idles fine but back fires when under load ?
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Topic author - I sleep in my van
- Posts: 589
- Joined: Wed Oct 13, 2010 2:07 pm
- Location: Barrington NH
Re: idles fine but back fires when under load ?
There is no cat on my van its an 89 and is not required in NH but thanks for the info I will need it when I move to California in the future.
Recently bought a 1989 Astro RS from Florida. Replaced stock engine witha 1997 5.7 vortec with TBI and replaced transmission with rebuilt 700R4 with mild shift kit.
Bought on Monday the 16th of April 2012
Bought on Monday the 16th of April 2012
Re: idles fine but back fires when under load ?
I think it was lifted that suggested pulling the o2 sensor infront of the cat to releive the back pressure when testing for a plugged cat. I thought that was a good idea if your ca is welded in instead of bolted. If its bolted you can just undo the clamp.
1999 Safari Touring edition.
trailer tow pack with a 3:73 posi
Bucket bench seats, Rear heat, Rear Airconditioning.
teal green
300 000 kms
AirRide air bags in the rear to fix soft stock suspension.
Onboard aircompressor to make it all work nice.
trailer tow pack with a 3:73 posi
Bucket bench seats, Rear heat, Rear Airconditioning.
teal green
300 000 kms
AirRide air bags in the rear to fix soft stock suspension.
Onboard aircompressor to make it all work nice.
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Topic author - I sleep in my van
- Posts: 589
- Joined: Wed Oct 13, 2010 2:07 pm
- Location: Barrington NH
Re: idles fine but back fires when under load ?
It does not have a cat converter, I removed it way before I did the engine swap.
Recently bought a 1989 Astro RS from Florida. Replaced stock engine witha 1997 5.7 vortec with TBI and replaced transmission with rebuilt 700R4 with mild shift kit.
Bought on Monday the 16th of April 2012
Bought on Monday the 16th of April 2012
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- I have my van tatooed on my cheeks
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Topic author - I sleep in my van
- Posts: 589
- Joined: Wed Oct 13, 2010 2:07 pm
- Location: Barrington NH
Re: idles fine but back fires when under load ?
its raining hard here in NH so when it stops I am going to check a bunch of things, ignition timing to be first because I am wondering if they set the timing without unplugging the wire on the distributor.
Recently bought a 1989 Astro RS from Florida. Replaced stock engine witha 1997 5.7 vortec with TBI and replaced transmission with rebuilt 700R4 with mild shift kit.
Bought on Monday the 16th of April 2012
Bought on Monday the 16th of April 2012
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Re: idles fine but back fires when under load ?
Just for kicks, while you have the timing light all set up, shine it at your fuel injectors while running to see if it is a nice cone shaped spray pattern, or a bunch of dripping drops. (air cleaner removed of course)markmitchinnh wrote:its raining hard here in NH so when it stops I am going to check a bunch of things, ignition timing to be first because I am wondering if they set the timing without unplugging the wire on the distributor.
I like to disconnect the battery for 5 minutes before I start on the tune up.
That way, I know the computer is basically at the default settings, and has cleared anything it may have learned or adjusted.
Also, is the gas in the tank very old?
2021 Yamaha Tenere 700 - Blue.
2016 Yamaha XSR900 - Silver.
1990 Astro - AWD - Brown.
1987 Astro - With 5 Speed & 4wd - Silver & Blue.
2016 Yamaha XSR900 - Silver.
1990 Astro - AWD - Brown.
1987 Astro - With 5 Speed & 4wd - Silver & Blue.
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Topic author - I sleep in my van
- Posts: 589
- Joined: Wed Oct 13, 2010 2:07 pm
- Location: Barrington NH
Re: idles fine but back fires when under load ?
I started the engine swap in August and there was possibly 5 gallons in the vans tank I added another 5 gallons at the shop with half a bottle of dry gas added to it.
Recently bought a 1989 Astro RS from Florida. Replaced stock engine witha 1997 5.7 vortec with TBI and replaced transmission with rebuilt 700R4 with mild shift kit.
Bought on Monday the 16th of April 2012
Bought on Monday the 16th of April 2012