1 Still have problems. FI idle issues Fri Mar 10, 2017 3:04 pm
Bekman
Silver member
Hi everyone,
Here is a link to a vid of my idle issues.
https://youtu.be/knJWesu7u6g
Here is what I have checked:
1985 BMW K100
Valves are in spec
Compression is in spec
All electrical connections have been cleaned and dielectric grass applied
New spark plugs
No air leaks, I had previous found a leak in the throttle shafts and replaced the throttle bodies (off a known running bike with steady idle and still has the blue marking on throttle linkage) and also new rubber and also sealed the harder rubber plastic intake to the manifold with Honda bond semi drying.
The fuel injectors were professionally cleaned and new o rings installed.
Hall sensors working fine.
Fuel pressure tested good on both lines as per spec
I have also replaced the coolant sensor with a used one. This helped the situation out to where you now see where I am at in the. Idea.
Now when I was trying to see if the coolant temp sensor was an issue, I unplugged the plug to the sensor that's screwed into the engine. I then plugged in the other coolant sensor while the engine was running. I had it grounded with an alligator clip. Now when it was running and I would ground the clip to the sensor the rpms would rise sometimes up to 3k. If I grounded the sensor directly to the engine the same thing would occur.
I have one question that I could simply answer but it's snowing today here in NY. I swapped out the sensors and when taking the one sensor out not a lot of coolant came out. So at the moment I'm thinking that the idle is hunting around as a result of not enough coolant in the engine so that when the coolant which is a different temp hits the sensor it's sending the correct info to the computer and then immediately sending the wrong info when the coolant isn't surrounding the sensor. Either that or I have some sort of issue with the wiring going to the computer.
I know the afm could be an issue along with the computer itself but I also have replaced the engine (compression was low on the original engine and was cheaper to buy one with good valve clearance and compression than having the heads done. Orig engine had 95k on it. It didn't look like I could get a 3 angle grind on the valves themselves and they are quite expensive.) When I originally started the new used engine for the first time it idled perfectly. This was also done with no coolant in the system at all. Just to see if it would fire up. The old engine had the same problems with idling as the new one has now so it definitely seems to be electrical.
Im wondering if fixing the vacuum leaks fixed all the original problems and it's just the coolant problem now. I'm going to try and check a little later in the day as it's an easy thing to do but I just want to start my own thread and have everything clearly stated as this has been a problem the entire time of owning the bike since August.
Thanks for your help,
James
Here is a link to a vid of my idle issues.
https://youtu.be/knJWesu7u6g
Here is what I have checked:
1985 BMW K100
Valves are in spec
Compression is in spec
All electrical connections have been cleaned and dielectric grass applied
New spark plugs
No air leaks, I had previous found a leak in the throttle shafts and replaced the throttle bodies (off a known running bike with steady idle and still has the blue marking on throttle linkage) and also new rubber and also sealed the harder rubber plastic intake to the manifold with Honda bond semi drying.
The fuel injectors were professionally cleaned and new o rings installed.
Hall sensors working fine.
Fuel pressure tested good on both lines as per spec
I have also replaced the coolant sensor with a used one. This helped the situation out to where you now see where I am at in the. Idea.
Now when I was trying to see if the coolant temp sensor was an issue, I unplugged the plug to the sensor that's screwed into the engine. I then plugged in the other coolant sensor while the engine was running. I had it grounded with an alligator clip. Now when it was running and I would ground the clip to the sensor the rpms would rise sometimes up to 3k. If I grounded the sensor directly to the engine the same thing would occur.
I have one question that I could simply answer but it's snowing today here in NY. I swapped out the sensors and when taking the one sensor out not a lot of coolant came out. So at the moment I'm thinking that the idle is hunting around as a result of not enough coolant in the engine so that when the coolant which is a different temp hits the sensor it's sending the correct info to the computer and then immediately sending the wrong info when the coolant isn't surrounding the sensor. Either that or I have some sort of issue with the wiring going to the computer.
I know the afm could be an issue along with the computer itself but I also have replaced the engine (compression was low on the original engine and was cheaper to buy one with good valve clearance and compression than having the heads done. Orig engine had 95k on it. It didn't look like I could get a 3 angle grind on the valves themselves and they are quite expensive.) When I originally started the new used engine for the first time it idled perfectly. This was also done with no coolant in the system at all. Just to see if it would fire up. The old engine had the same problems with idling as the new one has now so it definitely seems to be electrical.
Im wondering if fixing the vacuum leaks fixed all the original problems and it's just the coolant problem now. I'm going to try and check a little later in the day as it's an easy thing to do but I just want to start my own thread and have everything clearly stated as this has been a problem the entire time of owning the bike since August.
Thanks for your help,
James