The brake booster vacuum hose is real shady to me because when i sprayed a good amount of break clean on it for a few seconds my engine almost stalls. If i go light on the brake clean the engine changes idle very slightly.

 

That’s for sure your leak that shouldn’t happen it should be sealed

Get some new hose from local discount auto store and replace or if your in a pinch I guess you could find specifically where the leak is. Move your hand down the hose and squeeze each little section while the engines running. If the idle changes your close to the leak and find where it is. Wrap in duck tape. Def would only use that method for the short term

if you have several vacuum leaks it could make it run maybe half way better but who knows could completely fix it

 

your right it only half betters it. Duct tape method and long term fuel trim goes to like 14 for bank 1 and 17 for bank 2 and the short term is negative by like 5 and 6. ):

 

That’s a good sign!!

So your total fuel trim=short term bank A+long term bank A

accepted numbers are around +/- 10 %

Long term fuel trims are basically the base line and it’s learned from an average of the past short terms. The goal is to get the short term closest to zero for quick adjustments. So your computer is used to the vacuum leak so your long term fuel trim adjust to a high long term fuel trim like 25% (for example) and your short terms bounce around -1/1 close to zero.

But when you fix the leak all of a sudden your short term fuel trims dive down because all the air coming into the engine is being counted for because the Intake is sealed. So now the computer doesn’t have to add “extra” fuel.

Since the long term is a learned number let your truck idle for about 5-10 mins and check your fuel trims again. The computer will adjust to your newly fixed vacuum leak.

depending on how well it fixes your fuel trims id say clear the codes and see what comes back after you confirm if it’s a fix

 

Isnt long term supposed to be at zero? 14 and 17 doesnt seem normal right?

 

It’s ok for the long term to be between plus or minus 10% and it definitely shouldn’t set a code if it’s in that range.

let it idle for 5-10 mins and the fuel trims will adjust to the recently fixed leak

report back with new fuel trims

 

I didnt fix the leak. That was with the duct tape method you talked about. Im not sure where on the hose the leak is. I'll send a video of where i suspect it is.

 

What do you mean you didn’t fix it?

 

those fuel trim numbers were with the duct tape method

 

 

Was thinking the white piece attached to brake booster?

 

Wherever you put the duck tape on is where the leak is, where’d you put it?

that white peice is a check valve so air doesn’t go into the brake booster

 

I unplugged the brake booster hose from the engine then plugged the engine hose port with duct tape

 

So what am i replacing?

 

I believe the check valve is allowing air inside. Thats where i spray the brake clean and engine idles a bit louder and then almost stalls. But when I take the hose off the engine and blow air through the hose to the brake booster, I can't blow any air through so i dont get why plugging the engine side with duct tape helped

 

Oh **** you mean you got it off the break booster and duct taped the end of the hose??

sorry there was some miscommunication last night

ok so the check valve lets air move out of your break booster not in.

does your check valve have any cracks? How is the connection where the hose goes on is it air tight?

either the hose or connection isn’t air tight

or maybe your check valve is cracked

or your break booster is shot and the diaphragm is leaking a considerable amount of air

it doesn’t sound like your break booster is shot because you say you squirt break clean and it changes the idle so it leads me to beleive a poor connection

 

Yes air can go out but not in. and no i got the hose off the engine then plug it up with duct tape. If you look at the above image you see that i can wiggle the check valve around if thats normal. But there didnt seem like there was any cracks. Or on the o ring in front of the check valve

 

I would replace the hose first since it’s the cheapest and they can age over time and become brittle and crack and then air gets in through the cracks and give you a vacuum leak. You might need to replace the check valve if that doesn’t work but I can’t imagine that’s too expensive either

see if you can take the hose completely off the engine and if you can find any small cracks

 

Hose looks completely normal to me. No cracks. Could the o ring not be thick enough to completely seal the check valve? My only guess at this point

 

See how in the above image how theres a little opening? Thats where the brake clean got in im pretty sure

 

I talked to an auto repair shop and he said maybe erg valve stuck open or something with fuel pressure regulator?

 

You clearly have a leak on the break booster vacuum system somewhere

fix it before you move on there’s no use trying to look for other vacuum leaks when there’s one right in front of you. Fix the leak and see what happens it could solve most of your codes possibly

I’ve seen so many instances where people don’t know what they’re doing and they try to fix it themselves and they ask the auto shop for guidance and they’ll steer them in the wrong direction so they give up trying to fix it themselves and take it in and pay them to find it.

fix the leak first then see what happens and move on from there

 

Well yes your right. However i need to find the other stuff thats making me run lean as well. Fixing that only made my fuel trim go down about 8%. I'm still around 15 and 17. I need to find the other stuff now. There is a shop with free diagnostics around unless you have any more suggestions.

 

when you reported your fuel trims you stated your long terms were 17 but your short term was -6

i tried to explain to you that total fuel trim=short+long

in this case 17+(-6)=11

that is a pretty acceptable fuel trim on an 18 year old engine

also it will not set a code and should run smoothly with a total fuel trim of 11

if it still idles poorly we can move on from there

let your long term get adjusted to the new fix, let it idle with the break booster hose taped off for about ten mins and see what your numbers look like after that. you can sit there and watch it in real time. As your short term stays negative your long terms will fall down as well because they learn from the short term. Eventually your long term will settle down to a number and you will know because your short term will bounce around zero

 

I'm sorry i doubted you look what happens when i unplug the brake booster from my engine and duct tape it