'87 190E 2.3-16 idle issues

[krasuskyp]

Any thoughts how to remedy a throttle that intermittently sticks wide open? It's not a lube issue. Happens when I am @ idle and rev it up a few times. Also, after it revs, it returns past the 1000 starting point, bogs a bit, then settles into 1000. Sometimes it bogs first when I go to blip the throttle, prior to revving. Additionally, the cruise control cuts out on its own out of nowhere, and when I hit 'resume', the thottle buries immediately. Correlation? I'm told this all could be a mixture issue, needing to be richened? In the winter it was idling @ 2300 or so, and my mechanic says he richened the mixture which remedied that, but not the other issues. I tried fiddling with the spring loaded allen set screw atop the throttle, but only managed to have the throttle jam open (yes, I'm an idiot). It is not the 10 amp OVR relay, either. Any suggestions appreciated!!!

I also have a 16 valve that behaved similiarly. If you take a close look at the throttle body, there is a small grey switch attached to the throttle plate spring. I think the name of this is the throttle position switch. Remove the wire harness and the swtich with a 7mm wrench and closely inspect the rubber boot on the switch. I chaecked mine out and saw the boot was torn. I ordered a new switch, the part number should be on the switch, replaced it with the new switch and Voiola... Smooth idle.

It should run about 25 to 35 bucks and 15 minutes of your own time. I went thru all the mechanic BS checking the idle valve and replacing with 2 new idle valves, to no avail. Try checking it out and let me know what you find. Thanks, Joe

[krasuskyp]

Hmmm... Joe, thanks for the insight. I love short cut type easy CHEAP repairs like that, if that should be the case. Worth looking, I'll take a peek tonight. My tech told me idle control valve as well. Interesting to hear you did it x2 with no result. Did you have the same issue with the slight bog when revving, stalling after revving, and the throttle sticking wide open, etc. or what is just a rough idle?

Paul

'87 190E 2.3-16
'98 ML320
'58 TR3A
'99 Arctic Cat ZR500

That was exactly the problems the car had. Did you have the injectors replaced also? Mine has new injectors. Try the throttle postion switch on the throttle body first. Good Luck, Joe

problems, such as ignition and fuel injectors.

Check under the rotor to make sure all is well. Difficult to check distributor without an oscilloscope. As for injectors, if they are old, they could develop some gunk and do not move properly. This could lead to a spray that is not fully atomized, or worse, stays open too much at idle and leads to rough idle and poor fuel consumption. Yes, not everything is related to the OVP. If all else fails, think about injectors for high mileage.

[krasuskyp]

Thanks Joe for the clarification, and to "Hectortam" for your insight. Got 130k, not sure if prior owner did injectors, so I may do that next week. Any idea how costly I can expect that to be?

I'm also installing new wires tonight, Karlans from a wholesaler out in CA for $74. Hope they're any good. Joe, I'm having trouble locating that throttle position switch you referred to. Is it the one that appears to have a rehostat attatched to it under the throttle lever (what the lever returns to and rests on when not actuated, that is easily seen standing on the driver side and looking straight at the throttle where the mechanism ends)? Or is it further back up the throttle cable up toward the throttle body area and firewall? I'd like to get a good look at that.

I need to get this sorted out, it's running a bit rich. So rich that I just had my exhaust done, removed pre-cats, installed Catco cat, and kept factory muffler / resonator, and the cat rattled the next day. They cut it out and it was burnt already. Best part is that they're ordering me an OE one to put back in and now I'm running CATLESS. The power and sound are great, but I'm up for CT emissions in Sept. Oh well...

Tx again.

Paul

'87 190E 2.3-16
'98 ML320
'58 TR3A
'99 Arctic Cat ZR500

krasuskyp

It cost me nearly $300. That is because I could not find the cause of my rough idle. I checked compression, ignition, vacuum leaks, the famous OVP, and could not determine the source. I even checked the distributor (under the rotor) for worn out weights, etc. I finally gave up and gave it to a local mechanic who spent quite a few hours analysis (though did not charge me for it). He checked the distributor and the oscilloscope reading was normal. He finally found the source to be the fuel system. I had long given the fuel the OK since it seemed to run fine under high RPM. Anyway, he pulled out the fuel distribution, cleaned, added new gaskets, and now the engine runs smooth.

BTW, I agree with the throttle position sensor. That is a quick replacement and cheap. In my car, even the return springs for the throttle was gone/worn out. This car was ready to be donated by my friend and I rescued it. All it needs is a little TLC and should run fine. I just drove it the 75 miles to work to see what else it needs (need to keep the miles in my bimmer from creeping up too). It has a sound coming from the differential. Or it could be the bearings. I shall see, with 250+ K miles, what else may need replacement. Yes, the struts will be replaced when I have time (probably in 2 weeks from now).

Hope this helps, Hector