Tech Support September 2009 - Rear End

Where We Cure All Your Tech Problems
Here's where we act like we know something technical about cars. Feel free to ask us about your technical troubles. Write us at tech superstreetonline.com or Super Street c/o Tech Support, 6420 Wilshire Blvd., Los Angeles, CA 90048. Feel free to include a picture of your project or tech problem.

Q Hi, first I just want to say the mag rocks! So I have a '96 Toyota Corolla with a 20 valve 4A-GE blacktop. It idles high and boggs or misfires every now and then and idles around 1200 rpm. The only mods on the car are filters on the ITBs, an HKS header, Splitfire sparkplug wires, Iridium plugs, 2 1/4" exhaust and the JDM ecu. Sometimes there is black gunk that comes out of the exhaust when idling. Someone told me that it's running rich. How do I get it running correctly? Just like everyone I'm on a budget and I've been working on the car for eight years now. Any advice would help!
Ryan Olea
Via the Internet

A Troubleshooting a car with diagnostic equipment and the car in front of you can be a challenge, so you can imagine what it's like trying to do this solely based on information in an email. For starters, we'd recommend that you get a hold of an AE111 factory service manual (FSM), which can be downloaded off the internet pretty much everywhere. Next, check the basics such as fuel pressure, ignition timing and ECU codes (the AE111 Black Top ECU is smart and might be trying fix an intermittent problem). You might also try resetting the ECU to see if anything changes. Since you're running ITB's (individual throttle bodies), two key sensors that should be checked are the MAP (manifold absolute pressure) and TPS (throttle position sensor). After checking that your MAP sensor is working properly (per FSM), what you want to do is make sure that it's getting a solid vacuum signal from each cylinder. To do this properly, an external vacuum manifold should be used to even out the pulses from each cylinder. Next, to check the TPS, measure the voltage from idle all the way to WOT (wide-open throttle) and compare your readings to the specs listed in the FSM. Lastly, check for any vacuum leaks between the throttle butterflies and the valves. A vacuum leak in this area could easily throw off your air fuel mixture and idle. A trick to check for leaks is to block off the ISCV to see if it stalls the engine. Another trick is to spray carb cleaner around the throttle-bodies and the manifold while the engine is idling. If there's a leak, the carb cleaner will seal it for a second and lower the idle speed. If the idle screw has been messed with, reset it to FSM (factory service manual) specs. Unfortunately, we cannot cover everything in a tech email. Use the factory service manual to guide you the rest of the way. As another reference, check out the Club4AG Technical Forums. They have one dedicated to the AE111 20V Black Top motor: http://forums.club4ag.com/zeroforum?id=13. As for measuring if your engine is running rich or lean, don't rely on your friend's nose. The only way to accurately measure the mixture is to install a wide band AFR meter. If you plan to do any kind of tuning on your own, be sure to pick one up.

Q I have a '92 Nissan 240SX with an automatic transmission. I was wondering if any company has created an auto-to-manual transmission kit? The reason I ask is because I want to stay with the somewhat stout KA24DE and replace the transmission to a manual. I will be purchasing a rebuilt KA24DE within the year and figured I should just try and do it all at once.
Michael Gomez
Via the Internet