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  #1  
Old 03-15-2004, 10:08 AM
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84 500 air sensor plate adj

Have followed printed engine manual for instrucitons on adjusting air flow sensor plate [measuring at 1, adjusting with roller pin at 2 under the fuel fitting]. Engine seems to be always rich. Adjusting idle with air mixture screw will bring idle down but rich, raw smelling exhuast. And if bring down to 800 rpm then it will not start and flood all cylinders necessitating removal of plugs to dry off. New O2 sensor, new fuel dist, new warm up reg, new idle control valve, new idle control module, new fuel pump relay, new fueld filter, over voltage protector checks out. Car has no cat cons or air pump... rebuilt cylinders and new timing chain and rails.... just cannot get it to run right at idle and start like it should.

Question is I believe I have adjusted air flow sensor plate correctly according to manual but am wondering if it should be a little lower at idle [to allow more air] than what manual says?

My other option is maybe cold start valve continues to leak after starting the car? Could it be the fuel pressure regulators?

Thank you in advance. Great forum.






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84 500 air sensor plate adj-1984-500-sel-4.jpg  
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dloveless

1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.
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  #2  
Old 03-15-2004, 04:51 PM
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I think I understand. I have done the same project just on a 560sel. I always found I was rich when I put it back. It is not the base setting it is actually the fuel air mixture setting. Steve told me to make it lean by default and he was right. When you start it the air plate actually drops lower than where it is when sitting this richens the fuel and floods the car. so adjust the fuel air mixture lean. I then had the wife start the car while I pushed on the air flow plate untill I got it where it would start correctly and adjusted the fuel air mixture accordingly from there.
m
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2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #3  
Old 03-15-2004, 06:56 PM
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thanks mhingram !

I will try it. The manual sure seems to be lacking in this area.
Sure appreciate the advice.
will let you know how it turns out.


corrections to original post: 1) rebuilt cylinder HEADS and 2) also a new throttle switch should have been listed.
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dloveless

1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.
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  #4  
Old 03-16-2004, 07:51 AM
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dloveless,

I also have an 84 500 SEL. This is actually a very easy system to adjust once you know how. This is how I adjust mine, and some of the possable problems if it doesn't work.

First, get the engine up to operating temp.
Remove the air cleaner assembly.
Disconnect the o2 sensor.
Get a can of carb cleaner which will in this case act like fuel.
Spray just a very little carb cleaner into the air intake.
If the engine drops in RPM, then the engine is already rich and needs to be leaned down a little. If it speeds up it is lean. Adjust the mixture until there is no change or just a little speed up. At this time, If it is running to fast, then you have an ISC problem, or a vacuum leak. You can find the vacuum leak using the carb cleaner and using very short burst of cleaner, spray around different areas and when you hit it, it will change the speed of the engine. DO NOT spray on the dist, coil, or plug wires. When you are happy with the idle reconnect the O2 sensor.
Now if you have problems starting the engine when cold or after it has been setting, use the carb cleaner to find out if it is not getting enough fuel, or too much. From this you can determine which areas to investigate. If you do have problems, I have found that a pressure guage connected to the control pressure line can tell a great deal about how the system is working.

If you try this, let me know how it goes and we can go from there.
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  #5  
Old 03-16-2004, 09:48 AM
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Thank you Paul!

Appreciate the detail.

It may be two or three days before I get back out to her...maybe sooner.

Another note- the picture attached... the ? .... when re-assembling there was this T in that vacuum line and it had no cap on it ... do not recall during disassembly anything about it. I've capped it off now. Do you remeber if yours has a T in it there and is it capped? All I can think of is a vacuum line plug in point for a testing gauge or ? The vacuum diagrams I have show no T.

Thanks again.
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84 500 air sensor plate adj-84-500-sel-7.jpg  
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1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.
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  #6  
Old 03-16-2004, 05:57 PM
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Sorry dloveless, but mine doesn't even have a vacuum line in that area. when I got my car, part of the engine was under the hood, part in the trunk, and part missing. Now it is an American car with an 85 500 Euro engine and the fuel system is a combination of both with a few of my own changes so everything works together.
It runs great, gets 22 mpg on the highway at 80 to 90 mph.

These engines are acutally very simple and easy to tune once you figur out how they work.

Good Luck
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  #7  
Old 03-16-2004, 06:35 PM
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thanks again Paul

I hope I can figure out how to make mine run well. I think I'm getting on the right track.

