W201 EHA adjustment
 

Well I did it, ran better, put some Irridium plugs in it, and in less then a day it misses all over the place, runs really lean at the bottom end (O2 gauge tells me this).

As soon as this started I pulled the Irridiums, and put the coppers back in, cranked the EHA back to it's stock position.

This didn't affect the car at all.

Had my mechanic run a smoke test, replaced the rubber boot below the A/F meter it had a slight leak, still no improvement.

Mech ran a compression test 98 125 150 100.

It's hard for me to make any correlations in running behavior right now as I'm f'in pissed.

However assuming the plugs stressed the engine a little more, say a blown head gasket are these compression number bad enough that I should consider a rebuild?

Any suggestions?

1987 4 cyl 8V 5 speed M102 motor

that's some Horrible compression numbers. over 50 lbs difference b/w cylinders. Did you try a wet compression test after the (I'm assuming the 1st one was dry), how about a leak down test?

How much did you adjust the EHA? Did you then adjust the CO afterwards?

Have you tested your leads, see if they are still w/ in spec? How's the cap and rotor looking?

Jonathan

plug wires are about 1 year old, I will check the cap and rotor, but but but.

Yeah the numbers aren't great, but but but.

I keep thinking me touching the f'n thing caused the whole problem.

No leak down, no wet yet.

I'll look over the ignition first.

I'd be astounded if fiddling w/ the EHA caused your car to pop it's head gasket. How far did you turn your EHA btw? Which way did you turn it?

Did you drive the Snot out of the car for the one day it did work well?

What ever the case, you're in for some major work w/ those #'s! If your lucky it's just the head.

Jonathan

welly
 

So didn't seal the rubber boot fromt he A/F housing to the throttle body, what I get for doing the job at 9:00 on a work night right.

Put the EHA to +1/4 CW, sealed the rubber boot, replaced the plugs, adjusted the CO2 levels, and now we're better then ever.

Also I put motor restore and 20W50, to bump my compression numbers up.

Anyhow compression may be low/off but it runs better then the first day I got it, and starts/idles fine so I'm happy.

That was fun.

Can I ask - what is the purpose/result of adjusting the EHA?

More fuel at WOT. If too far though you will run rich throughout the rev band. 1/8 is about all you need to get more fuel flow at WOT, where you need it.....

Thanks.


How do you know if you need it? :D

Actually, from what I understand, I thought the EHA affected mostly idle and off-idle mixture, but WOT mixture is adjusted using the tower adjustment?

Never mind, I had it backwards. Here is a thread I had read back when researching for my supercharger project:

http://www.peachparts.com/shopforum/mercedes-benz-performance-paddock/112962-190e-m103-supercharger-almost-complete.html

Thanks.

So the tower adjustment does idle, but that doesn't really affect the WOT running?

How do you know if it's running too lean/rich at WOT then (apart from going on a dyno)? What sort of symptoms might you expect?

The Tower is the Base Idle Mixture adjustment. The EHA is used in conjunction with IACV to maintain a Stoic Mixture throughout the rev range. It only goes so far though and if enriched a hair will actually enrich at WOT more, but if you go to far then it can not lean enough to maintain Stoic Mix any longer.

You can see what is going on by having someone hold a VOM on the O2 wire while flooring it to see if mixture stays rich as the rev's go to redline.