?for JimG (or anyone) re throttle response variations

FlashBack · 09-21-2006, 10:34 PM

Since new,my 05 6M has been having a problem that nobody has been able to figure out. Unpredictibly, the throttle response goes very flat where it takes practically half the pedal travel just to accelerate normally. This happened often, before I installed my supercharger, and continues to occur now. Its not torque management, that has been disabled, and being a manual its not t/c. It is like a switch has been flipped on the throttle position and "tip in" becomes major "squash in". The power is there, but wayy down on the pedal. The cure is to remove the computer fuse for a minute or so. After doing so everything goes back to normal for awhile. Code readers come up with nothing. I do have a non origional stainless steel throttle pedal complete with the sending unit that I purchased from GM PARTS, but if that was miscalibrated I don't think the problem would be intermittant and temporarilly fixed with the computer disable approach. Besides , I believe that I fiirst had the problem even with the origional gas pedal assembly.
I have been thinking about getting the Corvette throttle body, and I suppose that if I have a faulty TPS in the stock TB the problem may be solved. If Jim G or anyone has any ideas about this situation, I would be greatful to hear from them.
Thanks Peter

Mike in AZ · 09-22-2006, 09:57 AM

Using a monitoring tool, you should be able to see the throttle position command from the throttle pedal assembly to the computer. Once you have found this, do a simple calibration check of physical position to computer sensed position. You will have to use some sort of measuring tool for the physical position, IE a tape measure to the firewall and get position readings every inch. This will establish a "baseline" of your throttle command.

After your phenomenon returns, repeat your calibration check. Look to see if the physical throttle position calibration matches what you had before....... This will tell you if the pedal is bad.

There may also be a way to calibrate your throttle body at the same time. I don't know if it moves without the engine running, though. If it does, get a set of position data that will correllate to foot pedal position input.

Sorry for the exercise, but with the right tool looking at your software, you should be able to isolate it to a component.

Regards,

Mike

frank belk · 09-22-2006, 10:05 AM

Quote:

Originally Posted by 6.0scSSR

Since new,my 05 6M has been having a problem that nobody has been able to figure out. Unpredictibly, the throttle response goes very flat where it takes practically half the pedal travel just to accelerate normally. This happened often, before I installed my supercharger, and continues to occur now. Its not torque management, that has been disabled, and being a manual its not t/c. It is like a switch has been flipped on the throttle position and "tip in" becomes major "squash in". The power is there, but wayy down on the pedal. The cure is to remove the computer fuse for a minute or so. After doing so everything goes back to normal for awhile. Code readers come up with nothing. I do have a non origional stainless steel throttle pedal complete with the sending unit that I purchased from GM PARTS, but if that was miscalibrated I don't think the problem would be intermittant and temporarilly fixed with the computer disable approach. Besides , I believe that I fiirst had the problem even with the origional gas pedal assembly.
I have been thinking about getting the Corvette throttle body, and I suppose that if I have a faulty TPS in the stock TB the problem may be solved. If Jim G or anyone has any ideas about this situation, I would be greatful to hear from them.
Thanks Peter

does the check engine light come on ? is there a code stored in the memory ?

FlashBack · 09-22-2006, 10:15 AM

Thanks Mike, good idea. I will try that this weekend.
Frank, if I ignore the problem and don't reset, the CEL seems to come on after a few days of cycles. The only code that has come up was a check clutch code, and there has never been anything the dealer could find wrong with the clutch and it works fine. So, i am not sure that isn't just a coincidence(but 3 times). I had Joe( our Magnuson dealer) check for stored codes on his HP tuner, but nothing was found.

JimGnitecki · 09-25-2006, 11:18 AM

It IS possible that your throttle pedal asembly is intermittently changoing its output voltage. Unfortunately, that can mean the electronic asembly itself, OR a partially corroded or partially disconnected (higher resistance) connection somewhere in the circuit, whose connectivity is varying with ambient conditions.

It is probably more likely that the PCM is detecting a "fault" of some sort, which is causing it to activate a MILD stage of "engine protection", in which it does not shut the engine down nor force it back to idle, but rather detunes it via spark retard or overriding of the electronci throttle control (with an electronic throttle, you have a vOTE but the computer has a veto

). Unfortumately, it sounds like the fault is intermittent. It can be very hard to find too, as the computer receives MANY sensor signals, and they are electronic versus physically visible.

The suggestion to attach a scanner is a good one, bUT you might have to drive around a LONG time before it can "capture" the vehicle in the act. If you own a diagnostic scanner, great. If not, this might not be a feasible idea, as no one is lilely to "lend" you one for days.

If you DO get a scanner on there, try to capture the event as soon as it starts, by pressing the "record" button on the scanner, and then download the file to a computer where it can be analyzed by someone who knows what to look for.

I haven't yet thought of a fast, relaible way of getting to the bottom of this one without the scanner . . .

