Bosch Super RO 488 plugs for M103?
 

Are the plugs in my '88 W124 the correct? If not I'd like to find the correct non-resister NGK plug. Anyone know a source?

Why non resistor? I used NGK TR5 which came out to $2 each.
http://www.ngksparkplugs.com/part_finder/car_truck_suv/results.asp?engineid=30015

I've read that the M103 was designed to use non-resistor plug but it seems no one stocks them anymore. I've always been very pleased with NGK plugs.

BP5EFS or BP6EFS for slightly cooler plug (highway driving). Until recently, I heard that Fastlane Phil stocked them. That may no longer be the case. Also, the MB Classic Center in Irvine apparently stocks the correct NGK plugs, and I can still get the correct Bosch H9DC0 at my local MB dealer. HTH

This info is from the archives so may or may not be correct. M103 originally
has non resister wire but had a resistor in each plug connector and non-resistor plugs.
At some point the big thinks decided to use resistor plugs and non resistor plug connectors and non resistor wire. So the answer to your question might be decided by what wire set you have. If what I said is not correct I would like to know what is correct.

This makes sense. AFIK its very hard to find non resistor plugs these these days.

This might help. NGK spark plug code
http://www.sparkplugs.co.uk/graphics...symbol_key.gif
The following spark plugs are specified for the M103
TR5
TR5GP
ITR5F13
TR5IX
So find one of these without the "R" in the name and you should be good.

Denso T20EP-U or T16EP-U

The model numbers I gave in my earlier post are the correct NGK plugs for the M103 engine. As for sources, it's true that you cannot just stroll into your local auto parts store and find the correct copper core non-resistor plugs. But there are lots of M103 motors in operation still, and we're finding plugs for them. It's worth trying the places I listed earlier. In addition to those sources, I know that there are several I-net vendors in the UK that stock these plugs and can fill orders within a week.

Resistor plugs work just fine and going out of the way for non resistor plugs is pointless. You will never be able to tell the difference from the drivers point of view unless you don't have resistor in both the wire or the plug which will cause interferance. In fact considering that the vast majority of us have upgraded out stereo and probably travel with more portable electronics today than anyone could have dreamed of in 1986 (cell phone, GPS, laptop etc) you are probably better off with resistor plugs and resistor wires. If you are going to use NON resistor plugs you need to make sure you still have resistorized spark plug wires like the factory originals. The vast majority of replacement wire sets don't have resistors.
cheers
Justin

The Bosch and Beru wire replacement sets have resistance built in. I wouldn't dream of buying aftermarket wiring sets for this car.

Get resistor plugs and non resistor wires. Whats the big deal? Having both resistor plugs and wires isn't going to hurt anything.

There has been a large amount of debating on this topic. I dont think its too much effort to find non-resistor spark plugs. I just bought a set of BP5ES's for my m116 and it wasnt all that expensive. $1.20 or so per I believe

******** has the T20EP-U's that I have in my m103 for $1.40 each....

The M103 when new and still now will perform at it's best when using the specified OEM or equal parts.

How do I know?

My M103 was purchased new, still own it, but now has the benefit of a period TurboTechnics twin turbo install.

What plugs do I run in my TT...?
NGK BP6EFS...
Easy to find?
All day long at around $2.00 each...;)

Ed A

Where to find? ******** has 'em but shipped from the UK. Anywhere in US?

?? You're looking for something closer than the several suggestions already made, including the ******** you yourself mentioned? Maybe, like your next door neighbor?