Anyone know where I can get a heated O2 sensor cheap for a 1988 GTA 5.7L? I think this is the problem because I have rough idle on cold starts after I installed the ZZ-9 Cam. After it warms up it runs fine. It smells very rich when it idles rough. Nothing was changed before and after the Cam install other than a Big Mouth Manifold and a TPIS level 4 PROM. Tried switching to a stock PROM and same thing. Could the O2 sensor not be getting hot enough for correct readings? The cold start up is fine on warm days (50*F and higher). The exhaust lift on the cam is now at .520.

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1988 GTA 5.7L Auto
355 ci. block, SLP Cold Air Intake w/ K&N, fully modified MAF Sensor, TPIS 52mm Throttle Body w/Air Foil, Fully Ported and Polished Plenum, Nikel-plated Ported SLP Siamesed Runners, Ported TPIS Big Mouth Intake Manifold, stock heads w/ 1.52 Comp Cams Self-aligning Roller Rockers, TPIS ZZ-9 Roller Camshaft, TPIS Valve Springs, Cloyes True Double Roller Timing Chain, TPIS Adjustable Fuel Pressure Regulator, Balanced Bosch 22 lb/hr Fuel Injectors, MSD 6AL, Taylor 10mm Wires, Bosch Platinum +4 Spark Plugs, MSD Blaster Coil, March Underdrive Pulleys, 6 3/4" Vibratech Streetdamper, TPIS Level 4 PROM, 160 T-stat, Low Temp. Fan Switch, Stock Distributor w/ Bronze Gear, SLP 1 3/4" Headers, Random Technologies High Flow Cat., Adjustable Borla Cat Back Exhaust, Level 10 PTS-3 700R4 Trans, B&M Holeshot 2400 Stall Converter, B&M Trans Cooler, TCI Aluminum Finned Trans Pan, Torque Converter Lock Up Switch, 3" Balanced Aluminum Driveshaft, 3.73 Richmond Gears, Auburn Pro-Series Differential, Aluminum Differential Cover w/ Main Cap Preloads, BF Goodrich Drag Radials 255/50 R16, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Hotchkis Tie Rod Adjuster Sleeves, Bilstein Heavy Duty Shocks and Struts, 1LE Springs, Energy Suspension Polyeurethane Bushings, Global West Tubular Subframe Connectors, Global West Steering Box Brace, HP Motorsports 3 Point Strut Tower Brace

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The problem is NOT the O2 sensor. The ZZ9 pulls less vacuum at idle. The fuel pressure regulator is vacuum referenced. Less vacuum at the fuel pressure regulator means HIGHER fuel pressures. The ECM cannot adjust the injector pulse width until you go into closed loop. Contrary to popular belief the ECM will not go into closed loop for AT LEAST 190 seconds on a cold start, 150 seconds on a warm start, and 30 seconds on a hot start. This is the minimum wait time for the ECM. That means that when you start the car in the morning that the ECM will not have a chance at going into closed loop for 190 seconds (3min, 10seconds). For 3 minutes your car will be dumping a LOT of fuel into your engine ... hence the rough idle and gas smell. Been there - done that. The only way to solve this is through a PROM change. A heated O2 will only ensure that once the minimum time has passed the car will definitely go into closed loop and be reading the exhaust correctly. However, you still have that initial 190 seconds to deal with. That requires a PROM change. Again - been there - done that. That is the reason the main reason that I started programming my own PROMs.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
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