I have a 2012 Buick Enclave, 160k miles. No check engine codes, but it’s surging between 1,000 and 2,000 rpms when under load. Idle is smooth. Fine at highway around 2,500 rpm. I replaced fuel injectors after I found a long term lean condition coupled with lower fuel economy. Surge is still here through it all. Any ideas?
Can you monitor real-time data when it is occurring on obd? I'd look at that to see differences in data compared to above 2k rpm when all good. Of course some things will be different/changing,.... shoot, just thought of something, check tps for a bad spot around that operating range. You should see resistance change smoothly with the accel and no jumpy spots..... gl.
Did any of the suggestions actually help you. I am having the same problem and I am thinking it is more transmission related. But if you solved it with any of these other suggestions I would like to know
Did any of the suggestions actually help you.
Mr Yonder,
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Check see if there be vacuum leak, do smoke test. You can also take off the air intake and with the engine on fully cover the throttle body and hear for sound. If engine dies, no vac leak and you got another problem. Could check spark plugs and coils as well as where they sit. If you got oil in where the spark plugs are, you got a gasket leak, coils though tend to cause more RPM related issues.
Have you pressure tested your fuel pump?
Any trouble codes? Any vacuum leaks?
Do you have electronic throttle body on that car?
When this issue first popped up, I pulled the spark plugs (didn't look bad for 150k+ miles) and replaced them. Then I checked live data and saw one cylinder bank had a very negative long term trim, so I figured it was a stuck open injector. After replacing that bank's injectors things got better, it went from a bucking surge to just surging... and the fuel trim on the other bank was a little negative, so I replaced those injectors too. Now the fuel trim is around zero... but the surging is still happening, although less often. No codes. I thought I'd get a code if there was a vacuum leak, but that's probably my next step. A bad coil should give misfire codes, right? The fuel rail pressure seems reasonably consistent at around 400kpsa.
The throttle position is an interesting idea, would it still happen with the cruise control on? How much jumping around is normal on that sensor. Like if I'm keeping my foot steady, and the car is steady at 45, should it bounce around only like 5-10%, or could it bounce 20-30%?