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Throttle actuator removal

31K views 41 replies 12 participants last post by  BBooth1986  
#1 ·
Does the intake manifold have to come off to get the throttle actuator off, or is there another way? I believe that my idle surge is coming from faulty wiring in thei unit and would like to replace it. Details on removal would be appreciated.

Thanks
Greg
 
#4 ·
Greg, your idle surge may not be related to the actuator. I replied one of your posts on EGR/Air-pump as a possibility. Looks like you're chewing through a list of possible sources. I understand your ambition to solve the bugger but yanking the actuator is no fun. Even less fun when not related.

Have you replaced the MAF sensor? I speak from a recent '94 E320 with idle surge or drift. The combination of a hosed MAF, temp sender and cleaning the throttle body cured it. That was including a collection of diag codes.

Can you provide a summary list of what you've tested, replaced or eliminated? Repeating CEL codes? Does cruise control work. Any ASR codes?
 
#5 ·
NO.

You don't have to take the manifold. I just did rewire my throttle actuator last week. All you have to remove is the black box at the top of your manifold in order to access the throttle actuator. I don't know exactly how it is called.Any way here is the link showing the picture. Unfortunately, I did not take pictures when i was doing mine.


MercedesShopWiki: W124 Engine Wiring Harness Replacement


Loosen the four hex bolts at the top of black box to remove.

Remove the rubber pipe mounted on top of the throttle actuator by loosening the clamp at the base by a long screew driver and remove. This will expose the 4 hex bolts at the top of the throttle. Disconnect the wire harness, spring and the linkage.

Loosen and remove the actuator from the top of the manifold. (you need to remove the old gasket and replace with new when installing back the actuator)

Follow the link for repairing throttle wiring. I think you gave that link to me on another posting.

Remember replace one wire at a time. By the you need a soldering tool to solder the wire in place.

Here is also a link for inside view of the throttle: Yet another ASR Problem; '94 S500


Raul
 
#7 · (Edited)
White Knuckles

My Car is a 1993 300E with the 3.2L M104

Here is a list of what I have done:

Replaced OVP relay

Cleaned MAF sensor (HFM type) with carb cleaner

Swapped MAF sensor with a known good one from a 94 E320, the one from the 93 worked fine in the 94 and the one from the 94 did not cure the idle surge.

Checked insulation on the wiring harness and found almost complete loss of insulation from the the point at which the harness exited the battery compartment.

Rebuilt the wiring harness with 205 degree C cross linked insulation automotive wire

Reinstalled the harness and repeated the MAF sensor swap and I still have the idle surge.

Cruise does not work, although it did until this problem started.
The auto down function on the windows also stopped working when this problem started.
The radio also went haywire at the when this started.

As far as codes go, I built the code reader, but could not get it to work. All I got was a steady light, no matter how I hooked it up. After replacing the wiring harness, I get no light unless I hook it actoss the + and - terminals on the battery. I was told by another on this forum that the code reader would not do me much good on this car so I sort of abandoned it. I am open to suggestions on it's use though

I appreciate the suggestion of additional areas to check before removing the throttle actuator. I would love it to be something easier to get to.

How did you clean the throttle boy?

When you say temperature sender, is it the one on the thermostat housing. How can I tell if it is bad?

Raul21263

Thanks for the reply, I did indeed point you to that link, I'm glad it worked for you. Did you get your hesitation squared away?

I will do as you suggest and verify that my insulation is failing prior to removing the actuator.

Greg
 
#11 ·
MY RPM HAS A LIMITER CUTTING AT 4000 RPM WHEN I REV THE ENGINE AT PARK. IT WILL NOT PASS 4000 RPM. PER JIM FORGION THAT THERES A LIMITTER THAT IS CUTTIN AT 4000 RPM. IT IS CODED IN A SECTION OF THE EPROM LOCATED IN THE FUEL COMPUTER MODULE AND CAN'T BE CHANGE UNLESS YOU BUY A CUSTOM CHIP FOR IT... COST ABOUT $1000.00. PER JIM IF THE CAR IS RUNNING FINE, ACTUATOR IS GOOD.

I AM NOT SURE ABOUT THIS AS I AM NOT FAMILIAR WITH LIMITERS ON RPM. T THOUGHT THAT THE MAX IS ON THE 6000 RPM MARK RED IN THE DIAL. I FIGURED THAT IT IS VACUUM LEAK AS I HEAR ISSING SOUND AT THE INTAKE MANIFOLD SIDE. HAVE TO CHECK ALL VACUMM LINES.


