So at freeway speeds (70-75) my Tahoe has a loss of power, it requires more throttle than usual to keep it at 70. I usually drive around 85-90 and have never had any problems until now, My foot naturally rested at this point and now at the same position it holds a little above 70. When driving through town (anything bellow 70) it runs just fine and when you floor it on the freeway (the only way to get it to go above 75) it revs up and goes like it always has. I have replace the plugs, wires and coils. I have a spectre intake system and that filter is clean. I do have a lift (Key and spacer with lift knuckles) and 33" tires but the problem has just started and I have had this set up for 2-3 years.I have no codes being thrown either. Any ideas on what this could be? I have in the past noticed that the vehicle has revved up to about 4000 rpm before it would accelerate but that has only happened 1-2 times since Ive owned the vehicle (4-5 years).Thanks in advance.
Loss Of Power at 70-75 MPH
- Thread starter jxw004
- Start date
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clandr1
Full Access Member
This alone makes me think it might be a problem with your transmission and/or torque converter.
Is there anyway to test these?
02DFWTahoe
Member
Is there any change in RPM while your cruising as if the converter isn't locked?
It seems to stay in the 2200-2300 range at 70-75 which is where it normally was when I drove at that speed, it just seems like when I press the gas pedal down more nothing happens until I literally floor it and then everything happens as it should. I will double check these number when I get off work just to be sure. This only happens at that speed though, getting up to it everything runs fine. Its almost like when It was governed at 80 before I had it removed.
---------- Post added at 01:57 PM ---------- Previous post was at 12:00 PM ----------
ok so at 70 mph my rpm is at 2100-2200 at 75 mph my rpm is at 2400-2500 and at 80 mph my rpm is at 3000 (its never been that high to my knowledge). I also can't get it to hold at a certain speed between between 76-90 bellow or above I can hold it. Even when I set the cruise control at 85 it revs up and once reaches 85 it backs off like it should but then it has to rev back up maybe a 3-4 seconds later on a flat highway. If this is all in my head then cool but if there is a problem I want to get it fixed.
clandr1
Full Access Member
I wish I knew... Hopefully someone here can help. If not, you might just have to take it to a good local transmission shop. I'm sure there's a way to test it.
SLCHOE
ASE Master Certified + (L1)
If you have a scan tool with live data, look up TPS %.
Then with key on engine off, slowly apply the accelerator pedal through the full range. The % should increase smoothly through the range. If it hangs or drops out where you normally rest your foot cruising down the highway, the TPS could be worn in that spot since it's worn more in that area than other places. faulty TPS readings can also cause transmission shifting issues.
IF you don't have a scan tool, you can similarly also back-probe the connector to the TPS with it still plugged in and watch the voltage to increase smoothly as you open the throttle.
TPS should have a range of ~0.5VDC to ~4.5VDC being that is is a 3 wire 5V reference based potentiometer (Your TPS should have 6 wires, TPS sensor 1 and 2). I'd also look at the TAC module.
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ccapehartusarmyINF.(ret)
Full Access Member
if its the knock sensor another thing you can do to confirm is monitor your fuel consumption a bad knock sensor will cause a noticeably more fuel consumption
so funny, when you first posted, my initial thought was " that describes bad knock sensors", lol and where we are today, you have the code..
knock sensor causes all sorts of problems and most defiantly a loss of power.
knock sensors pull timing when they sense , well knock, aka detonation. this happens mostly during hard acceleration and loads on the engine.
As chris stated, you will see a dramatic drop in MPG.
Replace both and the harness asap.
knock sensor causes all sorts of problems and most defiantly a loss of power.
knock sensors pull timing when they sense , well knock, aka detonation. this happens mostly during hard acceleration and loads on the engine.
As chris stated, you will see a dramatic drop in MPG.
Replace both and the harness asap.
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