Turboaction

At least I'm not the only one. Mine did it very rarely, but it has done it a few more times more recently. I hope it throws a code and gives me an idea which circuit is dropping out.

Welwynnick

Me too. I wouldn't worry.

Turboaction

Man, with this car, when it rains, it pours! Today on my way to work I got a check engine light. The car is down on power and it seems to be running on 6 cylinders. The car had a few misfire events when I checked the pending codes, but the cylinders were completely random. I'm guessing I'll be searching for a new coil pack or ignition module next.

I will say, so far this car is quickly on it's way to be as terrible as the car it was intended to replace. I hope once I get all the updated parts on this car the reliability improves. I always used to tell myself to get a car with high mileage, because those cars usually have all these issues sorted out already.

Welwynnick

Sorry to hear that, and welcome to V12TT world.

The lows are very low, but the highs go higher than you could imagine when its all working right (and most aren't).

You're probably right about the coil packs. Its the biggest weakness of the car IMHO. You may be able to get round the problem by replacing the spark plugs with new NGK IFR 6Q-G, and make sure the gaps are set to 0.7mm. The plugs last quite a long time, but they're time-consuming/expensive to replace, so sometimes people don't.

You may be able to help yourself with the coil packs. They overheat from their proximity with the turbos, so I made some better heat shields that stand off the packs, allowing air to circulate, and they reduce the peak temps on the coil packs by 6 deg C.



There are several upsides ahead. Here's one to look forwards to. The standard car isn't as quiet as it ought to be (at least none of the five W220's that I've owned were). There's a bit too much wind noise at speed, for a start. You can help that by cleaning the top edge of the windscreen and applying a bead of black mastic or sealant to the leading edge of the screen trim strip. If your car's like mine, most of the wind noise at speed will instantly disappear, and it'll be an even better luxo-barge than before.

Nick

Turboaction

Thanks for the tips! I like the idea of making a heat shield. My car has 94K miles and spark plugs will be on order shortly. Since the problem turned on out of nowhere, I'm guessing it's a coil pack or ignition box and not a plug. Either way, plugs will get replaced along with whatever electronic is broken.

I knew I'd be replacing a lot of parts when I bought the car, and it looks like I'll be fixing all of the problem areas in my first couple months of ownership. I just didn't expect so many things to die within 2,000 miles.

Turboaction

I checked the codes, and I have a cylinder #9 left bank misfire. Codes P20F3, P2050, P2059. The first code is for the ECI ignition module. It looks like I'll be measuring voltages to see what's going on.

I used to repair industrial electronics as a side job. What exactly in the coil pack fails? I'd have no problem pulling my coil packs and replacing all the power transistors.

If the coils fail, does anyone have a pile of old coil packs sitting around? I wouldn't mind trying to piece a few together to make a couple good ones.

Welwynnick

Here's the next tip, which is to avoid something bad happening.

ABC flexible hoses always fail - its guaranteed. The ones the engine compartment go first, because of all the heat. But they give good warning first. Then they stab you.

The first thing to do is inspect them, and look for signs of seepage. The hoses fail because the rubber perishes in the crimp joints , and the hydraulic pressure pushes the hose out in spectacular fashion.. If there's any sign of seepage, replace the hose, or else.

If you're handy, you can repair the hose cheaply and easily, rather than replace the whole assembly (and guess how charitable MB are about those).

Again, you can help to avoid these problems in the first place with heat shields. Use fire-sleeve or aluminised fibreglass sleeve on each flexible hose in the engine compartment. Look at the difference it makes using heat shields:

Without heat shield:




With heat shield:





These hoses were taken from the same location, around the bell-housing, but two were shielded. Although I did clean the shields up, the pipes are exactly how I removed them.

Nick

Welwynnick

By the way, be very, very careful removing coil packs. Did you spot the double "very" there?

They're fragile as hell (dealers break them all the time) and you can't simply pull them out.

