92 400E stumbling / missing
 

Hi all,

I have searched the archives and think I will proceed in this order to try to fix this - just looking for some reassurance if this is the right way to go about it...

1. Caps and Rotors
2. Spark plugs
3. Wiring harnesses
4. Give up and take it to the mechanic

Patient is a 92 400E with 52,000 miles. I left it parked for two weeks while on vacation. Weather has been fairly hot and dry here in the SF Bay Area.
This morning I started it and the Check Engine light came on and the engine was missing/stumbling (like it was running on 7 cylinders). A touch of gas and it fixed itself and the CEL went out and was running back on 8. At the end of the driveway it started missing again. Then I drove to work and it intermittently seemed to be missing. After work it was fine for a little bit then deteriorated to where it idles OK, but when traveling at steady throttle it seems to be OK but could be missing (hard to tell), as soon as you touch the gas a bit it misses, then recovers and gets up and goes. So it is not severe, but definitely not right and kind of annoying. The gasoline level was low, I filled it after work, no change as of yet - I figured maybe what was left in the tank might not be so good, but was normal CA-available Chevron 91 octane. Check engine light has not come on again since the first time this morning.

One last question. When ordering the rotor(s) the parts sites say you need an adaptor that is out of stock if the engine is under serial number 000041. Not knowing where to find the engine serial number, I think I will assume my engine is not one of the first 40 off the line... Also ******** Arizona seems to have pretty good price, quite a bit less than Phil whom I usually would go to for maintenance parts. The dealers around here are all expensive.

Car otherwise has been great in the year I've owned, it came without records but seemed to be cared for very well according to my mechanic. However, the parts listed above are most likely original. What I can see of the harness seems to be OK but is there a litmus test for this, i.e. if I poke a certain place and it falls apoart it's bad or if not, then it's good?

Thanks,
Jim
92 400E

If the caps and rotors are original, it is high time they are replaced. Might be a good time to check the plugs and clean and adjust or replace them.

I don't think that the 92 year was affected by the defective harness issue.

See about the rotor and caps first - either way, they need to be replaced. You will need 2 hex bits to remove them, so if you don't have a set, buy them first. Removal and installation is fairly straight forward. I think there might be a pictorial in the DIY section.

Good luck and let us know what you find.

A search of the archives should reveal that the first step is to build the code reader and read the fault codes.

The '92 was affected by the harness issue, or at least my '92 was.

Plugs, caps, rotors, and harness may ALL need to be done. Good news? They're all DIY-able.

Look at the ox sensor as well if it is not working as it should you may get a stumble as well. Your serial # is on you registration

You should be able to call a local dealer's parts department and they can look up your engine number if they have your VIN. You said you experienced the problem after the car sat a few weeks. Did you notice any preignition (valve ping) under acceleration?

Hi,

Thanks for the many replies. I will order the caps, rotors, and plugs to start and replace them. Although today it started right up and had no problems whatsoever.

I will report back with an update.

Thanks,
Jim

Could also be the slide (throttle actuator) well atleast that's what fixed mine,,, I got lucky and found a new one on ebay for $25

when you take off the distrib caps let us know how bad the GREEN CRUD was.

Well, I finally got around to pulling the car out of the garage and fixed it. Replaced the caps and rotors and it seems to run great. Then replaced the plugs for good measure. All parts appears to be original (plugs were Beru?). Anyway, so far the miss is gone and it wasn't a bad job at all except for the pasenger side wirewall plug, that one is tough to get to.
Thanks for the help,
Jim
PS - A little bit of green crud on the passenger side cap (but wouldn't have noticed it if someone hadn't mentionied it and none on the driver's side.). Both parts had a '92 manufacture stamp.

Remove the wiring harness bracket that's in the way and that one becomes easy to get to.