Following some very useful tips and advice, I decided to clean the throttle disk. Badly needed, it turned out, and the certain cause of overly fierce acceleration jerk from res. Problem cured; much better after the cleaning! I used the advice of blocking the gas pedal down to the floor, and turning on the ignition to open the disk and facilitate the cleaning.

I noticed that the throttle disk was not fully open i.e., vertical. Perhaps 5-10 degrees shy. I was going to follow Sam's advice for taking slack out of the cable on my 2005, but it didn't seem to have much slack. I thought first I would ask for opinions about the pedal full down, disk position, engine not started.
Should the disk be vertical when the pedal is on the floor?
Thanks.

 

look at app value and tp value

that’s all you need to know

 

By throttle disk I assume you are talking about the throttle blade? I have occasionally attempted mild cleaning of the throttle body and I recall propping the gas pedal down but NOT turning on the ignition. What is the purpose of doing so? I used throttle body cleaner to try and cleaning the bore but it is difficult getting to the underside of the blade. Did you try poking around down there with some rags or something or just tried spraying the best you could?

 

Sorry, but the acronyms and the wherewithall to access the information are unknown to me. Perhaps you could provide a little more info?

 

To be clear, the method of opening the throttle plate / disk is not at issue, and having used the pedal down / ignition on method of getting the disk fully open, the cleaning was carried out successfully. I used MAS sensor spray, as it turned out to be very good at dissolving the gunk.
The issue is that with the gas pedal fully down and ignition on, the disk doesn't open 100%. The question is: Why is that, and is that normal?
I suggested it is 5-7% less than fully parallel to the airflow. It just didn't look right.
Thanks

 

You should not spray anything on the throttle plate that can drip down and collect or pool beneath it.

instead, spray a clean cloth and wipe the affected surface with the cloth until it comes clean.

Z

PS: there’s MAF spray and throttle body spray. The better ones, such as the CRC brand, are formulated differently, and are not necessarily interchangeable.

 

Agree about the CRC brand and not getting a bunch of stuff pooling down the bore. But still do not see the need for having the ignition on unless you are measuring the position of the blade.

 

I suppose there is more than one way to accomplish the same thing here. It never occurred to me to turn ignition on, so I’ve never cleaned the throttle body that way.

 

The threads on this subject, and on YouTube, with regard to other makes, suggest that bad things can happen if the throttle plate is forced open, either because the positioning motor gear-train (if any) gets damaged, thus requiring a whole new TB (in later years like my 2005, anyway). or the electronics get confused as to T-plate position.
Given all that, whether true or not, it seemed like the totally secure method of having someone hold the gas pedal to the floor (or jamming it down with a telescoping rod, which is what I did), and then turning the ignition on to get the T-plate open is the only sensible way to proceed.
It is possible, reading other threads since my posting, I may not have had the pedal all the way down ' through' the kick-down switch, and that, in turn, may have caused the T-plate not to fully open. Another test will be made!
As I planned to clean the MAF whilst the duct was off, I used a known brand MAF cleaner, which works very well on the housing and T-plate deposits, and also evaporates rapidly. I used a giant Q-tip and a tooth brush to get everything loose, and finished off with the solvent on a rag. I didn't use very much of it, but it still took considerable cranking to get the engine to start.
Thanks
Thanks

 

Using a suitable ODB2 reader, you need to read the accelerator pedal position and the throttle position. If you look at the live data with the ignition on you should see both readings approach 100% at the same time. I assume this is what he means.

Richard

 

Thanks Richard. Without that thread link, I must admit that I would have been clueless. I'll try the wife-in-car-on-pedal, observational method first, though.