'88 300TE SSS ideas? - Page 2 - PeachParts Mercedes-Benz Forum

BENZ-LGB · #16 05-29-2006, 10:59 PM

I think that a rattling OVP is not good (not sure).

If bad, nail it to a stick and give it to a baby to play with

(J/K)

BTW did you ever find the "missing" hose leading to (or from) the breahter hose???

Let me know.

Merkey · #17 05-29-2006, 11:32 PM

I did not get the chance to pull off the airfilter yesterday or today..
Tomorrow will look better for me I hope!

simmo300e · #18 05-30-2006, 05:09 AM

OK, to address some of the minor stuff first. Your missing hose runs from the Fuel Pressure Regulator to the air filter housing breather hose, afaik it is only there to siphon off fuel if the FPR diapraghm springs a leak.

Your OPV should not rattle. If you open it up you will see a relay, which can get stuck. A malfunction in this unit affects current flow to the Idle Control Valve, which i assume is what you refer to as the IAC. There are also some soldered connections inside which crack and can cause problems. If you have antilock brakes, a faulty OPV will cause the ABS light to come on as it runs on the same circuit.

Disconnecting the power from the ICV while the engine is running will affect the idle as with no power the unit reverts to limp home mode, which iirc fixes the idle at around 600 rpm, less than normal, which is enough to get you home without idle control but you will find the motor has a tendency to stall.

Test the OPV by disconnecting the lead from the ICV and measure the voltage between the sockets while the engine is running. If the OPV is OK, there should be around 6v. If it fluctuates, or drops to zero, chances are the OPV is bad, Worst case scenario your engine control unit is shot. Mine was.

If there is a vacuum leak that is affecting the idle or smooth running of the engine, it will be in one of the two hoses that connect the ICV. They get hard and loose on the connectors over time. The pipe to the right of the unit is easy to swap, the one to the left that runs down and under the intake stuff is a three handed job to replace.

Automatic transmission, yoyo with that. Can't help you.

It might be your ignition but I'm not convinced from the symptoms you are describing. The rotor arm and contact points do wear but I would have thought the engine is more likely to be missing rather than stalling if that's the case.

As for the flat battery, check the voltage across the terminals with the car running, it should be around 13.5v if the alternator is working. If its less than that, there's your culprit. If you're lucky it will be worn brushes, which are easy to replace, if not you need to replace the alternator. There's some good info on this if you search, I'm in the middle of the same problem with our 230 as we speak and found out all I needed to know here

http://www.peachparts.com/shopforum/search.php?searchid=748096

Hope this helps and good luck getting it fixed.

Benz-lgb: the part circled in red is the Fuel Pressure Regulator, its function is to maintain fuel pressure in the CIS system. Although there is a hose to siphon off fuel if there is a leak in the diaphragm, I understand that they rarely malfunction. Unless you get water in your petrol, in which case they will end up in the bin with all the other expensive bits of injection system.

Merkey · #19 05-30-2006, 09:37 AM

Thanks Simmo... That will help me a lot!
IAC (GM speak for Idle Air Control, same thing!), but thanks for the MB name!
I might be wrong... but I am begining to think there may be two problems here.
The stalling... and the slight misfire when hot.
How much was the engine control unit?

I will write more later.

BENZ-LGB · #20 05-30-2006, 09:44 AM

Simmo:

Thanks for the info.

Now, could you take a look at the third picture (in my earlier post to Merkey)?

There is a part circled in red. It has an electrical connection leading from the part itself to the wiring harness (or loom as Merkey and his Brit expatriates like to call it

).

That part is connected to the throttle linkage. It has a cam mechanism that moves a plunger in or out (of the part) when the throtle linkage is actuated.

Any idea what that part is?

Thanks.

AF300E · #21 05-30-2006, 10:13 AM

Yeah. Its the released throttle switch (i think, i didn't look at the pic but by your description i think thats what you are refering to). It tells the fuel injection system when the throttle is realeased (coasting) and adjusts the eha to cut the fuel flow (not completely) i believe to improve fuel efficiency.

Please correct me if I'm wrong, I'd like to understand CIS-E as best I can.

JoeR · #22 05-30-2006, 10:45 AM

Try unplugging the EHA and see if the drivability problem changes.

Doing that will help indicate whether a problem is in the mechanical or electrical portions of the fuel control system.

BENZ-LGB · #23 05-30-2006, 11:14 AM

Quote:

Originally Posted by AF300E

Yeah. Its the released throttle switch (i think, i didn't look at the pic but by your description i think thats what you are refering to). It tells the fuel injection system when the throttle is realeased (coasting) and adjusts the eha to cut the fuel flow (not completely) i believe to improve fuel efficiency.

Please correct me if I'm wrong, I'd like to understand CIS-E as best I can.

Thanks mate.

Merkey · #24 05-31-2006, 10:12 AM

Yesterday, we went to a local lube shop to get the oil changed on the 300TE... no, dont freak out! I only let em do the oil... and bring my own filter!
Anyway, while we were there.. the was an 87 300E in the next bay.
LGB, I saw the line, and now I know what and where.. Looks easy to fix!

