m44 disco CEL sneeze sputter

[318iM44]

It's a stock 1998 m44, 5 speed, with stock ASC, 150k miles.

The CEL has been on for awhile, and now it's rapid flashing like a strobe light, without any pattern.

There is no flickering dashboard backlight at all, since the voltage is good.

Whenever it (strobing CEL ) happens, the engine would sneeze, sputter and cutting out, and wants to die, all that occurs below 3500 rpm.

But, when it's above 3500 rpm, it runs good (CEL stays solid on).
Idle always steady around 700 rpm, meanwhile the engine always shakes significantly when idling.

Erase and reset CEL many times, but same multiple codes ( random misfire, etc) come back after 5 miles of driving.

Parts replaced with stock OEM:
- All intake rubber boots or ducts, all vacuum hoses
- All Injectors Hoses (tree shape)
- All O2 sensors (before & after Cat)
- Coil
- Spark Plugs
- Spark Plugs wires set
- Shut off Valve ( mushroom shape, infront of the engine)
- PCV or CCV valve, and the hose
- Secondary Air Pump
- All ground wires are clean and tight.
- Etc.

WTH is happening here?

[xxxJohnBoyxxx]

Most times that I have a flashing CEL it is detonation and the DME puts the motor into limp mode. What code do you have on the CEL? You can get them pulled at most parts stores for free. I bet you have a multiple mis-fire. This can be caused by ignition or fuel. Since you have addressed the ignition system I would look at the fuel system for your problem. Also vacuum leaks can cause this since the computer goes into closed loop (Lambda) with normal driving and adapts to the vacuum leaks. When you start to accelerate hard the DME goes open loop and the adaption values will cause a fat or lean condition causing the multiple mis-fire.

Dirty fuel filter, rubber hoses that have swelled from the inside causing a restriction, bad regulator or fuel pump low pressure can and will cause the issue you are having.

My internet troubleshooting says look for a fuel delivery issue causing low fuel pressure to the injectors...

Fuel pressure should be around 40psi at idle and raise up to around 45psi when you are accelerating

Best of luck, John S

[318iM44]

Thanks John!

I went to get the codes scanned at local parts store a couple of times, and got about 18 to 26 OBD II codes, and got all the codes erased. (CEL always come back after 5 miles)

The guy was puzzled, since the car is still starts and runs, though its sneezes and sputter below 3500 rpm.

While idling, and the hood is open, i think i could hear slight "hush" by the exhaust manifold area, but it is not like fart sound (major leak).

If that is a very small exhaust leak at or below the exhaust manifold, would it be significant enough to mess the firing order?
(Given the CEL is randomly strobing, and the engine would sneeze and sputter, only below 3500 rpm)

I'd like to think it is a Fuel Filter or Fuel Regulator, or the hose. But the car runs good above 3500 rpm.

Would it stall the engine, if the fuel supply is restricted, when the engine goes above 3500 rpm?

[hotmilk400]

did you fix this issue? i am having the same issue. thanks