84-190e has miss - PeachParts Mercedes-Benz Forum

420sel man · #1 03-03-2003, 11:01 PM

(84K MILES, 2ND OWNER)I LOANED MY WIFE'S CAR TO DAUGHTER, WHEN WE GOT IT BACK IT HAD A MISS AT IDLE AND ON ACCELERATION. I COULD BEARLY DRIVE IT. MY WIFE IS NOT PLEASED..........SO I INSTALLED NEW PLUGS, WIRES, DIST. CAP AND ROTOR BUTTON. RUNNING A BIT BETTER, BUT STILL OCCASSIONAL MISS AT IDLE AND HESITATES ON ACCELERATION. NOT MUCH DIFFERENCE BETWEEN COLD START AND WARMED UP, BUT SLIGHTLY BETTER WHEN FULLY WARMED. AT LEAST I CAN GET IT IN GEAR AND DRIVE IT NOW (AUTO TRANS). NEW FUEL FILTER ABOUT 6K MILES AGO. FILLED TANK WITH HIGH TEST AND A CAN OF 2-IN-1 FUEL ADDITIVE. MY GUESS IS THAT I'VE GOT A CLOGGED INJECTOR BUT THE MISS SEEMS IDENTICAL TO AN ARCING PLUG WIRE OR A BAD SET OF PLUGS. I AWAIT YOUR COMMENTS AND SUGGESTIONS.

sbourg · #2 03-04-2003, 09:42 AM

It has a 'miss' like not firing one one cylinder consistently? Intermittently? Not firing on several cylinders at times? An ignition problem would cause lots of these symptoms, as would a vacuum/air leak, and take your daughter off the hook. A bent valve might be the product of abuse.

Steve

#3 03-04-2003, 11:23 AM

Last week, had an intermittent miss on one cylinder on idle and also on acceleration.

After a tune-up, it was even worse so I suspected one of the plug wires were bad (wire condition worse after being pulled during replacement of plugs).

Changed the wires and it was spot-on.

Azhari
Babybenz 1991 190e 1.8

420sel man · #4 03-05-2003, 10:21 AM

STEVE, THE "MISS" I'M TALKING ABOUT IS NOT MY WIFE OR MY DAUGHTER.......

THE MISS IS INTERMITENT, AT IDLE AND ON ACCELERATION, MORE SO WHEN COLD (40-60F OUTSIDE AIR) BUT IS STILL THERE AFTER THE FAN HAS CUT THE FAN CLUTCH ON (AFTER COMPLETE WARM UP.) IF I KNEW IF IT WAS MISSING ON JUST ONE CYLINDER, LIFE MIGHT BE SIMPLER....RAN A COMPRESSION TEST, ALL CYLINDERS CAME IN 85-90 PSI.... I'VE WORKED ON A LOT OF VEHICLES FOR YEARS BUT DATSUNS, VWS, CHEVIES AND FORD TRUCKS DONT HAVE ALL THE SAME STUFF AS THESE FINE GERMAN MERCEDES...SO............I'M TRYING TO GET UP TO SPEED HERE. READING OTHER POSTS, I REALISE THAT THE PROBLEM MIGHT BE IN THE COLD START VALVE, OR SOMEWHERE ELSE. HOW DOES ONE TEST A COLD START VALVE? WHAT ABOUT THE AIR INTAKE TEMP SENSOR? THE ENGINE COLANT SENSOR? I WOULD APPRECIATE A BIT A ASSISTANCE IN THE DIAGNOSTIC END TO FIGURE OUT THE SOURCE OF THE PROBLEM, I DON'T WANT TO HIDE THE SYMTOM, I CAN'T AFFORD TO THROW UNNEEDED PARTS AT IT EITHER. SEVERAL PEOPLE SEEM TO HAVE HAD SIMILAR PROBLEMS WITH MISS AT IDLE AND ACCELERATION AND HAVE CLEANED THINGS UP WITH TECHCRON. OTHERS SAY REPLACE INJECTORS. SHOULD INJECTORS BE REPLACED PERIODICALLY OR ONLY ON ABSOLUTE FAILURE? I'VE GOT A MANUAL ON CD BUT IT'S BEEN DIFFICULT FOR ME TO UNDERSTAND, MUCH OF THE DIAGNOTICS REQUIRES VERY SPECIALIZED EQUIP.

THANKS THANKS THANKS MY WIFE WANTS HER CAR BACK (SHE HAS MINE TILL I FIX HERS........)

