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E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 12-03-2013, 10:27 AM
tred421 tred421 is offline
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Question Rough Idle, Running Rich

Hey all, my son and I bought an '86 325es, rebuilt the top end, put it all back together and it runs, mechanically, but not well.

We have tried the following:
1. Tested the ICV for humming, tried adjusting the idle screw. Unplugging makes the engine rev higher, plugging in revs lower, with a miss.
2. Pulled the AFM, ohm test shows potentiometer still works. Unplugging the lead makes engine run very smooth, but after 30 secs engine stalls out. Can't give any gas while lead is off or engine stalls out.
3. Checked all fuses.
4. Verified O2 sensor and water temp sensor in place and connected, but not sure how to test for failure of these sensors.
5. Did driveway vacuum test (with brake cleaner) to look for vacuum leaks. None glaring.

General description of issue: Car will start better when cold, idle lopes as if camming. When warm will not start without giving gas. Under load (when rolling) acceleration ramps up strong under slow accel, but fast accel (punching it) causes engine to stall and sputter. Unplugging AFM cold or hot causes smooth idle, but is undriveable and engine stalls after about 30 secs. When all sensors are in place, runs rich with black smoke from exhaust, loping idle, intermittent acceleration.

Any more ideas of things we can look at in the driveway? We've come so far to be plagued by something that seems simple enough. The car did not act this way before rebuild began.

Thanks!
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  #2  
Old 12-03-2013, 10:39 AM
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hornhospital hornhospital is offline
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Try unplugging the vacuum line from the fuel pressure regulator (and cover the end of the hose to keep from creating a vacuum leak) while it's running. If it makes no difference, the FPR is toast. Disconnecting the vacuum line should default the FPR to full pressure, which at idle is too much, and will cause rich running, which is what sounds like the condition you have.
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  #3  
Old 12-03-2013, 10:45 AM
tred421 tred421 is offline
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Quote:
Originally Posted by hornhospital View Post
Try unplugging the vacuum line from the fuel pressure regulator (and cover the end of the hose to keep from creating a vacuum leak) while it's running. If it makes no difference, the FPR is toast. Disconnecting the vacuum line should default the FPR to full pressure, which at idle is too much, and will cause rich running, which is what sounds like the condition you have.
Thanks, will try this tonight and update!
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  #4  
Old 12-03-2013, 08:53 PM
tred421 tred421 is offline
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Welp, it looks like we are going to replace the FPR...the only change that took place is when we let the vacuum leak happen on the other end...which actually made it run better. More air...so it is def running rich. Didn't notice a change between vacuum line on, or off.
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  #5  
Old 12-15-2013, 08:21 AM
tred421 tred421 is offline
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Replaced the FPR, brand new, same issue. Now that's not a suspect, should we look at the ICV? Any other ideas?
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  #6  
Old 12-15-2013, 09:26 AM
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downhiller downhiller is online now
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what does the idle do when the engine is warmed up
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  #7  
Old 12-15-2013, 11:56 AM
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hornhospital hornhospital is offline
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Quote:
Originally Posted by tred421 View Post
Replaced the FPR, brand new, same issue. Now that's not a suspect, should we look at the ICV? Any other ideas?
Are you sure the vacuum line to the FPR is good?
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1995 318is "Bebe"; 1993 325is "Elvira" 1985 635CSi "Katja" 1984 633CSi "Sylvia"
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  #8  
Old 12-15-2013, 01:29 PM
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Is your cold start valve working?If it's staying on or leaking it will cause a rich condition.Also you need to adjust they ICV with the proper procedure or it won't work you can't just turn the screw and hope you get it to idle right.As a matter of fact if you've done that you may have damaged the ICV.(they're really touchy)
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  #9  
Old 12-15-2013, 03:08 PM
tred421 tred421 is offline
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Quote:
Originally Posted by downhiller View Post
what does the idle do when the engine is warmed up
It dies when warm, doesn't want to run at all. Runs rich all the time. Lopes when cold, dies when warm unless gas is given, then the missing starts.
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  #10  
Old 12-15-2013, 03:10 PM
tred421 tred421 is offline
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Originally Posted by toybuilder View Post
Is your cold start valve working?If it's staying on or leaking it will cause a rich condition.Also you need to adjust they ICV with the proper procedure or it won't work you can't just turn the screw and hope you get it to idle right.As a matter of fact if you've done that you may have damaged the ICV.(they're really touchy)
My son did indeed move the ICV. So, there's a process for setting it? I'll look around. We are just learning about these m20's...learning quickly. Thanks!
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  #11  
Old 12-15-2013, 11:09 PM
Billwill Billwill is offline
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Is the Throttle Position Switch (TPS) working properly.

