M30B35 engine problem.

Specific conversations and info for the BMW E28 M5 and M535i.
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magnustamm
Posts: 7
Joined: Feb 02, 2019 6:56 AM
Location: Estonia

M30B35 engine problem.

Post by magnustamm »

Hey I I have this kind of problem. Engine starts up good but it just revs up and down if i add throttle it revs faster but when it revs down it kind of just shuts down for a second and then revs up again. Here's also video about it.

https://www.youtube.com/watch?v=O-eNMNY ... e=youtu.be

I have cleaned all sparkplugs, ignition coil and distributor.
Preyupy
Posts: 231
Joined: Jun 21, 2012 12:48 AM
Location: Issaquah WA

Re: M30B35 engine problem.

Post by Preyupy »

It sounds like your ICV (idle control valve) is stuck open. It is trying to run the engine speed over 1350rpm. With the throttle closed ( Throttle Position Switch showing “closed throttle”) the ECU shuts off the injectors until the RPM drops below 1300 so the engine just cycles up and down.
magnustamm
Posts: 7
Joined: Feb 02, 2019 6:56 AM
Location: Estonia

Re: M30B35 engine problem.

Post by magnustamm »

Hey again. Well tested another ICV today still same problem. Could it be some kind of massive vacum leak? or i dunno. :(
Preyupy
Posts: 231
Joined: Jun 21, 2012 12:48 AM
Location: Issaquah WA

Re: M30B35 engine problem.

Post by Preyupy »

You could have an air leak somewhere. Try unplugging the TPS and see if it just revs up like you are holding the throttle open (be prepared to turn it off quickly if it starts to rev too high) at least this will tell you that the basic ECU is working correctly.
magnustamm
Posts: 7
Joined: Feb 02, 2019 6:56 AM
Location: Estonia

Re: M30B35 engine problem.

Post by magnustamm »

Yeah did this too. Nothing happened still reving up and down itself. i can rev it up higher but it has to be at the same time when itself revs up. when it revs back down then there is no throttle response and it feels like it cuts ignition for a second
Preyupy
Posts: 231
Joined: Jun 21, 2012 12:48 AM
Location: Issaquah WA

Re: M30B35 engine problem.

Post by Preyupy »

If you open the throttle by hand it runs ok? It really sounds like the Throttle position switch is telling the ECU the throttle is closed. It could just be the adjustment. You should be able to hear the switch click as soon as you move the throttle off the idle stop (AS in IMMEDIATLY!)
magnustamm
Posts: 7
Joined: Feb 02, 2019 6:56 AM
Location: Estonia

Re: M30B35 engine problem.

Post by magnustamm »

Right now I can't start it again because it's midnigt and my neighbour will kill me because I have no exhaust :D but I tried to listen this click and it clicks ill open tomorrow and look inside and clean it. what do you mean by hand? if u mean that I press that throttle link under hood by hand then no. Only this uper rev high point goes higher but nothing else. it still comes down from that.
magnustamm
Posts: 7
Joined: Feb 02, 2019 6:56 AM
Location: Estonia

Re: M30B35 engine problem.

Post by magnustamm »

Well here's a vol2

https://www.youtube.com/watch?v=YbJ-ER1 ... e=youtu.be

Right now it sounds like "inline 6 rotary engine" :laugh:
Preyupy
Posts: 231
Joined: Jun 21, 2012 12:48 AM
Location: Issaquah WA

Re: M30B35 engine problem.

Post by Preyupy »

Is your air flow meter hooked up? I could not see the connector in your video. With it torn apart that far there are at least 30 sensor, connectors and servos that should be checked. The fact that it is running at all is a good sign but it's probably just running in "limp home" mode because it is not getting all the information it needs.

Good luck, this is going to be a long electrical troubleshooting project. Do you have a copy of the ETM (electrical troubleshooting manual)? It is the best way to find all of the connections and sensors along with the wiring diagrams etc.
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