Fuel pressure regulator
 

Changed out the breather hoses from the air filter housing/valve cover/rotary idle actuator including new plastic T and joint.

Also swapped out the Fuel Pressure Regulator coz the old one had a little fuel leaking out the vac hose.

Readjusted fuel mixture with EHA on.

Drove car hard - 15 minutes of sheer pleasure, car drove like new.No hesitation from stop with A/C on.

After 15 minutes of pleasure, going up a slight slope at 80km/h, car started feeling like it was bogging down.

Felt like I was loosing power (or flooding).

When I cleared the slope, coming down the slope I could feel the familiar surging of the engine; and noticed that car started to smoke (running rich).

At a stop light, when accelerating, car hesitated severely, and surged while accelerating, still smoking.

What gives?

I stop the car, pull off the EHA and leaned my mixture till I got driveability back with the A/C on.

So now I'm back to square one.

I noticed however, that this problem of running rich seems to happen when the car is warm (with the EHA off - to exclude the electronics from the equation; pure mechanical injection).

Normally, the car is very driveable when first started; albeit hardstart (coz EHA is off).

Could any of the sensors affect the mechanical injection with the EHA off?Don't think so but I'm not sure.

Any ideas?

HELP!!!:(

Oh yeah, forgot to mention that fuel smell in the oil (checked at dipstick) was the other factor that prompted me to change the Fuel Pressure Regulator.

In any case...HELP!!!:confused:

Does the engine achieve closed loop control? A common easy view I take on these systems is to watch the activity of control at various different constant engine speeds, preferably under load. My break out leads are about ten feet long and I monitor while controlled driving.

The degree of control shouldn't be different by more than ten percent at any constant load. If the system can not maintain control the EHA current will peg plus or minus 12ma. The characteristic of control is what is required to evaluate. What happens to closed loop? Does it peg lean or rich?

Before doing any of that be sure that the airflow meter moves freely and there is proper 2-4mm free movement before the piston is lifted; and that the point of engagement is right at the base of the flat vertcle cylinder at the center of the cone..

Beyond this, one will need to evaluate system and differential pressure and the relationship to electronic control or you need to flow test. Included is a picture of a flow test on an electronic injected v8 BMW. The same equipment (differential flow meter) was originally designed for K-jet.

Thanks for your reply, Steve.

In fact I have been working on this problem for the past 2 weeks or so and I have been going thru' each and every sensor in the system and testing it to specs obtained from the forum/web/Haynes manual and where all else fails, I compare the readings to the parts in my kid brother's 190e 1.8 (same year/model).

Just to name some of the items - air flow potentiometer, EHA, engine temp sensor, air flow sensor, cold start valve, fuel pressure regulator, etc.

I had also DIYed a harness for the EHA to connect to my multimeter so that I can monitor my EHA current.

I had posted the results earlier but nobody seemed to be able to make anything of it (maybe my results were screwy) or maybe nobody took notice of my post.

In any case, here they are :

Key on : 10ma
Engine on : 0.25ma
Acceleration : -0.25ma
Decel : 5ma, -50ma then back to 0.25ma

I have also done the zero/basic position of the air flow plate.

At X11/3, I am getting 50% fixed duty cycle when warm which could mean a faulty O2 sensor or mixture being way off and system unable to correct (is this right?).

I have disconnected the EHA to eliminate the electrics from the equation.

It seems that even when the mixture is lean (to the point that the car barely idles at warm startup), it is still running a little rich - black smoke from exhaust when revved but slightly less than before.

I pulled the vent hose off my fuel pressure regulator and found fuel in it - so it was replaced.

I retuned the mixture with the EHA on and when I got the idle close to perfect (no flat spots), there was no smoke from the exhaust so the problem seemed to have been solved.I forgot to check X11/3 at this time coz I was too eager to get on with the test drive.

Car ran superbly for 20 minutes till I reached a slight incline.Then the car seemed to bog down like before and I see black smoke coming from the rear.

I go to a remote area for testing, and I find that the car is back to running rich as before.Hesitating severely on acceleration as though it was flooding.

I disconnect the EHA and leaned the mixture till I got driveability back (even with A/C on) albeit rough idling.

This was 2 days ago.

Visits to 3 different indies got me the same replies - bad fuel distributor; though I was skeptical, it seemed possible to me coz that would explain why I couldn't get the right mixture even with the EHA off.

BUt the whole process also made it seem to me as though the car was dumping more fuel than needed - as though it was receiving "false air" info.

With the high cost of the FD and unavailability of spares here (EHA and O-rings not available separately - only complete assemblies), I had to sit down and think it thru.