It sits under the throttle body and should "click" when the throttle is relaxed...if not then check throttle cable tenshion and that the (factory set) screw that sets the throttle butterfly gap to throttle has not been turned in. This switch should be tested at the ECU connector to check that it is electrically working.

The Blue sensor may be faulty so the ECU is not recognising the engine temperature correctly.....this should also be measured at the ECU connector; about 3,000 Ohms when cold and about 300 Ohms when hot.

Check the CPS lead is not shorting somewhere after replacing the head.
You sure the valve cover is not leaking air?

You sure the timing belt tenshion and timing is correct?...I do not know the 325Es so do not even know if it has a timing belt...they were never sold here in SA!

Last edited by Billwill; 12-15-2013 at 11:16 PM.
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  #12  
Old 12-15-2013, 11:09 PM
Billwill Billwill is offline
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Double post...nothing to see here

Last edited by Billwill; 12-15-2013 at 11:15 PM.
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  #13  
Old 12-16-2013, 02:28 AM
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OK so this is the basic procedure for ICV adjustment if this doesn't work it's fun with the Idle Control Module next,LOL.I found this already written at Ted's Bimmer Page and made a few alterations to the text where I thought it need it but it should get you through. The diagnoses below don't all make sense unless you follow the steps in the sequence shown.


1) Turn the ignition key to run position, but don't start the car. You should hear quiet buzzing sound from the ICV, and if you touch it with your fingers, a vibration. If not, either the ICV is bad or there is no control current.

2) Start the car. Run the system "open loop" by pulling the electrical connector from the ICV. The RPM's should climb to about 1500-2000, and then oscillate back and forth between about 600-1500rpm. If reconnecting the electrical connector has no effect on RPM's, your ICM (idle control module) is probably at fault. Your RPM's fluctuate because when the ICV is disconnected, the valve is stuck wide open, and the ECU is the only thing controlling your idle. The RPM's rise until it cuts the fuel flow, which causes RPM's to dip. Then it restores fuel flow, and the cycle begins again.

3) Cut the motor. Pull the electrical connector from the ICV and connect an ohmmeter across the terminals. The reading should be about 9-10 ohms at temp 73+-9F(23+-5C). If you get an open circuit, it's time for a new ICV. If the resistance is much lower, you've got a short, and your ICM may be roached too, from the resultant excessive current draw.

4) Disconnect the ICV hoses, and look into the outlet. Obtain jumpers and connect 12V across the ICV terminals. The valve should close tightly when voltage is applied, and open strongly when the voltage is removed. If there is no movement or the is sluggish, movement your ICV is bad.

5) Plug in the ICV electrical connector and turn on the ignition (engine not running!), all accessories turned off. Looking into the outlet again, the valve should be partly closed. If the valve is wide open and there is no vibration, you aren't getting any control current. To verify, unplug the ICV connector, and verify that you're getting voltage across it. If there's no voltage, your ICM is at fault.

6) Reconnect the ICV hoses and electrical connector. Hook up an ammeter in series the ICV. W/ the engine fully warmed up and idling w/ all accessories turned off, the current should be between 400-500 mA. If the current is wrong, adjust the ICV current. Turn the adjusting screw until you get 460+-10 mA at 700+-50 rpm. I posted this before and I think the last guy committed HariKari after reading it so don't despair you can always buy a new one or a good used one there kinda pricey .From your description I suspect it might be your idle control module ,I'll find the test procedure for it and post it latter.

