Hi folks,
So I've got an '88 325is that has had a lot of stuff addressed under my ownership but the thing's had an extended crank since before I bought it and still does despite a bunch of other stuff being addressed along the way of other repairs and general maintenance, catching the ol' girl back up on a few decades of neglect. 114k mi when bought, pushing 120k mi now (I don't drive as often as most people but when I do I like it to be in something that sparks joy). It'll start up pretty reliably but when it's the first start of a day or in some hours it tends to be somewhat reluctant.
Here's what's been done that's at all potentially relevant to this problem and skipping over not-motor-related stuff, all done either because I knew of the issue ahead of time (head decking, etc) or the parts were just cooked and in need of replacement.
'20:
-Timing belt, water pump (PO did this, I have receipts and paperwork)
-Head decked by reputable machine shop, head gasket, valve stem seals
-Coolant
-New fuel lines and a bunch of vacuum hoses
-Fuel filter
-Fuel pump
-Crank position sensor (original soaked in oil)
-Distributor cap
-New ignition hardware (spark leads, distributor cap)
-Spark plugs
-Oil
-Blue temp plug
'21:
-New AFM to throttle assembly boot
-Viscous fan clutch (original died on me, thankfully in december)
-Thermostat (twice, first was a dud part)
-Battery (old one went toast during pandemic, whoops)
'22
-Valve cover and oil pan gaskets (leaky!)
-Ignition switch (old one went bad on me)
-Smoke test (returned no vacuum leaks)
-Compression and leakdown test (strong on all cylinders, within spec)
-Oil changed w/gaskets
-Cleaned brown plug
'23
-Valve adjustment (was slightly out of spec on 2 cylinders)
-New TPS (found that old one busted for WOT position)
-Cleaned C191 plug, no corrosion visible
-Coolant flush (again, on schedule)
-Ran fuel system cleaner through
-New starter (below is why)
After about two years of ownership last fall the starter motor started to shit itself when particularly warm but would then start again if left to cool off for a while, and then later gave out entirely. With the new starter it has never failed to start in the time since (better part of a year). However, it still has an extended crank when cold (say, 3-5 seconds, depending on ambient temperature). That said, it's returned no vacuum leaks, good compression, fuel pressure is in spec when tested, my ignition hardware's still good, my starter and ignition switch and fuel pump are all relatively fresh. The only two things I can think of that might be causing this are the injectors losing pressure when sitting or the ECU being confused by something - I didn't have any luck doing a stomp test, but when I finish up some other unrelated work on the car tomorrow I'll check if my 12/87 production car has a 1.3 or 1.7 motronic ECU to see if that'll explain that given I already replaced the TPS (apparently a bad TPS can cause the stomp test to not work). I don't think it's the fuel pressure regulator as the pressure is in spec, and I'd rather not toss one at it without being pretty sure, and that's about the only part in the fuel system aside from the rail and injectors that hasn't yet been replaced. It did get noticeably better when the head stuff was done in '20, it had a loooooooong crank then, but it's still not as quick as a lot of healthy M20s I've seen video of cold starting.
Any suggestions on what this issue could be? It's relatively inconsequential given that she starts right up warm, idles smooth and in spec, and with the starter fixed I've never been stranded anywhere since, but my sense of being a completionist nitpick is nagging at me to deal with it once and for all.
So I've got an '88 325is that has had a lot of stuff addressed under my ownership but the thing's had an extended crank since before I bought it and still does despite a bunch of other stuff being addressed along the way of other repairs and general maintenance, catching the ol' girl back up on a few decades of neglect. 114k mi when bought, pushing 120k mi now (I don't drive as often as most people but when I do I like it to be in something that sparks joy). It'll start up pretty reliably but when it's the first start of a day or in some hours it tends to be somewhat reluctant.
Here's what's been done that's at all potentially relevant to this problem and skipping over not-motor-related stuff, all done either because I knew of the issue ahead of time (head decking, etc) or the parts were just cooked and in need of replacement.
'20:
-Timing belt, water pump (PO did this, I have receipts and paperwork)
-Head decked by reputable machine shop, head gasket, valve stem seals
-Coolant
-New fuel lines and a bunch of vacuum hoses
-Fuel filter
-Fuel pump
-Crank position sensor (original soaked in oil)
-Distributor cap
-New ignition hardware (spark leads, distributor cap)
-Spark plugs
-Oil
-Blue temp plug
'21:
-New AFM to throttle assembly boot
-Viscous fan clutch (original died on me, thankfully in december)
-Thermostat (twice, first was a dud part)
-Battery (old one went toast during pandemic, whoops)
'22
-Valve cover and oil pan gaskets (leaky!)
-Ignition switch (old one went bad on me)
-Smoke test (returned no vacuum leaks)
-Compression and leakdown test (strong on all cylinders, within spec)
-Oil changed w/gaskets
-Cleaned brown plug
'23
-Valve adjustment (was slightly out of spec on 2 cylinders)
-New TPS (found that old one busted for WOT position)
-Cleaned C191 plug, no corrosion visible
-Coolant flush (again, on schedule)
-Ran fuel system cleaner through
-New starter (below is why)
After about two years of ownership last fall the starter motor started to shit itself when particularly warm but would then start again if left to cool off for a while, and then later gave out entirely. With the new starter it has never failed to start in the time since (better part of a year). However, it still has an extended crank when cold (say, 3-5 seconds, depending on ambient temperature). That said, it's returned no vacuum leaks, good compression, fuel pressure is in spec when tested, my ignition hardware's still good, my starter and ignition switch and fuel pump are all relatively fresh. The only two things I can think of that might be causing this are the injectors losing pressure when sitting or the ECU being confused by something - I didn't have any luck doing a stomp test, but when I finish up some other unrelated work on the car tomorrow I'll check if my 12/87 production car has a 1.3 or 1.7 motronic ECU to see if that'll explain that given I already replaced the TPS (apparently a bad TPS can cause the stomp test to not work). I don't think it's the fuel pressure regulator as the pressure is in spec, and I'd rather not toss one at it without being pretty sure, and that's about the only part in the fuel system aside from the rail and injectors that hasn't yet been replaced. It did get noticeably better when the head stuff was done in '20, it had a loooooooong crank then, but it's still not as quick as a lot of healthy M20s I've seen video of cold starting.
Any suggestions on what this issue could be? It's relatively inconsequential given that she starts right up warm, idles smooth and in spec, and with the starter fixed I've never been stranded anywhere since, but my sense of being a completionist nitpick is nagging at me to deal with it once and for all.
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