So I have replaced the plugs, rotor, rotor cap and plug wires. I still am having a problem with a shaky idle and engine running rich. I have ordered a new oxygen sensor as I read on here that controls the fuel mixture. Upon reading other posts on this forum regarding running rich they have had no solutions other than one I read that stated he replaced intake gasket and o rings on injectors. Would love some more imput if any knows about a car running lean. I will replace anything that sounds like it could be the problem as it is a 20 year old car. Any help would be great.
Some possibilities besides o2 sensor:
http://forums.bimmerforums.com/forum....php?t=1385308
Joe M in WV
You are absolutely correct. This problem is so prevalent and it seems that once it starts running like this, you think you fix it then it happens again. These cars are so sensitive in running perfect that it is crazy. I have been battling this problem for 2 months now. I think I find the problem and it works for a little bit then the problem comes back again. I got fed up of trying to figure it out so I took it to a tech who works on these cars and he said to clean the injectors then the plugs and see how it runs. My car has no vac leaks, new intake gaskets, 02 sensor,fuel filter, etc,etc,etc.
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
how do you know it is lean/rich? is it only at idle? is it all RPM's?
unmetered air
temp sensor
bad computer
bad wiring
AFM
condition of engine- rings, guides, valves, compression- what do the plugs look like
conditon of ignition sys
condition of injectors
O2
fuel pressure
fuel filter
things i would consider when the mixture is not right.
[__] RUNNING: [__] NOT RUNNING: 86 PORSCHE 930
[__] RUNNING: [__] NOT RUNNING: 88 BMW 325is 200K+
[__] RUNNING: [__] NOT RUNNING: 2000 MERCEDES E320 WAGON
[__] RUNNING: [__] NOT RUNNING:99 GRAND CHEROKEE 160K::
[_:_] RUNNING: [__] NOT RUNNING: mazda B2200
[QUOTE=T77911S;21099986]how do you know it is lean/rich? is it only at idle? is it all RPM's?
You can smell it and see it in the exhaust.
New plugs
New plug wires
New rotor
New rotor cap
New fuel pump
New fuel filter
O2 sensor on order
Looking for someone who has a had a similar problem. I can blindly replace everything but that's not going to tell me what is wrong.
The PO replaced head and timing belt 8 months before I got it. I guess I could tear the whole head and intake of the car and start over but that seems a bit drastic at this point.
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
Idle or hard starting problems are most commonly caused by intake leaks and/or
a sticky or defective Idle Control Valve (ICV). The only reliable method of
locating intake leaks is to have a smoke test run on the intake and crank case
and to test the brake booster with a gage and vacuum pump. The complete list
of possible causes of an intake leak is:
Intake boot
Throttle body gasket
ICV hoses & connections
Brake booster, hoses, and connections
Crank case breather hose
Evaporative control hoses, valve, and expansion tank
Fuel pressure regulator & hose
Injector seals
Valve cover gaskets & bungs
Oil filler cap
Dip stick o-rings
Oil return tube o-rings
While leaks in some of those can be found by inspection or by spraying carb
cleaner on suspect areas, not finding leaks that way doesn't eliminate the
possibility. Only a smoke test will really work.
Once the possibility of intake leaks is eliminated, the ICV needs to be
removed and cleaned with carb cleaner until the vane inside moves freely. When
the ignition is switched on you should be able to feel vibration from the
ICV. If no vibration the ICV is bad, there's a problem with its wiring or
connector, there's a problem with the TPS, or the DME (or Idle Control Module
(ICM) on an ETA car) is faulty.
For the DME (or ICM) to control idle, the idle switch in the TPS must work
correctly. The switch should close when the throttle stop is 0.020-0.060" off
the idle stop screw.
The fuel system should be tested via the suite of tests in the Bentley manual
as invalid rail pressure can be a contributor to idle and starting problems. A
simple injector check is to pull the injectors, jumper the fuel relay to run
the pump, and see if the injectors are leaking. You can also point the
injectors into a towel, remove the coil wire, and crank the engine to see if
all of the injectors appear to be spraying in a similar fashion. The best
approach to possible injector problems is to have the injectors cleaned and
flow tested. Since raw fuel can or will be released in these tests, have a
fire extinguisher handy.
The O2 sensor can be a contributor to idle problems. The O2 sensor is a
scheduled maintenance item with a useful life of no more than 100k. If the
sensor has that mileage or more (or is of unknown age), replace it.
The AFM can be a contributor. If the vane doesn't move freely or the
resistance track is worn the DME may be receiving invalid data from the
AFM. And if someone has fiddled with the bypass air adjustment the DME may be
unable to stabilize idle. The bypass air adjustment should only be adjusted
per the procedure in the Bentley and with an exhaust gas analyzer. And even
then everything else associated with engine management has to first be
operating properly. If the AFM becomes a suspect, replacement with a good used
unit is the best approach.
