500E 1993 - Rough idle and potential limp home mode???

[svhamelly]

The other day, I felt a bit of a hesitation while accelerating from idle. Thought I'd need to check into it soon.
Today I changed the fuel sending unit o-rings... gas smell in trunk after fill up and also noticeable gas stain on tank around and under sending unit.
15 minute job...easy... and then drove to station to fill up with 93. On the way back car felt like it went into limp mode. Bogged down and stumbled on acceleration from low speed or idle. Drove a bit farther to try to find more symptoms. Manually shifted into 2nd with revs up seemed to run ok but still stumbled on acceleration.

Got home drove into garage and took the attached video.

Shut down car. It wouldn't restart... cranked fine and would almost fire up... 2 small backfires and then just cranking. Went out an hour later and it started but still very rough idle.

I've been reviewing all the posts here and seems like I should start with caps/rotors/insulators. I have found quite a few original parts on this car over my 18 months of ownership and am guessing those things haven't been addressed yet, so whether that solves my problem they probably still need changed.

My biggest issue is no climate control in garage and 90 degree ambient temps

View attachment SVH 500E rough idle.m4v

 

[gsxr]

If there was no ASR light on the dash, you almost certainly were not in limp mode.

The backfires and rough idle sound a lot like ignition system. Remove everything on both sides for inspection. Any idea how old they are (years or miles)?

 

[svhamelly]

Tonight (after the sun and temps went down) I pulled the caps, rotors and insulators... they actually all look pretty good, some condensation inside the caps but not much. No real dampness or wetness or slime on insulators like other members are seeing.

All the contact areas on rotors and caps look pretty good, some carbon buildup, but not all that much.
What I did find that is the most interesting is a very rusty connector pin on the left side rotor... the one that the coil wire connects to... I'm wondering if this is the culprit... all the other pins from spark plug wires are bright and shiny and in very good condition. I'll post some pics as soon as I figure out how to get them from my iphone to my new Macbook Air.... Airdrop doesn't seem to be working yet.

 

[svhamelly]

Left side cap...

 

[svhamelly]

OK, I removed caps, rotors and insulators... all looked pretty good except for that one offending rusty coil terminal on the left side cap... I cleaned everything thoroughly including the coil wires/terminals. Reinstalled all, using Loctite blue (haha well, Permatex blue which is what O'Reilly sells) on the rotor bolts... Also, nobody mentioned this, so please let me know if I'm going to destroy my engine , but I also dabbed some dielectric grease on all the connections.
I see why the rotor bolts "might" come loose without Loctite... the lock washers don't have much spring left in them and so probably don't lock the way they would when new. Just a guess.

Took him out for a drive and runs great. It's on the cooler side this evening and although I definitely got it up to operating temps (driving vigorously for 20 minutes) I am still going to try it in the heat of the day, since the 2 times it acted up was after it had been driven for 30 minutes in daytime temps... don't know if that's going to make any difference and honestly hope just cleaning things fixed my problem.

Thanks to all the other posts in the forum for helping me with troubleshooting and technique!!!