when downshifting to a stop the idle will fall low
#1
when downshifting to a stop the idle will fall low
I have a 97 and I recently straight piped it from cat back and put shifty headers on the truck runs fine except for when I downshift to a stop one I'm stopped the idle will fall low and then rise back up again. I'm thinking it from low back pressure but not sure any thoughts
#2
Senior Member
Mine was doing this for a while. Then one day it would not start. Replaced the fuel pump and it is smooth as glass now. I think its called surging, fuel pumps are known to do that before they go out.
#3
Mine does the same thing when I come to stop signs or traffic lights. Rpm's will be normal and then they will go down around 500, all my lights will get a little dimmer, heat will bog down a little and then it will shoot back up to normal. Happens real quick too. It's bugging the crap out of me!
#4
I talked to my college professor about this today he told me it could be the back pressure in my exhaust since it is straight piped. I noticed it also does it at higher rpm downshifting when there is back firing
Trending Topics
#8
Maintenance>Repairs
Its probably a vacuum leak, and based on the braking symptom its probably related to your brake booster going out. maybe a random hose with a crack in it too. Check those and let us know
#9
No it has nothing to do with breaking it's when downshifting if I shift into a lower gear and then press in the clutch my idle drops real low then comes back up. When I just press the clutch and brake nothing happens it stays normal
#10
Senior Member
When does it pick back up again ? Need more info. What's warm idle at in Park or N?
Idle should always be very close to 730 rpms at warm idle and coasting to a stop in gear.
If you really want help, you need to test a few things and be as accurate as possible.
Idle should always be very close to 730 rpms at warm idle and coasting to a stop in gear.
If you really want help, you need to test a few things and be as accurate as possible.