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Sluggish in low gears

3K views 30 replies 3 participants last post by  Mike770 
#1 ·
Hi all-
So I recently bought a 2.6 5 spd with 94k on ebay. She starts, idles, and she runs and there's NO check engine light and that bulb does work. However...

...when I step on the accelerator, under load, the car is super sluggish. This happens from 0-3200 RPM in 1st and 2nd gears. At higher RPMS and in higher gears it's fine. Sounds like major restriction but again, the car runs fine once it's moving faster

Now it is missing the air intake scoop (on order) but the cleaner unit is on. It's also missing one vacuum line from the back of a check valve between the thermo valve on head and the Mass airflow/intake under throttle the body. I'm pretty sure the missing line goes to the charcoal cannister and is part of the evaporative system. Seems like this wouldn't be it bc it's just vapor recycle but idk...

Car has new plugs + cap. I've checked the OPV. EHA looks fine (no visible leaks at least)

The only thing I've come up with is maybe a worn resistor strip in the MAS unit which I'm a tad hesitant to mess with. Any help is greatly appreciated. Thanks so much.
 
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#2 ·
If you pulled out of an intersection...with the intent of giving it a lot of gas, and flooring it, to go fast...would it go fast?
It should go fast if you deliberately keep your foot in it.

If I roll out of a corner slowly in the 190 and floor it....there's a delay in car taking off. Sorta like the gas pedal has to talk to the throttle, then the CIS plate goes up...ect. Mine is not a direct response car.

Maybe let a shop or person more familiar with the car drive it. They might say its fine.
 
#3 ·
Theres no hiccup or slight hesistation in terms of response or kick>gas. It's just really slow as if it's being kept back somehow by something and I don't know what. I've driven the exact same car without this problem so I know it's not ok.

That slight wait before kicking in you seem to be referring to is not uncommon for many cars with automatic transmissions. This is a (rare) 5-spd manual.
 
#4 ·
I have a 5sp 2.6 89. No hesitation issues at all. It is running almost as new at 180K miles.
I would fix all of your vacuum problems before doing anything else. Make sure you have a Mityvac hand pump to diagnose problems. Once all your vacuum issues are taken care of someone here will help you including myself.

Is your timing adjustment vacuum line to the ignition unit hooked up and not leaking for example?

After you are done fixing all your vacuum issues your economy/vacuum meter in the car should be fully pegged to the stop during idle. If not, keep working on your leaks.
 
#5 ·
The vacuum line to the EZl ignition is good with no leaks and the economy/vacuum meter on the dash shows that the car IS fully pegged to the stop during idle and that needle DOES go up and down upon acceleration.

I keep returning in my mind to that one line that goes to the evap system from the check valve to the charcoal cannister buried in the fender (that I can't get to easily). It's just I would think that if that entire evap system's job is basically to recycle some vapors from the fuel tank, wouldn't it be unlikely to draw much pressure or dramatically affect performance???

Next up is check the EGR valve for a diaphram leak. Does anyone know if this can be done without taking it out?

Thanks to all of you for your help.
 
#6 ·
Also...sorry...

Looking at this fuel delivery is making me wonder if this is not an air/vacuum issue at all but a fuel pump issue, e.g. somewhere in the two pumps, filter, and accumulator.

The manual doesn't explain how they work that clearly but why two pumps?. Do they both pump all the time or do they stage somehow progressively? And what does that accumulator do?

Or am I just losing focus here bc if the car starts and drives fine at higher rpms, fuel delivery is working?
 
#7 ·
If you are fully convinced that you do not have a vacuum problem and there is some fuel delivery issue here are some suggestions:

(1) Does the car behave the same during cold? If it does, I would agree that you most likely you have a fuel delivery issue. It could be other reasons though.
(2) If it is a fuel delivery issue, the most likely culprit is your EHA valve. It is a wear item and only lasts about 90K miles at which time they start leaking, Happened to me twice, at 90K and 180K miles. Both times when I replaced them it seemed the car gained a lot better performance and pick-up. So even before they start leaking they sort of loose their ability to properly control fuel pressure effectively. If you intend to keep the car, you will need a new one if yours is the original at 90K miles, very soon anyway. Unfortunately they cost ~$250 at AutoHausAZ, free shipping.
(3) Signs of bad fuel pump, accumulator, filter are quite different and do not behave like yours. Two pumps are used to make sure there is good steady fuel pressure under load as the mechanical CIS needs it. Pumps are replaced in pairs for $200 (parts only) and usually go >120K miles before they start acting up (your life will vary depending on usage)
 
#8 ·
Car acts the same cold as when warmed up. I know the EHA is often a problem bc I had a 2.3 that didn't start and replaced one and the car instantly ran perfect. But my car starts, idles perfect and this problem vanishes at higher rpms?
Plus I've always heard a bad EHA is binary- if it's bad, the car won't do squat and certainly won't have a steady idle.

