KyleH

iTrader: (1)

Over the past couple of times I've driven the car, I've noticed some strange behavior. It's correlated to an upgraded fuel system, which makes absolutely no sense to me, but I thought I'd at least mention it in the event anyone has any ideas.

This is an Aristo swapped car. I recently upgraded my fuel feed line to 8an and upgraded to a high flow ("Hellcat") pump. The issue wouldn't perhaps be so noticeable, if at all but for a flat shift logic I have on my Haltech that is operating my engine management. I'm still using the stock ECU for the transmission, drive by wire functions, as well as the rest of the car outside of the engine management.

The issue I'm finding in my logs is that the TPS (throttle position) is not correlating as well to the pedal position sensor as it usually does / should. What I'm seeing is a half second delay from the time I put my pedal down until the TPS is sending data to my logger indicating it is moving in concert with the pedal position. This in turn cuts my ignition and timing because the deviation between TPS and pedal position is usually only this divergent during a shift when the stock ECU closes the throttle body to reduce boost/power.

I took the laptop to the car with the engine off and did some logs and could not reproduce anything like what I am seeing on the road.

What I am finding is on the road rolling along at any RPM, in low gear, I put my foot down but the TPS signal is so unresponsive, the Haltech transitions to shift mode, and temporarily pulls timing and ignition. I keep my foot in it the entire time (keep in mind - the Haltech DOES NOT control the DBW) and finally the TPS will open up and the car will then accelerate.

Here's what log of that looks like. "Nitrous Pressure" is AKA my pedal position sensor. 100psi = 100% pedal signal. Scaling sucks on the logger, the pedal position sensor is ramping from 60% to 100%. "Cut Percentage" is the engagement of the flat shift - basically car is operating with reduced timing and partial ignition cut during this period.

A 500+ millisecond delay in the TPS signal indicating the throttle is opening relative to the pedal sensor.

I cannot reproduce this lethargic behavior in the garage.

In the garage, the pedal sensor and the TPS move very well together - as they have previously on the road. The TPS will indicate movement from closed to 90%+ in just 100 milliseconds.


During testing, engine off, TPS responds very quickly relative to the pedal position sensor.

I'm really scratching my head here. Keep in mind, this wasn't an issue a week ago. This interruption has never revealed itself before on the road outside of the expected behavior during a shift.

Does anyone know for sure if the throttle is always controlled by the DBW motor? What I mean is, there's a cable there operating the throttle from the pedal. I'm not sure how the DBW system works - if there's a clutch that allows a tight coupling / linking between the cable and the throttle except during certain times - such as during a shift, or when slippage occurs (if I had the traction control module for the Aristo ECU), or when the cruise control is operational, etc. If the electronic motor is ALWAYS controlling the DBW, then I'm curious if this is failing on my car. If there's a tight coupling in most all instances aside from exceptions, then I'm wondering if my Haltech is getting a bogus signal from the TPS - because there should be no reason for this latency. But if the signal was bogus, I would expect that to be consistently bogus.

TrueGS300

I'm thinking as I read that maybe the throttle motor is getting lazy. I don't see any reason for a fuel system upgrade to have an effect on it. So thinking of this logically. If it's the same principles as a GE throttle, we know the cable goes to the APP sensor, and the APP sensor's signal is used to run the throttle motor to open the blade accordingly. The TPS monitors this motion. Maybe it's the motor for the throttle wearing out? Getting slow? The cable doesn't give any direct pull on the blade. The app signal goes to to computer, computer to the motor, then the TPS signal back to the computer and it looks for the two to stay in sync.
However, there are so many external factors to consider on a modified car and stand alone computer. Hard to say.

KyleH

iTrader: (1)

I did a little additional discovery work today. I completely turned off my flat shift feature to try and better isolate the behavior. I exploded the TPS view on my laptop so I could keep an eye on it during my pulls. It was definitely misbehaving. What I'm not clear of is who/what is the culprit and exactly how to isolate the culprit. I feel confident it's either the:

A: TPS
or
B: Throttle body motor

Now I can only quantifiably monitor the TPS sensor. But by the seat of my pants, I can feel the car accelerate faster as the TPS reading increases. This makes me think that the TPS is okay, and it's my motor that's failing on the ECT-i throttle. When I am watching the TPS go from a lazy 60-65 and then pick up to 95 on the gauge, I am feeling it in the acceleration of the car at the same time.

