Throttle linkage adjustment

jcunning · 07-14-2008, 06:31 PM

I'm having trouble adjusting the throttle linkage to account for all of the specs in the Bentley. Currently I have the correct gap for the idle control switch and I believe the correct gap on the drag arm at the reversing lever, and I do activate (just barely) the full throttle switch when I press the gas pedal all the way down.

The strange thing is that when my wife pushes the gas pedal all the way down, I can then pull the throttle open another 1" at the throttle body.

I'm assuming here that I'm not really getting full throttle at the throttle body, but everything else seems to be in spec.

Is this normal?

The reason for this investigation is two fold. I'm getting a strange highway running hesitation cycle that I was hoping was the idle switch coming on and off as I maintain 70 MPH. The second reason is that the car seems a little sluggish at full throttle than what I was expecting for a 3.2 in a SC chassis.

I've already checked all of the other common problems, (O2, CHT, Airflow meter) that might cause strange running and I can't find anything really wrong to explain the symptom. It feels like it goes rich for a small period of time and then goes back to normal. Its the same feeling you get when the A/C compressor kicks in and drags the engine down. Except in my case there is no A/C installed!

My only other guess is maybe the fuel pressure is fluctuating, but it is hard to verify this in the car while running. I've checked fuel pressure with the car in the garage and everything seems okay. 37 psi at idle, 30 psi at 3,000 rpm.

Miguel Antonett · 07-14-2008, 07:22 PM

You are not getting WOT. Sometimes the linkage (rubber plunger) gets streched out with time and use, developing certain amount play... You should see a WOT when the pedal goes to the floor.

EAP · EAP's Garage

Did you ever get this answered?
I have the same question. With the gas pedal to the floor the throttle body linkage does not hit the wide open throttle stop. It goes just beyond the halfway point leading me to think that the butterfly is not opening completely.
Also, I don't understand Miguel, what is the "rubber plunger"?
BTW..I have an '84 3.2 MFI.

Tigerrat · Tigerrat's Garage

I think the throttle linkage on the 3.2 is normally adjusted at the transmission bell crank. That's where I did mine. 1" sounds like a lot although it would be less at the trans. . The WOT switch should come on about 2/3 throttle and can be adjusted by loosening the bolts and turning. There are slots I recall for this purpose. Ken

richde · 07-23-2008, 06:48 AM

Quote:

Originally Posted by Tigerrat

I think the throttle linkage on the 3.2 is normally adjusted at the transmission bell crank. That's where I did mine. 1" sounds like a lot although it would be less at the trans. . The WOT switch should come on about 2/3 throttle and can be adjusted by loosening the bolts and turning. There are slots I recall for this purpose. Ken

Mine was one solid mass, I managed to adjust it at the throttle body. Doing it wasn't pretty, but it worked.

CharlesJones · 07-23-2008, 07:33 AM

If the WOT switch comes on at 2/3 throttle is there any need to have it adjusted to get more throttle? I mean, is there any more juice to be had by getting more throttle once the WOT switch activates, or is it just necessary to make sure that your throttle opens wide enough to activate it?

Also, should you be able to hear the WOT switch activate? On my car I can hear the idle switch click on an off when I exerise the lever at the throttle body, but I can never hear the WOT switch come on.

Thanks.

janz · 07-23-2008, 08:35 AM

Ther is an electrical test for determining when the switch activates. I did this a while back and it was a continuity test that can be done on the cold engine sitting there not running. You inplug one of the connectors and test from one point to another. As I recall I opened my throttle and about 60% of the way to wide open the tester showed continuity at the test points all the way to wide open and then lost signal at the same point while releasing the throttle. I will find the paper info on it if no else posts, it comes with the Steve Wong chip as a make sure these things are working for full power before adding the chip.

EAP · EAP's Garage

Well, I adjusted my thottle linkage today. I had the throttle body opening about 50-75 percent of max. The dealer told me the limit is about 1mm gap between the throttle stop and the throttle body, the butterfly will then be open completely and be verticle in the throttle body. The carpet and the wooden floor board were the problem. I tightened the linkage in three places, at the pedal connection, at the transmission connection and at the throttle body connection. The difference in excelleration is dramatic.
Also, the Bently manual explains how to check the WOT switch. Since my throttle body was opening less than 75 percent the enrichment the WOT switch provides was intermittant. I believe this is the answer to the original post.
I hope I explained this well enough. The entire process is pretty easy to do. Let me know if you run into any problems. The performance impovement is well worth the effort.

jcunning · 07-27-2008, 07:08 AM

I think I finally have the linkage setup correctly now. Here is the procedure I used.
1. Check linkage at the throttle body and make sure there is .04" of gap between the idle switch.

2. Disconnect main linkage coming out of the car and adjust the linkage between engine and tranny to get the 1-2mm of slack as indicated by the book. The key point here is that this gap is created by pushing in the reverse lever by hand. If you just pull and release, there will not be any gap until you push the lever back.

3. Once this is done, you need to adjust the long linkage and the pedal at the same time. I basically used a bungee cord to hold open the throttle body to full throttle. Then I used a brick to hold the pedal down. I then went under the car to see how much distance I had between the ball of the reverse lever and the socket on the main linkage.

From there I basically had to shorten the main linkage at both locations and then lengthened the accellerator rod to get maximum travel distance.

I then tested both idle switch and full throttle switch to make sure they were working correctly. I really like using my Ohm meter with a beeping sound. Then I can be in the car and just listen for the beep to see when the full throttle sensor gets activated. On my car it is about 3/4 of the way down.