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  #1  
Old 08-04-2003, 12:12 AM
azhari
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Unhappy 190e running rich with eha on/off.Bad mpg.Help!

My 190e used to get about 420km before the fuel light came on.

Gradually, fuel mileage became worse over a couple of weeks.

Now, I'm down to 260km per tank with the fuel light on!

Car runs rich and is smoking - especially bad on acceleration.

Also, severe hesitation from stop.

The only thing that is good is that I don't have problems with cold/hot starts - turn key once without pressing accel pedal.Also, the idle is smooth - have never had any idling problems.

I have run the car with the EHA off (so I should be able to mechanically adjust to the correct mixture) but it is no different - still running rich and I lose cold start capabilities with the EHA off.But sometimes (very rarely), I noticed that with the EHA off I can turn the engine over with the 1st key-on w/o accel pedal so there may be a leak.

Leaning the mixture with the EHA off improves the mpg slightly but results in rough idle (like car wants to die).

So it looks like a mechanical problem.

Ignition stuff have been renewed (plugs, cables, filters, etc) and lube job recently done with fully synthetic oil (every 3 months regardless of mileage).

I have done several preliminary checks/tests on the car.

Coolant temp sensor - measures 277 ohms at 83 deg C (within spec).Car is not running cool and cooling system is working satisfactorily.

Pulled cold start valve with engine running and not leaking.Driven car with cold start valve disconnected but no difference.

I did test my EHA current with an analog ammeter.

Key-on = 10mA
Engine on = 0.25mA
Acceleration = Current goes to -0.25mA
Deceleration = From -0.25mA, blips to 50mA and goes back to 0.25mA

Resistance across EHA is 21 ohms at 83 deg C (within spec).
Voltage across EHA connector key-on (disconnected from EHA) = 3.96V

I also took off the connector at the air-flow potentiometer and checked the resistance at the terminals = 1k ohm with the airflow plate at rest.

At pin X11/3 :

Key-on = 30%
Engine on cold/or at 83 deg C = fixed 49.7% duty cycle

The fixed 50% duty cycle reading when warm seems to indicate an O2 sensor problem.

But the problem exists whether the EHA is on or off, so I may have to resolve the open loop mixture before I can connect the EHA and try to get the car into closed loop.

I have some thoughts on the problem :

Does the zero/basic position on the AFM plate affect the adjustment of the mixture - ie, if the zero/basic position is off, would it result in a car running rich even though the mixture has been leaned?

Also, would a faulty fuel pressure regulator result in running rich and can I test it?For instance, I have heard that pulling off the vacuum hose and finding fuel in it would constitute a bad regulator.

The vacuum hose from the regulator is connected to a breather hose T.One end goes to the intake (i think) and the other goes to the valve cover and air filter housing.I am trying to take off the breather hose at the valve cover with difficulty.

What connects the breather hose to the valve cover?Looks like a kind of a check valve of some sort.What is it's function?

I hope that you experts out there (like Steve Brotherton, M.B. DOC and others) can help me out with this issue.

I have been to 2 indie MB shops.

One told me that my fuel distributor "is not so good" without even doing any checking - probably wants to take me for a good, long ride.The other (left the car with the guy to check) told me that my car is running perfectly, good idle, etc.All he did was richen the mixture (i had leaned it) with the EHA on and told me that he had another similar complaint from a customer and it was "normal".

I don't believe it's "normal" coz the difference in fuel mileage is outrageous!The car used to get very good mpg!

I am very interested in checking/testing further but I need help from you guys out there.

Sorry for the long post and thanks in advance to everyone.

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  #2  
Old 08-04-2003, 12:32 AM
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Location: Florida / N.H.
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You may want to check this thread out ..there is a pressure base line setting before eha hook-up...

Setting up the EHA
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  #3  
Old 08-04-2003, 12:34 AM
azhari
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I think this is unrelated but a couple of days prior to the first reduced tank of gas I got, I cleaned the air temp sensor (connected to the air filter housing) with WD40 and also sprayed a little WD40 on the throttle microswitch.