Jim G

JimGnitecki · 09-25-2006, 11:20 AM

Mike: The throttle blade WILL open with the key "on" and the engine "off".

If there is a mismtach in expected versus actual voltage anywhere in the system, where the actual voltrage exceeds the xpected, the computer responds by snapping the throttle back to idle. You will see this at the physical throttle blade if the actual volatge produced is too high.

Jim G

JimGnitecki · 09-25-2006, 11:59 AM

Another possibility I remembered: failing ignition switch. This is a common problem on SSRs (and I udnerstand some other GM models), and when it starts to happen, you get wierd, unpredictable issues like the one you have. Have your dealer look up the ignition switch problem.

One other thing, putting the Corvette / GTO throttle body on will change the voltage mismatch yet again. An 05/06 SSR will not fully open a Corvette / GTO throttle body, as 2005SSR6speed has discovered and documented. I think he got about 83% throttle blade opening at "WOT".

Jim G

FlashBack · 09-26-2006, 09:12 PM

so, aside from my problem, but related line of thought- could the problem with the corvette throttle body on the SSR just be a mismatch between the sending unit at the gas pedel and not in a main computer program, and be easily addressed by swaping out that sending module or the whole accelerater assembly (if they are interchangeble)
My problem is not a loss of power, its all there i think, but just much further down on the pedel.

BUDDYWHITE · 09-26-2006, 09:32 PM

It may sound overly simple but I am working on my second bad ignition swith but it is intermittent so the GM techs dont catch it. I am waiting for it to go out. Anyway I have had some wierd shut down and intermittent throttle response related to the switch. From what i was told is that it is not necessarily the mechanical switch itself but a relay off the switch that sometimes goes bad and can be intermittent til it does. Just something to check out.

2005SSR6Speed · 09-26-2006, 09:41 PM

The SSR computer puts out 83% TPS Voltage to command 100% ETC. The throttle blade is actually only missing about 1-2 degrees of movement with the C6/GTO/Z06 Throttlebody. The C6/GTO/Z06 report 88% TPS Voltage to command 100% ETC so the difference is in the operating system for the computer. The throttle body flows more air then the stock Throttlebody so it is up to you on whether you change it or not. I along with many others (05-06 SSR's) here have converted to the C6/GTO/Z06 Throttlebody with great results.

The problem that you are seeing with your throttle is most likely the aftermarket pedal assembly or the ignition switch as noted earlier.

JimGnitecki · 09-26-2006, 10:32 PM

2005SSR6speed: If I am understanding what you wrote above correctly, you are saying that the 83% voltage is in fact sufficient to open the GTO/Corvette throttle body to within 1 or 2 degrees of fully open? (essentially full open)

I thought you had physically determined earlier on your own SSR that the 83% did NOT fully open the throttle! In fact, I recall you posting that on the truck board and asking for assiatnce in figuring out the solution.

What changed?

I am starting to think that a 90mm GTO/Corvette throttle body would work better on a modified 03/04 SSR than a 90mm 05/06 SSR throttle body does, as there would be less of a mismatch between voltages, with the result that the 03/04 pedal assembly could be allowed to move further before it triggers an overvoltage that prompts the PCM to force the engine back to idle for safety reasons. What do you think?

Jim G

2005SSR6Speed · 09-26-2006, 10:38 PM

With the 83% TPS voltage commanded by the computer we are only missing a few degrees of movement as opposed to the C6/GTO/Z06 which command 88% TPS voltage to get the full movement. The truck guys are seeing less throttle movement then the 05-06 SSR and we have been trying to get HP Tuner to figure it out. I really dont think that the extra little bit of movement needed to be fully opened on the SSR will make any real difference. Keep in mind that the trucks are missing about 15-20 degrees of movement and they are still flowing alot more air then the stock throttle bodies they came with which are the same as the 03-04 SSR's. The 03-04 SSR's have a different problem all together as you have noted with your SSR, you get too much movement and had to use a throttle stop.

redssrloaded · 10-01-2006, 10:35 AM

I am by no means mechanically inclined to enter this conversation but I think I had the same problem. The car just stopped having the pickup it used to have ( I think that's dumbing down terms for us non-mechanics). It was the ignition switch. Change it and your problems are solved. The top stopped working, the key was stuck in the ignition key, and the car was quite sluggish.

FlashBack · 10-01-2006, 01:49 PM

Thanks for your reply red., but my problem turned out to be simpler. It was just a bad connection with the accel. pedel plug. All is OK now.

JimGnitecki · 10-01-2006, 05:12 PM

6.0scSSR: This might be a good time to mention that the connector that connects the throttel pedal assembly to the wiring harness under the dashboard has a "safety clip" on it, to prevent loosening or disconnection.

It is a royal pain to get out of there when swapping pedal assemblies, or pulling the pedal assembly for diagnostics, so I wouldn't be surprised if it had simply been removed at some point and not re-installed.

Jim G