Topic: Another CIS attempt (Read 6433 times)

drewprof · « **on:** May 13, 2009, 12:00:48 PM »

As you all know my car is a notorious "staller"

Ok, so today I pulled out the big guns so I can redo the EHA setting and the fuel to air mixture.

Throughout the tests the fuel pressure stayed at 5.2 bars steady. This was taken at the lower fuel distributor chamber test outlet.

I kept an ammeter in series with the EHA; I stuck a voltmeter in ports 3 and 2 of the test knob and I also attached my oscilloscope to the same ports.

The results taken by the ammeter, voltmeter and scope were all flaky and I couldn't get a steady setting after I adjusted the EHA and tried to set the idle mixture.

When the car's ignition is on but engine off I measure 20mA going through the EHA while the voltmeter would sometimes register 6V and sometimes 0V; the scope will of course follow along by showing a square wave (I presume is a reference signal for Lambda) would be at almost 50% duty cycle or simply at zero if the voltmeter reads nothing. That in itself is a problem since it's not consistent. I think the ECU is fried and flaky.

When the engine is started and if the car starts, sometimes the ammeter will read 0mA then it will steadily climb to 10mA which tells me that it's dumping in more gasoline. The fuel pressure is steady so that tells me that the fuel pressure regulator is just fine. Typically the EHA should only draw +1mA to -2mA from what I understand.

As to the Lambda adjustment, it didn't matter if I went one way or the other, the car will eventually stall. I tried to lean or enrich the mixture whenever I acquired the signal (remember sometimes I get nothing) but the car would stall as soon as I insert and push down on the 3mm allen wrench (I think that's normal since it will push down on the plate as well).

No matter which setting I tested the car would eventually stall. Sometimes it starts right away sometimes it's a pain and I have to try over or give some gas.

Could it be the crank sensor giving bad feedback?

Could be a major vacuum leak that I am too stupid to find? I blocked the breather hose with my finger but the car hardly reacts and even the meter readings stay the same for that moment.

What else can I do short of giving up and taking it to an "expert"? (if there is such a thing)

drewprof · « **Reply #1 on:** May 14, 2009, 09:17:39 AM »

Sio I tested the car today after I have left the CIS gauge hooked up overnight to monitor how much the pressure drops.
It had dropped to 3.5 BAR (50psi). I started the car and it stayed at 3.5 BAR... I have no clue what's wrong or if I am going at it the wrong way! The car this time didn't stall but the needle didn't budge either.

HELP!

drewprof · « **Reply #2 on:** May 15, 2009, 01:01:13 PM »

So I did more tests today:
I tried using a dual hose (one with a manual valve) to connect to the test outlet (lower chamber) and the outlet for the cold start valve (a/B configuration as seen in the manual on the CD)
I notice that I got 4 Bar this time but no change in reading if I turn the hose's valve on or off. This is telling me that the EHA is not regulating, that is if I am using the tool properly (which I always doubt).

I went ahead and retested by using a single hose this time. I connected to the upper chamber to read the system pressure and I got 4 Bars (well below the 5.6 Bars as required in the specifications)
I went ahead and reconnected that single hose to the lower chamber and I got the same reading. Again no difference in pressure but no matter what and if the the gauge was correct I have a low pressure situation here.
This could be attributed to a weak fuel pump but that sucker is new?

and it's Bosch?

?
Ron, do you think I should order another pump?
Larry, what is it I am doing wrong with the tool? Is there something I need to do to make it read correctly? It has a bleeding button that I tried but that didn't make any difference.

drewprof · « **Reply #3 on:** May 15, 2009, 04:38:30 PM »

I went out again and this time I removed the fuel pump relay and and started the fuel pump with a short without starting the engine. All I got is 2.5 bar.
I put back the relay and started the car but all I got is a little less than 4 Bar.
I swapped the fuel pressure regulator but got the same results.

I am leaning towards a weak fuel pump.

