Sad story - friend has to sell his ZX

[Gollum]

TPS doens't control the mixture though, it controls transient changes. It's used for enrichment when the AFM or MAF wouldn't sense it quicky enough.

 

If the TPS isn't adjusted correct I guess it MIGHT, just MIGHT be sitting on idle while going 15mph, but you'd notice drivability problems I'd imagine.

 

You should be able to loosen the TPS and rotate it to play around adjusting it, and get a feel for how it works. I've never played around with a VG30E, so I can't help you there, but on my L series engines I normally keep the TPS almost all the way counterclockwise and I can get it while still idling correctly.

 

Basically, you want it to idle normall, and then as soon as you push the throttle the revs should go up. If it's not adjust right then making that sudden throttle change will cause the engine to bog down before reving up. What's happening here is that the engine breathes the air immediately availible to it, but no fuel as been added because the AFM/MAF hasn't changed yet. Once the air has started moving due to the change in vacuum the AFM/MAF senses the change and the ECU adds fuel, and the engine starts to rev upwards.

 

So unless like I said, the TPS is telling the ECU the throttle is either OFF or WOT while testing at 15mph, it shouldn't really affect the test.

 

Now, if it were a full range TPS it might be a different story. But what it's there for is still the same, when harsh throttle movements occurte the ECU needs to be able to adjust before the other sensors pick it up.

[MatMan]

That reasoning makes sense to me. And, by that logic, it seems that the ECU either isn't getting the correct message sent to it, or it's not sending the correct message for the mixture WRT engine RPM.

 

Either way, I will pull an O2 sensor off the car we took the AIV unit from, and compare it to the one that's on this car, as well as adjusting the timing (from the tested 16*) to see if the motor still maintains performance. Maybe I should crack opent he EGR, just to prove to myself that the tech was correct... If nothing else, maybe I can bottle brush the tubes.