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Well crap, now its getting a little worse. It now does it without the A/C on sometimes. But still only when warm out. Chilly mornings, she runs flippin great.
I did disconnect the MAF and it still ran the same. Weird though, no CEL. Truck was warm, closed loop, I thought for sure it would give a CEL.
I am pulling the TPS this weekend, it is a new one, but with most aftermarket replacement parts, there can be bad ones.
Quote:
Originally Posted by GarageLogic
Geez, this is a weird one. Something makes me suspect that it's EGR and/or Idle Air Control Valve related...
I was looking at the IAC a few days ago and was going to probe more into that. IAC is adjusted differently with A/C on but if the IAC is going bad, that may explain why it does its "sometimes" with A/C off. Could be sticking?
I was looking at the IAC a few days ago and was going to probe more into that. IAC is adjusted differently with A/C on but if the IAC is going bad, that may explain why it does its "sometimes" with A/C off. Could be sticking?
Sure could be. It's a long-shot, to be sure. But not much else is making a lot of sense.
In a weird way, the fact that it's getting worse is probably a good thing. Eventually you'll know for sure.
Whatever it is, I want it to fail soon. Then I can fix it. Im not replacing anything unless I know its the issue.
What still bugs me is no CEL. Usually the stumble is for a couple of seconds, but I've been able to get it to last 7 or 8 seconds and not a blip of that light. I know the CEL works though.
I have a friend that has one of those pro portable diagnostic tools/scopes that monitor in real time. I may have to give him a call and a 12 pack.
FYI - A TPS (Throttle Position Sensor) is like the volume control on an old radio/TV where you would turn the knob to increase volume. It lets a little electricity through at low volume, then lets more and more electricity through as you turn the knob.
And it has metal "wipers" which rub on a special surface as it is turned back and forth - That surface wears down after years of use and may no longer make good electrical contact in certain areas. In the case of the radio, there could be dead spots or the speakers would emit a "scratchy noise" as you turned the volume up/down. Here is a picture of a TPS taken apart... http://www.sportbikes.net/forums/att...lls-tps_11.jpg
With a TPS, each time you move the accelerator pedal up/down, it also moves that TPS sensor. So imagine what it looks like on a vehicle with high mileage! Quite worn!
And the job of the TPS is to tell the engine computer how far open the throttle is (or how much you are pressing on the accelerator). Based on that and other information, it gives the engine more or less fuel via the injectors.
If the TPS is worn, it will be telling the engine computer the throttle is at a different position than it actually is, so the amount of fuel delivered to the engine will not be what it should be.
Probably good to replace those if your vehicle mileage is getting to be around 80,000 miles or more. Definitely replace them at 100,000 miles.
Well crap, now its getting a little worse. It now does it without the A/C on sometimes. But still only when warm out. Chilly mornings, she runs flippin great.
I did disconnect the MAF and it still ran the same. Weird though, no CEL. Truck was warm, closed loop, I thought for sure it would give a CEL.
Any other thoughts?
Are you saying it didn't turn on the CEL driving it with the MAF disconnected?
Are you saying it didn't turn on the CEL driving it with the MAF disconnected?
yup, drove it around the block, no CEL. I then disconnected a couple other sensors, and CEL lit up. Plugged it back in and cleared the code. Tried again with the MAF and nothing. Maybe I should try giving more throttle but i gave about 25%, which should be enough.
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