Help! I just bought my first GN, and was doing some spring cleaning. Took a reading of my TPS and was 4.80 to 5.3 at closed throttle and decreased as the throttle was opened (engine off). Reading with engine running at idle same, did not check at WOT. This seems backwards to everything I have read, which says I should be around .4 at closed and 4.80 at WOT. Bought a new TPS, same Reading. Car idles high most of the time when started(2,000 to 2,400 RPM's), but occasionally I will get lucky and it will idle around 1,000 after warm up (based upon stock tach). The engine was rebuilt by previous owner (not stock)about 5,000 miles ago, but I wouldn't think that wouldn't affect my TPS, would it?
Does anyone have any trouble shooting ideas??
Thanks, Chris P.
sounds like two of the wires in the tps harness have been reversed....
Are you sure you are checking voltage on the correct wire? What year is your GN? I believe the 84-85 Turbo Regals have two of the wires reversed on the TPS. Actually, since they came first, the 86-87s must be reversed.
Brian
Thanks Brian and Steve. It is a 87 GN. I am using a 3 prong device that plugs into the TPS (a friend bought it for his 94 ZR1 vette with fuel injection), and allows you to measure it inline, and then you hook the volt meter to it.
So we think we are reading it correctly. Assuming we are not, which of the 3 wires at the TPS should we be reading? Are we reading it at the right spot?
Thanks, Chris
I would eliminate the harness you plugged in as it may be wired differently for a Chebby.
Probe the dark blue wire going to the sensor and the other probe to ground.
Look for .42-.44 v at idle and say....4.3v or better at wot with the floor mats out of the way, key on, engine off. There is no magic or better in higher readings at wot contrary to some claims that 4.6 or 4.8 is required.
Your idle will probably be too fast or erratic if you exceed .46 with the engine running.
Don't use the 'Vette jumper; it's wired opposite of the 87 GN. The three cavities are A, B and C. You should meter between B and C. A is +5 volts, B is the signal (.4 - 4.7v) and C is sensor ground. The 5.7 engines have the same pinout as the 85 turbo motors, and the exception is our good 'ol 87 turbo.
-John Spina
http://www.casperselectronics.com