GermanStar · « **Reply #4 on:** May 15, 2009, 06:25:51 PM »

Did you run a volume test on the fuel pump? I recall Larry telling me you want 930cc for a result.

Not sure where Larry is. I think he's vacationing with his new boat in Somalia.

drewprof · « **Reply #5 on:** May 15, 2009, 06:40:06 PM »

What did he name his boat? SS-CIS?

I will have to go back to my campus to get a container for measuring volume. Tomorrow is Graduation Day so maybe I will see if I can sneak in the chemistry lab.

CIS Flow Tech · « **Reply #6 on:** May 15, 2009, 07:43:24 PM »

Sorry for coming late to the party, I have been very busy with work and Luise remodeling the inside of the boat. I was going to say the line of the test gauge with the valve should go to the cold start fitting, also jump the fuel pump to eliminate the relay, but you have been there. You tried another pressure regulator, (I was going to send you an old one I tested) so now we are down to restriction in the fuel strainer, fuel filter, or fuel pump took a crap. I always say don't assume a part is good because it came out of a new box, always test everything. You need over 3 bar to open the injectors, you should have 5.3 to 5.6 bar, and return 930cc per min minimum out of the fuel pressure regulator back to the tank. Steal your wife's Pyrex measuring cup from the kitchen it is marked in ml which is the same as cc. I was going to say she may "cut you off" but I think someone said that already happened, so you have nothing to lose.

Larry

drewprof · « **Reply #7 on:** May 15, 2009, 08:53:55 PM »

Cool, tomorrow afternoon (after my students' graduation ceremony) I am going to first check the strainer near the fuel distributor. I will manage somehow to get a a measuring cup and a chrono

drewprof · « **Reply #8 on:** May 16, 2009, 01:21:24 PM »

Ok, this is weird!

I removed the fitting from the main line and cleaned the strainer by spraying carb cleaner then blew with my mouth the opposite way then rinsed it again.
After I installed it I tested the fuel pressure by testing the main fuel pressure only, so I used a single hose to make sure I don't get confused.
I jumped the pins on the relay sockets (engine off) and the pressure this time jumped to 4 bars.
I removed the jumper, put back the relay and fired the car up; the pressure dropped to 3.2 bars.
I shut the car down after a few minutes because the pressure wouldn't budge then I removed the relay and jumped the socket again. The pressure remained low at 3 bars.
I waited a few minutes then the pressure started to build up and stopped shy of 5 bars and stayed there.
At this point I removed the jump, put the relay back in and started the car. The pressure dropped down to 4.7. I waited and watched it build up to 5 then 5.4, 5.6 and I was hoping it would stop there but it continued to climb. By now it was at 6 and the car started to shudder. I just waited to see what happens and the pressure went all the way up to 6.6 and stayed there.

While doing all these pressure tests I stuck a voltmeter on pins 3 and 2 to test for Lambda and the voltage was study at 2.66V DC. It would sometimes fluctuate up but not much. If I pull the throttle cable that brings the voltage up to 8 or so then it drops back to 2.66V. Moving the throttle seemed to have no effect on pressure.

This is weird! How's the pressure suppose to regulate at 5.6 Bar max like described in the CD? Is the fuel pressure regulator bad? Maybe the fuel accumulator is bad? Maybe the tank/lines are dirty and that's why I suddenly had a higher pressure reading after I cleaned the strainer?
Maybe the fuel pump is bad since it's cranking out that much pressure no, unlike yesterday where it was low? Short of replacing EVERYTHING I don't know what to do

drewprof · « **Reply #9 on:** May 22, 2009, 11:43:27 AM »

RESET
Let me do this over

Phase 1
Measuring Main Fuel Pressure

This time I am measuring the line itself

Overview:
Setup

Bleeding container and other environmentally sensitive stuff

Where to connect

Connection

Let it rip: Where and how to bypass the fuel pump relay to get the pump pumping
Short these two connectors

The red and black wires are connected together on their other ends.

