CzyRanger
Member
- Joined
- Jul 25, 2019
- Messages
- 61
- Reaction score
- 10
- Points
- 8
- Location
- North Carolina
- Vehicle Year
- 1988
- Make / Model
- Ford Ranger
- Transmission
- Automatic
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@Bird76MojoWell, the link I posted states:
Common Signs of a Failed Brake Booster
Don't know if you have a bad brake booster?
Here are three common signs that your brake booster may have failed:
You need more effort to apply the brakes (stiff brake pedal).
The brake pedal doesn't return to its original position by itself.
The engine rpm goes down when you depress the brake pedal at idle.
So, I'm not sure about that booster being bad.. It may be vacuum problems after all.
This is the weirdest thing... So it's only after driving about 3 miles, which would warm the truck up a fair bit.. Hmm...
I would think the truck would then be in closed loop since it's warmed up. The ECU is actively controlling the air/fuel mixture.
The O2 sensor then comes in to play to tell the ECU what the A/F mixture is and the ECU adjusts accordingly.
So now I'm questioning all sorts of other things..
O2 sensor, TFI module, coolant temperature sensor, ECU, etc..
Diagnostics are gonna have to get more involved now. I'm thinking getting a vacuum reading would be good. Trying to pull codes again couldn't hurt either..
@RonD are you seeing this? Any clues? I'm running out of ideas here, and I hate for him to be throwing new parts at it until it's fixed, as that gets expensive quickly and is no way to work on anything.
@Bird76MojoI've been reading on some other forums (different make/model of vehicle) about people have a hard pedal and increasing RPM when applying the brakes. There's an internal leak in the booster in their case.
https://www.sl113.org/forums/index.php?topic=2067
I was thinking your truck would have the check-valve on the outside of the booster, but I guess I'm thinking of another year of Ranger. The valve may be in-line, in the middle of the hose? You'll see it if there is one. A little tiny round canister looking thing.@Bird76Mojo
So you are talking about the line that goes from the intake to the brake booster which fits in the grommet in the brake booster? Also... I've read about the internal leak and thay it can cause a lean condition... But would it cause the symptoms I'm having is my question? Thanks again.
@Bird76Mojo @RonDI was thinking your truck would have the check-valve on the outside of the booster, but I guess I'm thinking of another year of Ranger. The valve may be in-line, in the middle of the hose? You'll see it if there is one. A little tiny round canister looking thing.
Anyway, yes, pull that vacuum hose off of the intake, put your thumb over the port on the intake, or cap it off. Start the truck and see how the idle is doing.
Check for any brake fluid inside of that hose. It should be dry inside.
While it's running, press the brake pedal. The idle shouldn't increase since the booster is no longer hooked up. The pedal will of course still be hard to press.
I'm wondering if the brake booster has an internal leak on the atmospheric side or between the booster and the master cylinder...
Well. That seems like a bad IAC to me.@Bird76Mojo @RonD
Well I did those tests.. video below. Thanks fellas! I appreciate you all.
Brake booster test:
IAC valve test:
@PetroleumJunkie412Well. That seems like a bad IAC to me.
If it is, I'm guessing it was stuck partially open. Would explain lean code and sh*tty idle.
Get ready to go through a few of them to get a good one.
Standard Motor Products Idle Air Control Valve https://www.amazon.com/dp/B000C7XPGW/ref=cm_sw_r_cp_apa_i_Q8ArDbWHJ7VCM
Order two of them. Odds are one will be good. Test both of them, leave one in your truck as a spare. Not a bad idea to leave a known good MAP, TPS, and TFI in a sealed ammo can in the cab as well with tools to change them. Aftermarket ain't what it used to be.
Saw it!@PetroleumJunkie412
I posted a second IAC valve video right before you posted. Did you see that one? Anyway... So would that explain my main issue here? The whole driving for 3 miles or so and then it start "popping/backfiring" and having to smash the gas pedal to get it going..? Thanks again!