You have to lever them out, front, center and rear, a millimetre at a time.

Nick

Turboaction

Good tip on the ABC hoses. I have a hose that goes from the valve block in the front to the right front strut that's starting to weep a little green. Once I get another replacement ABC pump I'll take that hose off to get R&R'd at the local hydraulic shop. They should be able to replace the rubber section for $100 or less. The pressures in the ABC system aren't anything unusual. I'll definitely consider insulation for the hoses near the exhaust. I know all too well what heat does to rubber.

I'm going to check Howard's thread to see how he repaired his coil pack. I really don't want to do the job twice, but at the same time, I don't mind saving a few dollars since I'm in the middle of buying a new house.

Turboaction

I will definitely heed your caution! I know how those tubes can create suction, and with 12 of them I bet they really get stuck! I'm going to have to be extra careful if I'm going to try to save this pack and rebuild it!

What I don't understand is how I failed both coils on a cylinder. Are the coils driven in parallel for a cylinder with a single transistor? If this is the case, a dead transistor is likely the culprit.

Welwynnick

Good. Here's the next tip. Coil pack failures used to mean a new coil pack every time, and that's always expensive.

However, MotorKing has recently (too late for me) started making new coils just for our V12's.

Do a search for "Mercedes Ignition Cassette"

Turboaction

Well i'll be damned, look at that! I imagine with a set of 6 I could have enough parts to rebuild at least one coil if not both.

Any idea if both coils have to fail on a cylinder before getting a misfire code? I'll pull my coil pack tomorrow and check it out with my multimeter. It should be easy to determine which coils and which FET's are dead.

Welwynnick

1. Repairing a hose is surprisingly cheap - I pay about 25 GBP each. Its a big, efficient and competitive industry that Mercedes really ought to tap into. I use hoses with compression fittings that go over the end of (clean) bare pipes. The steel pipes are mostly 10mm OD with 2mm walls. The hoses are SAE 100R2T 3/8" two wire hose. Its all industry standard stuff, and the pipe, hose and fittings only cost a few pounds.

2. There are three options to repair a hose - compression fitting, flare fitting and welding. Compression fittings are considered reliable. I started using them three years ago, and had no problems. They also allow you to replace the hose without removing the whole pipe assembly.

3. Compression fittings are the most flexible, and allow you to make sure the hose isn't in twist or tension when you install. That's really important. Never tighten the fittings until the hose is in its final installed position. Its difficult to resist.

4. The coil pack is tricky. Its difficult to remove the cover without damaging it, but it can be done. The failure may be coil, transistor or connections, but its difficult to figure by diagnostics.

5. Howard is the man. His thread should be compulsory reading for all W220 and V12TT owners. But here's another tip that I don't usually give away. There's a guy on the other forums called ricebubbles, and I strongly recommend ready every word he's written. He documents everything brilliantly, like this:
http://www.benzworld.org/forums/atta...l-service-menu
The mbworld and benzworld W220 encyclopedias are very good, but those two guys are brilliant.

6. This is what I did to the pump output pipes on my first TT. Compression fittings and Aeroquip firehose. Everything under the hood get too hot, unless its metal. If only Mercedes could have made replaceable ABC hoses (like brake pipe flexible hoses) then life would be much easier. And just imagine if they were all the same length - everybody could carry a spare! But I'm getting carried away and dreaming a bit.

Turboaction

I'll have to ask around to better understand how the compression fittings work. From my understanding, a hose company crimps the fitting on to a new rubber section of hose, then you take that assembly home and tighten the compression fittings on to the steel sections of the line. Does this sound correct? I agree that it'd be a good investment to replace all of the ABC hoses in the engine compartment. I don't mind spending a few dollars up front in order to make this car reasonably reliable.

I should probably make another thread for my next question, but I'll throw it up here anyway. My rear climate control always blows hot air, and my front climate control (heat/AC) works fine, but in order to get a comfortable temperature I need to set the controls to about 55-60F (much lower than the 70F I would expect). I'll be testing the temp sensors and actuators with the STAR tool once I get the engine/suspension taken care of.

