W124 M104 High Idle No CC - Page 2 - PeachParts Mercedes-Benz Forum

RobertFini · #1 10-10-2018, 12:42 AM

I've been chasing an idle problem on my '94 E320 wagon also, except my problem is that the idle is too low, and then erratic - hunting and surging from 400 to 900 RPM and frequently stalling. The car runs perfectly fine otherwise, pulling like a freight train at full throttle and holding a nice steady speed with the Tempomat engaged. I most recently replaced the ETA with a remanufactured unit from BBA, and while it's better, with much more responsive throttle coming off idle and fewer stalling episodes, it's still hunting and surging.

The folks at BBA have issued an RMA for me to return the unit under warranty, but I'm beginning to suspect the T/LLR unit. Both upper and lower engine wiring harnesses have already been replaced, along with the OVP relay and a slew of other parts. There are no significant vacuum leaks and I'm not getting any codes on the DM or pins 8 or 14.

Can anyone tell me what the T/LLR unit does and how it generally acts when it goes bad? Thanks in advance.

Best REgards,
Rob

Stevester 500E · #2 10-10-2018, 01:19 AM

I had the same issue and it was the ETA.

gjones8131 · #3 10-16-2018, 08:32 AM

I was thinking T/LLR was my problem but swapping did nothing...

Now wondering if its the purge valve..when I checked a few month ago was all good, pulsing nicely w/ hot engine. Now it isnt pulsing at all and seems stuck open, would give sign of vac leak. Does anyone know if purge valve always runs on warm engine?

Also anyone have a handy list of the vacuum line part #s? I want to replace all the fittings just in case and it would be a b***h to pull them all, measure, and then wait while the order processes

gjones8131 · #4 11-06-2018, 06:05 PM

Hi All,

Had some down time today so I pulled the purge valve to bench test for operation. First, a bunch of charcoal fell out of the unit, not a good sign. Im also getting no pulsing when I apply 12v to it. Sprayed it w/ some WD40 as I've seen on the forum and no luck.

Can anyone w/ more experience confirm for sure that it is dead and needs replacing? Not sure if more WD/40 and time would bring it back or if it is kaput.

gjones8131 · #5 11-12-2018, 06:55 PM

Well I am nearing the point of desperation, i.e. throwing parts at the darn thing, so hopefully someone has a more intelligent solution.

Replaced the purge valve and every rubber vacuum line near the engine but still no luck. Does anyone know if the main engine computer (what connects to the upper harness) could have any role in the idle and cruise control?

I know this car was driven for many many years w/ the eco junk harness, so possible that computer is burnt. Otherwise, thinking the secondhand throttle or EGas/TLLR modules could actually be bad. Running out of options at this point so any suggestions are welcome