89 190E 2.6 intermittent limp mode - PeachParts Mercedes-Benz Forum

long-gone · #1 02-05-2011, 02:22 PM

My Daughter's '89 190E 2.6 (76K) intermittently goes into limp mode. At least that's what it sounds like she's describing. I've seen at least one post that asserted these models don't have a limp mode.
She'll be driving along and the car will suddenly lose power for about 15-30 seconds or so and then return to normal. It may do it once or several times over a few miles. It doesn't do it everyday, maybe once or twice every week or two. It normally runs exceptionally well and strong, and it has never done it for me when I go to check it out.
The last time, it lasted for several miles and until she got to a friends house and shut it off (which seems to demonstrate a worsening of the problem). When it occurred she couldn't get the car to go over 20 mph. She tried flooring it, as if to get it downshift for more power (I told her she wasn't going fast enough for it to downshift) but it had no affect on the condition. Interestingly she said when she gave it gas the rpms would go way up but the car wouldn't go any faster. I thought it may be the tranny when she told me that, but when I arrived to test it it ran fine. Strong and smooth and shifting perfectly. T-fluid level and color is fine so I highly doubt it's the tranny.
It doesn't stall or even threaten to stall, it just won't go, like a prolonged hesitation, so I'm back to thinking limp mode.
I have an OVP to swap, and I'll test the temp sensor when I have chance to look it over this weekend.
Sound familiar to anyone? Will the EZL trigger a limp mode if the crank sensor posts a bad signal? Any other suggestions?

duxthe1 · #2 02-05-2011, 07:30 PM

The car doesn't have a "limp mode". You are simply experiencing a malfunction of some sort. You may have the fuel pump cutting out intermittently. I'd be suspicious of the fuel pump relay on that model.

long-gone · #3 02-06-2011, 03:27 AM

Well, I got a little clarification from her tonight. She says it only happens when accelerating from a stop, like a prolonged hesitation. She says she tries to give it gas by pushing all the way down on the pedal and it sometimes seems to start to "kick in" as she lets up on the pedal. In the mean time, the tach does respond (the engine revs up) when she gives it gas but the car doesn't respond acceleration-wise. It eventually begins to act normally. It could happen anytime after the car has been driven a few miles and doesn't seem to matter whether it's the first time the car has been driven that day or if it's been used several times already.
As mentioned, the last time it happened it lasted for a few miles until she got to her destination (and hasn't happened again since).
I don't see how the rpms can respond to her giving it gas without the car commensurately accelerating unless the tranny isn't transferring the power. She said she tried manually shifting to lower gears while it was happening with no affect. When I got there minutes later to check it out the car ran perfectly with no indication whatsoever of the trans slipping or any poor shifting.
I'm going to switch cars with her so I can get a better idea of what's happening before I mess with anything. Are there any transmission components or cables from the accelerator linkage that could intermittently cause something like this?

mak · #4 02-08-2011, 09:33 PM

if the OVP is intermittent than the car does run in the basic Limp mode. The ABS light may come on and very difficult cold starts
The OVP and the Fuel Pump relay if old will certainly give a lot of problems in CIS-E engines. So should be a priority check
A partially choked fuel filter could exhibit similar symptoms. The last check would be the fuel pressure Regulator .

mak
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