M119 hesitation, missing and stalling

[aldedmon]

For those of you who have been experiencing intermittent engine stalling and misfiring issues, I think I have the smoking gun . My issue was my car would start up and run fine . As it would reach Op temp, it would hiccup occasionally , but still run fine. As I proceeded it would eventually stall. Wouldn’t matter if I was driving it or performing this experiment in my garage . The culprit WAS NOT primarily the RED insulator caps which would shows some condensation. The problem was actually the Distributor Caps/ Rotors. I’d been chasing this issue for years . So although the Caps, Rotors / insulators were “ new” the problem still returned . BOSCH = BAD for M119. BREMI = GOOD.
Bosch and manufacturers who follow their Rotor / DC design have a limited electrode surface area and will corrode particularly in high humidity areas.(Houston) BREMI has a design that has a much larger electrode surface contact area. Therefore the spark can find multiple areas to arc and stays cleaner longer ...
The first cap is the BREMI. You can see that the 4 peripheral electrodes are almost completely exposed , Whereas the Bosch design shows just the face of the electrode and the rest is covered in the mold.

 

[aldedmon]

Similarly with the rotors, the BREMI rotors leading electrode is almost completely exposed and check out the center of the design where the spark Arcs. It’s open allowing the spark multiple pathways. Now compare that to the Bosch design which A only has a fingernails length of electrode protruding and B the center of the rotor is closed with a circle of electrode there embedded into the mold . That circle gets corroded quickly as does the short finger length protruding electrode
See BREMI VS Bosch designs in photos ( beck arnley as shown is same design as BREMI)

 

[aldedmon]

I was plagued by this issue for years and after researching and ultimately installing the BREMI Caps and Rotors , I am finally Done with this frustrating issue. So if your having these issues, check out your R’s and DC’s. You can remove them and remove the oxidation with 400 grit sandpaper and see if that doesn’t resolve your issue. It would mind fit a while , then I’d not drive the car a month and go for a drive and STALL...
Oh by the way, if it STALLS, don’t call the wrecker yet... let it cool off (go get lunch about an hour’ish) ... it’ll start back up like new again ... till it gets hot again !

 

[gsxr]

How long (or, how many miles) have you put on the Bremi parts?

Also, you had the issue described where you'd park the car for a month, then go for a drive, and after 20-30 mins it would stall (or misfire), then not-restart until after about an hour - that is classic symptoms of the insulator issue, not caps/rotors (unless a cap or rotor is defective). There are many threads with hundreds of posts discussing this in detail, and the issue has been solved multiple times with new insulators and the same old caps/rotors.

 

[aldedmon]

I know , I read damn near all of them. I was adding from my personal experience that insulators were not the resolution. I’ve had these parts on since 2018. The design of the rotors coupled with Houston Humidity and sporadic driving WITH BRAND NEW BOSCH PARTS lead me back to the same frustrating starting point ... till I made the switch. I’m Just saying if the insulators are due for change , the Caps and Rotors probably are too . Kill two birds and be happy

 

[195910]

I understand your point, the increased surface area is supposed to give more correct paths for the voltage, but there might be another issue with the design. I am using the BERU cap which has the same design, but they were contaminated by the moisture and oil.

 

[gerryvz]

I would love to see a photo comparison of caps and rotors from Bosch (aftermarket), Bosch (MB factory part), Bremi, and Beru.

 

[gsxr]

Pics of Bosch and Beru aftermarket are at the link below. Beru aftermarket rotors are reboxed OE.

Index of /images/M119/EZL/caps+rotors

I never purchased OE caps but last I heard they looked the same as Bosch aftermarket. And I never had Bremi to get photos of either.

 

[195910]

I agree with Gerry (pronounced with J or G ? ) We need a side by side comparison of a new production 2018/2019 OE caps with Bosch caps and Beru.
We might be looking to a reboxed 3x over priced unit.. or a different quality level.

Guys from the M-B Club GB were using OE and still had issues.

BTW, what is the ohm values for the terminal? I am getting around 950 ohms with terminal 1 at 1036 ohm. Terminal 1 in Old cap was at 18K ohm !!

 

[gsxr]

Caps AND rotors should both have ~1000 ohm resistance per terminal, give or take ~10%.

Plug boots should be 2000 ohms.

Plugs should be zero.

 

[195910]

Caps AND rotors should both have ~1000 ohm resistance per terminal, give or take ~10%.

Plug boots should be 2000 ohms.

Plugs should be zero.

Thanks Dave,

I am surprised of the results, the old Bosch OE right bank cap had terminal 1 at 18-19k ohms and terminal 7 at 1.8k ohms.
The beru is in spec, I am Cleaning the Beru caps again with acetone, making sure to soak the terminals. then air dry for a couple of days and reinstall.