Hi all,
I am really enjoying the '93 245 (228,000 mi, B230F) I just got a month and a half ago. It drives well, and I am really enjoying getting my elbows greasy as I'm slowly going through the needed engine tune up activities.
I love how simple everything is...it just makes sense- if you've been under the hood you know what I mean. And if it isn't so simple I always scour the BB-love it!

Anyways- back to the reason for the post...
The engine sounds (to my somewhat untrained ears) as if it is getting unmetered air, or, the injectors are clogged/dirty, or, the valves are out of adjustment. Hopefully not 'all of the above' It's hard to describe the sound, but you would know it if you heard it...remember when you were a kid and made helicopter or machine gun noises (pass air through your teeth together, tongue forward/up). Ok, the car does not sound exactly like that but imagine that kind of sound along with the low growl of the lovely B 230F. Maybe you get the idea. This noise is matched to engine speed.
The engine idles very nicely at normal rpm, but does not accelerate all that quickly, but it goes. Not a whole lot of power (We have a 940 of same year/same engine so I have some comparison). The codes are all 1-1-1 for terminals 2 & 6. Fuel economy seems low- I haven't been able to crunch any numbers yet (need a full tank first) but it seems real quick between the 1/2 tank mark and the red zone...although the gauge does not seems all that accurate anyways.

So my plan of attack/tune up is this:
1. thoroughly check for vac leaks/unmetered air (I'll first try listening through some tubing, but I can also try propane if that is a recommended test...) I already checked them briefly but I need to do a more detailed search.
2. Use some in tank injector cleaner (I have some laying around the house, so it's worth a shot)
3. I think it will be useful to replace the injector seals, vac testing (step 1 should tell me if it's really needed)
4. Check and Adjust valves/replace hushers...but with the smooth idle I'm wondering if this is needed.
5. timing belt (overdue)

Before I do step 4, is there a way to diagnose the need for valve adjustment without taking off the valve cover? What are some symptoms that would lead to needing a valve adjustment?
Before I do step 5, will simply adjusting the timing belt tension roller (as shown in Bentley 215-1) make any difference in how the engine runs?

What I've already done to the car:
-cleaned contacts on coil, dist. cap and rotor, regapped plugs. Dist. cap/rotor and plugs will be replaced soon...but for now they're 'refurbished'
-new airfilter
-cleaned pcv system, but did not bother with the oil separator box (seems fine)
-partially cleaned throttle body (didn't remove it from the manifold, so I couldn't get to all the nooks and crannies)
-replaced CPS/RPM sensor (that was fun!...)

I hope this post isn't too long- I just try to describe everything as best I can.
Thanks for reading! All advice welcome.

Koos

Hi there,

I agree with your praise for the shade-tree friendliness of the 240. Absolutely.

My impression of the symptom you are chasing is same as Smitty's, I think. Or it could just be in the way you describe the noise. Exhaust leak.

And a small one will draw in oxygen and "confound" the oxygen sensor somewhat. Take that reading on the sensor - the important part is that it is switching and doing so once a second or more. This gives you a view of all four cylinders' mixture as one. To see the individual performance, read the plugs. An original intake manifold gasket will be brittle and cracked in 2009, so consider that as a reason for any differences before going to injectors or valves. Give your throttle body, flame trap, and idle valve a bath while you're at it.

So, recapping some:

Step 1: Read the oxygen sensor. It is the only feedback the engine has.
Step 2: Sniff out any exhaust leaks.
Step 3: Read the plugs.

PS - always reset the computer (not the OBD) after any changes you make.
--
Art Benstein near Baltimore

Those who get too big for their britches will be exposed in the end.

Hmmm... quite a description there.

I think a clogged injector is low on the list of culprits, although a poor spray pattern is certainly possible given the age + miles. Techron is the good stuff to use. To do a binary check (it works or it doesn't) of the injectors, hold a long screwdriver to each injector in turn and put the handle up to your ear as the engine idles. You should be able to hear the injector pulsing.

You probably won't get the noise you describe anywhere on the *intake* side... those would probably be a sucking or hissing sound. I'd be inclined to look and listen around the exhaust manifold and downpipe. Carefully feel around the exhaust manifold to see if there's a "freeze" from a leak, but watch out - you can get a nasty burn.

That said, and exhaust leak generally won't result in sluggish performance. A restricted exhaust *will.* I would get under the car and look for a seriously deformed piece in the exhaust system, like around the axle pipe (which is already obscenely flattened when it's bent during fabrication).

Rarely, a cracked downpipe (near the 2 into 1) ends up confounding the oxygen sensor resulting in an ultra-rich mixture, but that doesn't align with your symptoms.

I wouldn't worry too much about valve clearances right now unless you're bored. You might get a little more noise from a loose valve, but that's about it. Valves would have to be pretty far out of spec to affect performance.

If you have a compression tester, use it, and that will give you a good idea of the valves' condition. But you need to pop the valve cover to see 'em and work on 'em.

I recently did my injector seals ('92, 230K) and the old ones had taken a set and were hard but not brittle, but I don't think they leaked. I just had the seals and hand and some extra time one night.

If your t-belt is *really* tired, it's possible that valve timing is off a few degrees. That will get squared away when you do the t-belt.

Last suggestion - check the O2 sensor output with a DMM. A failing sensor won't have the correct output range, and your air/fuel mixture will be off as a result, adversely affecting performance.

Just a few things to look into!

--
In God We Trust. Everyone else, keep your hands where I can see them.

Thanks for the feed back guys!

The bottle of fuel injector cleaner did help a little. Certainly it didn't hurt.
There is an exhaust leak that I know of (and need to get welded at some point) but it is at the back at the inlet to the last muffler- it's 'patched' right now but comes loose once in a while. Would that affect performance or not as much, since it is after the cat?

I will check the other things as well- O2, exhaust manifold. One step at a time.
Enjoy the rest of the weekend!
God Bless,
Koos

The exhaust leak you describe is aft of the catalytic converter and O2 sensor, so it won't affect performance (unless you ascribe to the rice-rocketeer school of coffee-can sized "mufflers").

Post back with what you find on the other fronts.
--
In God We Trust. Everyone else, keep your hands where I can see them.