I'll let you knwo how it goes

don
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1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.
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  #8  
Old 03-22-2004, 11:26 AM
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Been frustrating so far

Tried both methods and could not get idle down and car running smooth and starting. Best I could get was 1200 idle and then it was starting a bit hard when warm. When I idled it down to 800 [engine at oper temp] it was a very rough and loping idle, varying by 150-200 rpms and sometimes quitting. If I revved it up to say 2500 and let off it would stay at 1200-1400 for 30-60 seconds before going down to the 800 range.

Although installed a new Idle Control Module [ICM] in February as old one tested bad, [and a new Idle control slide Valve- [ICV] after that], after many hours went back and diagnosed the ICM again and appears got a bad one. The test for battery voltage with key on engine off at the ICV plug in is zero.

The test of jumpering the proper plugs on the ICM plug in to check for ICV operation [audible click] is successful.

The wire check for continuity from the ICM plug to the ICV plug is good.

So am getting a warranty replacement on the ICM and will let you know how it turns out.

Frustrating problem after the rebuild.
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1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.
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  #9  
Old 03-26-2004, 03:04 PM
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solution turned out to be...

the rebuilt Idle Control Module I bought was bad... it was a rebuilt and when repaired (under warranty) it made all the difference in the world in setting the idle. I wonder how many parts I did not need to replace? Arrgh!

Still having minor problems with a bit of a rough idle but have not had a lot of time to change the fuel/air mixture screw. At least now I have a idle around 750.
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1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.
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  #10  
Old 03-26-2004, 08:56 PM
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good news even if frustrating. I did the same thing with mine so I know the feeling.
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Martin Ingram
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2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #11  
Old 03-26-2004, 09:46 PM
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Pmckechnie: Will this method work on my 420 sel? If so can you explain how and what to adjust.
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  #12  
Old 03-27-2004, 10:19 AM
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Yes, this will work on any CIS system as far as I know.
First unplug the O2 sensor which is located in the right exhaust pipe near the manifold. The engine should still start and run.
Remove the air cleaner assembly. Located between the air intake and the fuel dist is an adjustment hole. It MAY have a plug in the top of it which will need to be removed. Using a 3 mm allen wrench, turn the adjustment screw (which you can't see, it is about 2 in down in the hole.) Turn it CCW to lean it out, and CW to richen it up. Now using the carb cleaner, spray a very,very small amount in the air intake. If it speeds up, it is running lean and can be richened up a little. Be carefull and don't turn the adjustment screw very much, maybe 1/16 turn or less each time. It is very sensitive. If the engine rpm drops a little when the carb cleaner is sprayed in, then it is running rich and you can turn the adjustment CCW to lean it down just a little. Repeat this process until there is very little change or speeding up just a slight amount. Reconnect the O2 sensor. Again with the engine warmed up, try spraying the carb cleaner again. There probably will be a change but it shouldn't be much of one. If it runs worse with the sensor connected (very rich or very lean) then it may be time for some serious computer diagnostics.
Now Keep in mind, this proceedure is assuming every thing else is working as it should. Some problems could be covered up by making this adjustment and probably will continue to cause problems like poor mileage, other running problems, etc. So if you have a problem that just started, it is probably not going to be fixed by adjusting the mixture. Mixture usually doesn't change quickly, but over a long period of time from engine wear, etc. (that is unless someone has been working on it and adjusting it when it didn't need to be.) Also when other parts are replaced such as pressure regulators or possibly even exhaust components it may need to be touched up.
If all goes well, replace the air cleaner (making sure it is clean) and you are done.
By the way, it will probably take you longer to read this than to do it.
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  #13  
Old 03-27-2004, 10:46 AM
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You can do this just as easily while using the duty cycle or lambda reading.
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2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #14  
Old 03-27-2004, 11:48 AM
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I have only briefly read all the replies, but it doesn't seem that anyone has touched on the main problem here.

In the first post the concept being adjusted is idle speed. Here is the problem. One CAN NOT adjust idle speed on that motor and the adjustment at #2 is NOT for idle speed. It IS for fuel mixture.

Any adjustment at #2 that affects idle speed is WAY OFF proper setting. The proper mixture can only be guessed at without using measuring tools of some nature. The narrow band of proper mixture sits within the larger band of all mixtures that run the same.

Use the technique of EHA current for the best judgement of mixture.
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Old 03-27-2004, 02:58 PM
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The MAESTRO has written!!!
READ attentively!!

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