Welwynnick

The parts and materials for a hose are cheap, but the crimping tool costs thousands, so you do need a hydraulics company to crimp the fittings. Its occurred to me that with an ABC system having about 25 flexible hoses, a keen DIY owner might even consider buying a used crimper, and making lots of spares.

The fittings slide loosely over the end of a bare pipe, and the nut is tightened to clamp the annular ferrule onto the pipe. Its a compression fitting because the ferrule is compressed onto the pipe. The ferrule has some ridges on the inside to bite into the pipe, so once its fitted, its difficult to get off again. Its like heavy duty domestic plumbing, using steel instead of copper.




Preparing the pipe is important. You can cut the old flexible hose off with a saw or even a plumbers pipe-cutter; I've used both successfully. Whichever you use, the pipe must be completely clean inside and out.

Getting the length of the new pipe is important, and I wouldn't expect to get it right first time. There's some tolerance and latitude for error and adjustment, but not much. This is the most difficult bit.

Once a compression jointed hose is on, its easy to remove and replace. The ferrule becomes an integral part of the steel pipe, and really you leave the nut and ferrule on the pipe and only change the hose and crimped joints, rather than the whole assembly.

This is the sort of approach that Mercedes should have used all along, rather than having proprietary pipes assemblies. The ABC system has to fit into some tight spaces, so many of the hoses necessarily have contorted shapes, but the hoses should be installed at accessible positions, and MB should have expected to be able to replace them easily, rather than vainly hoping they would last the life of the car. The rest of the hydraulics industry figured that out a long time ago. Flexible hydraulic hoses never last forever, and while nobody will guarantee their life, I've read a great deal and found that 5 to 6 years is considered the maximum reliable life. That's obviously not enough for a car.

Regarding the AC, I've never had to do any work on any MB, but I think Brian Rice's document in item 5 above is a great place to start.

Nick

wallyp

I suggest using the pipe cutter rather than the saw. It is almost impossible to ensure that you don't get metal bits ("sawdust") in the tube, and it's difficult to make absolutely certain that you get it all out.

Turboaction

Good advice! I have a small pipe cutter that should work well. That coupled with a quick de-burr operation should be all it takes.

I thought I'd give an update on my coil adventure. I removed the coil in about 45 minutes, and printed a couple dozen nylon wedges to release all of the clips on the plastic cover of the coil. I've separated the halves and will be checking the coils and transistors with my multi-meter tonight.

I'm curious if only the IGBTs fail on the board, or if the P channel MOSFETs also are prone to failure. I guess I'll see what came in the repair kit and go from there. I checked online, and I can replace all of the IGBTs and MOSFETs for about $85 on both coil packs. If the transistors are what kill the coils, it might be cheap insurance. None of my coils are visibly damaged or burnt.

Turboaction

Well, I have to say I'm a little baffled. The spark plugs have a gap of .7 mm, and all the transistors test OK on the coil pack (including the bad #9 cylinder). The coils are also all more or less the same resistance. The only thing I can think of is if the coils are arcing to ground rather than going through the plug. Either way, I'll replace both coils and transistors on #9 and see if it makes any difference. If not, it sounds like I might start chasing the ignitor module. I know it has been supersceded by a newer part number.

Welwynnick

I'm going to attempt the same thing this weekend. The first thing I did with my silver 600 was change the RHS coil pack, and now the black 600 has 1 to 6 misfiring. Having two V12's is ridiculous but convenient, as I switched ignition power supplies to confirm there was nothing wrong with that! Of course it could still be a wire, a connector or a ground.

I still have the old coil pack, which I held on to for spares, so perhaps now is the time. If I can fix that without having to buying another new coil pack, that would be the final piece to the solution of low (reasonable) cost V12TT maintenance.

I've no real idea what it is that tends to fail in the coil packs.

