M119 injector pulse

[markland556]

I have been trying to get my 94’ 420-500 swap all wrapped up and am stuck with a horrible running condition. It’s running extremely rich, poor idle, undriveable. I’m looking for more information of what can influence the injector pulse cycle on these LH systems. I am running at about 4.2ms right now and should be somewhere in the 2.5 range if I’m correct. The MAF reads 30Kg at idle, saw another video of someone with a 500 that had the same readings so that seems to be ok, but have a used replacement on the way for further testing as new or rebuilt ones aren’t easy or cheap to come by.
Swapped LH modules between 4.2 and 5.0, exact same. Non asr car, throttle actuator tests good. It’s just got me stumped, hoping that someone that has dove into all the ins and outs of LH injection might have some tips.

 

[gsxr]

MAF reading at HOT idle should be closer to 20 kg/kr. It will read higher at cold start, 40-50 at first, gradually dropping as it warms up.

Injection time varies with load etc. Is it 4.2ms at hot idle? What EZL are you using and what LH module?

 

[markland556]

It’s 4.2 and idle and raises when revving. That’s cold or hot idle. The car runs extremely rich throughout the throttle range judging by the smell and tons of exhaust smoke.
I’m getting 30 no matter hot or cold, it does got up to 40-50 when I push the gas a bit. Running the 5.0 ezl from the w140 I got the engine from. I have both a 4.2 LH that came with the car and the 5.0 LH from the 140. No change with either. I don’t think I’ve tried the old 4.2 ezl.

 

[gsxr]

Something is wrong but I'm not sure what. The MAF readings are higher than normal. If you can source a known-good MAF, I'd swap that next. How about MAF readings at higher RPM's? When hot, a steady 2000rpm should be roughly 60kg/hr. You can also disconnect the MAF and see if the engine runs any better; it will go into a fail-safe mode and use intake pressure (from the EZL) to estimate airflow.

Tons of exhaust smoke isn't a good sign. Was the engine a known-good motor prior to installing?

 

[aliking]

yes the MAF reading is high, mine reads 30.8 and need replacement

 

[markland556]

Readings are high even with maf disconnected. The engine ran great from the donor car, it just had a cooked trans. Maybe I’ll have to look at intake pressure readings from the ezl. I can’t talk to it via sds, not sure if that’s normal or not for a 124, it’s been a while. I’ll give the 4.2 ezl a shot to see if anything changes. I’m interested to know how the LH determines the pulse width, assuming that’s an output value based on other readings and not a calculated value based on O2 readings as that just doesn’t make sense.

Appreciate the help. Man, I’ve got a w163 that’s pretty much got the same issue as this thing as well, supposedly a bad Ecu, second one fixed it for about an hour and I’m back to it dumping so much fuel it won’t even run 12ms pulses while cranking. Gave up on it yesterday and bought a 164 for the wifey.. smh