I've got an '87 TBI setup, previous owner has removed pretty much all the smog stuff and put a new exhaust setup without a catalytic converter. I know this engine is not in fantastic shape, and I know it's always going to reek a bit like gas without a catalytic converter, but I'm hoping I can at least try and do something to get it to waste a little less fuel.
I spent 10 minutes or so driving around the neighborhood while logging with WinALDL. The tables aren't very populated, so I might make another run at it later.
Looking at the tables, it looks like the BLM is set to run rich? The O2 sensor voltages seem to be about where they ought to be for a good AFR, but it's definitely running rich, so maybe I've got a bad O2?
I put all the log data and tables in the excel sheet, BLM and O2 are there as text files.
I'd really appreciate any insight into what I might be able to do to try and get this engine running a bit better. Also, I ought to mention, at some point during the drive, it seems like the IAC valve pegged open, and when I put it in park in my driveway, it was idling at almost 2000 RPM. Never had this happen before, wondering if its related to being in ALDL mode? Everything seemed fine after I restarted the engine.
Thanks!
Ben
I spent 10 minutes or so driving around the neighborhood while logging with WinALDL. The tables aren't very populated, so I might make another run at it later.
Looking at the tables, it looks like the BLM is set to run rich? The O2 sensor voltages seem to be about where they ought to be for a good AFR, but it's definitely running rich, so maybe I've got a bad O2?
I put all the log data and tables in the excel sheet, BLM and O2 are there as text files.
I'd really appreciate any insight into what I might be able to do to try and get this engine running a bit better. Also, I ought to mention, at some point during the drive, it seems like the IAC valve pegged open, and when I put it in park in my driveway, it was idling at almost 2000 RPM. Never had this happen before, wondering if its related to being in ALDL mode? Everything seemed fine after I restarted the engine.
Thanks!
Ben
Moderator
Shorting or using a 10K resistor across A & B of the ALDL connector will change how the engine runs. A higher idle is one affect. No need to short or use a resistor to data log.
The BLMs are way too high, fuel pressure could be low or the O2 sensor is cold.
RBob.
The BLMs are way too high, fuel pressure could be low or the O2 sensor is cold.
RBob.
This is the L05 with the 1227747 ECM, and I get nothing via ALDL without the 10k resistor.
I'll check the fuel pressure. As for the O2 sensor, I had given it plenty of time to warm up. Does the 10k mode prevent the engine from going into closed loop? Would that effect the BLM readings?
I do think it's possible I've got an issue regarding fuel pressure, as startup cranking it's longer than it should be, and I get a loud ticking sound from the throttle body relative to rpm, that can be heard in the cab. I replaced the FPR when I rebuilt the throttle body, maybe I botched the install somehow.
Thanks
I'll check the fuel pressure. As for the O2 sensor, I had given it plenty of time to warm up. Does the 10k mode prevent the engine from going into closed loop? Would that effect the BLM readings?
I do think it's possible I've got an issue regarding fuel pressure, as startup cranking it's longer than it should be, and I get a loud ticking sound from the throttle body relative to rpm, that can be heard in the cab. I replaced the FPR when I rebuilt the throttle body, maybe I botched the install somehow.
Thanks
Moderator
The ALDL stream on the '7747 ECM is always transmitting, if a 10K resistor is required then something is wrong.
RBob.
RBob.