CARS RUN WELL WHEN TESTED IN MY NEIGHBORHOOD TO 60KM PER HOUR. I DON'T HAVE THE ISURANCE YET AS I HAVE TO HAVE IT AIRCARED. JUST BOUGHT THE O2 SENSOR.

I ALSO DID THE REWIRE FOR THA MAF HARNESS AS THEY ARE ALSO GONE.

HOPE YOU WILL BE ABLE TO FIX YOUR THROTTLE.

RP
 
#9 · (Edited)
Excellent, a Biopsy on the harness pre-surgery. Now you have a worthy shot. The overview was helpful. I indeed thought you were on the E320.

Pulling that baby doesn't look too bad. Splitting the molded connector to re-wire looks like the only challenge. The actuator pics (thanks raul) show a grungy throttle butterfly plate. Look down the intake with a flashlight, my plate looked similar with brown crust on the edge as well gunk in the throttle body bore. I'm not a fan of carb cleaner as a first choice for this but I'm sure it would work. I poured a couple ounces of SeaFoam (Google if you don't know the product) in a spray bottle and with clean rags wiped it out after a few squirts to soften things. Cleaned up well. I was careful not to press or try lifting the plate, its hooked to a motor gear drive. I sprayed a couple shots of carb cleaner on the plate pivots to clear any hiding goo.

The old MAF created a surge or RPM drift - 13,000 two seconds, drop to 900 for two seconds, back up to 12K - on and on. After a replacement MAF it held 700-900 much better but varied. I replaced the dash temp gauge sender as drifting but I'm fairly certain it's not related to idle. The throttle cleaning did it, 700 always.

The window, radio and other phantoms are probably not related. Have you swapped or have an OVP relay? It is reported to be the very one when multiple ghosts appear. Sorry the harness job was unrewarding, that had to be fun. The actuator has idle and cruise duties and hopefully is where the evil lives. Getting the code tool operating may be a bonus but if the storage registers are locked up you may not get any output. I'd consider taking it to Mr. Dealer and directing them to pull the codes (tee-hee). If they can great, post the codes and go fix your tool. If they can't, pay a minimum fee for the attempt. Codes reveal great info. fighting these things.

Good luck with the rewire.
 
#12 ·
I feel your pain bro. I was near calling a priest to perform an exorcism on mine when it was acting up.

I'm guessing you're in an electrical field by reading terms like "ring-out" wiring. You'll need good soldering skills when ya crack that actuator open. If you're not a hobbyist or pro, I'd be glad to reply some soldering tips and tricks.

This is the fix.

(Murphy's law of the last thing you think of )
 
#14 ·
I am a Mechanical engineer by training, but I have been interested in electronics since high school back in the 70s. I actually started in an EE program but realized the I was more interested in the mechanical side of things.

Electrical repairs are not such a big deal, you just need a systematic approach to troubleshooting. I am constantly amazed by individuals who will tear into an expensive engine or transmission with no fear, but will run screaming from an electrical problem more involved than changing a fuse.

Greg
 
#15 ·
Eric, Raul, White Knuckles and Sergio

Thanks for all the suggestions. I pulled the TA off the 300E yesterday and found that all of the insulation was gone at the connector and inside the TA itself. No wonder the damn thing wouldn't idle! I spent yesterday afternoon chasing down 24 and 26 gauge wire and a #20 torx bit with a hole in the center. My son and I finished the replacement wire by wire from the circuit board to the connector this afternoon and put the car into relearn mode. We took it for a quick drive and It runs beautifully now! It is smoother than it ever has been!

Thanks again!

Greg
 
#17 ·
White Knuckles

I'm feeling pretty good right now. I did find a rough idle yesterday evening that I chased down to a loose low voltage connection on the rear coil. But once I made a better connection she smoothed right out again.

I had several black things that fell apart during the course of this project. The biggest problem was the egr and air pump connectors. They caused some serious hair pulling to figure out polarity.

The other was the air resonance valve. I'm not exactly sure what it does, I assume that it reduces intake noise or turbulence by allowing the streams to mix? Anyway, when I took it it off to get at the throttle actuator, it came out in pieces. It seems to still work after I put it back together.

My problem now is that cruise control isn't working nor is the auto down on the windows and the radio changes volume like it is possessed. Since the car is still in relearn mode and the radio is speed sensitive I am wondering if the volume problem is related?

I checked the voltage to the battery at idle and it is 17V and 17.5 @ 2k rpm. I figure that I need to get a voltage regulator. I just need to figure out how to get to it and get it off. Any suggestions?

Thanks
Greg
 
#18 ·
White Knuckles

I checked the voltage to the battery at idle and it is 17V and 17.5 @ 2k rpm. I figure that I need to get a voltage regulator. I just need to figure out how to get to it and get it off. Any suggestions?

