This is a '91 190E 2.3 with rotary idle air valve. The valve meters air from the rubber plenum below the airflow meter, and discharges it into the port area of the intake runners - i.e. after the throttle valve. This intake port connection uses a Y-shaped rubber hose that connects to the air valve with one branch, and the other goes to plumbing that connects to the valve cover port, the air cleaner, and a small line to the fuel pressure regulator.

I have replaced most of this rubber plumbing, but haven't been able to identify all of it. I fear disconnecting the old rubber for inspection until I can obtain new, since it is likely it will rupture. So, I am uncertain what hidden components may lurk there.

I would think there would have to be a check valve of some sort in this second branch of the 'Y', and wonder why there is any connection at all from these components to the intake port - bypassing the metering circuit?

I have an intermittant high-idle condition, and not understanding what all is done here troubles me. Thanks for any input.

Steve

I have included a pic - unfortunately the lettering didn't come out clear when jpegged.

Attached Thumbnails

 

So what you need to know: is any connection at all from these components to the intake port - bypassing the metering circuit? that would cause this high idle condition ...

I don't know .... anybody?

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Still hoping someone knows the answer?

Steve

Thanks for helping keep the thread alive, Haasman. Anybody know the answer?

Steve

Steve

I know someone has the answer. I did a search but did not come up with a lot of threads using: Idle Circuit 190e air. One fellow posted all the work he did, impressive, and not one reply. You may be interested in seeing what he had done.....

'89 190E Stalling (I've done my homework!)

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Thanks for the link, Haasman. I don't think that fellow's problem is much like mine, but he certainly has put a lot of diagnosis into it.

My problem used to be worse, and included a stall when I would come to the first 'stop' of the morning. This was due to a ruptured hose from the idle valve to intake manifold, and is why that item is 'new'. There is still some old rubber in the system, and the feel of it at connection points is a bit loose - potentially air leakage that might be significant at low flow rates.

The bottom of the air meter unit is rubber, molded to slip over the throttle body. A port on it attaches to a hose that goes to the input of the idle air valve. Neither of these parts has been replaced, so the plastic joint connecting them fits suspiciously. The only 'unknown' section is the area I mentioned between the manifold port and the cam cover port. It LOOKS like unrestricted joins of straight rubber tubing, but that wouldn't make sense. I may end up disassembling it - risking ruptures developing - since it would appear any rubber with the right ID will work.

Still, the nature of the problem is that it disappears if I turn the ignition off then restart. Idle returns to 700 rpm. This would appear to hint at Stevebfl's finding of resistance in the OVP relay, but I can't get the @#$ thing to come apart. So, I'll splice in a diagnostic connection to monitor it's voltage output while I drive, and see if that is the problem. If it's bad, it's cheap to replace. If it's good - real expensive!

Steve

Steve,

thanks for the update. I have a 2.3 as well.

Thanks for your patience in explaining specifically what you are trying to solve. I get it now.

Keep us updated ... this is going to interesting.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

An update on my odyssey. As I feared, getting the correct hoses is a problem (of identification). The two I received yesterday - after lengthy phone researches with a parts house - were incorrect. I also received the OVP and replaced it - no time to hookup to and monitor the output from the old one. Since I was in the neighborhood, and all else had failed, I removed the entire hose assembly from the output of the idle air valve, to study its function and get part #'s.

As you can see, there are three hoses connected together, the part #'s embossed on them. The plastic connector between 19 87 and 21 87 is an ordinary barbed tube. The one between 21 87 and 43 87 has more elaborate plumbing, but no moving parts. It contains a shaped funnel terminating in a small hole - the metered PCV orifice mentioned in other posts, and the only opening between the hoses. The small port visible at right angles is open to the 'breather' side of the assembly, and connects to the pressure regulator safety port.

The hose I need to replace is the 21 87. All three look similar in the photo, but the end hoses are new, compliant, and seal well onto the plastic connectors. The center one is old, hard as bakelite, and certainly brittle. It no longer grips the connectors tightly, and certainly will leak air some. I could not remove it from the connectors without fear of breaking it.

Other old rubber in equal need of replacement are the bottom of the air flow meter plenum, which I received the correct part I believe, and the hose from that to the input of the idle air valve - and that was the other incorrect hose. The latter part I still need to identify somehow, but I won't pull all THAT apart until I have the new hose in hand.

Anyway, idle and drivability were on good behavior for the drive in to work today, so the OVP may have been the main component causing the problem. Since intermittant, I'll give it some time to make a positive judgement.

Steve

Attached Thumbnails

 

A final note - the problem has not reoccurred since the OVP was replaced - a couple weeks now. Since I replaced it, I replaced the rest of the rubber plumbing, but am convinced that was not the significant issue. The date of the OVP replacement is the date the problem was solved.

Steve

More than likely, you're going to find that the THROTTLE VALVE SWITCH is NOT closing at IDLE . . .

This is the cause of this problem in the MAJORITY of cases . . .

It is remedied by:

Cleaning the THROTTLE BODY with carb cleaner and checking the THROTTLE BODY STOP SCREW adjustment, and then checking the THROTTLE SWITCH to be sure that the IDLE CONTACTS are CLOSED at IDLE . . .

Also check to be sure that the ACCELERATOR CABLE is NOT too TIGHT causing the THROTTLE BODY NOT to return to IDLE . . .

On the '87 190E 2.3:

I noticed that if I try and adjust the throttle cable to remove the slack at the pedal by tightening it at the throttle body, the arm moves off the switch.

How do I remove the slack but keep the throttle switch closed at idle?

Hopefully this makes sense.

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Is the RETURN SPRING still intact ? ? ?

Yes, I believe it is. The gas pedal has a bit of movement before it actually starts to move the throttle linkage. This is what I am trying to remove.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

It SHOULD HAVE . . .

You DON'T want it TIGHT . . .