okay, sorry. I searched for the answer for my question about the location of the fuel distributor (under the air filter box).

Now, which screw are we talking about. I've seen some discussion about the EHA valve adjustment, so this sounds like what you're advising. Here's a pic I stole from Fastlane (this site). Can somebody point it out for me?

Okay, so my mechanic felt bad for me and said he'd do free diagnostics and a tune-up for me. He had it all day yesterday and it looks like about 75% of the symptoms with the rough idle and hesitation were the result of the emissions shop playing with the mixture. My car aced emissions, but it runs horribly. So my mechanic said that he was able to drastically improve the hesitition and idle issues.

However, he has the car for another day so that he can try to improve the idle even more. It's still giving him an erratic "hicup" or "bump" every few seconds or so... which is how it behaved before I brought it to the emissions mechanic. So I have to wonder if my car will flunk emissions again since it's set this way. Oh well, that's another 2yrs down the road.

He said he's checked all of the relevent wiring and the insulation is good. He said I have no vacuum leaks. ICV has been cleaned and is relatively new. OVP relay is brand new. O2 sensor and fuel distributor are new. He put in new plugs under warranty because apparently they were trashed (even though they are only like 8k miles old, max). New wires, rotor, coil pack. New injectors. He said he made the EHA valve adjustment as part of his tune up. I still have this coughing at idle apparently... I also suspect that I probably have a hesitation issue, although he didn't he didn't mention it and I didn't ask when we spoke yesterday.

What the "h" "e" double hockey sticks could be causing this extremely ellusive problem?!? Any other ideas?

Okay, my mechanic did a free diagnosis. He adjusted the fuel mixture/pressure. The car idles perfectly and there is no sign of hesitation anymore. However, the car still dies a couple of times when cold-starting.

The german car shop/emissions shop that did the work on my car will never get my business again. They replaced the EHA valve and the crank position sensor... They also did some diagnostic work. $1,400 later, my car was running worse than ever, but was able to ace emissions because my car was barely burning enough fuel to run. Idiots.

When I look back at my first post, the code that this shop pulled for the check engine light said:

“Oxygen sensor shorted to positive, MAS Fuel pump relay circuit 87 not functioning"

They reset the code. So when I took it to my regular mechanic, he was unable to pull it for himself. But he told me he got the car running great, aside from the cold start issue. All he charged me for was spark plugs. Apparently the fuel mixture ruined them. But his recommendation was the MAS Control unit, which houses the fuel pump relay.

Suddenly the lightbulb went off in my head. That's what the damn code was in the first place. If that first shop had pulled their heads out of their you know whats, they would've tested the 02 sensor and the MAS Control unit/fuel pump relay first. but they assured me that my car's self-diagnostics were so old and "rudimentary" that they are almost always wrong. I have a new 02 sensor, so I'm pretty sure it's not that. And based on what I've read on this site, the MAS Control unit connects to the O2 sensor, so any 02 sensor issues could be caused by the MAS Control unit.

My regular mechanic will get my business every time from now on. Now I need to try and find a working used MAS Control Unit. I can't believe that little box is $400!!!

I'll report back when I try the MAS Control Unit. MAybe it will make my A/C work again too, since I've heard a bad MAS Control unit can cause the compressor to stop working. alright, you guys are probably sick of me by now. lol.

Well Im glad to hear you have your car on the verge of runnning perfect Pete!!
Chris

__________________
94 E320 with:
18" ///AMG Monoblock II's,AMG Gen II front bumper, H&R spings,500E sway bar, Bilstein sports, Eisemann Exhst, K&N,E500 Headlamps, Crystal Clear Corners, Avantgard Grill ...and more stuff to come! oh yeah 241k miles!!


My Car WOO HOO...... Now SOLD
New car.... 2001 Jaguar XJR!!!!

Hey Chris. I don't see too many bnzsporters over here!

I have the transmission rebuild and the MAS control unit replacement left. Then the car should be running well... It better be after all the money I've put into it!!!

Old thread, I know. But I finally have it in my tight budget to buy an MAS Control unit. After some hard searching, I was able to find a rebuilt unit for $270, plus a core charge of $65 which will be refunded to me. I will flip out if this doesn't fix my problems.

I feel a loyalty to the Fastlane and wish I could've bought it from Phil, but this is $122 cheaper after shipping, and Phil doesn't sell the rebuilt units to my knowledge. If the price difference were smaller, I would've bought a new one...

I'll let you guys know how things go when I get the part on Tuesday.

Ya done yet??

Chris

__________________
94 E320 with:
18" ///AMG Monoblock II's,AMG Gen II front bumper, H&R spings,500E sway bar, Bilstein sports, Eisemann Exhst, K&N,E500 Headlamps, Crystal Clear Corners, Avantgard Grill ...and more stuff to come! oh yeah 241k miles!!


My Car WOO HOO...... Now SOLD
New car.... 2001 Jaguar XJR!!!!

ha ha, hey Chris. The bungholes told me they were gonna ship the part on Thursday last week and didn't get around to it until like 5pm last night. So I won't get it until Thursday. But you better believe I'm gonna pop that sucker in the minute I get it. I'm a little nervous about it though. I'm sick of spending money on repairs and I'm not completely convinced that this will solve it. But it's my only lead at this point...