Here's a video -
I've never noticed (not to say it hasn't been present) the illumination of the check engine light when I'm revving the engine. But it's clearly present and I was curious if it was the ECU recognizing a misalignment of the TPS and APP sensor. I scanned the car for codes, and while I found 4, I'm not finding any related to the TPS - they seem related to the MAF I no longer have:
P0100
P0110
P0135
P1656

Anyone have any experience trouble shooting this system? A used ETCS-i for the Aristo is $500 on ebay and would be a used part to boot. Kind of hate spending that kind of money on 20 year old parts. I'd like to do away with this system altogether, but as long as I'm using the stock ECU to control the transmission, I'm afraid I'm stuck with it.

Another log. This is without interruption of the flat shift. About 2.5 seconds it took the TPS to move too ~100% after the pedal position (VPA) was already sitting at 100%.


TPS greatly lagging the VPA (pedal position sensor). 100psi 'nitrous' = 100% VPA signal.

TrueGS300

You might want to join a Haltech forum and present this data there. I have been tempted to join AEM's forum a few times for various issues I had with my infinity ecu. Looking back I wish I did because of how long it took my to research and figure out some issues I ran into. But I'm pretty well through my process now. If you are doing a lot of the tuning yourself, you could probably get a lot of good insight on your logs as you move forward from experts on your system.

KyleH

iTrader: (1)

Yes I am on the Haltech forums, although they're relatively light in terms of activity, much like here. Reason I posted here was I believe this to be more of a Toyota / VVTI / GTE issue, not really a Haltech problem. But honestly as popular as this powerplant is across the tuner world, I might have equal luck in the Haltech forums.

I had a thought yesterday - based on some additional reading, there's anecdotal evidence that the stock ECU will decrease the throttle opening when it detects knock from the engine knock sensors. I'm now wondering if I have something that is replicating knock or a knock sensor otherwise failing that could be the culprit. I was only logging one knock sensor - and it wasn't showing anything in the way of knock (wouldn't expect any running e85) but I went ahead and started logging my second knock sensor to be sure it wasn't picking anything up. The only material difference in now vs. before is there's now an empty fuel damper (it's attached to the side of the block) along with the dangling banjo fuel fitting off the back of the head/rail that are no longer utilized. I just don't see either of those things creating enough vibration / noise to be picked up as knock - but I'll log and make sure.

KyleH

iTrader: (1)

Quick update here - I disconnected the battery for about a minute and reconnected. I then drove 500 miles on a road trip in the car with my family, during which time, for sake of my health and marriage, didn't do any WOT pulls.

The net of the update is after that battery disconnect and 3 day road-trip, I got home and re-tested the throttle behavior and found that the issue is no longer present. That's right, the throttle is back to responding properly and fully with the input from the pedal sensor. I don't know why. Read on for further findings from the ECU that were available to my scanner when I returned home.

I returned home and pulled the following codes from the stock ECU in addition to those listed above:

P0171 - MAF related
P1300 - Ignitor Circuit Malfunction (hmm)
P1349 - VVTI

None of these immediately jump out as concerns. I don't have the MAF, so I can ignore 171. 1300 is one I suspect is accurate and maybe something I need to pay attention to if I am consistently seeing it. I've not read up about it, but I also am not noticing any running issues with the car. 1349 may or may not be anything. The Haltech is operating the VVTI, so I'm wondering if the operation of that is out of parameters from the stock ECU expectations, and therefore causing the error.

Even so, none of those errors indicate to me a problem that would correlate to the behavior of the throttle relative to the pedal sensor. Head scratching continues...

TrueGS300

Well if you had done some WOT pulls you may have got the throttle related issues too.. Maybe some sort of limp mode is trying to activate. Same thing got my car to stop acting up. After disconnecting the battery, the VSS issue I was having went away and I could actually go into boost. But I'm worried it will happen again under the same circumstance. Meaning when I get it back on the dyno it will go into limp mode again.