92 400E running issues

[Jhilly]

Im stumped. Got 14.5 volts on battery when car is running. Starts and runs idling no issues. Drive it and once i get up to any speed when i start to slow down he car surges, gauges go nuts, after a few times doing this the car stalls.

Replaced upper harness, lower harness, not throttle. Rebuilt alternator last year. New battery last year. New lower harness last year. New plugs, wires, coil only one.

It sort of acts like its in limp mode but Ive been driving it when its in limp mode and it doesnt seem to be the case. It acts like its depleting the battery. Once it stalls check the battery and it has 12.5 volts. Go to start everything powers up turn key nothing. Jump it starts right up runs for hours and has 14.5 on the charging system the entire time.

 

[gsxr]

Can you explain "gauges go nuts" in more detail?

Also "...Go to start everything powers up turn key nothing. Jump it starts right up..."

When you turn the key to start, does it crank but not fire, or won't even crank?

 

[Jhilly]

gauges go up and down rpm, speed, oil once i slow my speed down to say 1500 rpm it begins to surge from almost stall to 1000 to 1500 then stalls. Throw car in neutral starts back up.
All gauges come on, buzzer is strong, turn key to start position no crank, all gauges go dead, lately. Earlier today there was really labored roll over and eventual start. Seems like battery drain but when its dead or just after it dies on me there is 12 volts on the battery.

 

[gsxr]

gauges go up and down rpm, speed, oil once i slow my speed down to say 1500 rpm it begins to surge from almost stall to 1000 to 1500 then stalls. Throw car in neutral starts back up.

OK, so the gauges are probably bouncing due to the RPM surge.

All gauges come on, buzzer is strong, turn key to start position no crank, all gauges go dead, lately. Earlier today there was really labored roll over and eventual start. Seems like battery drain but when its dead or just after it dies on me there is 12 volts on the battery.

Next time this occurs, turn on a light you can see - headlights, or the overhead dome light. When you turn the key and there's no crank, see if the light turns off or turns very dim, until you release the key. If so, you may have a defective battery with an intermittent shorted cell. These will read ~12.5v with no load, but will drop to near zero volts when a load is applied. Strange this would be intermittent though. If you have a battery from another car to test with, swap it out and see if there's any change. At only 1 year old, the battery should be under warranty.

Odd thing is, the idle surge shouldn't occur when running, as the alternator should be supplying normal 14v.

 

[Jhilly]

Began with surge to almost stall but had no effect on gauges. Now its effecting the gauges and power steering. I'm leaning toward a bad battery. As I use a kill switch on the battery when not using the car as I have the dreaded parasitic draw and have to been able to do the pin replacements

gauges are doing stuff bouncing up and down even when driving at 60mph rpm dropping oil sender, speed

 

[gsxr]

Ohhhh. If you have an undiagnosed parasitic draw, you should work on that as well... if it's related to the 38-pin diagnostic connector X11/4, that can cause all sorts of weirdness...

HOW-TO: Replacing the 38-pin Diagnostic Socket (X11/4) | "HOW-TO" Tutorial Articles

When I recently purchased my 500E it had a crippling Battery Drain which would totally drain it overnight. Removing all of the Fuses & Relays did not eliminate the parasitic drain. I did discover that the LH module was causing the current draw as it was not shutting down when it should be. As...

www.500eboard.co

 

[TerryA]

@Jhilly,
Have you checked that the small wire on the battery+ terminal is bolted down tightly? It powers all of the computers. If that wire is loose it can cause havoc.

Also a defective ignition switch can cause a lot of problems.

Just a few suggestions.

lol

 

[Jhilly]

I have not on the wire. I replaced the ignition a year ago

 

[Jhilly]

So last night driving home dash lights strong as I drive dash dims. Slow down, dash lights dim, surge 1500 to stall, hammer down keeps running. Park turn off, try to start again all dash light dead, hear again a strange sound from the computer area then it stops. Darth, I affectionally call her, took a brake. This morning, one weak roll over then everything dead. Got in my truck!

 

[Jhilly]

Get home. Dead. No roll over no dash lights. 12.5 volts on battery. Jump starts right up. Strong lights, etc...13-14 at battery running. Today just really surge at low rpm...Gremlin for sure....thanks for all who gave me input! Darth is a mysterious villan for sure!

 

[gsxr]

Put a voltmeter at the battery and have someone try to crank the starter, when it's "dead". See if the voltage remains steady at 12.5 or drops near zero.

 

[Jhilly]

Drops to zero when key is turned. Then back to 12.5 volts on battery

 

[gsxr]

Drops to zero when key is turned. Then back to 12.5 volts on battery

Sounds like a shorted cell in the battery. Take the battery to your local FLAPS/McParts and have them load-test it, pretty likely it will fail...