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-   -   W140 (1994 S420) Engine Issue - I'm Stumped (http://www.peachparts.com/shopforum/tech-help/380272-w140-1994-s420-engine-issue-im-stumped.html)

LWB250 08-22-2016 08:10 AM

Yeah, I've already gone through everything to make sure it is connected and clean. That was my first thing to do, especially since this cropped up after the car being exposed to a really high humidity environment.

Dan

Ferdman 08-22-2016 10:20 AM

LWB250, when were the Oxygen sensors last replaced? I have had a sluggish acceleration problem with an inline 6-cylinder engine resolved by replacing the Oxygen sensor. Fortunately that engine has only 1 Oxygen sensor. Your engine has 2 Oxygen sensors because of the dual exhaust. The recommended replacement interval is 100,000 miles.

Frank Reiner 08-22-2016 02:04 PM

LWB:

In the event that the car is equipped with ASR, consider that if the throttle controller has a fault that mimics a slippery road condition, or is receiving a signal from the transmission selector that indicates "winter", the throttle opening will be restricted until vehicle speed is above the threshold that you have indicated.

TX76513 08-22-2016 02:23 PM

Quote:

Originally Posted by oldsinner111 (Post 3629426)
one time I had a power issue that lasted a year.It was my crank sensor plug,not fully plugged in.

Yes the ones that plug in like an "RCA" audio plug are bad about coming unseated (and I guess that's why they changed to a snap plug).;)

clarkz712 08-24-2016 07:58 PM

the 140 has an engine computor and a diagnostic module check both for codes then reset and make sure they are gone then road test and recheck both control units for codes

97 SL320 08-25-2016 05:45 PM

Does the transmission shift through all 4 gears? ( you might be pulling out in 2 or 3 rd )

A transmission torque converter with a slipping stator sprag will cause lower power from a stop since you are not getting any torque multiplication. ( similar effect to pulling out in 3rd ) Checking for this consists of selecting drive, holding the brake on then pushing the throttle wide open and measuring engine RPM, this is converter stall speed. This test won't damage a good transmission but will cause a trans that is due to fail to fail.

A low stall speed can indicate a slipping stator sprag or low engine power.

If the ASR is active and trying to pull the throttle down, the triangle should be flashing. And I think it pushes the pedal back at you.

If you unplug the rear ABS sensor that should disable the ASR taking it out of the loop. ( you probably would need a scan tool to clear the code however )

Unplugging the O2 sensors will place the car into a non feedback mode and it should run fine if the O2 sensor is bad / rest of the system is good.

On the highway at say 40 MPH, if you stand on the throttle, does the car accelerate briskly? Does the trans downshift during this?

LWB250 08-28-2016 09:43 AM

DAS/HHT said the EZL or coil was bad - looking into actual values showed that the left distributor, or the cylinders it drives, weren't firing.

Swapped coils and the problem remained.

Checked wiring between the EZL and coils, OK.

Got a used EZL off of eBay for $100 and installed it this morning.

Car runs like new.

Dan

Ferdman 08-28-2016 11:21 AM

LWB250, glad that you resolved the problem. For future reference, Beckmann Technologies may sell reconditioned EZL's for your engine.

LWB250 08-28-2016 12:16 PM

Thanks for the suggestion, Fred.

I had looked there, but they don't do anything pre-1996, so no LH systems, only HFM and ME.

Dan


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