I'm Confused!!!!!!!! Remove SPOUT Plug and SC Idles Better

edspringer

Registered User
I have been fighting a very rough idle problem for a year in my 94 SC auto. I have spent a lot of money and time chasing this problem and frankly it has turned me against ever owning another SC.

A little history. My SC idles at about 650 RPM and shakes so bad my radar detector almost comes off the windshield. I replaced the motor mounts 2 years ago with solid mounts and they are still good. I can coast at any speed, put the shifter into neutral and the engine will run at 1700 RPM until the car stops moving. The engine RPM immediately drops to 650 RPM and shakes the whole vehicle. I have concluded, through troubleshooting, that something is causing my IAC to turn off at idle. I have the TB stop adjusted a little open and the bleed screw backed almost all the way out. If I adjust the TB properly, the car will not idle. Basically, I have bypassed the IAC to get the car to idle. I have no codes but due have a intermittent CEL when I climb a hill in OD with the converter locked.

So the other day I was reading the posts. DECIPLED1 had a post describing almost the same idle problem I have and how he pulled the SPOUT plug and his car ran better. So I did it and followed his procedure. The car still idled rough so I drove it to work with the SPOUT plug removed. The first light I stopped at, it idled at 900 RPM and was pretty smooth and it continued like that the rest of the day. Plus it seemed to have better throttle response. However, when I start it cold first thing in the morning, it will not idle and I have to restart. when I put the SPOUT plug back in it is back to the same old shake the radar detector off the windshield ilde. I'm going to run without SPOUT plug until someone smarter then me can convince me to put the plug back in. Standing by for input!!!!!

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36# Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, 190 l/h Fuel Pump, 38# Injectors, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, 76mm CL MAF (Clear Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.
 
You list a 70mm BBK.

You want the IAB opened 1.5 turns and adjust the idle screw so it just lifts up on the throttle stop.

I see you also listed a C&L MAF :( and that is most likely your problem. You have incorrect A/F caused by the MAF. The C&L causes more drivability problems than I can go into. Since you have #38lb injectors you cannot install the stock MAF back into the car as the A/F will be rich. Two suggestions, One is pull the C&L off the car and get a Pro-M MAF. (Pro-M just went out of business) :( The other is put the stock MAF back on the car with stock #36lb injectors. Proper setup when increasing the injector size is to reprogram the EEC so you keep the proper A/F ratios.

Rich
 
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