Bleed the instrument

No more bubbles

Read the friggin instrument

Shut the pump by disconnecting the short (remove the wires)
then read again

Please submit your observations and analysis before I proceed any further. Also do submit any future steps I should take based on this result.

drewprof · « **Reply #10 on:** May 22, 2009, 12:23:36 PM »

A little over an hour has elapsed and I am getting 3 Bar with the pump off all that time while the gauge remained inline.

drewprof · « **Reply #11 on:** May 22, 2009, 04:59:25 PM »

I am guessing that my leakdown test is ok since it held near 3 bar after an hour.
So now what? I went ahead an removed the air plate assembly with the fuel distributor

I noticed a crack here

Tonight, I am taking this unit apart to inspect.

Digmenow · « **Reply #12 on:** May 22, 2009, 08:04:43 PM »

Did you take this picture with your foot?

Sorry. I'm in a stupid mood tonight.

drewprof · « **Reply #13 on:** May 22, 2009, 08:56:14 PM »

The wife does all that, I have no talent for pictures and stuff like that.

drewprof · « **Reply #14 on:** June 01, 2009, 08:37:13 AM »

I put everything back in with new rubber boot and vacuum hoses. I adjusted the EHA and set the idle air mixture. The car is working, hasn't stalled but I think I have another problem.
When I opened the trunk I heard noises from the gas tank. It sounded like I have an open faucet in there with some gurgling here and there. Is it possible that it's the return fuel making that noise, and if so, could be that the fuel accumulator is shot? Or maybe 190E do have that noise back there because I never heard that in the 560SEL. Could also this explain why I get erratic low fuel pressure readings when everything is hooked up?

Here are some updated pictures:
Air plate adjustments
http://s713.photobucket.com/albums/ww134/drewprof/190E_FuelDist_AirIn/

Putting it back together
http://s713.photobucket.com/albums/ww134/drewprof/190E_CIS/

CIS Flow Tech · « **Reply #15 on:** June 01, 2009, 07:54:19 PM »

I haven't been getting any emails saying there is a new post to see, so I thought there was no activity here, and have been very busy.
The low fuel pressure is not good the fuel pump could be on its last legs. They can cause intermittent problems. It looks like you deadheaded the pump against the gauge, if so it should have pegged the gauge and broke it, it should deadhead way more than 6 bar.

Larry

drewprof · « **Reply #16 on:** June 01, 2009, 10:40:55 PM »

I am hearing like a running faucet when I open the trunk. Do you think maybe my fuel accumulator is gone?
I would hate replacing the fuel pump and finding out it's not it. That's has been my story lately. I just spend on a new crank position sensor and other knickknacks but I am not confident that the stall is resolved. The fuel pump is fairly new and it's a Bosch and these things ain't cheap. I am heading to the junkyard as soon as I can and see what I can do.

drewprof · « **Reply #17 on:** June 06, 2009, 05:50:19 PM »

I replaced the fuel accumulator just to see if the gurgling and faucet noises will be gone but that didn't happen. The car still stalls too.
This time it even stalled while coming to a stop, so it didn't even wait for me to go to a complete stop.

When do I give up?

drewprof · « **Reply #18 on:** June 06, 2009, 06:59:44 PM »

Oh, I have offered a $50 reward in many forums for anyone that can solve this problem.

drewprof · « **Reply #19 on:** June 12, 2009, 07:57:10 AM »

Okay, so I installed the right pump this time. The vendor took back the other one and sent me this one that looks like the original I had in the car a year ago.
The car stalled!
After idling for four minutes it just died. No surging, rumbling or hesitation, it simply died.

Fuel pressure at the line with engine off and relay shorted 3 bar
Fuel pressure with relay in place and engine on 4 bar.

I am still getting low pressure readings.

News:

Author Topic: Another CIS attempt (Read 6433 times)