Thanks
Greg
You definitively need to replace that part ASAP. It is "extremely"easy. Disconnect the battery first and the regulator just screws in on the back of the alternator. Lift the car enough to get under there. No need to remove the alternator. I think all you need is a Philips head screwdriver.
 
#21 ·
Serg is right .5V is high for a regulated output.

The radio and cruise may be related to the actuator fix. Quick and dirty - the radio can have the speed send input nixed on the radio connector. Cruise could be retired. If it's a simple connector issue or a cold solder joint it may be worth a revisit. One concern would be over working the thing and creating a total failure. Plus, its a great excuse to upgrade the stereo. The window deal is not related.

The actuator internally uses a variable resistance strip and wiper contacts to tell the brain throttle position. It is fine as the system goes nutty when they fail. Not serviceable and when worn out, the actuator is a write-off. They also have bi-metallic coils for temperature variable needs. I would not explore the internals as cannot be effected from your wiring job.

Evaluate the probable life left in the car and consider a basic revisit on the connector then quiting while ahead. I know it's hard to stop poking. You still have an 80 percent on the actuator report card.
 
#22 ·
Sergio

They want $75.00. I figure that thats a little high, but at this point, I pay it. I'm also getting new low voltage connectors for the coil as the rear one doesn't fit as tightly as I would like. I figure I will just replace all three. MB of Lancaster is charging $11 each for the caps and $3.00 each for the contacts.

Greg
 
#23 ·
Thanks again for all of the input. I replaced the voltage regulator and the low voltage connectors on the primary side of the coils yesterday. Voltage is now 14.11 at idle and 14.13 at 2k RPM. The new voltage regulator solved my cruise control and auto down problem on the windows as well! I am now a very happy camper:)

Thanks again
Greg
 
#26 ·
Hi Raul

Yes, I was successful in rewiring my throttle actuator. Thanks for the pointers along the way. After i got the idle squared away, I ran into some over voltage problems due to a bad voltage regulator, but now my car is running excellent. I need to get it inspected and put some nuw rubber on it and i will be good to go, hopefully for some time.

Greg
 
#27 ·
I do not mean to hijack the thread, but was wondering if someone may think that the voltage regulator may be my issue. My cruise does not work. It used to work intermittently and I resoldered the amp and it stopped working. Since I have tried two replacement amps and after the CEL came on for the throttle actuator, I had an INDY replace it with a tested used actuator. The cruise still does not work and I even replaced the brake switch and checked the tire size and pressure. Would the MAF cause the cruise to stop working? I think my MAF is working alright.

If it is the voltage regulator, where is it located and how can I test?

Thanks,

Hank
 
#28 ·
hank3d

I don't think the MAF sensor could cause the problems with the cruise control, but a bad OVP relay could cause it. The OVP ( over voltage protection) relay is behind the battery and has a fuse on top. They are known to fail over time so if yours is original you might want to replace it.

The voltage regulator is on the back of the alternator. You have to drop the underbonnet and remove the plastic cover on the end of the alternator. Remove the two retention screws and put in a new one. You can check the voltage regulator by checking the battery voltage at idle and at ~2500rpm. The voltage should not vary by more than a few tenths of a volt. If it does, the regulator is bad.

Greg
 
#32 ·
Hank3rd

The codes i'm talking about are the ones from the 16 pin diagnostic port next to the battery. If your indy pulled the codes and replaced the actuator, I'm not sure what else to tell you to check. The CC signal gets compared and modified by a lot of sensors, including the fuel pump cutoff. Maybe someone more knowledable can chime in.

Greg
 
#34 ·
The DIY sticky is an excellent idea! I just stumbled across it. I would like to add a further comment regarding rebuilding your wiring harness. Do not simply splice into the existing harness inside the engine bay (300E and E320) even if the insulation looks good near the battery. You may wind up with an electrical short inside the computer connector housing and have to redo the harness (ask me how I know). If you rebuild a harness on a 300 series it is best to rewire all the way to the computer connector. You will have to reuse the old pin body as they are not available, but the pin body housing is available from MB for under $20.00 US.

Greg
 
#35 ·
Kudos to all who contributed to this thread.

There's a helluva lot of info here about the "ins and outs" of several key 94 E320 trouble spots....engine wiring harness, the TA unit, and good troubleshooting info on the symptoms of voltage regulator troubles. (Not to mention the excellent Wiki DIY link on Engine Harness Replacement. Both now bookmarked.)

My coupe has yet to experience any of these woes in its 104K odo life but, as well chronicled in many forums, they are right up there with death and taxes as eventual, if not imminent, events.

Thanks.