Replaced the water pump and thermostat in my 98 olds bravada and now it "surges" when driving. Took it to an auto parts store and they hooked it up to their machine and it "could" be one of three sensors.. temp sensor, map sensor or maf sensor.. HELP

Cooling Fan ! What year Tahoe ?

Depends on the noise. Tapping or knocking is rod bearings, engine side. Whining is the transmission side. Torque converter, pump, and parts further inside the transmission.

4.6 engines cadillac water pump front of the engine behind a cover.if you see thermostat housing you will see water pump drive belt you need a water pump tool to remove water pump.you can buy the water pump socket removal tool at any auto parts stores.

I'd start by replacing the thermostat. If that thing is stuck shut, that would be why it heats up so fast. Follow your top radiator hose to where it connects to the engine. remove the housing it fits into (usually 2 bolts) remove the gasket and you'll see the thermostat (cheap looking aluminum thing with a spring in it) Cheap part at the auto store, just make sure you put the new one in exactly how the old one was when you took it out...some have "breather holes" at the top so just pay attention when you remove the old one. Since you replaced everything else...I can only see that being the cause. should cost you around 12 bucks for that and the new gasket. Should take about 15 minutes to replace as well. Have fun and let me know how it went!

Hello! Thermostat needs to be replaced, but the cooling system should be "back flushed"...Go to a local auto parts store and purchase a back flush kit (under$10)
It's a plastic tee that is installed in the heater inlet hose... A garden hose connects to the stem of the tee and cooling system is flushed out of the top of the radiator...Let it run until clear...Install thermostat...Cap off the tee...Add a gallon of 50/50 and the rest with Distilled water...Leave the cap off until all air bubbles out (even after thermostat opens)...With heater set on high...Install cap when all air is out...Guru...Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Most offen its the encoder motor it is a electric motor the engauges the All wheel drive its located to the passager side of the transfer case and can be bought from auto parts store for around 170.00$

You made no mention of thermostat or radiator cap, both are common problems. The cap you can have tested at any good auto parts store, to see if it's holding adequate pressure.

Well, the secondary air intake malfunction has to do with the air pump I read. Water can get into the air pump in some models and the pump would have to be replaced. However, I have heard that some OEM pumps have a short hose that accumulates water sometimes, causing a recurring problem.

Also, there is sometimes a 20 or 30 Amps fuse that controls the pump.

However, I think, that even though they cleared the code at Advance Auto Parts, and it wouldn't start, that the no start condition is not related to the air pump problem, since the air pump problem is more of an emission control to reduce pollution and doesn't feed directly into the combusiton chamber.

I think that you should check the fuel injectors to make sure that they are working. They should click when under pressure with fuel, and allow fuel to enter the combustion chamber.

Maybe check the fuse for the FI or fuel injectors.

It seems like your vehicle is getting spark since it runs briefly when you spray brake cleaner into the air intake.

Thats the time ur cooling fan would start.
I will check the cooling fan functionality first before going ahead.

Aftermarket fuel pump failure? Try "thepartsladi" store on eBay for low price GM OEM parts. Could also be wiring harness to fuel pump.