Nick

Turboaction

Well, I thought I've give an update since I finally got the car back in working order. I replaced the ABC pump a second time with another reman unit from BuyAutoParts.com. This one works fine and doesn't throw a code for low flow. So, if you want an ABC pump for about $500 and are willing to try a few before you get one that works, then this is the place to get one.

I also replaced both coils on cylinder #9 that was misfiring, along with all the spark plugs on that bank. I now have no misfire codes or ABC codes.

Once I get the climate control working properly, this car will be peachy. Right now the car is comfortable if the temperature is set to about 57 degrees F.

tusabes

How much were the individual coils and where did you buy them ?
Btw rock auto has abc pumps for $300 and Napa auto parts for around $400
Same hit or miss quality

Welwynnick

Good job, that's the kind of post I like to see. I assume you pryed the cover off and removed and replaced the offending coils with new King-whatever parts? Did you find any way to identify a faulty coil by inspection or measurement? I'm still struggling with that. I have two "bad" coil packs, and I'm trying to make one good one. I haven't been able to measure anything useful. I did continuity and insulation on everything, and they were all the same. In some cases I could see burns and bulges, and I replaced those. I tore some bad coils open as well. (they're pretty tough)

Some interesting observations, now: You can replace the coils easily enough, but you do need to remove the coil pack cover. I've removed two, and its no problem if you're VERY careful. There's a youtube video of someone trying to repair their own coil-pack, but they're ham-fisted, and they destroy the cover in front of your eyes - how not to do it. There's nothing to see, either. You can remove the coils by unscrewing and yanking the foil connections off, but you need to open the lid to solder new ones back in.

I think it IS the coils themselves that fail, rather than anything else. They get hot and overheat at the same point, about a third of the way down, along the metal seam. In bad cases you can see a burn, discolouration or bulge (in which case its very bad) but sometimes there's nothing visible. In that case, there are unfortunately no measurements you can take to identify a faulty coil. You just have to pull and record the DTC's when the engine is misfiring.

Other interesting thing is that the metal chassis casting of the coil pack is pretty robust. By reputation, I was expecting to find it rather weak and worryingly flexible, but it was nothing like that. Of course, the PCB is split into two, making it less vulnerable to bending damage, which is obviously good. I won't worry too much about them in future. I'll still take care, but it looks OK to use reasonable force (just not like a garage gorilla).

Nick

kraut56

Nick,
good stuff!

I too have several spares, but have never actually needed one.

What I found was that the red silicone insulator inserts sometimes break down, i.e. they cross fire from the spark plug top right thru the silicone sideways to the metal tube.

Replaced the red insert, and no misfire codes since.

BTW: MB says replacement of these inserts is MANDATORY on each coil pack removal/installation (maybe they know something). I just wash them with dishwash soap and then use a bit of silicone di-electric.

BTW2: I run regular, not iridium spark plugs with great results!

Turboaction

Thanks for the tips!

I bought the replacement coils/plugs/FET's on Amazon


I actually mix and matched plugs! This kit came with 6 Denso iridium platinum plugs, so I bought some Autolite iridium platinum plugs and used one of each plug in each cylinder. I actually had to gap the Autolite plugs, as the gap was WAY too big. I was able to gap the plugs without touching any of the contact surfaces.

I 3D printed a couple dozen nylon wedges to release all of the clips on the lid of the coil pack at the same time. This made prying it off incredibly easy.

I will take apart one of the "bad" coils and see if it looks failed below the metal case. If it looks bad, I'll label the other one good (unless you guys know a misfire code will be thrown with only one failed coil pack).

Turboaction

I will likely do this next time. If I'm messing with the coil packs every 25-50K miles, I might as well use regular plugs. The plugs in my V10 Dodge lasted 100K miles and they were regular $1 Champion copper plugs.

I've also been told not to use platinum plugs in turbocharged applications. It's funny they're OE in this car. They don't typically work well in applications around 150 hp/liter.