Anyone else have any more knowledge of these?

I actually yarded an entire MAS unit incl fuel distributor and EHA just yesterday off a 2.6. That's the good news. The bad news is that car had 255k on it....
 
#9 ·
Not so Mike. Read my thread titled "EHA valve leak" from last year. In there you can see my findings as well as others after an EHA valve replacement (after thread 7).
EHA does seem to wear out and the results are not always "binary" before it completely goes.

A bad EHA may effect both hot and cold "sluggish" operation but do not quote me on that. BTW I would not trust something that is pulled off a 255k mile car without rebuilding things as you have no history and these are wear items.

You should also test the AFM pot electrically. That is another wear item that only lasts somewhere between 150K-200K miles it seems.
 
#10 ·
First of all, THANK YOU. You guys rock!

An update: This AM before work, I went through the vaccuum lines -- replaced missing evap can line, ignition line. I couldn't get to the two throttle body lines but the rubber looked ok. What I did discover was a monster CRACK in the line from the diaphram (EGR/purge solanoid) to air assembly hose. Also added a beat up/patched air intake scoop and cleaned the throttle body.

The sluggish low rpm problem has improved slightly but it persists...

Dolucasi, Re: this darned EHA, I'm going to try and rich up the lambda mixture first then go there. This is bc I've read German factory settings on all these 190Es run lean wnd this applies to the lambda as well as the EHA which also is adjustable, albeit not easily (Source: HOW-TO: Adjust the EHA (Electro-Hydraulic Actuator) in the CIS-E fuel injection)

As for an AFM pot elec test? Sounds like a good idea. Thanks. I'll look it up and try to perform it this weekend.
 
#13 ·
Yes you can not rebuild the EHA. You mentioned you took the entire FD (I think) so I was not sure if you were going to use parts of that including things like the AFM pot, AFM mechanicals etc.

The EHA is somewhat adjustable it seems but I have never had to try that.
It does have a screw in that face that mates with the FD.

On the pot operability, please read my recent post on a different subject that goes over the pot as well.
H.D. who is an expert helped me with that. It is titled "idle stumble and race"

http://www.benzworld.org/forums/w201-190-class/2792770-idle-stumble-race-very-infrequently.html

Cheers!
 
#15 ·
Doesn't seem like this is me but the thread does mention a vacuum leak from the...HVAC?!?

Never considered this. I double-checked and my economy needle is NOT fully pegged as I indicated, previously (sorry). It stops about 1/4" of left end. So still might be a vacuum leak. First, I'll take off stuff to check the ones under the AFM but I only see one vacuum line to the interior in the bundle of stuff left of the brake booster. Someone please tell me if a HVAC leak source is a wild goose chase because chasing this prob down is starting to feel like a full time job.
 
#17 ·
Update: I replaced vacuum lines to/from evaporative system, thermo-vac sensor on block, missing check valve next to the brake booster. The schematic I have, doesn't show this check valve but I saw mine was missing after looking at junkyard 2.6 and a 300E with the same motor. I also replaced the heater valve.

Ducati, you stated that one of the lines near the booster goes to that Heater valve but in the schematic I have, it shows both lines going inside the car - the one on the Heater valve line runs to the 4-way switchover behind the dash inside?
 
#18 ·
Hi Mike, I'll assume this is directed at me (Dolucasi) . We do not know the details about your car (year/model/etc). And the design might have slightly changed over the years. I know 89/90/91 has it so that the splitter is behind the firewall at the break booster. It splits into two and one goes behind the instrument cluster to split again (one for cluster vacuum meter, the other to the HVAC controls). The one by the brake booster has the other line go to the HVAC heater control valve that decide how much hot coolant to let in to the heater core inside. This valve is on the passenger side behind the firewall.

But for us to better answer your questions correctly and not mislead you please complete your profile. It is important.
 
#19 ·
Dolucasi, yes, I was specifically addressing you. I mangled your name. Sorry about that. Really appreciate your help.

My 190E is an '89 2.6, 5-spd manual with 90k miles and some issues...

I'm still puzzled by this vacuum from intake bc I've seen similar year 2.6s and neither had the vacuum line from the Heater Control Valve run to next to the firewall near the Brake Booster. Both went directly inside. At any rate, mine are as you suggested but my dash needle is left side, not pegged.

