Ok, I've been out multimetering the ecu inputs and outputs while driving today, first place I looked, the tps, is giving low, possibly 0 sometimes (though hard to tell on a digital multimeter, lower values than it should be at idle anyway) outputs, just as the wild bucking hesitations on my car kick in.

Basically, can anyone tell me what could cause these incorrect outputs from the tps? I'm thinking the only possibilities so far are a dud tps, or maybe a bad ground to it. Does the tps get it's input directly from
the throttle cable? or is there something in the middle that could be buggering up every so often, sending a dodgy signal to the tps, which sends the dodgy signal onto the ecu...??

Charlie

 

It has a reference voltage of 4.5 to 5 volts. It has a ground and it has a output to the ECU.

You really need to ohm the tps out using a meter. Preferably a analog but digital will do. See the free download at http:www.fc3s.org. Look in the Fuel section.

The ground singnal might be suspect it it ohm out ok. Add an additional ground to to the present ground wire at the tps if the ohming out proves to show no opens etc.

If you look at the wiring schematic, you will see that the ground for a number of sensors are all tied together using solder joints or splices. Its always possible that a bad solder joint might cause your problem.

But the best thing to do is ohm out the tps thru its full range.

 

Either I'm not understanding you, or you're not understanding me

The tps checks out fine when setting / checking it with the resistance method, and it's also fine 96% of the time when checking the voltage at the ecu while driving, it's just when I get these wild bucking hesitations that the voltage drops severely. I'm after reasons for this happening. Are you suggesting I monitor the resistance while driving somehow?

As for grounding sensors, I've added a ground at the pressure sensor, and will add a ground at the tps tomorrow.

Charlie

 

Things sometimes breakdown under heat. I've seen one tps plunger that was stuck internally. The black plunger moved but there was no tension behind it. Add the extra ground, look for a good connection at the tps plug and ECU. No. Not suggesting monitoring the resistance while driving. Its either breaking down inside the tps or the ground is intermittant or one of the wires is making intermittant contact. No novel ideas from here. I see you've done most everything. Is the car bucking under hard acceleration or just moderate pedal? Hard acceleration might be the orifice in the boost/pressure sensor missing and causing a spike.

 

cheers hailers. it breaks down at all load levels bar idle, though usually starts at low levels with a slight increase of throttle.... I hadn't thought of the loose wire possibility, very much hope it's not that...

Charlie