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April 2014 Question IT

Fixing what you broke

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Got a burning question or simply need some advice with problems you've encountered while wrenching on your current/future projects? Ask our automotive guru Eric Hsu anything—literally, he's going to answer every single question, as long as it's automotive related.

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Mazda RX-8 20B Swap

I own a '04 RX-8 and the car has given me some hiccups from the start (the thing wouldn't start after a week out from the dealership because of fouled spark plugs), but I love the car especially after reading the possibilities of the rotary. With all these dreams of rotaries dancing in my head I had the epiphany many rotary heads have with a 13B. What about a three-rotor? Enter the 20B. How feasible is this in my car without it becoming a garage queen? How much of a budget do I need to do it right? Who or where can I look to find info on this swap? Can the original six-speed transmission be used? I know it's been done before. Enter your May '11 issue with one of the best examples of an RX-8 with a 20B built to perfection that I still drool over. Now I know a little in my scouring of the Internet and forums, but there's a lot of crazy stuff being thrown around so trying to sort through it is a bit of a headache, to say the least. Hence why I come to you. If you could help me figure out fact from fiction and any answers I would be ever grateful.

-Carlos Keller, TX

The 20B is a pretty expensive engine. The costs of the parts alone to install a 20B into your RX-8 will probably be triple the value of your RX-8. That's fine if you're down with dropping that kind of cash, but then you'll either need to figure out how to install it and get it running, or fork out the same amount of cash to have an experienced shop install it for you. Try contacting Ron Bergenholtz down in Houston, TX, at JTran Motorsports. Ron built the Bergenholtz Racing RX-8 that successfully ran in Formula D. He's been building street and race cars for a long time now.

You can run the RX-8 six-speed transmission, but that's about it. Just about everything forward of the transmission will need to be replaced. Engine mounts, cooling system, induction, engine harness, turbos, intercooler, and more will all need to be custom fabricated. Then you'll need a stand-alone ECU and fuel system as well. All in all, it'll be a very costly swap and will take a good deal of time to get it all done right.

Integra DB8 EVAP Valve Issues

I just finished my '95 Integra GSR four-door build after six long months. The engine has been blueprinted with Type-R pistons, but at low rpm the car is misfiring. The car still has plenty of power that you can feel. My initial diagnosis, although it could be wrong, is that it is related to a vacuum problem. The engine is currently running the stock GSR intake. I like the way it looks and want to keep it, but here is the problem: Intake Air Bypass Solenoid - IAB (36163-PT2-004) and Purge Cut Solenoid Valve Assembly (36162-PT3-Q01). I have no idea if they are working or not, but what I can tell you is that they both look very similar and have some type of round little cap that is cracked. The IAB, as you probably know, goes on top of the intake manifold and the Purge Cut Solenoid goes under the manifold connected to this vacuum tank thing. So, if I wanted to get rid of those bad boys, is it possible? If it is, what do I need to do? Is it a good or bad idea? Please point me in the right direction. I have been working on it for almost six months getting this thing done and when I think it's finally done, this problem comes up. I can't wait to drive this car.

-Julian P., via

The intake air bypass solenoid is necessary for a street car because it controls idle speed. Of course you could also just adjust the throttle stop screw to hold the throttle plate open for idle, but you'd lose the functionality of idle speed under different conditions (A/C, cold start) and deceleration fuel cut (good for fuel economy). I recommend keeping the Intake Air Bypass Solenoid, but you could ditch the Purge Cut Solenoid, especially if you've removed the charcoal canister. The purge solenoid exists to purge the charcoal canister and dump the buildup into the intake manifold during high vacuum situations. With a '95 OBD-I ECU, you can remove the Purge Cut Solenoid without any ill effects. If you wanted to be extra sure, you could just leave the solenoid plugged in without any hoses attached to it. Or you could also measure the electrical resistance of the solenoid with a voltmeter and simply plug in a resistor of similar value and remove the purge solenoid.

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