AHHH ive tried everything... still not running right

[MattM]

M52b28, Full OBD2

Engine runs like shit.

It starts fine, idles about 500 for 10-20 seconds, then drops to around 250 for another 30 seconds, before it sputters out and dies.

Throttle response has HUGE hesitation... literally like 20 seconds. If im quick and make it to the throttle and hold up open a bit, it will stay running...

- quadruple checked all vacuum lines
- cleaned ICV twice
- cleaned throttle body
- replaced MAF
- replaced MAF boot
- replaced fuel filter
- replaced spark plugs

One other interesting observation, header bank 1 (cyl 1,2,3) stays warm to the touch, while header bank 2 (cyl 4,5,6) gets SMOKING hot(normal temp?)

HELP im getting really frustrated with this

[e30e]

How's the fuses, dumb question I know....but with obd2 those fuses can be a mother fer......

Other thought, is yes you've checked the vacuum lines but are they the correct places, are any of those lines in the wrong place?

[MattM]

which fuses are you referring too? not many fuses in the way of the engine running.... when it sputters out and dies i can go and turn the key and it will start back up again and repeat.

Vacuum lines are all hooked up properly, i disconnected and plugged the hose that goes back to the exhaust valve just to eliminate that system from potential errors...

[luckysnafu]

Can you hook up a code reader and get us the codes? It's pretty easy to wire up a connector for a generic OBD2 code reader.

What happens to the idle when you disconnect the MAF?

What are you running for an intake?

[Boosted E30]

I bet you have a missfire on 456 and thats why the header gets so hot so fast. If you have a known working set of coils swap them out and see if it fixes it. Or change coils 456 with 123 and see if the 123 header gets super hot quickly.

Also check the rubber boots that go from the coil to the plugs and see if there are any cracks in them that could cause them to arc.

[Wanganstyle]

ok-

start with the missing symptom; lets see if your engine is using ALL 6 cylinders!!!!!!



Multimeter EACH coil pack and see what the 3 wires are showing:

1 should be ground at all wires
another will be 12v+ on IGN+ position power on
another wire will be Direct to ECU and color coded.

use Multimeter to check the above 3 items on all 6 coilpacks.

then check for 12v+ at all injectors
and for continuity between injector 1-6 and ECU.

IF you have only HALF the cylinders hot when running, then something is not working uniform on your fueling/sparking.

[MattM]

i have a code reader, the only code i am getting is fuel tank pressure sensor... its not hooked up

Ill try some of this stuff tonight

[Wanganstyle]

Code reader won't help u diagnose improper wiring mistakes, only useful for 100% original car to diagnose broken sensors etc

Code reader is close to useless in many swaps, it cannot tell you if the harness is physically wrong.

Multi meter or even a simple test light would show u the end of the tunnel....

[ExViTermini]

My obd1 m50 acted this same way. Twas the ecu.. :(

[MattM]

Code reader won't help u diagnose improper wiring mistakes, only useful for 100% original car to diagnose broken sensors etc

Code reader is close to useless in many swaps, it cannot tell you if the harness is physically wrong.

Multi meter or even a simple test light would show u the end of the tunnel....

im almost 100% sure the harness is correct, i spent about 3 days in the ETM's marking and labeling everything, and writing a pinout for the x20

[Wanganstyle]

im almost 100% sure the harness is correct, i spent about 3 days in the ETM's marking and labeling everything, and writing a pinout for the x20

I am always like this......but multi-meter tells the TRUTH.

if 1/2 the cylinders are not running (as your symptoms seem to show) then 1/2 the cylinders are not getting fuel or spark.

if hand can touch headers, than those cylinders = not working.

I have always found some idiot simple mistake when I am 110% uuber sure of my self :P

last time I connected my Crank position sensor to oil level by accident and thought the DME was bad...

[MattM]

well, sounds like im going to pull my intake mani off tomorrow and go through everything! If all is good ill assume the ECU...

[bimmerteck]

Make sure the O2 sensors are installed into the correct banks. ;)

[etxxz]

1) ^^ yes.

2) my engine did that when i had huge vaccuum leaks. Try to rev it to keep it from dying, after a minute or so, does it idle steady? If so, you messed up some hoses, check all. specially those connected to the Idle control valve. Hell that could be the cause. BTW, if you're running obd2, you can't just get another ecu.. you'll need key and ewsII module as you probably already know.

3) Do you even get even firing or does it sound like a v-twin?

[luckysnafu]

Make sure the O2 sensors are installed into the correct banks. ;)

If he can read codes there would be multiple codes thrown for having the O2 sensors switched. I had that problem when I installed new ones. The car still ran/idled and drove, just not very well.