However, the air temp sensor was checked by testing resistance while blowing at the sensor.It varies and the values are within spec compared to a new one.

The microswitch also has resistance values when closed/open depending on which terminals you get the readings from, so I guess it is working.

Hope you guys can help me here.
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  #4  
Old 08-04-2003, 08:31 AM
azhari
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Thanks for the link Arthur...

but I had read that post earlier and am looking for more info on adjustment of the mixture with the EHA off.

Any idea how the fuel pressure regulator works?

As I mentioned in my earlier post, I read that if you pull off the vacuum hose and find fuel in it, the regulator is history...is this a fact?

Earlier this afternoon, I pulled off the vacuum hose from the regulator.By accident, the edge of the hose broke off from the regulator.

However, pinching the hose and releasing it did nothing at all to the engine's idle!

Also, closing the hole for the vacuum hose with my finger at the regulator and exposing it did nothing (duh!).

I am thinking maybe the vacuum hose is clogged up.

If there is no vacuum to the fuel regulator (like my current setup coz the hose broke off), will the engine get a default enrichment?

Check out the photo I took of the regulator with the vacuum hose (in red) disconnected.Engine idles the same with or without the hose connected and car is still smoking.

Wonder if this is the root to my problem?

Any help appreciated.
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190e running rich with eha on/off.Bad mpg.Help!-post1.jpg  
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  #5  
Old 08-04-2003, 08:51 AM
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Location: Florida / N.H.
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< >>

Yes . the vac to the regulator is what sets the pressure according to engine vac spec.. so, if the hose has no vac., you will get High fuel pressure [ rich] .
The pressure will actualy go as high as the pump will put out.
Try to grab some engine vac somewhere and get it to the reg
with a hose to see if the reg will lower the fuel pressure...
I don't have much info on that model, so I don't know pressure specs......
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  #6  
Old 08-04-2003, 09:47 AM
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This is not the way it works on our 190E. The hose goes to the breather side of the pcv orifice, so it would be unlikely to detect much vacuum there unless there is a problem with the engine. The hose simply provides a pathway for fuel if the regulator diaphram ruptures - hopefully back to the air cleaner.

Steve
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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
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  #7  
Old 08-04-2003, 09:53 AM
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Ok.. scratch mine..
Thanks, Steve...
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  #8  
Old 08-04-2003, 10:55 AM
azhari
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Thanks for your input guys.

I saw an earlier post/solution in Vadrill's post and this has confused me a little.

Hesitation in accelerating from stop

I have the same split on the breather hose to my valve cover and I also have the same hesitation on acceleration from stop.It so happens that the "vacuum" hose for the fuel pressure regulator also connects to this breather hose at a T.

Steve - damn, I was just about to "pop" the champagne...you burst my "bubble"!

Nevertheless, I will change out the vac hose to the fuel reg as well as the breather hose it is connected to - valve cover/intake/air filter housing.

Where do I go from here?

With the EHA off, I am still running rich and leaning the mixture till the car barely idles only results in very rough idle but still smoking.

Any ideas?
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  #9  
Old 08-04-2003, 11:40 AM
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The plastic 'T' is actually the pcv device. The plumbing to the firewall side of it is at manifold vacuum, and all hoses need to be in good shape. Still, a vacuum leak would lean out the mixture, so I doubt if that is your problem. Running rich - at a guess - sounds like a sticking control plunger in the fuel distributor - not returning all the way to idle rest. Since I have never worked on one of these, hopefully you can get some more experienced advice.

Steve
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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
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  #10  
Old 08-04-2003, 02:05 PM
azhari
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Steve

sounds like a sticking control plunger in the fuel distributor - not returning all the way to idle rest

I have yet to check my Air Flow Meter plate.But if that were true, then a zero-position of the plate on the venturi that is too low will cause fuel to leak.

