TPS vs. Ignition Timing vs. Fuel Pres.

[k0pi]

Hi ZTHians... need some explanation regarding how a Throttle Position Sensor (TPS) relates to Ignition Timing and Fuel Pressure (Fuel Injection).

Having headache trying to figure out matching the setup properly to get smooth running on my 4G92P. Just recently plugged in Works 70mm throttle body and trying out Piper's 286 cams, but having bad jerks when throttle is opened below 5% or below 2000rpm before a go, and I miserably lost all the torque and bhp I had before...

Just to make it easy to focus, these are the 'problems' I couldn't figure out :

1. What happens to Ignition when TPS voltage is increased, and decreased? (current base : TPS = 0% throttle = 0.480v / WOT = 4.265v, Ignition = 12 - running high CR)
2. What happens to Fuel Pressure when TPS voltage is increased, and decreased? (current base FP : 37psi)
3. What happens to Fuel Pressure whe Ignition is increased, or decreased?

I just need to know the relativity between these 3 matters, before sending the car to a tuner (so I could observe and determine the 'tuner' actually know what he's doing... its kinda hard to find a good tuner who sincerely interested tuning a 4G92p these days, so most I observed only go quarter heartedly to tune it, and end up me doing the digging most of the time for refinement). Or maybe I could just understand the relation/concepts and could actually get a good baseline tune before making way to the dyno for AF tuning... or, I am missing out anything important that warns, DON'T DIY.

Tuning tools available : SAFC2, adjustable fuel regulator, timing light.

please help, because it's badly pinging now.

 

[Izso]

I've never actually messed with TPS before. All handled by the ever smartass Siemens VDO.

I think your FP is stock right? Sounds stock - 37psi. I'm thinking you probably have set the ignition timing set too aggressively to ping at low RPMs. Why don't you retard it a few degrees and start from there.

The way I do it is I have minor adjustability for my ignition timing and I use a AFPR. I advance the igTime about a few degrees then compensate with a higher FP to reduce knocking at high rpms. Low rpms the ECU usually takes over.

 

[k0pi]

Thx for the reply Iszo... will try to use your method. Probably the distributor is too advanced...

Currently, I'm just lost with figuring out the base tune of those 3 things to make my car driveable before setting the cams and the A/F.... some other infos I got from the others on the net recommends for higher TPS voltage output to the ECU to prolong the injectors time to open at lower rpm for more fuel, and more advanced ignition point at those lower rpm. Those on Mitsubishi's wiring.

seeking 2nd opinion if those recommendations are legit... I'm still collecting all ideas on how to go about this before trial and error session with the real thing.