Then I have to do the transmission. Then cruise control. Then the A/C conversion. Then fix my crooked / tilted drivers' seat. Then fix the passenger headrest that won't go up and down. And finish the damn car stereo. Why do I have to love my car so much? I feel like I'm a woman married to a wifebeater. and I keep coming back to him. ha ha

I feel your pain,and that was part of the reason I sold my car, AFTER I fixed all the little problems....and now I miss her. So dont do as I did, keep her!!

Where did you have your throttle acutator rebuilt? I had mine done by www.4mercedes.com. Too if your is anything like mine was, after it was rebuilt my cruise worked perfectly!!

Chris

__________________
94 E320 with:
18" ///AMG Monoblock II's,AMG Gen II front bumper, H&R spings,500E sway bar, Bilstein sports, Eisemann Exhst, K&N,E500 Headlamps, Crystal Clear Corners, Avantgard Grill ...and more stuff to come! oh yeah 241k miles!!


My Car WOO HOO...... Now SOLD
New car.... 2001 Jaguar XJR!!!!

Well, that list of stuff are things on my to-do list. The list of stuff I've actually done is WAY WAY longer.

So I haven't done anything with the cruise control yet. I'm praying that my cruise problem is the electronic module. So one of these evenings I'll resolder the circuit board. But I have a creeping suspicision that it's the actuator like yours... Cuz my cruise worked when I took my car in for the head gasket job and didn't work when I got it back. So maybe the linkage or the actuator were damaged... I've read that it's a huge PITA to get to the actuator...

I pretty much never use cruise control, so it's not worth it to me to spend any money on it. But if I can fix the cruise control amp for free and that solves it, I will be very happy. That will be the first free repair I've ever done to this car!!

Ah so your buying a new mass air flow sensor?? I replaced that too on mine along with the harness, the actuator, the spark plug wires and boots, the trans, the trans and motor mount, the flex disk...yada yada yada!! lol

Chris

__________________
94 E320 with:
18" ///AMG Monoblock II's,AMG Gen II front bumper, H&R spings,500E sway bar, Bilstein sports, Eisemann Exhst, K&N,E500 Headlamps, Crystal Clear Corners, Avantgard Grill ...and more stuff to come! oh yeah 241k miles!!


My Car WOO HOO...... Now SOLD
New car.... 2001 Jaguar XJR!!!!

Actually, no. I'm replacing the "MAS Control Unit". It's that electrical relay right next to the battery that has a knob on the top with the "I" and "O" positions in the top. It's in an aluminum casing. It interacts with tons of components... the fuel pump relays are actually housed inside this unit on my car. If they weren't, this would've only cost me like $50. Instead, it will cost me $275 after I get money back for the core charge... that that's just for the rebuilt on. new ones go for $400ish. $500 from the dealership.

It literally takes 10 seconds to swap out. I figured I could handle that DIY!!

The mas air sensor is something else.

Alright. So I got the MAS Control Unit today and installed it. The car started up immediately, so it seems that this has cured my cold start problem.

I took the car for a 1 1/2 test drive... Drove in the city, on the highway, and everything in between. The first hour was great. I could hardly tell the car was running.

And just when I was telling my wife how glad I was that the problem was FINALLY solved... thump... thump-thump. The car starts erratically missing at a red light. Not horribly, but enough to give the car a good shake every once and a while. The hesitation is gone, it seems. But I'm willing to bet that it will come back in a few days.

I'm at wits end you guys. Please help. I have a long long long list of repairs. I've extensively searched this forum. I've spent tons of money. I've talked it through with my mechanic and he's baffled. He can't even think of what to try next, he's done everything he can think of. I brought the car to another shop thinking that they might have a different perspective, and they just made the car run worse. This is a mechanical device and it simply must have a solution somewhere. For those who don't feel like going back and reading everything I've done:

-Plugs, wires, cap, rotor
-Fuel Distributor
-Injectors
-Cleaned ICV - seemed pretty new when I did this
-Replaced OVP
-Replaced MAS Control Unit (which houses the fuel pump relay on my car)
-Coil pack replaced
-Head gasket, valve job
-02 sensor
-Crank position sensor
-EHA valve
-Had mechanic mess with the mixture, this solved the problem for around 100 miles then it came back
-Mechanic inspected all relevent electrical wires and vacuum hoses, no problems noted.

The only other possible part that I don't think I've done that this forum mentions is the "speedometer sensor". From what I've read, a bad one could have an effect on idle, it doesn't seem that the symptoms match mine. Maybe it's the throttle actuator like Chris mentioned?!? I'm just throwing any idea on the table that I can come up with. This car is a POS... I'm so frustrated.

I'm dying here, please help! I love this car too much to give up, but I'm getting close! I may have to start a new thread since nobody seems interested in this one anymore...

Did you check and lube the complex accelerator linkage in the car. I have a 300CE and once in a while the linkage seems to hang up when I come to a stop and keeps the rpms at a higher level than normal idle speed in drive position (600 + is normal). I then lube the linkage, or just shut down the engine and work the accelerator to the floor and release. Then the system works fine. This is just an occasional happening with mine, but thought I would mention it.

__________________
Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

Thanks for your reply. I don't think that's the problem I have though. My car idles at right around 600rpm. It's extremely smooth and the idle speed doesn't fluctuate at all. But then all of a sudden it hicups. It's not a constant shake, it's a series of single thumps. There's no rythmn to them; it's very random.

Anyway thanks again for taking a look. Anybody else?