Helpppp 525 whipplecharged TPS voltage
 

hey guys I have a 540 whipplecharged motor, approx 850-900hp. Have had an on going hard start either cold or hot, was investigating this weekend at the lake and decided to Probe my TPS and see what kind of voltage it was reading. Was at 4.79 which according to whipple is high, so I loosened the Allen screws and re adjusted to 4.45 which is within spec of whipple. Went to go fire it back up 2 hrs later and fired up great BUT ran extremely rough and wouldn't get up on plane. So I re adjusted it back to the 4.79 volt it was originally and it now it barely fires and runs terrible! What did I do wrong here !!!! Please !

you didn't test the tps right,you probed the 5v logic line,probe the other wire to the blk wire.at idle/tps rest,,it should be .5-.75v.I'd also look at the water sensor which is a yell and blk wire near the front of the motor.
In the end you may have to scan it and measure fuel pressure.whens the fuel filter been changed last?

Fuel filter is begging of the season,l gauge was reading proper fuel pressure. I get flustered with computerized motors !

You need to ask whomever installed and tuned your engine what idle TPS voltage and WOT voltage should be. idle being most important and typically to what the tps is adjusted/set to.

As s30 said, one wire is 5 volt reference, and you more than likely checked that. Another wire is ground, and then the third is the one you read so you can check/adjust. Idle is typically under 1 volt and WOT in the 4 volt range somewhere. Again, ask tuner what to set idle tps voltage.

The best and ultimitely, the easiest, and most sure fire way to set the TPS is with a scan tool. I'm sure there has to be a Merc dealer nearby that would help with the use of a scan tool. You can set it in a matter of about 2 minutes. It will show you percentages....0% when closed and 100% when WOT. There will be no guessing and wondering this way. OR, it wouldn't be a bad idea to own one. They are about $500 and worth their weight in gold when you have an issue with an EFI engine. Maybe you have a buddy or 2 that have EFI engines and ya'll can split the cost.

You not only want the TPS to show 0% at idle, but you want it to respond immediately when you touch the throttle. You also want it to hit 100% right when it hits WOT.
Eddie

He has a 540cid and hasn't said if MEFI or something else ? He does get a little confusing, I admit.