Last edited by toybuilder; 12-16-2013 at 02:34 AM.
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  #14  
Old 12-16-2013, 10:29 AM
tred421 tred421 is offline
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Will check out all of these first good weather...and update. Thanks all for the next steps, sometimes that's enough to keep going and not stare at it from the window.

With that said: the top end was replaced, and timing was done meticulously, as far as my talent goes. The timing belt was placed with both indicators at top dead zero, turned by hand two full rotations and checked again. It has not been checked since the motor was first fired.

Another clue...when I pull the lead from the MAF sensor, the car idles at about 1100 rpm, like a top; for 30 secs...then dies.
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  #15  
Old 12-16-2013, 10:33 AM
tred421 tred421 is offline
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Quote:
Originally Posted by Billwill View Post

Check the CPS lead is not shorting somewhere after replacing the head.
You sure the valve cover is not leaking air?
Brand new valve gasket, torqued to specs, but pretty sure we're ok on the valve cover. Wouldn't that make it run lean? Or would that throw off the TPS causing it to add more fuel?
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  #16  
Old 12-16-2013, 10:36 AM
tred421 tred421 is offline
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Quote:
Originally Posted by hornhospital View Post
Are you sure the vacuum line to the FPR is good?
Yes, brand new line installed, with new clamps.
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  #17  
Old 12-16-2013, 11:09 AM
tred421 tred421 is offline
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Found this page, got a lot of shooting to do, but might save some time in the end. Now I know what "Ted's page" is toybuilder! hehe

Last edited by tred421; 12-16-2013 at 11:23 AM.
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  #18  
Old 12-16-2013, 03:26 PM
tred421 tred421 is offline
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Ok...so...

1) Turn the ignition key to run position, but don't start the car. You should hear quiet buzzing sound from the ICV, and if you touch it with your fingers, a vibration. If not, either the ICV is bad or there is no control current. Got buzzing. Found the ICM, but just found it at this point, no tests done.

2) Start the car. Run the system "open loop" by pulling the electrical connector from the ICV. The RPM's should climb to about 1500-2000, and then oscillate back and forth between about 600-1500rpm. If reconnecting the electrical connector has no effect on RPM's, your ICM (idle control module) is probably at fault. Your RPM's fluctuate because when the ICV is disconnected, the valve is stuck wide open, and the ECU is the only thing controlling your idle. The RPM's rise until it cuts the fuel flow, which causes RPM's to dip. Then it restores fuel flow, and the cycle begins again.Unplugged the ICV and let the engine warm a bit...idle going from 1200 to 2K...plugged it back in and I kid you NOT, the car started running like a top!!

I must've had something stuck in the ICV, or thereabouts...because just testing fixed the issue!! We've been driving for 30 mins, no issues!!
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Old 12-17-2013, 08:06 AM
tred421 tred421 is offline
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A summary of what was really done:

New plugs, new FPR, refurb rebuilt top-end, new timing belt, new water pump, refurb master cylinder, new gaskets, fresh fluids.

To get the car running right...in addition to getting lucky, I changed the position of two sensor plugs over the water pump. My son had inverted them somehow...we matched them up as one has only one pin and the other has two pins. Unplugging the ICV and plugging it back in changed something in the fuel delivery, after plugging back in...runs like a champ, pulls strong, idles smooth.

Thanks all for the ideas and help, I've learned so much in the past few months, and my son and I will have a strong car to build on.
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  #20  
Old 12-17-2013, 08:15 AM
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toybuilder toybuilder is offline
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Yeah I like Ted's page though some of his short cuts/rigging it to work I don't agree with.I think you should fix it so it's no longer an issue these cars are all going on 30 and when you rig one thing it usually just makes other things go out faster.It's great to have all the procedures already typed out , I'm terrible at typing,I'd paid somebody when I was in college if it was more than a page or two. That's great it started working maybe you just had a vacuum leak or bad connection at the ICV and fiddling with it to test it pushed everything back to tight.Like I said those little buggers are pricey so it's good that one works.
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