m50 non-vanos running issues

[e304lyfe]

Having running issues with an m50 non-vanos I swapped into my e30.

Here are the details in as short a format as I could make it:

m50 NV, 100k mile motor, sat in my garage for probably 5 years, purchased from a totalled e36. swapped it into my '88iS in November and it has never ran right since. g260 trans w/ JBR 7.5 lb flywheel and OE rear end.

symptoms: stumbles and never catches idle. runs rich, nearly stalls or stalls every 10 seconds as it hunts. revs freely w/ no load, but when driving it feels bogged down and can't accelerate quickly. doesn't buck just relatively consistent poor acceleration.

here are parts i've replaced:
coil packs with another used but low mileage set
original cam sensor was OE, replaced w/ aftermarket new
crank sensor is new
MAF's x2 used
ECU's x2 used
Intake manifold / TB / IAT / TPS x2 used
fuel rail / FPR x2 used
fuel injectors x2 (1 set came w/ motor, another rebuilt)
ICV x3 (1 def was good as it came off my convertible which i drive daily)
blue coolant temp sensor replaced w/new
Spark plugs (new NGK BKR6EQUP)
o2 sensor (new bosch)
new fuel filter (just for the hell of it... m20 did not have fuel delivery problems though)
engine wiring harness (replaced w/ another spare, only modification done to x20/c101)

a few more details:
engine ground on motor mount and on shock tower are connected and clean.
checked compression, high 19X psi in each cylinder.
checked fuel. near 3.5 bar
all vacuum lines new and smoke tested
CEL functions, but no codes reported. (unplug TPS, or other sensor, CEL comes on... so I assume all is well) Codes were checked w/ Peake Research scanner.

The current thought of my mechanic (I gave up after I did all of the above except the smoke test) is the 402 DME may not be able to compensate and find idle w/ the significantly lighter 7.5 lb flywheel, and a chip tune that bumps the idle a bit might correct this. And as for the running issue... motor ticks a bit, so possibly sticky/stuck lifters (as motor sat for a while) are causing the car to not be able to accelerate. Does this all sound plausible?

Also, if someone has a chip tune that bumps the idle for a LTW flywheel, I am currently on the hunt for this.

Any fresh ideas? TIA!

[berlow94]

Why 7.5 lbs? Thats awful light!
Pretty sure M50's came in most cars with about 25 lb. flywheels. Have you taken the valve cover off to assess cam's/valves?

[e304lyfe]

Why 7.5 lbs? Thats awful light!
Pretty sure M50's came in most cars with about 25 lb. flywheels. Have you taken the valve cover off to assess cam's/valves?

That is what my m20 came with, and it never "felt" much different then my other e30's w/ stock flywheels on m20's, so I really didn't think twice and swapped it all onto the m50 when I installed it.

It looked very clean under the valve cover... Did not notice any unusual wear, gouges, etc. when looking at cams, etc.

[amcink]

Subscribed. This is of my interest

[Dphraner]

you say your at 1.5bar i think your fuel pressure is low, it should be 3bar or 3.5bar. the number should be stamped into the regulator so check that

[e304lyfe]

you say your at 1.5bar i think your fuel pressure is low, it should be 3bar or 3.5bar. the number should be stamped into the regulator so check that

Oh, sorry... mistype. fuel pressure was around 50psi, so 3.5 bar.

[e30rapidic]

my S50 would not idle at all with a lightened flywheel and the stock chip. I got a chip from TRM with an idle increase....smooth as silk now

[MR E30 325is]

Upon doing lots and lots of research for the 8.5lb UUC flywheel I installed this last winter, I was happy to find out that you definitely need a chip wth an increased idle to pull off the weight.

I am unsure if you are familiar with what a flywheel actually accomplishes, apart from being connected to the starter and starting your car, but too low of a programmed idle will cause the engine to fluctuate due to the lack of rotating mass smoothing things out.

Get a tune from TRM and find yourself much much happier.

[e304lyfe]

I have yet to find any tunes for a 402 DME to bump the idle for a flywheel. TMS, TRM, Technica, and MarkD do not have this software. Remind me never to work with another non-vanos motor.