2021 ford bronco sport Big bend 1.5 liter eco boost automatic with 102000 miles
New issue Rpms are dropping at idol sometimes
I drove on highway for 30 miles running good. I stop for gas and when I turned car back on my rpm’s would drop and almost stalled out. Then rpm’s would jump back up to normal level. Run ok for 5 seconds then drop down again. I waited 5 minutes it did not stop. When I drove it another 3 miles to my house the rpm’s would jump around a little. I have a video but can’t attach. started car today. Idol was ok. But when driving rpm’s were going up and down.
I have a video but can’t attach.
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How old are your spark plugs and filters? Have you performed a complete diagnostic scan for codes and live data? That would be a good place to start.
And had the upstream catalytic converter replaced
If the catalytic converter went bad after just 5 years that indicates a possible engine problem causing contamination. (In comparison after nearly 30 years and over 375,000 miles my original is still OK.)
dealership said it was running good
They would tell you everything was fine if one of their people put a dead fish under your seat. (What smell?)
I can take to auto store to run the tests
An auto store will do a quick check for codes but they will not likely look at or analyze live data.
I thought might be throttle valve I was going to clean.
Cleaning the throttle body and MAF sensors, using the appropriate cleaners, is a good idea.
I got the serpentine belt changed.
had the upstream catalytic converter replaced
instead of having someone randomly shoot parts at it, take it to a skilled diagnostician who will actually take the time and use the proper tools to analyze the problem and pinpoint it.
I have a torque converter shudder that’s been around for a while.
well a failing TC can certainly bog down an engine.
I drove on highway for 30 miles running good. I stop for gas and when I turned car back on my rpm’s would drop and almost stalled out. Then rpm’s would jump back up to normal level.
This sounds like your purge valve is acting up. Ford has had purge valve issues for years; my and my wife's '17 Mustangs constantly have issues with their purge valves. Typical Ford nonsense these days.
Get a scan tool and select live data. Scroll down to fuel tank vacuum. It should always maintain equilibrium. If fuel tank vacuum is a constant negative number, the purge valve or something else EVAP system-related is likely your culprit. When the purge valve stays open, too much fuel can get into the engine, causing it to run rough. It borderline floods out.
My '99 Ranger's check engine light never came on in the time I had it (it still worked, too). I had it for about 6 years and I put 55k miles on it. When the frame cracked, there was 300k miles on it.
Do as @chucktobias suggest, scan it and see what's off, sounds like the surging could be the fuel pressure, It "could be" a lot of things.. start simple with the basics, scan it.I stop for gas and when I turned car back on my rpm’s would drop and almost stalled out
spark plugs are new about 500 miles on them
At same time as spark plugs I got the serpentine belt changed. Did a transmission drain and fill. And had the upstream catalytic converter replaced
dealership said it was running good but haven’t had it tested yet. I can take to auto store to run the tests
I thought might be throttle valve I was going to clean. And I have a torque converter shudder that’s been around for a while. But ford is denying it is an issue
I’m at dealership now took a week before I could get an appointment. they have been running diagnostics. Can’t find an issue. I showed them video. Live data looks steady they say. I asked them to look at fuel pressure. And to check my coils and throttle body. I’m waiting for them to get back to me.
They said it’s my purge valve. $675 to change out. Last thing im fixing on this car. I don’t think the dealership knows what’s going on. I spoke with the mechanic and took a drive with him while the live data was hooked up.