2007 Tahoe 5.3l AFM DOD delete thread
- Thread starter Taheezy_88
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Hmmmm... I have a Tech2 and can check mine this week and report back, if it would be helpful.
Might help square the loop..
I got a chance to watch my MAP numbers on my ODB iPhone Ap while running errands. The idle pressure jumps quite a bit as soon as you drop it into gear, so load makes a very big difference, as opposed to sitting and idling.
I suspect the lowest idle vacuum you might see would be engine idling backing down a driveway (essentially the lowest engine load), other than when you crack the throttle open and things haven't caught up yet, but in that case, you also aren't using the brake.
I suspect the lowest idle vacuum you might see would be engine idling backing down a driveway (essentially the lowest engine load), other than when you crack the throttle open and things haven't caught up yet, but in that case, you also aren't using the brake.
ShootinHeavies
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This is close to the same we were seeing in the snap on unit, and through the gauge. Under power and above idle the brakes work as normal, but the pedal shudders and brakes are softish backing up. Been talking withe the shop and they are going to go through the tune, and I am purchasing the tuning software to have, but it doesnt seem that the reading we are getting are all that far off from this video.
ShootinHeavies
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If possible it would help since we are running the same cam setup.
The one I posted was just sitting in my garage at idle. I suspect if you were backing down a driveway, at idle, it would be even lower. It really changes under load and in deceleration coming completely off the throttle but the engine under load (engine braking). so it would jive that you are seeing worst case backing down a driveway.
George B
¯\_(ツ)_/¯
Do these boosters still have a check valve?
George B
¯\_(ツ)_/¯
Yup, I was wondering if the OP has a leaky check valve on the booster.
Good idea. There are three *********** into that chamber (Actually 4 if you count the master cylinder), the check valve and two sensors. I wonder how much all that matters when it comes to leak down of the vacuum? Also, if it was just a minor leak, a fresh start before you have any serious engine braking pressures to store vacuum, again would be the worst case for how much assist you are getting.'
One thing that confuses me is the softish pedal and shuddering report. Anytime I have had vacuum boost issues, the pedal gets extremely hard, versus soft. But those are all pre-abs experiences.
Wow, pene-trations is censored.
Here is a better clip of my Yukon at idle with a few throttle blips. I found the "intake data" page in the Tech 2 diagnostics, better than trying to figure out what the barometer is saying today and doing the math by hand...
ShootinHeavies
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Well after messing with this for weeks and basically going over the entire install, buying HP Tuners to play with the tuning, we couldn't get it to quit throwing the service brakes message, so we swapped cams to a TxSpeed stage 2 and retuned. Absolutely no issues with the brakes with the TxSpeed cam. The BTR cam was 111 lsa and the TxSpeed 112 lsa, but no low vacuum issues, not sure if the BTR grind was just off or what, but were saving it for another build with hydro boost brakes anyways. Again, apologies for derailing this thread.
crownvic31
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Good info
NardDog
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Allot answers here, I couldn’t read them all but I didn’t see any mention about the torque angle degrees tool for the head bolts. Maybe it was Idk but dont forget that.
