Anyone ever experience a breakdown of their 20V's VVT? I'm uncertain but I believe my pulley may be failing. Power is inconsistent, sometimes under heavy throttle I get a nice pull and other times the engine seems like it's choking off, there doesn't seem to be rhyme or reason to when it happens either. I plan on wiring in an LED to make certain that the VVT is actually getting the signal, but for now I could use some feedback on your guy's experiences

I had the same with my Celica AT200 with blacktop swap. Sometimes it pulled straight away but sometimes it hesitated a bit, a feeling as if the vvt is kicking, then vvt off, then on again, etc.

I couldn't find a solution for it. I had all ignition parts brand new and the engine was stock.

I believe my VVT signal is good so I'm thinking mechanical. Sounds like you had the same issue

Very unlikely it's the VVT. It can't really be felt by the seat of the pants. I suspect you have another issue.

May be worth looking into...... http://forums.club4ag.com/zerothread?id=85825

Make the necessary checks to TPS for proper function and adjustment. Check the o2 sensor as we'll for proper function (you can use a DMM for this although a lab scope would be preferred). Apparently 20v's are picky in regards to the quality of the sensor. It may be worth the investment to buy a denso unit if you havn't already. Also are you using an afm?

Running a Denso or a Bosch, can't remember. The power output is really inconsistent, sometimes it gives me everything and other times it really feels lacking, kinda curious as to whether or not it might be the TPS.

Check for any glitches in the TPS with a DMM. Make sure that it is adjusted properly as well. Check the FSM for the specs on that but most cars will be less than 1v with the throttle closed, and will increase to about 5v at WOT. Test with the key ON and the engine OFF just so you're not revving the nuts off the engine while testing.

When I was working on it I remember the TPS showing a good signal but I'll have another go at it after finals

I've also bought a new tps (and set it up by the manual) and oem o2 sensor and the problem didn't solve. At WOT your o2 sensor can't be the problem, cause it running in open loop then i think.

onnaj wrote:I've also bought a new tps (and set it up by the manual) and oem o2 sensor and the problem didn't solve. At WOT your o2 sensor can't be the problem, cause it running in open loop then i think.

Correct. The ECM operates in open loop during WOT. If either of you guys are running AFM's I would suggest testing them for proper operation. The MAP sensor as well can cause bogging issues in my experience if it is the wrong one or not working correctly.

I moved to a blacktop electronics setup because I had issues with the AFM. I'll swap in a different MAP and give it a go, see if the problem resolves itself. I'm also going to disconnect the VVT and see if the effect is related, although this may throw a code

Don't worry about it throwing a code. If it does throw a code it should clear itself after it's reconnected and the ignition is cycled off and then on again.

The reason why I'm concerned about the code is that it may put the car into limp or at least a reduced map. Not worried about hurting the engine or anything, that's why the diagnostics exist. I'll try to give it a go in a bit, in finals right now

yoshimitsuspeed wrote:Very unlikely it's the VVT. It can't really be felt by the seat of the pants. I suspect you have another issue.

VVT can be felt, especially in mid-range RPM... It can also be heard, especially with open throttles.