As far as "sluggishness in low gears" -
I've gone through ignition and am in the fuel system. Fuel pumps appear ok, filter replaced, and I just took the injectors to be cleaned and bench-tested. A place near me does it cheaply so why not? Plus the rubber injector holders were hard and stuck anyway.

If these cleared injectors don't miraculously solve this, my next guesses are:

1. Bad EHA - This, of course, was the first thing you suggested but, I'm still here, trying to save myself from spending 300 bucks.
2. AFM Pentiometer - bad contact in some part of needle track/spectrum.

Once I go through those though, I'll be fresh out of ideas :|
 
#20 ·
At 90K miles Mike, your EHA is probably on its way out, so you will have to replace it one way or another in the near future.

Do the AFM pot test, and report on the results. AFM pot is just as expensive as the EHA and less likely to be your problem. I am yet to see an AFM pot that is better than mine (at 180K miles) in the junkyards with lower mileage cars. Any my acceleration is very good and mine is the same year as yours (and 5 speed as well). AFM pot problems will make the acceleration less smooth with gentle acceleration but not sluggish. Meaning, if you floor the pedal it should just go, whether you have a minor AFM pot issue or not. If it does not, you have other issues.

Do me a favor though, can you check the build month of your car in 1989/88?
It will be printed on the driver side door. And how much oil are you burning?
 
#21 ·
One last thing Mike, take a picture of that brake booster area and post it. It should look identical to mine as mine is also an 89', and there are other active members with '89's who can help you. You should have a splitter/check valve for your heater core on the passenger side, assuming your heater still works.
 
#22 ·
Here's some pics--

Pic1: Door tag. Build month 02/89.

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Pic 2: Current vacuum setup next to Brake Booster. The white check valve was missing when I bought it so I added this and bracket.

1-4. All lines pictured originate at intake runner.

1. RED, from white check valve, it runs down under wiper motor then quickly disappears near the right side of Heater box. Hard to see.

2. RED2, runs to Heater Check Valve and is attached to the top of its diaphragm.

3. ?

4. ?

*


Pic 3: Exhaust side. There's no EGR on the manifold and it appears to be a factory pipe delete. However... as you can see, this manifold has a TON of rust and there's NONE on any other part of the car (not even a speck of surface rust underneath) so it could very well be a swap from another car for a later delete. There's no smog pump and no California emissions sticker.

I ruled an exhaust leak out as a major cause for the sluggishness bc the car runs fine at higher speeds, gears. Perhaps I'm wrong on this. I do have plans to sandblast and put a fresh gasket on but I'm not anxious to add an EGR unless needed.

*

"AFM pot problems will make the acceleration less smooth with gentle acceleration but not sluggish. Meaning, if you floor the pedal it should just go, whether you have a minor AFM pot issue or not. If it does not, you have other issues."

It goes, and it's smooth. It just goes very slow, as if held back at low speeds. Upon acceleration, it makes a LOUD roaring air noise that's pretty deafening even with the windows up. It also roars when I step off the pedal as if it's taking too long to close the air flap on AFM.

I will run the multimeter tests on the Pots and report back.
I do have a JY spare from a high mileage 2.6 plus the EHA from that same car.

As far as oil consumption, I've barely driven it in the three months I've had it bc I've been trying to sort it but the previous owner said she added 1 quart every 1200 miles.

Thanks once again for any and all help. I love this car but I'd love actually being able to drive it a lot more :)
 

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#23 ·
Mike, I will reply separately on your vacuum lines to keep it concise.

I am afraid to be the bearer of bad news however your engine is one month prior to when Mercedes realized the camshafts and rockers were too soft and changed them in March-April time frame. You are probably OK for the time being as I'm still on the originals at 180K miles but sooner or later you will have to replace those. OEM parts are extremely expensive so I got mine sourced from a '90 JY car at 118K miles for $56 only and they look to be in exceptional shape. Do not worry about this just yet though, you've got a ways to go.

Your oil consumption (if the PO was not lying) is spot on. At 90K miles my car was burning about 1 quart every 1200-1500 miles. That deteriorates slowly and at 180K miles we are down to 1 quart every 500 miles. That is another defect in that the valve guides were too soft and wore out prematurely. Valve Guides are dirt cheap but the cylinder head has to come off for the replacement. Again, you do not have to worry now but writing is on the wall in 50K-60K miles, unless you would rather preserve your Catalytic converter as the oil burning will ruin it in the next 3-4 years depending on the miles driven.