I still cannot get my head around the Vac gauge... every day, every stop, and idle condition, its in a different place!
Is there a static vac test that will show me a leak down?
Maybe I am getting fixated now, but I do notice the fuel gauge jumps around a bit too! Its kinda jerks... could it be a bad connection?

BENZ-LGB · #25 05-31-2006, 10:32 AM

Quote:

Originally Posted by Merkey

Yesterday, we went to a local lube shop to get the oil changed on the 300TE... no, dont freak out! I only let em do the oil... and bring my own filter!
Anyway, while we were there.. the was an 87 300E in the next bay.
LGB, I saw the line, and now I know what and where.. Looks easy to fix!

I still cannot get my head around the Vac gauge... every day, every stop, and idle condition, its in a different place!
Is there a static vac test that will show me a leak down?
Maybe I am getting fixated now, but I do notice the fuel gauge jumps around a bit too! Its kinda jerks... could it be a bad connection?

It has to be a bad connection or a vacuum loss.

Like I said earlier, mine jumps around. Since my daughter used to drive it all the time I can;t remember if it had always done it or not. All I know is that, like you, I notice it all the time.

The gauge in my 420SEL was smooth and right on. To the left at idle or coasting, to the right when accelerating.

I am glad that you were able to figure where the hose goes...I'm sorry that my pics didn't help

Did you see my third picture? And F300E's response?

check your release throttle switch (and the wiring leading form the switch to the wiring loom).

Merkey · #26 05-31-2006, 10:41 AM

I did see your pic and it was very helpful... I knew exactly what you were talking about, and the pics proved that point!
Just seeing it in person was the icing!

I am going to drive the car every day for a while, and get an overview of the performance and conditions.
If its a general concesus that the OVP is shot, we will get a new one.
I will do the tests that simmo suggested, and we will go from there

I find it difficult to describe the miss at idle and low revs. Its not there when the engine is cold or indeed when first at operating temp. It starts after about, say 20 mins of driving.... I want to say that it maybe electrical and "heat soak" related, but of course I might be wrong!

BENZ-LGB · #27 05-31-2006, 02:02 PM

Is the miss like a "burp" or a hiccup"?

Merkey · #28 05-31-2006, 08:50 PM

Hiccup.
All the way to at least 2500rpm on a light throttle, I think I can feel it.
After that I feel it may be there, but I cant feel it.
Its not consistant, like a bad wire or plug or valve.... sometimes it double hiccups inside 2 or 3 seconds... then goes 20 or more secs between misfires.
Again only when hot.

Merkey · #29 05-31-2006, 10:04 PM

Simmo...
I checked the voltage between the two terminals of the ICV... 12.5V ish.
Is that right?

LGB....
Well, look at this!
I thought it would be a nipple... but, no... of course... my life is not that simple!
So there must be some special... super expensive rubber fitting/part for this! DOH!

BENZ-LGB · #30 05-31-2006, 10:25 PM

Quote:

Originally Posted by Merkey

Simmo...
I checked the voltage between the two terminals of the ICV... 12.5V ish.
Is that right?

LGB....
Well, look at this!
I thought it would be a nipple... but, no... of course... my life is not that simple!
So there must be some special... super expensive rubber fitting/part for this! DOH!

Dang...maybe time to go to the dealer with a copy of the pic and see what they have in stock. I know, from looking at mine that on the end at the breather hose tehre is a red connector. At the other end, the nippleless end, there is a black rubber hose. In between, there is a clear plastic hose.

Simmo says it is basically a syphon hose, so the black end is probably just "shoved" into the fuel pressure regulator. No big deal, just need to buy the right hose.

BTW, that is the wiring harness (or loom for you guys). Treat it carefully.

If you look at my pics, you will see where Enrique ran new wires from the ICV back to the "black box."

Before that, the car was stalling constantly -- 2 or 3 times in one single run. Now it still stalls, but it is only once in a blue moom. So I assume more wires need to be replaced....

I can;t help you wiht the hiccup part. My 300TE idles buttery smooth (smooother I think than the newer E320). Still, however, it does hiccup, it shudders, but then it catches itself up and it is back to normal.

In fact, I drove ther 300TE to Burbank Airport to pick up my daughter (the 300TE's former caretaker). So she of course insisted on driving "Alice" for old times' sake.

When we got home, we were stopped at a light and the car hiccuped. She looked atme, afraid that it would stall, but it did not. It caught its breath again and ran fine.

I had a bunch of vacuum hoses changed. Over time, as Psfred said, rubber vacuum hoses get old, brittle and crack. The W124 had (as far as I've been told) Benz's new fuel saver engine management systems. I think that the integrity of all the vacuum circuits is very important for these puppies to run right.

So, how do you feel about replacing bad hoses?

BTW, the rubber hose leading from your ICV back to the engine (the hard one to replace) looks pretty good in that picture.

So you are lucky....