Anyone can confirm if this is correct?

If so, then the zero (and basic) position of the AFM plate is crucial in getting the right mixture.

UKEvo had advised me to do this earlier but I thought it only had bearing on the idle.Never looked at it from the plunger point of view.

But I hope someone can help me confirm this.

Also, if the plate is set too high/low, what is a good way for correction?

I may be wrong but I read somewhere that if it's too high, you tap it down (somewhere) and if it's too low, you can pull lightly on the bolt at the top of the plate.

Anyone?
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  #11  
Old 08-04-2003, 02:32 PM
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I wouldn't guarantee the airflow meter plate will track the plunger, if the latter is sticking. However, I suppose the plate rest could be gummed up and preventing a full return, or a problem with the linkage, and all cause the same symptom.

If it needs adjustment - which seems unlikely given the way the problem developed - I would take the airflow meter out for examination, leaving the distributor attached.

Steve
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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
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  #12  
Old 08-04-2003, 10:27 PM
azhari
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Is it OK to push the plate down and spray a good dose of carb cleaner in there?
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  #13  
Old 08-05-2003, 10:38 AM
azhari
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Fuel pressure regulator

With the vacuum hose pulled off, I can see fuel pooling in the regulator, and some of it has seeped out.

I have read from other posts that if fuel leaks out from this end of the regulator, it is shot!

If this is true, then my regulator is shot.

Normally, how does a regulator go bad?And if it does, what effect does it have on the car?

Really in need of information and at the same time, really keen to learn how the car works!

Hope you guys can help me out here.

Thanks, y'all.
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  #14  
Old 08-05-2003, 11:25 AM
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"Is it OK to push the plate down and spray a good dose of carb cleaner in there?"

Probably, but the bottom of the plenum is rubber - make sure the cleaner will not harm that. I used rubbing alcohol on shop paper towels, pushing down the vane and thoroughly cleaning the inside of the venturi and the contacting edges of the vane. Do this with the engine off - it will immediately stall if you try it with the engine on, and you don't want to be there if an intake backfire should occur, anyway.

Removing the distributor/airflow meter unit isn't too difficult or messy, and the rubber plenum can then be removed for complete inspection of the mechanism. If your idle circuit hoses are old, why don't you replace them and the rubber plenum at the same time as the regulator, and it will make this operation just an extension of that repair. Order the saddle that holds the rotary idle air valve too, as it gets hard and brittle and difficult to remove non-destructively. Aftermarket, none of these parts are very expensive.

Steve
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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
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  #15  
Old 08-08-2003, 02:22 AM
azhari
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Quote:
Removing the distributor/airflow meter unit isn't too difficult or messy, and the rubber plenum can then be removed for complete inspection of the mechanism. If your idle circuit hoses are old, why don't you replace them and the rubber plenum at the same time as the regulator, and it will make this operation just an extension of that repair. Order the saddle that holds the rotary idle air valve too, as it gets hard and brittle and difficult to remove non-destructively. Aftermarket, none of these parts are very expensive.
Steve

I replaced the idle circuit hoses and have an appt to get the fuel pressure tested wiht a techie.

On my own, I tried to get the fuel distributor off to see if it is leaking fuel.

Thought of getting just the cold start feed off to get at the 3rd torx bolt that holds the distributor down...but NO GO!

Despite using 2 open end spanners for the operation (duh!), it would not come off!The cold start fuel line would twist together with the nut attached to it.If I had turned further, I'm sure the line would break!But I did get to the point where fuel was driping out from the crack but no further.

I will have to get the same techie to help me with this, but it will be next week coz it a National Day weekend!

By the way, I've seen In my Haynes that the fuel distributor has an O-ring but I need the part number!Parts guy says he has never sold one!Mine, although is a 1.8 it is an 8 valve 102, so it should be the same part as the 8 valve 2.3s in the US.

Thanks again, Steve.

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