Sputtering off idle and low rpm shifts

[roguetoaster]

The one on the car is a rebuilt unit about two years old. I do have a spare I can try. The car has a refreshed top end, cop , all new hoses and running a tms comforti chip. It's weird becuase it runs fine till it warms up then goes to shit at low rpm and smooths out in higher revs but still a bit off.

Didn't know that a warm engine was a factor earlier. When at operating temperature try unplugging the O2 sensor, and possible other ancillaries one at a time to see if the operating condition changes.

[m42'd]

Well guys I don't know.... I bought new plugs and let it warm up in the garage. Tried to drive around the block but once it hit temp in the middle of the gauge it drops a cylinder until I hit higher revs and smooths out. Then back at idle it's drops a cylinder again, It actually started small backfires when missing at low rpm and idle . So lost on what could cause this. If my motor was done wouldn't it run like crap cold as well? The car runs fine until it warms up..... tried unplugging the o2 sensor and nothing changed , didn't even light up the check engine which is wierd. The cel light does blink when it misses but it's not storing any faults. The stomp test was 1444

[m42'd]

those are the wrong plugs

BKR6EK dual electrode. try those first.

I had br6ek dual electrodes in.

[m42'd]

Thinking I might try a new intake hose.... the heat from a warm engine would make it more playable and if I had a pin hole it could be expanded with a warm boot? Does any of my symptoms sound like a intake boot hole? Before I drop money on a new one..

[mike.bmw]

Have you tried swapping the stock chip back in?

[TobyB]

Try this, it's easy.
Get it to misfire, pop the hood and clamp your timing light's
inductive pickup around each plug wire in turn. See if you can
see it lose spark when it's misfiring, or if the pattern changes.

That would help diagnose a failing coil pack or dme... or crank sensor,,,


(lemmee guess, you went cop)

t

[m42'd]

Yeah it's cop

[5Toes]

ever figure this out? I would not leave anything to be assumed. It sounds to me like a vacuum leak now... have you done the mess under the intake?

My car runs similar if the icv hoses pops out of the socket in the intake boot (big vac leak).

I am willing to bet when hot something is flexing and letting un-metered air in. The craziest shit happens, you never know!

stomp test is reporting no codes so according to the ECU everything is in good order. I say Vac leak almost definitively...

do the mess under the intake. remove the intake manifold completely while youre in there:

A. it makes it a hell of a lot easier
B. you can definitively check for intake leaks
C. good practice, and you can get your fuel injectors rebuilt at this time ($35 per MEPEH on this forum)

for all the new gaskets, the injector rebuild, and a new intake boot/vac lines its $100. do it :)

[m42'd]

No have not fixed it yet. how can do tell if the "mess under the intake" has been remedied? Ther is a hose the tees to a nipple under the tb and connects to the vc Ben hose, one to the icv and intake boot and that's about it... whish I could post pics. I did post on the fb page I could add pics there if you don't mind taking a peek. I really need to get her back on the road... registration is due in May.

[roguetoaster]

Your post is difficult to read. If the multiple port connectors under the intake manifold are still present and connected the mess sorting has not been done.

[m42'd]

Sorry, on the intake boot, one is plugged and one connected to the icv. Other than that the valcover vent hose connects to the nipple under the throttle bodie. It's how I bought the car all the hoses are newer less than 3yrs old with no visible cracks

[m42'd]

I tried a different maf and still ran like it's on three cylinders and then would pull normally after about 2500 rpm. The exhaust will pop and the car smells a little sulphuric I need to do a compression test but don't have the tester. I'll try to post a clip on the fb page.

[roguetoaster]

I'll try to post a [something I want help with] on the fb page.

Good luck with that.

Did you go through the suggestions we all posted above and try them, or are you just doing your own thing?

Also, giving us piecemeal information about the problem is not ideal, maybe revise the first post with all of the info and what you've done so far? We're here to help (mostly), but we're M42 aficionados, not miracle workers, Jim.

[m42'd]

Good luck with that.

Did you go through the suggestions we all posted above and try them, or are you just doing your own thing?

Also, giving us piecemeal information about the problem is not ideal, maybe revise the first post with all of the info and what you've done so far? We're here to help (mostly), but we're M42 aficionados, not miracle workers, Jim.

Ok.... I posted there to show a clip of what I was talking about incase anyone from here would care to take a look. So far I've addressed the advice given to me except compression check. I'm listing results as I go. Not sure what your problem with me is.

[m42'd]

The car is fixed ended up being a worn boot on one of my coil packs