leblanc1

iTrader: (2)

Throttle Position test.

Michael Yount

iTrader: (1)

Does that supercharger have some sort of bypass for low throttle opening/cruising?

Talk to us about the history -- was it driving/behaving fine and all of a sudden with no warning or slow degradation it just started doing this?

leblanc1

iTrader: (2)

My throttle position is reading at 26.3% at idle and also engine off/key on position. I don't know if it's supposed to be that way based on my tune or what.

Does nobody have any further suggestions?

Michael Yount

iTrader: (1)

If that number represents that the throttle is 1/4 of the way open at idle -- something is definitely wrong there; were it that open, you'd see revs through the moon.

Further suggestions -- see my questions above....#42.

leblanc1

iTrader: (2)

The bypass you speak of is on post #37 in the video. It's a boost bypass valve that's vacuum controlled.

Just a few days ago, the car ran really well. Strong through all throttle settings, no issues except at a stop when I put the car in neutral. That's when the RPMs would drop to 400 and hunt back up to 900 and go back and forth a few times. Sometimes, it would stall when the RPMs got too low.

Also, I noticed that the RPM fluxing ONLY seems to occur as I'm rolling to a stop...as soon as I actually stop moving, then it seems to settle in at 900 RPM. I don't understand the correlation of engine idle RPM between rolling and not rolling. Some have mentioned the VSS....but what about it and how it relates, I'm not sure.

So I decided first to clean the throttle body. I removed the throttle body, sprayed a little bit of throttle body cleaner and wiped out some minor carbon buildup on the butterfly and the inside of the throttle body. After putting it back together, it operated the exact same as before.

Then, I thought maybe I had a fuel delivery issue and I changed out the fuel filter/regulator. That's when the troubles started that you're seeing in the videos.

I thought maybe my fuel pump wasn't delivering enough fuel pressure but as you can see, I get a solid 58psi no matter what RPM the engine is running at.

I get no check engine lights.

That's pretty much the history of how I got here.

leblanc1

iTrader: (2)

But the throttle isn't open 1/4 of the way at idle, you can see that by the video of the butterfly valve operation.

Michael Yount

iTrader: (1)

I'm pointing at the same thing you are - something wrong with that 25% number - clearly the throttle is barely open at idle.

leblanc1

iTrader: (2)

At full throttle, it says it's about 88%....but I've read that some tunes just cause those numbers to be that way. 88% equals 100%. Is it possible that 25% equals 0%...it's just the way the tune is? I don't know the answer. I'm trying to get with my tuner over email, I no longer live in the same state.

Michael Yount

iTrader: (1)

Nothing wrong connecting with tuner - but the tune didn't just change on it's own. Did you do any work on the car before it started acting up?

leblanc1

iTrader: (2)

Agreed....the tune shouldn't just change. But...has it ever happened that a PCM just lost, adjusted or changed a tune on its own?

I did no work on the car up to the idle RPM flux issue and since then the only things I've done are throttle body clean and filter/regulator change.

leblanc1

iTrader: (2)

I took the car for a quick spin up the road. I still get the RPM flux at idle. Riddle me this...it only fluxes if the car is rolling. As soon as it comes to a stop, the RPM settles in at 900 RPM. But as I'm rolling to a stop, it's hunting between 400 and 900.

Notice in the video I roll into a 2d gear start and punch it....no hesitation, no lag, just power. Don't mind the grind into 3d....oops.

Project GatTagO

iTrader: (7)

TPS at 26% with the engine off, means nothing. That could simply be a "IAC" park setting. Meaning, at engine start up, it wants more air...For start-up, IAC park and cranking PW is the starting AFR.

Andrew

Michael Yount

iTrader: (1)

26.3% at idle is what we were pointing at...

Michael Yount

iTrader: (1)

It's not just the fluctuating idle as your vids show - it pops and spits and stalls when trying to free rev.

leblanc1

iTrader: (2)

Agreed. I still have both symptoms. It's drivable...but the symptoms are annoying and worrisome. I still don't know what to do with it.

Michael Yount

iTrader: (1)

When it's acting up, but there are no codes -- makes me wonder if the ecu hasn't started malfunctioning....

leblanc1

iTrader: (2)

So what are my options to get a data read that can actually give me a better idea of what's happening? Is HPTuners my only option?

Michael Yount

iTrader: (1)

Someone else will have to chime in....I don't know.

leblanc1

iTrader: (2)

Still having the issues. I replaced the plugs tonight, same results. I also listened to my injectors, each seems to be firing with good patterns, nothing abnormal on a listen test.

The hunting RPMs at idle when I come to a stop seems to have improved....doesn't happen as often. But the prevailing concern is misfiring under load.

If I punch the gas, the nose of the car dives for a second like the engine misfires then the power kicks in all the way through 6500 RPM. But every time I hit the gas in the 2000-3000 RPM range, it can't seem to respond to the demand and the power disappears for a second, then comes back.

Still not getting any codes.

Surely somebody has some ideas of what else to look at.