The points I'm making above are informational only, none of this will effect the way your car is running now. I have the problems above and it does not effect the way my car is running in the slightest.

Now on your JY spare parts, I have to caution you against using JY spare parts for EHA/IACV/OVP/AFM pot. I have fallen into that trap by swapping in those parts for diagnoses on an obscure stall I have, and even at 180K miles, I have yet to find a JY part that behaves better then the parts in my car. Those are all wear items (well except IACV) and should only be replaced by OE new ones.

Especially the OVP/AFM pot, you will not find a better one in a JY than your original. I just ordered OVP and AFM pot from AutoHausAz,
$238 for one and $47 for the other. At least free shipping and no tax.

I have been trying to diagnose a spontaneous stall at idle once every 2-3 days and have been swapping in JY spares and got nowhere in the last 3 months. All my originals are back in the car as the car performs best with the originals.

Again, from your syptoms, I doubt your problem is the AFM pot, but do report on the readings when you sweep the flow meter.
 
#24 ·
On your vacuum lines Mike, all I can definitively say is that yours is identical to mine. I should have taken more pictures when I dismantled my dash and also replaced the Heater control valve on the passenger side firewall.

I'm guessing #2 red one is coming from your heater control inside and heads to the HCV in the firewall. Not sure what #1 does.
I believe the green one goes to the vacuum gauge at the instrument panel (vague memory of that line being green) so the white one must be heading over to the HVAC switch over control unit located inside the dash behind the glove box.

But these are just mere guesses on my part. You can disconnect them one by one to figure out the cause/effect and to also see how they effect your vacuum gauge.

Sorry, my memory is failing me at this point.

Even though you should work on getting your gauge to peg all the way, at this point, from the description of your concern with sluggish acceleration my money is still on the EHA unit. This all assumes you have a good ignition control unit , fuel pressure is not an issue and you have good compression in the engine.
 
#25 ·
D
Yes, I am aware of this update I missed, only bc I already have a minor rattle somewhere in the valvetrain (sounds near 3 or 4). I fully expect to be pulling the head and rebuilding the top at some point. No big deal. I can get it done right for 250 bucks if I pull it myself (800 with a new performance cam ;).

For now, the compression is great, and, as you suggested, it's not part of my current problem.

Onto diagnoses--

I put my freshly cleaned injectors back in with new seals, widened my plugs to .039, swapped in the JY EHA valve w' fresh O-Rings and took her around the block.

No change at all.

Onto the AVM POT TEST

Pin 1+3 = 4-9V

Pin 1+2= 5-12v

Now these numbers are way outside spec according to the manual, which says, unequivocally:

"Voltage higher or lower: replace air
volume meter."


Maybe we have a winner?

Since the screw holes have play so this thing can be repositioned, I'll try moving to a different/better part of the resistor track before I buy a new one or try the JY one I have which does, I gotta say, look mint.
I will bite the bullet and buy a new EHA, just to eliminate it altogether. Ouch.

I should mention here that I cannot get ANY duty cycle reading. I feel like I should be getting something, bad pots or no bad pots, but the HZ feature gets broken on cheap multimeters like mine so I need to try a better one before I freak out.
 
#26 ·
I swapped in a third JY check valve and it pegged the needle left like clockworkl. Maybe you're onto something re: the complete unreliability of JY parts lol. I will say, unrelated issue, that my A/C works great when the car is cold so I'll be getting behind that dash soon enough to deal with the blend flaps/vacuum switchover valves back there. I did replace the heater exchange valve so I have that going for me.

A/C is a necessity here in Texas but it's still not as important as

Power
 
#27 ·
On your AFM pot, you should unplug it and take resistance measurements (1-2, 2-3, 1-3) with the AFM plate closed.
Then press the plate down slowly ans make sure the resistance value changes are smooth (no jumping around) and take measurements like I did in my post I referenced before. Your numbers should be close to mine if it is a good pot.

- Cheers
 
#28 ·
Update: After buying an expensive EHA and dialing in the Pot, my first problem remains, although the car is running slightly better. I am currently rebuilding the Fuel Distributor. I started another thread about this specifically, but, after rebuilding it, I have a plunger that isn't moving up and down as freely as it should.

And so it goes on....
 
#31 ·
Update:

I put in the rebuilt distributor. It took a few tries to start but it's running

A W E S O M E

Much quicker and smoother, hiccup-free acceleration. Basically, drives like a new car.

Now onto AC and front struts.

Thanks for all the help!!!!
 
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