My options were to get a used FD or tackle the problem on my existing FD (if it were possible).

This m,orning, at a whim, I bought a can of carb cleaner.With the aid of my spare vac hose (I also replaced the split breather hoses, regulator vent hose and pcv), sprayed the underside area of the FD by pushing down the air flow plate.

Test drove the car.

Damn!

Like new!

Really!

No black smoke (not that I can see from my rearview mirror) and no hesitation from acceleration.Also no bogging down when accelerating at speed and now the car can go above 80km/h (not before) without effort.

I am now monitoring the fuel mileage to see if it is improving.

I have not richened the mixture and neither have I reconnected the EHA as I want to keep the variables maintained and see if the mileage improves.

Sorry for the long post but I just had to get this stuff off my chest.

Steve, I appreciate any thoughts you may and apologise if my sequence of testing seems irrational.

Please advise me where necessary coz I enjoy working on my 190e (and driving it) and I wanna learn as much as I can about it.

Thanks.:D

DIY EHA harness
 

By the way, I kept getting questioned by pedestrians if I was doing "race testing" on my car coz they could see my wire harnesses from the bonnet and the FLUKE digital/SANWA analog multimeters in the car!:D

Cheers.

I've got my fingers crossed and hoping the best for you. I hope I get a chance to work on mine this weekend. I sure miss driving that thing!

Unfortunately your problem does sound a lot like one way the fuel distributer fails.

As easy as all this electronic testing is, it is based on the concept that proper application of control gives the proper measure of control.

Overall, it seems to me that your electronic controls are functioning they just keep getting different results from the same control.

One way this happens is when the EHA can not control. The way the EHA controls is by its ability to function as a precisely controllable leak to fuel return from the lower chamber of the fuel distributor. The upper chamber pressure is being controlled massively at the external fuel pressure regulator. From the boundless (in theory) source of regulated pressure fuel a small oriface openning allows fuel to flow into the lower chamber. it flows in at a precise rate and if the container were totally contained in a small time the fuel woul be at the same pressure as the upper chamber. As it happens the flow rate out through the EHA when disconnected (zero ma) is slightly greater than the flow in, allowing the pressure to be reregulated lower than system pressure. The difference in these two pressure the lesser subtracted from the greater gives differential pressure.

As long as there is differential pressure fuel can flow to the injectors. The proper dif press at zero ma is .4bar. Total lean correction -12ma cuts the diff press by .1bar (approx) and decel cut-off -60ma (-50 in your case which I think is right) produces zero diff press and no fuel flow.

The fuel distributor problem I have seen involves a restriction in the supply hole to the lower chamber. This causes the EHA leak to be greater by comparison and one case had a zero ma diff pressure of 1.4bar. The other one I can remember was less but still around one bar.

When you look at the pressures used for proper control: Base - .4 bar, lambda correction ,1bar lean or .1bar rich from .4, one can see how devastating to control a diff pressure of 1.0 or 1.4 can be.

one way this can be suspected from electrical testing is to watch your lambda set point (closed loop median amprage). If at idle you have closed loop control median about zero ma then by holding the engine to 2000rpms you should still have the same median. if it goes off the scale I'd look at pressures.

Thanks for the info, Steve.

Theoretically, it does seem to me like a failing fuel distributor but I am not sure, YET.

Luckily, I still have the EHA harness connected to the EHA with the leads near the driver's console for testing.

I will hook up my ammeter again and look at the lambda set point.

At this point, even if all tests conclusively confirm the replacement of the FD, I am already very contented.

I have got more information in this thread than I could ever dream of and the real reward to me is fully understanding how my car works!

Thank you, Steve, for taking the time to convey the info that you have.

Cap'n - I have had my fingers crossed since this morning; but I seriously doubt that the problem will be solved as easily as that!:pBut who knows...

I'll let you guys know how it goes.

Cheers.:D

Before I do anything else...
 

I'm gonna take the car out for a blast down the freeway while I still have it set lean with the EHA off.

Just in case the O2 sensor is fouled up, I'm gonna run the crap out of it!:p

Cheers.:D

This sounds very similar to the problem I was having with my 2.3

What happened originally was the engine was replaced, and whoever was getting it to run, did not know that older models of a 190 have different amperage in the EHA then the newer models since 86 I believe.

So my car was set for 0mA in the EHA, which caused it to actually run really lean, and as a result the car hesitated like no tomorrow, but was driveable.

After testing and testing and learning all the thories of the engine, all it took to correct the engine was a slight turn of the air/fuel mixture on top of the Fuel distributor and the car was running like new ever since.

