This is a photo of my undercarriage (front half).The diagram overlay of the CAT is from the W201 CD.Is that just a stage of the exhaust or is that a CAT?

I've been trying to confirm the existence of a CAT in my car but have been getting contradicting info.

With my VIN no., the parts guy is able to provide an OX sensor and says that my car has a CAT.

The wrecker, on the other hand, who deals in only Benzes, says that the 1.8 never came with a CAT.

Anyone?

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Yes, that sir, is a catalytic converter.

Gilly

Eeeeeks!

I gotta check my duty cycle!

I spent abt 2 months troubleshooting the car running rich (which turned out to be a foiled fuel distributor); all the while still using the car as my daily ride.

I don't know if the CAT is screwed (i doubt) coz my fuel mileage is 10 to 11km/litre after I swapped out the FD.If I have a CAT, I wonder if the OX sensor is still OK?

Thanks for the info, Gilly.

I just checked my Mercdes history disc (got almost anything you need to know in it, except tech info ) and it says the 190E 1.8 DID have the Cat.

Gilly

Thank you very much for taking the trouble to confirm, Gilly.

I think I may have a partially clogged CAT coz ever since the FD swap, I have a slight hesitation on acceleration.

What are the symptoms of a clogged CAT?Are they obvious?I know of the sulphur/rotten eggs smell, which I do not have on my car.

Also, there is a tiny hole in the muffler.

When I accelerate hard to overcome the slight hesitation, the exhaust sounds like there's water in it.If I ease off the pedal, the sound subsides.

If I gradually accelerate, the car hesitates slightly and then after 1200rpm, it's like a slingshot effect.

I don't know if this "watery sound" thing is due to the hole in the muffler or whether it's an attribute of a foiling CAT.

Cheers.

Doesn't sound like a bad cat to me. This whole "slingshot" effect at 1200? Not a cat. It would struggle and stop accelerating by 1200 or so, gets worse at higher rpm's.

Gilly

Cool!

So I probably will take a look at the airflow plate basic/zero position next.

If it's the position is off, it may cause hesitation, correct?

Thanks for the really useful information, Gilly.

That problem could just be so many things. I guess the airflow sensor plate wouldn't really "jump out" at me first, but sure I suppose it could be. Unless someone has messed with it, i would think in terms of a "bad" position sensor though, not the adjustment. If that thing is off too much the engine will just die, as in quit.

Without my own test drive, it's hard for me to judge, but in general my gut reacton would be to start with checking the plugs (wear, type, gap) and the cap and rotor, maybe check cam timing. I assume the basics like this have been covered already, but I don't really know that for sure. What about air and fuel filters? Has a fuel pressure and quantity test been done? What about fuel quality and octane? I'd hate to start recommending "shotgunning" any kind of sensor in it without knowing the basics. Folks get in more trouble with these MB's by jumping into some suspected "sensor" or something like that, and not even bothering with the basics. Try pulling the fuse out of the OVP and see if it does the same thing. The engine will RUN with the air flow meter not even working, so if you pull the OVP fuse it's running without even the control module, much less the air flow sensor, so if it still does it in that condition, it tells you something kind of basic is wrong.

Gilly

I fully agree with you on the "shotgunning" issue.

The plate zero/basic position was one of the checks I skipped when I had the problem with the FD so I just want to get that checked out to spec.

Most of the sensors/switches/pots/etc had been tested to spec when I was troubleshooting the FD issue.

Fuel pressure regulator was also swapped out becoz it was venting fuel - stuck diaphragm.

Basic stuff like plugs/cables/cap/rotor/etc done.

As the car is running great right now, albiet the slight hesitation, I will be going thru' the car again - this time at my own pace.

Will advancing the timing do anything for the hesitation assuming that all the electrics/mechanics check out ok? I run 98 octane fuel.

Thanks.

'Scuze me, 98 octane fuel? You live next to a dragstrip?

You can't easily adjust the timing on it, it's electronic ignition.

Gilly

Yeah, yeah...keep on goin'... We only have 92, 95 and 98 octane here so I go for the 98!Hehe!

What abt adjusting the timing by rotating the distributor body?Does that work?

And then there's that variable round EZL resistor plug on the left fender...does that affect the timing?

Cheers, Gilly.

I think you have exactly the same car as me. 91 1.8 190e manual?

I've been having an intermittent hesitation problem myself. Replaced fuel filter and spark leads and its still there. Only happens every hour of so of driving.

I have decided that it might be either dirt or water in the fuel tank or a defective fuel pump pressure reg or relay.

Anyway back to your car!

The ezl resistor has six positions which I beleive go something like

6 lowest advance unleaded petrol
up to
3 highest advance unleaded petrol (position s I think, I've not got a picture handy and its dark outside)
Then
2 leaded fuel low advance
1 leaded fuel high advance

What I dont know if is 2 and 1 give more advance than 3. In this country leaded had a higher octane than unleaded.

I'm waiting till I next visit my parents as my dad has a timing gun so I can check for sure.

I've tried the positions 3,2 and 1 and I have left it on 1 as there seemed to be a bit more torque at low revs.

Position 3 or S is the position most people recommend.

Yes, our cars are the same spec, although mine is an auto.

I will be looking around for more info on the resistor.

I'll be checking the CD, and also recall seeing a couple of posts on this topic with resistance values.

Cheers.

Found one very good thread.

Changing EZL reference resistor to alter ignition mapping on a W126

I noticed that if I use 92 or 95 octane, I get less fuel mileage with the resistor in S.

With 98 octane, I get to 400+km before the low fuel light lights up.

I wonder what's the logic, would it mean that with the resistor in position 2 (for 95 octane), if I use 95 octane fuel, I would get the same performance as using 98 with the resistor in S?Albeit lower fuel costs?

Hmmm.....

You should get better performance in the S position as long as the fuel is good enough to prevent knocking or pre ignition.
I'm not sure if these cars have a knock sensor. I dont think they do, so the car doesnt "know" what fuel its using.
If the 92 octane is causing knocking perhaps this would reduce your power / increase consumption.

Over here in the UK the fuel is 95 or 97octane and mine seems fine on the 95 with the resistor in any position.