Engine shut off after bump.

[MStokes]

Morning guy's got a strange problem. Just had used engine installed about a month ago, now sometimes when the car's CCR is set on performance mode & hit a bump in road, the car dies. The car will restart but it seems like something is loose. Before I put car in shop, is there something I can check? Does it sound like a loose crank sensor maybe or a ground they left off when engine was changed out. If I need a new crank sensor, is it hard to change or do I let shop do it? Thank's again for all help.

[viper8907]

Check your connections at the battery. On my old 92, the battery terminals would always work themselves loose, and it would die at random times, but it would either always start back up, or I would have to tighten them up, and then it would work fine again for a few weeks. Then I finally put some loc-tite on it.

[mntnbkr]

You can check the main engine ground fairly easily. It's located on the "front" of the engine between the starter and the A/C pump.

Other than that I would check every connection that you can to make sure they're all secure... including the harness at the PCM, and where the harness goes through the firewall (directly behind the passenger side strut tower).

Good Luck.

[MStokes]

Sounds good, thanks for everyone's help.

[MStokes]

Hey mntnbkr, could a very loose motor mount on front of engine cause this? Found one. I'm gonna kill my mech. I will have CEL reset tonight. Maybe with proper ground, I will not need a new pre-cat sensor after all. thank's again.

[mntnbkr]

I doubt it, but it might contribute a little by allowing the engine to move more than it should thereby pulling on a wire or connector with more force than it otherwise would when you hit a bump.

Theoretically though, the engine should run without the motor mounts attached at all, so I doubt that's your problem.

Adam

[mntnbkr]

Also, a way of troubleshooting this (a very rudimentary way at that) might be to let the vehicle idle while you wiggle with the various connectors and harnesses that are easily in reach. DO NOT get yourself caught in the belt though. Like I said before, I would concentrate on the area near the PCM, or where the harness goes through the firewall. Wiggle the wires and connectors, and if the car stalls, then you know that your problem is near that area.

Actually, on the connector that goes through the firewall, there should be a hex bolt that secures the engine side of the harness to the firewall side of the harness. You will probably have to pull back a sheet of protective mastic that is stuck over the connector (to shield it from water dirt and grime) in order to expose the connector. If the hex bolt wasn't secured, then that harness may not be connected all the way. If your mechanic forgot to tighten a motor mount, I hate to think about what else may be loose or overlooked.

On a side note, I am fairly new to the Bonneville and I just recently joined the forum. My first experience with a Bonneville (before even driving one) was putting a new engine in my '99 SSEi. The reason I'm telling you this is because the problem that you're having my be common problem (completely non engine related) that I just don't yet know about yet being a relative noob.

I would definitely check the main ground wire though.

[93RedSled-SSE]

Don't overlook ICM connector.

[mntnbkr]

I was just thinking about that while I was in a meeting here at work...but 93RedSled-SSE got to it first. Definately check the ICM connector directly beneath your coil packs.

[MStokes]

Got the motor mount secure. Car seem's to run better. Will check all other connections and post how car does going home tonite. Thank's everyone.

[MStokes]

Thank's to all who responded. Loose motor mount on front of engine caused problem. Car ran great going home.

[mntnbkr]

Wow, I'm very surprised that this was actually the problem!!! I'm glad we could help though.

[93RedSled-SSE]

Thank's to all who responded. Loose motor mount on front of engine caused problem. Car ran great going home.

Possibly, the motor was getting shaken and, in turn, some item on it was killing the engine. Anyway, yeh, glad you have smooth sailing again.