuiend 05-13-2016 05:25 PM

55kpa at idle in TS is extremely high. I average between 30-35kpa depending on the load of engine at idle.

Itty 05-13-2016 05:38 PM

20* is a lot of timing for idle.

Rshannon81 05-13-2016 05:50 PM

It is a lot of timing. And 55 is insanely high. But I would like to know the cause of it. It's really bugging me.

shuiend 05-13-2016 06:10 PM

Set your timing at idle to around 17. Then lean it out to mid 14s for afr.

Rshannon81 05-13-2016 06:13 PM

When I do that, it doesn't like to idle as smoothly. Anything over 14.0 and it's unhappy. It will just just around a lot. I was "told" it had low compression wiseco pistons, and a cometic head gasket. I've done a compression test and it seems pretty normal.

Stealth97 05-14-2016 09:40 AM

Either you have a leak somewhere or cam timing is off.

Rshannon81 05-14-2016 04:25 PM

There's no way there's a leak, I've done a boost leak test half a dozen times. I suppose the cam timing could be off.. It runs, drives, and boosts just fine. I'll look into that.

ryansmoneypit 05-14-2016 06:11 PM

My tired 1.8 idled in the 45-48 range. Ran fine. Never found a cause. New engine build is like 28-33

Rshannon81 05-14-2016 06:17 PM

Compression test came out at 175 across the board. Oil brought them up to ~195 across the board.


All times are GMT -4. The time now is 12:20 AM.


© 2024 MH Sub I, LLC dba Internet Brands