One thing does leave me worried however, on the beginning, azhari metnioned that he got 450km out of the car before the fuel light came on. I can only get 450km out of the car from pure highway driving, on the streets I get up to 350 and although I never let the fuel light go on, I have to pump up to 45L of gas to fill up, and according to the manaul, I only have a 40L fuel tank.

Now what I would like to find out is why my car would not start when I had the mixture set right on 8mA. I had to richen it to get it to start, with the correct mixture setting it would not start. Can anyone think of anything?

This is cold or warm starts, but mostly warm if I remember correctly.

I would really love to be able to get 450km out of my car on regular streets and not just pure highway driving.

And it also looks like I have about 11 months to do this before my final emissions test which I would like to pass without any problems :)

xp

xp

I normally fill up with about 44 litres when the fuel light comes on after doing 430 to 450km city driving (approx. 10km/litre).

My 1991 190e 1.8 Euro RHD has a 55 litre fuel tank as per my Haynes manual.

I have yet to reconnect my MM to my EHA harness and take the readings again while driving.

A recap on my car's existing setup - EHA off and fuel mixture leaned to the point that it idles a little rough.

Problem - car running too rich with EHA on/off, black smoke and severe hesitation off the line.Suspect "more than necessary" fuel being dumped while engine is running.No external fuel leaks and gas mileage horrible - 260km when fuel light goes on.

Meanwhile, my latest findings since spraying the underside of the FD (by pushing down the airflow plate) is that now when I park and leave the car idling, it doesn't leave a sooty mark on the pavement.Before, 2 minutes was all it took to get a sooty spot the size of my palm on the pavement.

Before the carb cleaner trick, even with the EHA off and mixture leaned, the car would still hesitate slightly off the line and smoke if accelerated hard.Fuel mileage closer to 300km when light goes on.

My tank was only left with 1/4 when I did the carb cleaner thing so I'll top it up today and clock the fuel mileage.

If it improves, my next step is to richen the mixture with the EHA on and try to get the car in closed loop.

By the way, I have been following your threads for a while and all I can say is GOOD JOB!

I will report my findings and further checks/tests as I go along.

Thanks guys.

Cheers.:)

Steve Brotherton,

Drove with my MM hooked up to the EHA harness.

Key on : 10ma
Warm engine idle : 0ma
Accel : -2.5ma (2000rpm)
Decel : From -2.5ma, to 5ma, -50ma, then 0ma.

Seems like I'm screwed.

By the way, having sprayed carb cleaner onto the underside of the FD on Saturday improved performance and fuel mileage slightly improved.

This evening, problem cropped up again.

Severe hesitation at accel, smoking and bogged down performance (flooding).

Pulled aside, waited a little, did the carb cleaner thingy (3 short squirts).

After 15 minutes, drove off and performance much better, but still smokes on hard acceleration.

I noticed a major difference after the cleaner trick is that the engine feels more free-revving immediately after application.When it starts bogging down, the accelerator feels heavy in that the car will not rev up easily.

Mind you, I'm driving with the EHA off and mixture leaned till idle is rough.

Correct me if I'm wrong, but isn't the FD plunger lifted proportionally to the deflection of the air flow sensor plate?

It seems like the plunger is sticking - it stays in the upper position even though the air flow sensor plate moves back to basic position upon release of the accelerator pedal.

I have read from my Bosch fuel system notes that the control pressure opposes the force that is applied to the control plunger by the air flow sensor plate pressure.

Hence, if my regulator is new, it would seem that my fuel distributor is toast!

Or is my plunger gunking up?

But if so, I think it would have been resolved by the first application of the cleaner "trick".Now, I have applied the cleaner twice since Saturday.

I wonder what the relation is between the cleaner "trick" and the fuel distributor plunger?

sbourg - about 2 weeks ago, you posted your guess that this problem "sounds like a sticking control plunger in the fuel distributor - not returning all the way to idle rest".

At this point in time, I think this is the problem.

stevebfl - if this is the case, is it the point of no return for my FD?I am on the verge of bleeding it, taking it out and soaking it.Would this do any good?

Appreciate any thoughts you guys may have.

Thank you.:(

EHA current
 

Stevebfl

Appreciate any comments you may have on my EHA current values.

Thanks.

Bummmmmmmpppppppp...

You haven't given me much with the values three posts ago.

The only values I would be interested in, if I'm trying to evaluate hydraulic control would be various closed loop ranges at various FIXED and STABLE constant load/rpm ranges.

In other words I'm looking for how the electronic feedback views the different fuel flow rates. For these purposes we must leave accel enrichment out and decel cut-off is only of value to prove it happens.