Improperly adjusted or malfunctioning valves will affect idle and starting. As
can compression issues from ring or cylinder wear. A valve adjustment is
called for every 15k. A useful diagnostic is to run compression and leak down
tests on the engine. And aged ignition wires, plugs, distributor cap, or
rotor can cause problems. Insulation does break down with time and heat. And
since the youngest E30 is going on 19 years old, if the ignition system is
original or the plugs are old replacement is indicated.
Although not usually a problem, a bad DME temp sensor is a possibility. That
generally won't cause an unstable idle, but can cause hard cold or hard hot
starts and/or a rough idle. As can problems with the timing reference sensors.
When all other possibilities have been eliminated and idle or starting
problems persist, replacement of the DME, or if applicable the ICM, is
indicated.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
Fair enough... The mixture is controlled by the DME. It looks at engine temperature, AFM data, O2 sensor data, and rpm to pick a pulse width for the injectors. That map data is modified by learned fuel trim based on data from the O2 sensor. For DME to control the mixture properly it needs good data and the fuel system and injectors must be operating properly.
In many cases there won't be a single cause for a rough idle or running rich and it will be a combination of factors. For example an intake leak will cause the DME to run a richer fuel mixture as will an aged O2 sensor. A bad FPR can result in abnormal rail pressure. If the pressure is low it will drive fuel trim in the positive direction and if too high can result in excess fuel being delivered. Leaking injectors will deliver more fuel than called for but the DME. Conversely one or more injectors that aren't flowing correctly will cause the DME richen delivery to compensate, which results in some cylinders running rich. Misadjusted valves can interfere with engine breathing and cause idle misfires. A bad ECT sensor can make the DME think that the engine is running colder than it is and thus need a richer mixture. A bad AFM lies to the DME about how much air is entering the engine.
While any one of the causes may not have a big affect, if more than one are present they can add up to become a noticeable problem. Intake leaks and fuel pressure are easily diagnosed and a new O2 sensor is easily installed. The other possibilities can be diagnosed or eliminated with a bit more work.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
OK I will try some of this when I get home tonight sounds plausable that some of this may be contributing. Thanks!! I will keep posting as I want to try and do 1 thing at a time O2 sensor on its way gonna start there. Should have that by Wednesday or Thursday but will check vaccume hoses as well. If I unplug the AFM and it idles the same would that be an easy way to test that?
Also is there a special tool to pull the injectors? Thanks again.
Last edited by ReidSFX; 01-10-2011 at 12:06 PM. Reason: Automerged Doublepost
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
If there are intake leaks, disconnecting the AFM will probably make the engine run better. But I can't emphasize enough the importance of having a smoke test run. There are just too many places that can contribute to intake leaks that you can't identify with visual checks or by spraying carb cleaner around.
Wet down the injector seals at the manifold with PBlaster well in advance of when you pull the injectors. Then carefully pry up on the rail. Work back and forth on the rail until the injectors come out.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
PBlaster is a penetrating oil and is available at many auto parts houses.
It is possible to test the AFM, but the easiest way of telling whether it is the problem (which I doubt) is to swap in a known good unit.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
Both of those could be a sign of intake leaks. Disconnecting the ICV should cause the idle to rise to about 950rpm.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
see my reply on "failed smog test" thread....
there are a number of reasons this could be... try the simplest. the coolant temp sensor, and not the one for the gauge the one that goes to the computer.
Also on a side note getting a smog/ emissions test done would help greatly the gases emitted by the engine helps exponentially when diagnosing older OBDI cars .... just saying..
Stomp test?
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
if the car stalled when you pulled the electrical connector on the ICV, the throttle plate could be misadjusted. (you did not remove the ICV, you just unplugged the connector, right?)
steam clean the engine before removing the injectors. there is a lot of dirt around the injestors and you dont want it in the engine.
when you have the injectors off, that is a good time to replace the hose from the intake to the valve cover.
jim,
it looks like there is an air temp sensor in the AFM, is there a way to test it? would that make a car run bad?
[__] RUNNING: [__] NOT RUNNING: 86 PORSCHE 930
[__] RUNNING: [__] NOT RUNNING: 88 BMW 325is 200K+
[__] RUNNING: [__] NOT RUNNING: 2000 MERCEDES E320 WAGON
[__] RUNNING: [__] NOT RUNNING:99 GRAND CHEROKEE 160K::
[_:_] RUNNING: [__] NOT RUNNING: mazda B2200
Yes the IAT sensor can be checked. A bad sensor will affect how the engine runs, but intake air temperature doesn't have a large effect of engine operation.jim,
it looks like there is an air temp sensor in the AFM, is there a way to test it? would that make a car run bad?
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
2004 S500 4matic w/AMG body kit
2004 Range Rover HSE
1997 Volvo 850 GLT
1997 Audi A4 Quattro V6
1996 Toyota Land Cruiser
1990 325ic
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