It’s not running correctly

5strmtrp · May 23, 2020

The past few weeks my truck isn’t running well.

I’ve changed the plugs n wires, cleaned the MAF, cleaned the intake out, put mid grade fuel in but it’s still acting funny.

Oil level is where it should be, trans fluid looks pinkish, coolant level and color are good.

It stutters at slow speeds and at highway speeds feels sluggish.

After driving it and parking it, as it’s cooling down I hear a loud thunk, metal like, sounds like it’s from the back but uncertain.

Both my son and wife have heard the noise but also couldn’t determine where it was coming from.

It seems as if it’s not getting all the power it should.

My thoughts,

exhaust, ie cats or muffler.

fuel system not up to *****, but Do not have a fuel pressure guage.

Can the AFM be this issue? Do not want just by a plug in do dad to find out it’s not and pee my funds away.

Thoughts?

Paul
5trmtpr

Doubeleive · May 23, 2020

the maf sensor can cause those issue's just cleaning the maf does not "fix" it, if it is defective or going out then replacement is the only option.
this doesn't mean go out and buy a maf, it's just something to consider and look at with some type of scanner tool, another thing to check is the fuel pressure you should have 60-65lbs pre-start (key on only), and then you should have about 45lbs when running give or take a smidge.

you can rent a fuel pressure tester from most autoparts stores or buy a cheapy one for around $25-30 harbor freight has them

iamdub · May 23, 2020

Dragging rear or parking brake?

5strmtrp · May 23, 2020

iamdub said:
Dragging rear or parking brake?

I would consider that, however my parking brake hasn’t worked since I bought it. That’s over 10 thousand or so ago. This is something that’s been getting more n more noticeable.

The MAF, How would you test it?

Paul
5trmtpr

iamdub · May 24, 2020

5strmtrp said:
The MAF, How would you test it?

Paul
5trmtpr

Bare minimum would be to watch it's readings with a scan tool that shows live data. You'd need to know how many g/sec it should be reporting at X RPM and at X load.

iamdub · May 24, 2020

5strmtrp said:
The MAF, How would you test it?

Paul
5trmtpr

Bare minimum would be to watch it's readings with a scan tool that shows live data. You'd need to know how many g/sec it should be reporting at X RPM and at X load.

swathdiver · May 24, 2020

5strmtrp said:
The past few weeks my truck isn’t running well.

I’ve changed the plugs n wires, cleaned the MAF, cleaned the intake out, put mid grade fuel in but it’s still acting funny.

Oil level is where it should be, trans fluid looks pinkish, coolant level and color are good.

It stutters at slow speeds and at highway speeds feels sluggish.

After driving it and parking it, as it’s cooling down I hear a loud thunk, metal like, sounds like it’s from the back but uncertain.

Both my son and wife have heard the noise but also couldn’t determine where it was coming from.

It seems as if it’s not getting all the power it should.

My thoughts,

exhaust, ie cats or muffler.

fuel system not up to *****, but Do not have a fuel pressure guage.

Can the AFM be this issue? Do not want just by a plug in do dad to find out it’s not and pee my funds away.

Thoughts?

Paul
5trmtpr

Forgive my poor memory, what truck is this? Year, Model, Motor, Driveline, etc.?

If you plan on keeping this thing in top form, get a Tech-2 or equivalent, you're guessing without one. An inoperable parking brake is still suspect, what's it doing while not working right? If this is a 4x4, how does the transfer case fluid look? What is its temperature? Running a graph of the O2 sensors can tell you a lot about how the engine is running. What is the Long Term Fuel Trim on the Fuel Pump? You can only know these things with a dealer level scan tool. If you live near me here in Florida you can stop on by and we'll put mine on it and have a look.

Rocket Man · May 24, 2020

At the very least get an inexpensive obd scanner and check for codes. Could be lots of things.

5strmtrp · May 24, 2020

swathdiver said:
Forgive my poor memory, what truck is this? Year, Model, Motor, Driveline, etc.?

If you plan on keeping this thing in top form, get a Tech-2 or equivalent, you're guessing without one. An inoperable parking brake is still suspect, what's it doing while not working right? If this is a 4x4, how does the transfer case fluid look? What is its temperature? Running a graph of the O2 sensors can tell you a lot about how the engine is running. What is the Long Term Fuel Trim on the Fuel Pump? You can only know these things with a dealer level scan tool. If you live near me here in Florida you can stop on by and we'll put mine on it and have a look.

You know I should of learned by now.
2014 Tahoe SSV, 5.3 L, 6L60 trans 4x4
113,*** miles.

Appreciate the offer of stopping by, but I’m way North of ya, Easton,PA! Home of Crayola crayons!

Just checked the rear brakes, not dragging, in fact the cable isn’t attached as the “finger” that holds it in place is broken clean off. That is in need of a rock auto visit!

The symptoms only started over the past 5000 or so miles.

I have changed out the coolant oil and rear diff fluid. The trans oil and transfer case oil are good per say, it’s on my list of to do in the next few weeks.

I’m going to ask my neighbor if he has a scan tool, I have to learn how to use one of em. Really should just get one.

Paul
5trmtpr

5strmtrp · May 24, 2020

Rocket Man said:
At the very least get an inexpensive obd scanner and check for codes. Could be lots of things.

I’ve got an auto gauge that can read codes or at least tell me what they are, no telltale codes to see unless they are deeper than this little thing can do.

Paul
5trmtpr

wjburken · May 24, 2020

5strmtrp said:
2014 Tahoe SSV, 5.3 L, 6L60 trans 4x4
113,*** miles.

Put this in your signature.

Might be worth buying/renting one of these to see what your fuel pressure is doing.
https://www.autozone.com/test-scan-...ova-fuel-injection-pressure-tester/273356_0_0

What did your old plugs look like when you replaced them? And odd coloring, carbon/soot build-up?

It’s not running correctly

5strmtrp

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Doubeleive

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