A Little Idle problem solved

[320iAman]

My idle was dropping below specifications and holding, after checking a few items I figured out it was related to the Frequency Modulation Valve (FMV) not making adjustments, I checked out the usual items ,connections to the relays in the relay block, relays, O2 sensor and so forth and these were all good. I then checked the G1 and G2 Grounds of the ECU, these brown wires have ring terminals on the ends and are grounded to the motor and cylinder head thru an M6 x 50mm Bolt securing the Distributor Flange to the cylinder head and which houses the Distributor and oil pressure device. Upon looking closely I found there was motor oil that had seeped thru , I cleaned this off and the ECU system started up and idle went back to normal. Oil is an insulator and a good conductor of heat and bad conductor of electricity. To keep the oil from running down the threads and interfering with the G1 and G2 Grounds of the ECU I lightly coated the threads with Permatex High Tack # 80062--good too 500 F and not expensive.

Randy

[320iAman]

I may move G1 and G2 from the Distributor Flange to the firewall where there is no heat or oil seepage chances, it was commented on early on in the run stage that heat from the cylinder head eventually will make the insulation on the G1 and G2 - ECU ground wires brittle, another discussion, yet , this is true of all wires connected to the engine as well. The Ve for all intensive purposes is the same secured to the firewall or the Distributor Flange. Its an item that needs periodic inspection and cleanup ,ect if necessary, if G1 and G2 is left in the OEM Place.

Randy

[320iAman]

I decided to transfer G1 and G2 to the firewall. I cut the terminal ends with some to spare and put in two extension wires with splice connectors,extension wires same mm diameter as original and attached G1 and G2 to the firewall. No more potential issues of motor oil seepage or heat. With car semi warmed up-off cold start circuit-the idle dropped down and the FMV kicked in and took the idle back up to specifications, at this point my was idle was seeking, O2 Sensor Cycling or Fast Temporary Enriching then Leaning. At full warm up, the idle is more stable and this is where I set idle to curb idle speed for the MT.

Randy

[epmedia]

Great info Randy. I don't know why bmw chose to put those grounds there! They should have known better, because eventual oil leaks... On the 2.0 m10, there's a ground bundle that can attach to the oil dipstick tube. lol

[320iAman]

Robert , I dont know either , looking forward I'm glad I got them on the firewall now and took out the problems of oil seepage down the bolt effecting the ecu grounds,,, clean grounds everywhere is a plus and a must. The problems that can arise can mask this issue until all else is good, that is how I found it.

Randy

[320iAman]

Here is G1 and G2 ECU grounds relocated to the firewall to eliminate any motor oil getting on them and interfering with ECU operations. The Heat shrink secured in white clips obscures seeing G1 and G2.
DSCI0318.JPG

Randy