New member, long time lurker. I know this is a pretty common issue as I've done a lot of searching on the topic and can't find quite this specific case. I've also read up in the Bentley manual on this issue as well. My 87 325e has always "almost" died after cold starting for the past month or so that I've owned it. However, it's always caught- just barely- but it has. Once it catches, it smoothly idles. The sequence is Cranks > Starts right up > RPMS dip way low > idles smoothly. The idle got a little funky when warm, gently wandering between 700 and 900 or so RPM, so I thought I'd clean out the ICV (idled generally dead steady when cold).
So, I removed the ICV, blasted the inside of the valve in both openings with throttle body cleaner, causing a lot of crap to come out of it. Reinstalled, and immediately had the starts-then-dies syndrome. Cranks for about 2 seconds, fires right up, dies. After about 3 tries, it fires right up, almost dies, then catches and it's good to go. I figured at the time that the ICV was just sorting itself out and that it was a one time thing.
After that I did some other maintenance- replaced the air filter, removed the elbow feeding the throttle body and cleaned the throttle butterfly with TB cleaner, removing some deposits there as well. Re-assembled everything and took it for a drive. The car now idles and runs better than ever. Smooth as could be, dead steady, pulls all the way to redline smoothly. No more wandering idle problem. But, now I have this cold start-then-die issue. Here is what I'm thinking on this:
- Could have not tightened a hose properly on the intake side of things. Possible, but why would it idle and run so rock-steady? Why would it start OK when warm (although it does almost die when warm, just not as bad)
- Could be the fuel pump relay shutting off power because the computer is not telling it the engine is running or the relay is bad- but why would it start fine warm? Could the relay have a personality?
- In disassembling the intake system, could I have bumped or disturbed the MAF in some way? Ill check the flap on it but again, why does it run fine otherwise if that's the case?
- Could I have killed the ICV? If so why does it idle better than ever once it starts?
- Could I have eliminated a vacuum leak somewhere only to now highlight another one? Like plugging one hole in a dam only to have another now show itself? If so, again, why smooth idling and running otherwise?
Troubleshooting-wise could I jump the fuel pump relay and start it with a jumper in place or is that a no-no? I guess that would rule out the relay right away.
So, I removed the ICV, blasted the inside of the valve in both openings with throttle body cleaner, causing a lot of crap to come out of it. Reinstalled, and immediately had the starts-then-dies syndrome. Cranks for about 2 seconds, fires right up, dies. After about 3 tries, it fires right up, almost dies, then catches and it's good to go. I figured at the time that the ICV was just sorting itself out and that it was a one time thing.
After that I did some other maintenance- replaced the air filter, removed the elbow feeding the throttle body and cleaned the throttle butterfly with TB cleaner, removing some deposits there as well. Re-assembled everything and took it for a drive. The car now idles and runs better than ever. Smooth as could be, dead steady, pulls all the way to redline smoothly. No more wandering idle problem. But, now I have this cold start-then-die issue. Here is what I'm thinking on this:
- Could have not tightened a hose properly on the intake side of things. Possible, but why would it idle and run so rock-steady? Why would it start OK when warm (although it does almost die when warm, just not as bad)
- Could be the fuel pump relay shutting off power because the computer is not telling it the engine is running or the relay is bad- but why would it start fine warm? Could the relay have a personality?
- In disassembling the intake system, could I have bumped or disturbed the MAF in some way? Ill check the flap on it but again, why does it run fine otherwise if that's the case?
- Could I have killed the ICV? If so why does it idle better than ever once it starts?
- Could I have eliminated a vacuum leak somewhere only to now highlight another one? Like plugging one hole in a dam only to have another now show itself? If so, again, why smooth idling and running otherwise?
Troubleshooting-wise could I jump the fuel pump relay and start it with a jumper in place or is that a no-no? I guess that would rule out the relay right away.
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