420sel man · #5 03-19-2003, 10:09 PM

I'M STILL SEARCHING FOR THAT MISS. COULD SOME ONE EXPLAIN TO ME THE ROUTING OF AIR THROUGH THE IDLE AIR VALVE. THERE IS A U-SHAPED HOSE (#1) FROM UNDER THE FUEL DISTRIBUTOR AREA THAT GOES TO THE IDLE VALVE, THEN A HOSE (#2) TO THE IDLE AIR DISTRIBUTOR. ON THE OTHER SIDE OF THE IDLE AIR DISTRIBUTOR THERE IS A HOSE (#3) THAT CONNECTS TO THE AIR FILTER HOUSING AND THE VALVE COVER. I ASSUME #3 IS NOT A VACUUM HOSE. AM I CORRECT IN THINKING THAT #1&2 HOSES ARE? IS THE AIR GOING THROUGH THE IDLE CONTROL VALVE REALLY AIR AND FUEL MIXTURE ON ITS WAY TO THE IDLE FUEL DISTRIBUTOR? OR IS THE AIR GOING THE OTHER WAY?
I HAVE READ A LOT AND AM CONTINUING TO READ OTHER'S POSTS OF THEIR PROBLEMS AND FIXES. I AM DETERMINED TO GET TO THE BOTTOM OF THIS PROBLEM...
YOUR REPLY IS APPRECIATED!!!!!!!

COLIN R

PS I did a second compression test with a different gauge, all were 145 +/- 3 PSI...

MTI · #6 03-19-2003, 10:52 PM

COLIN, DO ME A FAVOR . . press the caps lock key, Thanks.

kjsabat · #7 03-19-2003, 11:15 PM

Start from the basics. You need to check compression on each cylinder. 174 to 123 PSI min. Maximum compression difference 21PSI. Also check your firing order. 1-3-4-2. Cylinder #1 in TDC, pointer on timing cover must be aligned with 0 on the harmonic blancer. Remove distributor cap, rotor must be pointing toward notch on distributor body rim. Rotor turns clockwise. Remove covers from spark plug wires to make sure you have correct firing order. Do not race engine at idle, or drive the car. It may result in broken connecting rod.

Paul · #8 03-20-2003, 12:48 AM

before you start taking your dist out or yanking your engine apart, start from the real basics. if it's a vac leak it would be a constant miss.figure ot if it's a fuel delivery miss or an electrical miss. more than likely it's just a bad plug surpressor. measure the ohms from end to end on each plug wire. probably 1.5 on that car. see if they are all even. it's the first thing you should do and the easiest and and is the problem for an sharp miss at idle most of the time.
paul

420sel man · #9 03-20-2003, 08:59 AM

OK.... The miss is intermittent. Please note, I've put in new plugs, wires, cap and rotor. This is not a case of crossed plug wires... the car is driveable, it hesitates sometimes, stalls some coming to a stop or starting from a stop, sometimes.

Also note, I rechecked compression with different gauge, at 145 +/-,it's OK.

Any one with info on those hoses connecting to the idle control valve???? I am interested in understanding how the idle control valve works with in the whole CIS-E system. Also, there are three terminals on the valve. Why three? It looks like a solenoid type device, but that would only require two wires...

thanks again for the help!!!!

colin

sbourg · #10 03-20-2003, 10:07 AM

"I'M STILL SEARCHING FOR THAT MISS. COULD SOME ONE EXPLAIN TO ME THE ROUTING OF AIR THROUGH THE IDLE AIR VALVE. THERE IS A U-SHAPED HOSE (#1) FROM UNDER THE FUEL DISTRIBUTOR AREA THAT GOES TO THE IDLE VALVE, THEN A HOSE (#2) TO THE IDLE AIR DISTRIBUTOR. ON THE OTHER SIDE OF THE IDLE AIR DISTRIBUTOR THERE IS A HOSE (#3) THAT CONNECTS TO THE AIR FILTER HOUSING AND THE VALVE COVER. I ASSUME #3 IS NOT A VACUUM HOSE."

The #1 hose is the idle air intake from below the aiflow meter. The #2 hose is the output to the 'idle air distributor'. The #3 hose connects to the hose between the air cleaner and the valve cover, and the joiner is the plastic pcv device. It has a small orifice to meter the blowby into the idle air distributor, and a small safety port (open to the valve cover side) connected to the back of the fuel pressure regulator. Any leaks in the idle air system will give false metering mechanically and electrically.

If the hoses have not split, they will still harden and form leaky connections. I replaced all hoses and the rubber plenum of the airflow meter - anywhere rubber interfaced a connector. I also had to replace the rubber mount for the idle air valve (which I cleaned), since it was no longer flexible enough to remove and reinstall the unit without tearing. All parts were inexpensive except the rubber plenum, which was still only about $25.

