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E21 (1975 - 1983)

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Old 08-28-2008, 09:39 PM
XJ Fanatic XJ Fanatic is offline
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Location: Allentown, PA
Join Date: Aug 2008
Posts: 14
Mein Auto: 84 318i
Some M10 and L-Jet questions

Alright so give me what you got...

Here's my problem (did some trouble searching today):

Start the 318 and have to hold the throttle about half way for 2-3 minutes until it warms up than it will idle but buck a bunch/be rough. Tap the throttle at this point and she stumbles ALOT. Get above about 2000 rpm and smooths out. Some times she won't start unless my foot is on the gas at WOT.

Vehicle is an 84 318i with an m10 and auto trans. 54,660 on the motor.

Battery charging good, grounds look good.

Plugs are new, gapped at .030, is this correct?

Cap/rotor look good along with the wires

ICV tests fine according to haynes manual, but is not operating and no power is going into the plug

Running rich, very rich, I feel this is related to a temp sensor but which one, could also be something to do with the cold injector, what is the best method of testing this?

MAF has been tinkered with in the car's past, anti tamper plug was drilled out to show screw

ICV was plugged originally when I started looking at it, its the only way of keeping the idle down currently.

What do each of the 3 temp sensors do, there are 2 with bosch rec plugs on them, 1 with 2 spade terminals

Does anyone know the fuel rating of the injectors, all 5, I ask because I have 6 good 19lb jeep injectors sitting on a fuel rail in my garage, same plug same size body as the bimmer's

Is there any way of testing the Idle control unit under the dash

What is this thermotimer and where is it located?

Where is the fuel filter located also.

I know I could eliminate the ICV entirely, but It gets cold during the winter and would rather not do this. Also I just got the car, and want to get it running good stock before I modify it.
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Old 09-25-2008, 06:47 AM
nich.j.anderson nich.j.anderson is offline
Bum Shop Rat
Location: Westminster, CO
Join Date: Sep 2008
Posts: 19
Mein Auto: MKIII Jetta VR6, E30 318i

You're probably the only other one with an '84 318i on here. I've been posting under E30, but it may make more sense to post under here. Anyways I've been working with the same problem. I've been able to get my hands on a 318i for cheap because of this same problem.

Only my ICV doesn't close, I think it sounds like yours is stuck closed. Anyways I only get to work on mine a couple hours a day at school, so I've been spending alot of time thinking about it.

I have a wiring diagram, and for the control units it says what signal each wire is for. So I'll list them off for you, they're given a number and a wire color, not sure if you can use that or not but I'll give it to you. I'll also give you the component that the signal/input/output comes from.

7 Blu-Yel Park/Neut IN if AT leaves diagram (into dash?), if MT goes to Vacuum Solenoid
2 Grn-Yel Power OUT Vacuum Advance Sol./vac advance cont. relay
10 Blu-Grn 32 degree temp IN Temp Switch (32 degree F)
12 Blu-Red Closed throttle IN Throttle Sw
3 Grn Engine RPM IN Goes to diagnostics connector the - side of coil
9 Blu-Wht A/C on INPUT Evap Temp Sw, and of diagram (think that means into dash)
11 Blu-Blk Comp on INPUT Low Press. Cutout Sw./Fuel shut off relay
6 Wht Cool Temp IN Coolant temp sw/sender
1 Blu-Red Idle speed cont. To Idle Speed Sol.
5 Blu-Wht Idle speed cont. From Idle Speed Sol.

My 318i was idling at 3k, so I plugged where the ICV goes, then it wouldn't idle on it's own. The timing was way off so it was hard to start. So I got a plumbing valve from homedepot, installed it in place of the ICV and started it with it open, then slowly closed it till it I had it idling at 1500, because of how advanced the timing was. Then backed off timing, till it smoothed out a bit, then I would lower the timing, then retard the timing, and back and forth till now it's idling perfect. Now that it's safely idling on it's own I'm able to let it warm up to see where the problem is.

The ICV valve closes when connected directly to power, so the valve is fine. But even after allowing the engine to there is no signal through the connector for the ICV which goes directly to the Idle Control Unit (which is under the dash above the glove box BTW). But I hear that it is very unlikely for the unit it's self to be faulty. Because I didn't want to let the car idle at 3000 rpm to warm up, especially after it's been sitting for a few years, I wasn't able to see that coolant temperature wasn't showing in the instrument cluster. Which is one of the signals that the Idle Control Unit acts off of. So I have a good feeling I've found my problem.

For you it sounds like the ICV might not open, may be timing, and fuel inj as well.

Good luck, I hope this helped in terms of Idle Control. Looking at diagram, the Injection Cont. Unit and the Idle Cont. Unit both share the throttle switch. Make sure it knows that the throttle's closed. Because I would think that it would close the valve if you were giving it gas, also if the Injection Cont. Unit thought you were giving it throttle, it would give the injectors more gas, but if the throttles not really open at all that would make the mixture rich. If your Idle Cont. Valve isn't receiving signal then it should be idling like crazy, like 2000-3000 rpm. The Cold Start Valve could be it too, which would be related to the thermo time switch. Which is "on top of thermostat housing, at front of engine".

Hope this helps,

Yo, my name's Nick
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Old 09-25-2008, 06:48 AM
nich.j.anderson nich.j.anderson is offline
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Location: Westminster, CO
Join Date: Sep 2008
Posts: 19
Mein Auto: MKIII Jetta VR6, E30 318i
Fuel filter is under Fuse/Relay Box, I believe
Yo, my name's Nick
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