m20b27 loss of power, sputter

[shaferbm]

I am needing to nail this issue down before I grab parts. When starting, it will sometimes stall unless I give a bit of gas to at when cranking. When cold, it starts idles low, then idles normally when warm. Sometimes there is a surging idle/ high idle. I have a spare icv, and had the same issue when I swapped them.

Secondly, while driving sometimes after getting into it, there is a sudden loss of power, and I have to barely touch the gas for it to be driveable without sputtering. Is this fuel pump? There is a audible whine from the fuel pump when outside the car.

I'm thinking maybe grab a tps, and new fuel pumps?
Could this a fuel starvation issue? The i checked the fpr, and it was working properly.

I'm pretty sure there are no vacuum leaks, Ive recently fixed several vacuum lines, and a few gaskets.

[shaferbm]

Bump


Sent from my LG-E970 using Tapatalk 4 Beta

[dnguyen1963]

If your fuel pump is whining then it is a suspect, but erratic idling/sudden loss of power still suggests that you have vacuum leaks. I would have a smoke test done to eliminate any vacuum leaks then tee in a pressure gauge and monitor the pressure during a drive to see if you have any pressure drop.

[DesertBMW]

Mine does the same. It is just a symptom of aging M20. All parts check out perfect but it never runs right. That's the fun of having M20, its not a boring engine so it reminds to think of it everyday.

[shaferbm]

Mine does the same. It is just a symptom of aging M20. All parts check out perfect but it never runs right. That's the fun of having M20, its not a boring engine so it reminds to think of it everyday.

No way. Just because it's aging doesn't mean you automatically get these problems. You get these problems because there is something wrong. As for an update, I've ordered a cheap tps (known to be working) from another member. I've tested the fuel pressure while driving and having the issue. Fuel pressure seems to be good. I get 30 psi while idle, ~35 psi normal acceleration, and just under 40 psi under WOT.

I've been reading and some have had similar issues with (as far as sputter, and loss of power) a bad coolant temperature sensor. According to the Bentley manual the ECU bases air fuel mixture based on coolant temp, 02 sensor, and the afm.

EDIT: Smoke test is also in the works, as that may be more likely than the Coolant temp sensor.

[Mr. Tasty]

I've been reading and some have had similar issues with (as far as sputter, and loss of power) a bad coolant temperature sensor. According to the Bentley manual the ECU bases air fuel mixture based on coolant temp, 02 sensor, and the afm.

EDIT: Smoke test is also in the works, as that may be more likely than the Coolant temp sensor.

interesting...

[shaferbm]

interesting...

Why is that?

[nickskater09]

Had what seems like kinda the same issue as you (sputtering under acceleration, wont idle,) I had to change AFM and DME to get it to fix itself and go away.

[bigredguy]

I have a similar problem on my car as well. Havent found been able to find any issues yet. Unlike you, I do not have a fuel pump whine. I thought maybe spark plugs, injectors, or even a clogged air box not getting enough air. Those were my few thoughts, that I just never got around to checking out. Mine isnt every time I go and try to have fun though, once in a while at most.

[shaferbm]

I replaced the Icv with a known working units, and replaced the Altitude sensor (essentially a barometric pressure sensor). The Altitude sensor on my car was exposed and was corroded. It's no longer sputtering, and is idling the way it should, so this seems to have alleviated the issue.

Sent from my LG-E970 using Tapatalk 4 Beta