Riddle of the EF that wouldn't start
11-27-2010, 09:36 PM
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Riddle of the EF that wouldn't start
See if you can call this one, these forums were very helpful, but I didn't find the answer here. Here's what I was looking at:
Put a new motor in my CRX DX with MPFI swap (OBD0). The car had been running perfectly for some time until it threw a rod in the d15b2 mini-me, so I replaced it with standard d16a6 (no VTEC) running on a virgin PM6. The motor (d16a6) "supposedly" ran strong before it was pulled. After getting it in the car would fire and pop a couple times then nothing. If I turned off the fuel pump (have it wired to a kill switch) I could get it too run, albeit very poorly, for about five seconds or so. If I turned the fuel pump back on while it was running it would immediately flood out and die (all plugs wet).
ECU showed no codes
Fuel pump runs for two seconds when ignition turned on (normal)
Distributor and wires installed correctly (even tried another one, no change)
MPFI swap wiring is perfect (I checked it several times)
Main relay checks out fine
Swapped in two other PM6 ecu's (no change)
All plugs getting a spark
Compression measured at 170 to 195 in all cylinders
Fuel Pressure at measured at 41
ECAV checks out fine
IAT checks out fine
TW (coolant temp) checks out fine
TPS checks out fine
If both the IAT and TW are unplugged, the will start and not quite idle, but can be kept running by working the throttle. However, it runs terrible, with almost no throttle response and won't rev up much. The ECU shows the proper codes when those sensors are unplugged.
What do you think?
The car runs perfectly now with the same motor.
Put a new motor in my CRX DX with MPFI swap (OBD0). The car had been running perfectly for some time until it threw a rod in the d15b2 mini-me, so I replaced it with standard d16a6 (no VTEC) running on a virgin PM6. The motor (d16a6) "supposedly" ran strong before it was pulled. After getting it in the car would fire and pop a couple times then nothing. If I turned off the fuel pump (have it wired to a kill switch) I could get it too run, albeit very poorly, for about five seconds or so. If I turned the fuel pump back on while it was running it would immediately flood out and die (all plugs wet).
ECU showed no codes
Fuel pump runs for two seconds when ignition turned on (normal)
Distributor and wires installed correctly (even tried another one, no change)
MPFI swap wiring is perfect (I checked it several times)
Main relay checks out fine
Swapped in two other PM6 ecu's (no change)
All plugs getting a spark
Compression measured at 170 to 195 in all cylinders
Fuel Pressure at measured at 41
ECAV checks out fine
IAT checks out fine
TW (coolant temp) checks out fine
TPS checks out fine
If both the IAT and TW are unplugged, the will start and not quite idle, but can be kept running by working the throttle. However, it runs terrible, with almost no throttle response and won't rev up much. The ECU shows the proper codes when those sensors are unplugged.
What do you think?
The car runs perfectly now with the same motor.
12-01-2010, 08:13 AM
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Re: Riddle of the EF that wouldn't start
Turned out that the cam timing was way too advanced, maybe 50 degrees on the crank (25-30 on the cam).
I didn't take the timing belt covers off when the new motor was installed, so that wasn't a possibility I had considered. The flooding kept me thinking an electrical issue must have been messing up the ecu, and the compression readings led me to disregard the motor itself as the source of the problem. Now I realize that by disconnecting the IAT and TW sensors the ecu was retarding the timing enough that it could just barely be kept running.
Hope this helps somebody else in the future.
I didn't take the timing belt covers off when the new motor was installed, so that wasn't a possibility I had considered. The flooding kept me thinking an electrical issue must have been messing up the ecu, and the compression readings led me to disregard the motor itself as the source of the problem. Now I realize that by disconnecting the IAT and TW sensors the ecu was retarding the timing enough that it could just barely be kept running.
Hope this helps somebody else in the future.
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