L98 main engine ground issues?
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,261
Likes: 4
From: Middle River MD
L98 main engine ground issues?
My L98 recently started cutting off and back on for a split second while going over bumps and/or shifting hard through the gears. When this happens the dash maxes out and gauges pegged as if I just turned the key to restart. I figured the main ground could be the culprit. At first I thought one of the battery cables were loose, but they are fine. Anyone experience this and find the ground to be the problem?
Burning Brakes
Joined: Nov 2004
Posts: 897
Likes: 12
From: Land of Whiskey Rebels, PA
There are a bunch of grounding points. One of them is on the passenger's frame rail, below the A/C, near the firewall. Condensation drips off the A/C unit onto the frame rail, so rust develops under the wire terminal. Result? Little or no contact.
Take it off, clean the terminal, clean that spot to bare steel, apply some anti-oxidant. I used NoAlox. PenetrOx is good. Some guys say to use anti-sieze. Clean threads on bolt and tighten it down. Use the same procedure for all grounds. All grounds need to be CLEAN and TIGHT.
Go to www.helminc.com and order a Factory Service Manual. It shows where ALL the grounds are.
Hope this helps.
Take it off, clean the terminal, clean that spot to bare steel, apply some anti-oxidant. I used NoAlox. PenetrOx is good. Some guys say to use anti-sieze. Clean threads on bolt and tighten it down. Use the same procedure for all grounds. All grounds need to be CLEAN and TIGHT.
Go to www.helminc.com and order a Factory Service Manual. It shows where ALL the grounds are.
Hope this helps.
Team Owner
Joined: Aug 1999
Posts: 24,017
Likes: 634
St. Jude Donor '10
There is one behind the battery, its a piece of all-thread on a plastic block with several wires grounded together. The all-thread came loose on my 88 causing the problem you describe. I used a nut and bolt to hold them all together confirming the fix.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Check IP and ECM grounds on the main engine ground point ;the big bolt above the oil filter
That is the main power feeds ( red/org wires ) from the battery , not a ground point
Still a good place to check for loose contacts
Still a good place to check for loose contacts
Last edited by rodj; Jan 5, 2012 at 07:43 PM.
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,261
Likes: 4
From: Middle River MD
Thanks...I did get the car on lift and tightened up the ground by oil filter. It was a little loose, not much. Seemed to improve at first but its acting up again....probably wasnt the real cause. Will look into other suggestions provided. I'll tell ya its sucks when your takin off like a rocket just to have car fall on its face just as you break 'em loose on the 1-2 shift. Same thing while going over bumps. Car stumbles and dash looks like the key was just turned on when you start car. Trip meter also resets when this happens. That explained the horrendous gas mileage when calculating at my last fill up
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Thanks...I did get the car on lift and tightened up the ground by oil filter. It was a little loose, not much. Seemed to improve at first but its acting up again....probably wasnt the real cause. Will look into other suggestions provided. I'll tell ya its sucks when your takin off like a rocket just to have car fall on its face just as you break 'em loose on the 1-2 shift. Same thing while going over bumps. Car stumbles and dash looks like the key was just turned on when you start car. Trip meter also resets when this happens. That explained the horrendous gas mileage when calculating at my last fill up
Another strategy is the "wiggle test", with the car idling, wiggle wires and connectors, looking for a reaction.
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,261
Likes: 4
From: Middle River MD
I agree, checking (and cleaning) all the grounds should be your next move. I would also check the B+ connections, including battery cables, both ends. Since the problem shows up with a bump or other "nudge" to the car, I would suspect a loose/dirty electrical connection, and it may not be on the ground side. There is an off chance that there is an internal weak spot in a battery cable or other wire that is common to the circuits that hiccup.
Another strategy is the "wiggle test", with the car idling, wiggle wires and connectors, looking for a reaction.
Another strategy is the "wiggle test", with the car idling, wiggle wires and connectors, looking for a reaction.
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
My L98 recently started cutting off and back on for a split second while going over bumps and/or shifting hard through the gears. When this happens the dash maxes out and gauges pegged as if I just turned the key to restart. I figured the main ground could be the culprit. At first I thought one of the battery cables were loose, but they are fine. Anyone experience this and find the ground to be the problem?
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Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
My L98 recently started cutting off and back on for a split second while going over bumps and/or shifting hard through the gears. When this happens the dash maxes out and gauges pegged as if I just turned the key to restart. I figured the main ground could be the culprit. At first I thought one of the battery cables were loose, but they are fine. Anyone experience this and find the ground to be the problem?
Turns out the nut that holds the grounds to the bellhousing came loose. Every time I went hard on throttle, over bumps, etc. it exhibited this same behavior.
Cleaned the ends, slathered them with dielectric grease and it's been running fine ever since.
Good luck!