If you plan to replace all this, the FI assembly will have to be removed - involved but not difficult - which is also the only access to the top bolt of the left motor mount. If you are thinking of replacing the mounts, you might want to coordinate the jobs.

Steve

420sel man · #11 03-20-2003, 01:31 PM

Thanks Steve,

Often answers lead to more questions in the search for the real answers...

Somewhere in this forum I read: The search for MASTERY is the start of a journey, not the end. One who attains MASTERY and stops seeking is no longer a MASTER......

The joiner or plastic PCV device, if anything like PCV's on other cars, it is subject to clogging, corrosion dirt etc. and subsequently will allow excess air into the manifold.... am I right?

I ordered the hoses and will try to put them on later today. I didn't order 'the rubber plenum', it looked like it would be a good afternoon's project. Perhaps next week...

I am interested in understanding how the idle control valve works within the whole CIS-E system. What is the source/pathway for the air going through the IDLE CONTROL VALVE on its way to the IDLE FUEL DISTRIBUTOR? Assuming that the air came through the air filter, it looks like it would then pass by the throttle plate. Anyone have a schematic of the air flow through one of these CIS-E systems that shows where vacuum is highest or lowest??? Why would air go from a plenum area into a small hose the through a valve etc.

Also, there are three terminals on the valve. Why three? It looks like a solenoid type device, but that would only require two wires...

Thanks again for the help!!!!

colin

sbourg · #12 03-20-2003, 02:58 PM

The rubber plenum connects the airflow meter housing to the throttle body. Taking the idle circuit air from this junction allows it to be metered. If you think about it, functionally the idle air valve bypasses around the throttle valve. You want it to serve the function of adjusting the air leakage around the throttle plate to maintain a constant idle speed - or vary it according to temperature, etc, inputs to the controlling ECU.

The airflow sensor plate will deflect in a correct metering of the idle airflow, and adjust the secondary fuel pressure for correct mixture control, both from its mechanical connection to the fuel distributor and the electrical feedback to the ECU from the sensor on the side. The ECU then fine-tunes secondary pressure via the EHA on the fuel distributor.

The plastic pcv device has only an orifice for metering. There are no moving parts, so nothing to wear out. Worst case scenario is that it would be plugged, and all crankcase vapors would pass to the intake via the air cleaner element. However, I would treat this device as fragile - as with all the plastic connectors. I carefully cut the old, hard hoses off to prevent damaging them. The new hoses are pliable and don't present a problem.

I don't know why there are three wires on your idle air valve. I know ours has only two contacts.

Steve

420sel man · #13 03-20-2003, 10:15 PM

The old hoses for the idle air circuit were not cracked, but were hard and needed replacing so I installed new ones. No real change. There is still hessitation when raising engine speed from idle, an occasional miss at idle. I have noticed that the 'economy gauge' needle is about 1/4" toward the right at idle. That is, vacuum is less at idle. At 2000 rpm the vacuum is highest (far left) but then swings 1/4" to the right as the speed drops to an idle. Am I right in thinking that this is because the idle air valve is bleeding air in and thus reducing the vacuum?

Also the plastic connector between the breather hose and the short hose to the idle air distributor is just a connector, no small orfice or restrictor.... Am I missing a critical part? The engine used to be so smooth and I don't think someone would have just snuck in in the middle of the night and snitched a small part like this. Any one know of a part # for a pcv for this engine?

IDLE AIR DISTRIBUTOR???? how does it work/function? Are there any schematics showing air flow or routing? From where to where?

once again, my idle air valve has three terminals--- anyone know what they are for? I would like to test it to make sure it is operating correctly. The throttle plate moves when I disconnect the idle air valve so I'm guessing it is doing something.

I am determined to learn enough to understand and fix this miss/hesitation so I can report back what the source of the problem has been...

Thanks!!!

colin

kjsabat · #14 03-20-2003, 11:24 PM

Why are you so sure, your problem is related to Idle Speed Air Valve? You said, you have an intermittent miss. Typically intermittent miss is relatedd to a failure of primary ignition circuit.
I refer you to Haynes manual. It has a good chapter on troubleshooting ignition system for your model. It will take you about 30 min to an hour to fully test your ignition.

420sel man · #15 03-23-2003, 08:51 PM

kjsabat

I took your suggestion and tested the ignition system. It all checked out OK....

I went on to test the heated O2 sensor, it too tested Ok....

Also found test values for that 3 pin idle control valve, it tested OK to.....

In the mean time I noticed that when fully warmed on a warm day the car seems to run OK..... so I'm now checking the coolant sensor at different temperatures---- will let you know -- it tested OK at 80 deg C and at 40 deg C. Will test again when completely cooled down.

Any other areas I should look at?

colin