m20 having odd starting problem.

[e30loverSC]

Today my 87 325is has been having a little trouble getting going. On a cold or hot start( after it sits for about 5-10 mins) the car start runs smooth for 1 sec. then drops idle skips, and misses really bad sometimes stalls. Some times if you give it gas it will rev up but skip really bad and sometimes it bogs out and stalls. After you start again or keep it from stalling after about 15 secs or so it will run smooth like normal. And it drives fine after it gets going? HELP



NEW SYPTOMS:
code: 1222 Lambada
only acts up after its been sittting for 15-25 min or at first start
Sometimes it will idle extremely low but no stall and then suddenly come back to normal and not move.
sometimes no stall just idle surge until it got close to operating temperature
At operating temperature ran normal no issues. Sometimes idle would drop just below normal and go right back and stay constant

[llll1l1ll]

Is there a strong fuel smell?

If so, you might have the same problem I did (or still might have).

I would pull the plugs and see what they look and smell like.

Also, try disconnecting your battery to flash the computer's memory and then see how the car runs.

[e30loverSC]

Yes there is a strong smell of fuel and plugs only have 6k on them

[e30loverSC]

Help!! THis morning i started her up and it idled but it went up and down between 800-1500. Idk whats wrong with it

[llll1l1ll]

If you "flashed" your ECU/DME by disconnecting the battery, you car will have a funky idle for a few run cycles.

Yes there is a strong smell of fuel and plugs only have 6k on them

Sounds like an injector won't turn itself off.

I had (or still might have) a similar problem. The car would run as if it had a busted rocker arm. Turns out, cylinder number four injector was spewing so much fuel to the point that the spark plug couldn't ignite it. Fuel was leaking out of the exhaust pipes.

Your problem sounds similar.

I would recommend you try doing the simple things first: O2 sensor, TPS, CPS. Also, check to see what ECU/DME you have. You can find it by opening up your glovebox and unscrewing two screws that hold a plastic cover to the "ceiling" of the glovebox. Above this "ceiling" is your ECU/DME. You'll see a a green sticker with a ton of numbers on it. Check to see what the last three numbers are (it's either going to be 173 or 153). If it's 153, try using a 173.

That's the step I'm on now. My car has gone through about five or six run cycles and the problem has not came about yet. I will see later on today when I head out.

[e30loverSC]

well now ive got new symptoms. CAr doesnt stall but idle surges up and down only when not fully warmed up. Once warm the idle is calm. Also at idle i get code 1222 from the stomp test. maybe ECT?

[e30loverSC]

help new symptoms added

[jlevie]

Idle or hard starting problems are most commonly caused by intake leaks and/or
a sticky or defective Idle Control Valve (ICV). The only reliable method of
locating intake leaks is to have a smoke test run on the intake and crank case
and to test the brake booster with a gage and vacuum pump. The complete list
of possible causes of an intake leak is:

Intake boot
Throttle body gasket
ICV hoses & connections
Brake booster, hoses, and connections
Crank case breather hose
Evaporative control hose and valve
Fuel pressure regulator & hose
Injector seals
Valve cover gaskets & bungs
Oil filler cap
Dip stick o-rings
Oil return tube o-rings

While leaks in some of those can be found by inspection or by spraying carb
cleaner on suspect areas, not finding leaks that way doesn't eliminate the
possibility. Only a smoke test will really work.

Once the possibility of intake leaks is eliminated, the ICV needs to be
removed and cleaned with carb cleaner until the vane inside moves freely. When
the ignition is switched on you should be able to feel vibration from the
ICV. If no vibration the ICV is bad, there's a problem with its wiring or
connector, there's a problem with the TPS, or the DME (or Idle Control Module
(ICM) on an ETA car) is faulty.

For the DME (or ICM) to control idle, the idle switch in the TPS must work
correctly. The switch should close when the throttle stop is 0.020-0.060" off
the idle stop screw.

The fuel system should be tested via the suite of tests in the Bentley manual
as invalid rail pressure can be a contributor to idle and starting problems. A
simple injector check is to pull the injectors, jumper the fuel relay to run
the pump, and see if the injectors are leaking. You can also point the
injectors into a towel, remove the coil wire, and crank the engine to see if
all of the injectors appear to be spraying in a similar fashion. The best
approach to possible injector problems is to have the injectors cleaned and
flow tested. Since raw fuel can or will be released in these tests, have a
fire extinguisher handy.

The O2 sensor can be a contributor to idle problems. The O2 sensor is a
scheduled maintenance item with a useful life of no more than 100k. If the
sensor has that mileage or more (or is of unknown age), replace it.

The AFM can be a contributor. If the vane doesn't move freely or the
resistance track is worn the DME may be receiving invalid data from the
AFM. And if someone has fiddled with the bypass air adjustment the DME may be
unable to stabilize idle. The bypass air adjustment should only be adjusted
per the procedure in the Bentley and with an exhaust gas analyzer. And even
then everything else associated with engine management has to first be
operating properly. If the AFM becomes a suspect, replacement with a good used
unit is the best approach.

Improperly adjusted or malfunctioning valves will affect idle and starting. As
can compression issues from ring or cylinder wear. A valve adjustment is
called for every 15k. A useful diagnostic is to run compression and leak down
tests on the engine. And aged ignition wires, plugs, distributor cap, or
rotor can cause problems. Insulation does break down with time and heat. And
since the youngest E30 is going on 19 years old, if the ignition system is
original or the plugs are old replacement is indicated.

Although not usually a problem, a bad DME temp sensor is a possibility. That
generally won't cause an unstable idle, but can cause hard cold or hard hot
starts and/or a rough idle. As can problems with the timing reference sensors.

When all other possibilities have been eliminated and idle or starting
problems persist, replacement of the DME, or if applicable the ICM, is
indicated.

[e30loverSC]

Thanks for the write up! Much help cleaned ICV and unplugged battery seemed to fix problems.