88 Accord Weber backfire or dieseling issue

[Xaisk]

I got my Weber installed and have been driving it for about a week now.
Its working perfectly fine however when I shut the engine off, sometimes it will backfire and blow the rubber cap off the intake manifold that I had to seal.

Its not really a big deal, I used vacuum caps to seal it temporarily till I can get aluminum to plug them.

I just reach under the car and pick the cap up, put it back on and drive if it happens.

Also.

The big fat silver metal pipe that went into the exhaust manifold has no end to it, was temporarily plugged with a cork. Its the bigger of the 2 pipes going into the exhaust manifold. Itll blow the cork out sometimes resulting in a wierd sound as I accelerate. It hasnt had any negative affects but im worried exhaust fumes that havent been through the converter could be entering the cabin. I dont smell any gassy smells till I open the window.

Im wondering if the backfire or diesel or whatever it is doing could be because of that pipe being there. It has the tendency to blow the cap off less if the cork is out of the pipe.

Could there be to much exhaust fumes inside of the exhaust manifold that is causing this problems?

How did you guys plug that stupid hole up? Id rather plug it at the exhaust manifold itself to completely remove that pipe all-together.

It ONLY does this when I shut the engine OFF.

[2ndGenGuy]

In my experience, it's because your engine is running lean. I would try adjusting your idle mixture screw just like 1/4 to 1/2 turn towards the rich side, that's cleared it up for the few Webers that I've set up. It seems like the "lean best idle" guide really does set it up lean, sometimes lean enough to cause the dieseling after the car is run for a while. It doesn't usually take much to get rid of that, especially if your car is running pretty well otherwise.

[greentee76]

When I first did my weber it would diesel when I shut it off because the throttle return spring that comes with the kit is not sufficent to close the throttle plates all the way. I used a larger spring from a diesel truck and made a bracket to hook it to.

As far as the pipe from the exhaust manifold, I cut them off about 2" from the manifold and fold them over on themselves and welded them.

[2ndGenGuy]

^^ Oh yeah, having a good return spring is very important! The spring on the shaft itself is not good enough, you really do need an external spring.

[Xaisk]

In reply to everybody.

I have a friends dad who says he thinks the fuel mixture is a bit rich. That could be the issue but ive been to busy to go out there and mess with it. Working on moving out on my own.Ill test the theory as soon as I can 2ndgenguy.

I have also read that that could be the issue with the issue Greentee. It sounds like the spring isnt strong enough. Do they manufacture stonger versions of the same size spring possibly? That would be alot easier to install than an external plate and spring. Im going to look into it.

As for the pipe. Did you do it while it was on or off the car? (im pretty sure off but double checking) and what kind of welding tools did you need? I have a welding gun but I dont think its strong enough for that type of metal. It hasnt been used in years either so its probally not going to work as good as it used to.

[greentee76]

Yeah I did the pipe with the manifold off when I was doing my engine "refresh". I just used the wire feed welder (mig) at work. Like I said I kind of flattened it and rolled it up like a tooth paste tube. The welding might not have been necessary at all.

[JordanQ]

I got my Weber installed and have been driving it for about a week now.
Its working perfectly fine however when I shut the engine off, sometimes it will backfire and blow the rubber cap off the intake manifold that I had to seal.

Its not really a big deal, I used vacuum caps to seal it temporarily till I can get aluminum to plug them.

I just reach under the car and pick the cap up, put it back on and drive if it happens.

Also.

The big fat silver metal pipe that went into the exhaust manifold has no end to it, was temporarily plugged with a cork. Its the bigger of the 2 pipes going into the exhaust manifold. Itll blow the cork out sometimes resulting in a wierd sound as I accelerate. It hasnt had any negative affects but im worried exhaust fumes that havent been through the converter could be entering the cabin. I dont smell any gassy smells till I open the window.

Im wondering if the backfire or diesel or whatever it is doing could be because of that pipe being there. It has the tendency to blow the cap off less if the cork is out of the pipe.

Could there be to much exhaust fumes inside of the exhaust manifold that is causing this problems?

How did you guys plug that stupid hole up? Id rather plug it at the exhaust manifold itself to completely remove that pipe all-together.

It ONLY does this when I shut the engine OFF.

yes, its most definatly because there are too much exhaust fumes in the inside of the exhaust manifold.

that single handedly is the problem. fix that.