Gross misfire when trailer lights connected and lights on

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tanvanmanwithaplan
I am merely driving my van
I am merely driving my van
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Gross misfire when trailer lights connected and lights on

Post by tanvanmanwithaplan »

I’ve got a strange one.

Van build and updates:

2001 AWD Astro 155k on the odometer. 5” lift 30” Gener Grabber AT2 and steel 15” pro comp powder coated wheels. Recently replaced pads and rotors on the front with ceramic ones and a 30” light bar, fog lights, a jeep bumper, a jerry can holder with padlock, and a hi lift jack on the back. Either the transfer case or the front diff started binding due to extreme offroad abuse so I pulled the front driveshaft about a year ago. I believe the bunding was due to placing a full sized spare on the right rear wheel after blowing out a belt in the original one. This tire had less wear on t so it was a little different in diameter. We were the mountains deep in colorado when this happened so we kept on wheeling and drive back through kansas with it kike that. It didnt start acting up severely until months later.

The Problem:

When i have a trailer connected, everythig works fine. Blinkers, brakes and hazards. On the van and on the trailer. Bur when the lights are on, after a while, the engine starts having extreme misfires and loses power, to the point where it couldn’t even maintain interstate speed on one occasion, with a light coleman pop up camper behind it (probably 2500 lbs).

When you stop, it will idle rough and want to die but never quite die. Once when this happened ob the way back to Missouri from Florida, it spewed out a ton of antifreeze out the overflow when we stopped. It was bizzare. The engine bay will get REALLY hot as well, but the coolabt temp will seem stable. When that happened, i did verify there was coolant in the hose by squeezing it and checked the radiator and it was brinmed full. My only explanation would be a lot of instantaneous heat radiating due to detonation during misfiring. Since then i have flushed the whole coolant system then replaced the radiator, installed a new thermostat and rad cap and nothing like the heating/coolant issue has happeed again

SUMMARY:

Because of the correlation between the trailer, headlights and problem, i believe it has GOT to do with that wiring somehow, the trouble is i dont even know where to start. Should i just cut the trailer witing off and start fresh again? I have noticed that whoever installed the current trailer light wiring did a DIY job instead if using the provided trailer wiring by the facotry jack bay. It is still there.

QUESTION:

What do you all think? Should I rip our the wiring and start fresh or start goung to town wirh a meter? Or is this something dumb and theres an amazing solution u havent even thought of?

Tom

Astrophysics
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Re: Gross misfire when trailer lights connected and lights o

Post by Astrophysics »

Hi Tom,

I once had similar problem on full size Chevy G20 camper/ window van.

My problem was that I had a house battery also in the camper van. Both my starter battery and the Aux house battery were charged by the old school method of a diode isolator. The problem was that my house battery was 5 years old and demanded too much current to try to charge it. This dragged my alternator down. I was driving back from the desert of Joshua Tree and my dash volt meter dropped to 10 VDC . Fortunately , I had wired in a circuit breaker switch in the charging line to the aux battery and was able to switch that path to be off. Then I drove the Chevy in 3 rd gear on the freeway to increase rpm and luckily the main battery slowly charged back up and I made the trip.

AP

WE7X
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Re: Gross misfire when trailer lights connected and lights o

Post by WE7X »

Tom,
I have one significant question before going into 'possibilities'?
Does this problem only happen when towing the trailer; but is not a problem when driving just the van?
Or has it always been a problem since the episode with the trailer?

My gut feeling is that for some reason the system voltage is going low, causing the misfire etc.
If your alternator output is marginal for some reason; the extra load needed for the trailer lighting and battery charging my be just too much for the alternator to supply.
A voltmeter, at a minimum, can tell you a lot. Do not rely on the dashboard mounted one. It is not accurate enough (and not portable) to give you the detail you need. You my have to resort to an in-line ammeter, to find out what circuits are drawing power, and how much.
If the problem seems to be only when the trailer is attached, then try running it without the trailer battery hooked up. If all the lights work correctly, the battery charging circuit would a prime suspect. Have the trailer battery tested at a reliable shop.
Let us know what you find, if anything, or nothing.
Rod J
WE7X aka Rod Johnson
Forest Green Metallic '98 LS AWD
Issaquah, WA
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