I have an 02/1988 325i cabrio in that needed an engine replacement. I changed it with a known good engine out of a parts car that I had, an 01/1988 325is. The engine ran spectacular when pulled, with no issues or other funny business.
I installed the engine and got it running. Immediately, I knew something was up. It hardly ran on its own. After some quick diagnostic work, I realized cylinders 1 and 6 had no fuel being delivered to the chamber. After swapping the fuel rail w/ injectors and pressure regulator, off the old engine, the idle smoothed out and it was firing on all six, as it should. I hooked up the AFM and went to to take it out for a test drive. It was then, that I fired it up and it promptly died. It wouldn't run with the AFM plugged in. It also won't rev past 1/8 throttle. It backfires through the intake (anything past 1/8 or 1/4 throttle) and bogs down, to the point of being undrivable, obviously.
Here's what I've done.
-new set of Bosch 7909 (WR8LC) to replace the platinum plugs someone installed. No change.
-swapped AFM from a known good, running vehicle. No change.
-unplugged TPS, CTS (blue), ICV and 02 sensor. No change in idle or rev-ability.
-tested fuel pressure (at the rail) and it is within spec. 48lbs with vacuum hose unplugged, 43lbs with hose plugged in, and promptly increases to 50lbs when opening the throttle, with the hose connected (pressure goes up, even when backfiring, so I can say it isn't a fuel delivery issue).
-smoke tested, no leaks anywhere.
-swapped distributor cap/wires, no change.
-new CPS, no change.
-swapped front crank pulley, no change.
-tried a 380 DME from a known good, running vehicle, no change.
-inspected fuel injector harness and its connector, no issues, applied some dielectric grease. No change.
I'm close to out of options. My next project will be assuming it has a faulty engine wiring harness, at this point, but I don't really want to change it, just for the sake of changing it.
Any advice or suggestions would be much appreciated.
Austin
I installed the engine and got it running. Immediately, I knew something was up. It hardly ran on its own. After some quick diagnostic work, I realized cylinders 1 and 6 had no fuel being delivered to the chamber. After swapping the fuel rail w/ injectors and pressure regulator, off the old engine, the idle smoothed out and it was firing on all six, as it should. I hooked up the AFM and went to to take it out for a test drive. It was then, that I fired it up and it promptly died. It wouldn't run with the AFM plugged in. It also won't rev past 1/8 throttle. It backfires through the intake (anything past 1/8 or 1/4 throttle) and bogs down, to the point of being undrivable, obviously.
Here's what I've done.
-new set of Bosch 7909 (WR8LC) to replace the platinum plugs someone installed. No change.
-swapped AFM from a known good, running vehicle. No change.
-unplugged TPS, CTS (blue), ICV and 02 sensor. No change in idle or rev-ability.
-tested fuel pressure (at the rail) and it is within spec. 48lbs with vacuum hose unplugged, 43lbs with hose plugged in, and promptly increases to 50lbs when opening the throttle, with the hose connected (pressure goes up, even when backfiring, so I can say it isn't a fuel delivery issue).
-smoke tested, no leaks anywhere.
-swapped distributor cap/wires, no change.
-new CPS, no change.
-swapped front crank pulley, no change.
-tried a 380 DME from a known good, running vehicle, no change.
-inspected fuel injector harness and its connector, no issues, applied some dielectric grease. No change.
I'm close to out of options. My next project will be assuming it has a faulty engine wiring harness, at this point, but I don't really want to change it, just for the sake of changing it.
Any advice or suggestions would be much appreciated.
Austin
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