Plenum Butterfly Adjustment

[Bill Z]

I need some technical advice. and may some wording.

What do you call the throttle butterflies in the plenum on my Typhoon. I
think my off idle baugh (hessitation) is because the stop on the plenum was messed with.
The little seal that seals the adjustment screw had been removed. I was
told that the TPS was suppose to be .5 volts and I couldn't get it there.
The stock TPS isn't adjustable, so I used my Dremal tool and made it
adjustable.

OK. I figure the stop is out of specs, the TPS isn't in sync with the throttle so
the air fuel mixture at idle is all screwed up. So, I get the 'off idle
hessitation'. Sounds right?

How do I get it right? How do I set the butterflyes (or what ever they
call it) back to specs? Then I can set the TPS back to .5 volts. Then, maybe, things
will start running right.

Where do I look?

Any real good suggestions?

 

[leroy]

Re: Plenum Butterfly Adjustment

There is no need to adjust the tps. The ecm can compensate for voltage differences. I like to set the throttle stop screw to get about 20 IAC counts, hot idle, in drive.

I don't think the throttle stop screw or tps have anything to do with your problem.

Start with a tuneup and fuel pressure check.

HTH,
Jim

 

[Divergent Lightning]

Re: Plenum Butterfly Adjustment

if a tuneup doesn't fix the problem then it may be clogged injectors....

 

[Bill Z]

Re: Plenum Butterfly Adjustment

I had just installed new wires, cap, rotor & plugs. It really ran crappy before. The tuneup helped with everything except the 'off idle' problem. I will check to see if the IAC count is around 20 hot in drive.

I guess if the count is high, I open the butterflys and if it is too low I close them.

About the injectors. This is my only daily driver. I have been using Lucas injector cleaner the past 5 or 6 tanks of gas. Now, they may need to be replaced. I guess they are about 70K miles. What do you think?

 

[Divergent Lightning]

Re: Plenum Butterfly Adjustment

Well, I know that even using that injector cleaner stuff is suposed to help, I have found that getting them taken out and then flow matched can be a serious improvment. Specially if they have never been matched before.

 

[nightdiver]

Re: Plenum Butterfly Adjustment

There is no need to adjust the tps. The ecm can compensate for voltage differences. I like to set the throttle stop screw to get about 20 IAC counts, hot idle, in drive.

I don't think the throttle stop screw or tps have anything to do with your problem.

Start with a tuneup and fuel pressure check.

HTH,
Jim

What he said :tup:

 

[critical]

Re: Plenum Butterfly Adjustment

Try setting the tps voltage a full 1.25 volts. The factory set them this way. That is why it is non-adjustable! They are different settings than your run of the mill 4.3. Your old tps may have been fouled out w/ oil.

 

[critical]

Re: Plenum Butterfly Adjustment

Oh, and the butterfly adjustment is called "minimum air" setting. I set mine a while back, and it idles smoother than it did before. If I can remember how to set the min. air , I will let you know. I for got the details.

 

[Bill Z]

Re: Plenum Butterfly Adjustment

Oh, and the butterfly adjustment is called "minimum air" setting. I set mine a while back, and it idles smoother than it did before. If I can remember how to set the min. air , I will let you know. I for got the details.

Thanks.

I appreciate any help like that that I can get.

 

[Bill Z]

Re: Plenum Butterfly Adjustment

Guys,

With your help I was able to find this information (see below).

After reading all of this, I have two questions that need to be answered before I attempt this.

1st. How do I put the ECM in diagnostic mode?
2nd. what is the charging system and how do I turn it on?

__________________________________________________________

The base engine idle adjustment procedure (minimum air rate) is recommended annually or when modifications such as installing a different chip are done. The minimum air rate adjustment is essentially calibrating the true base engine idle RPMs in correlation with the electronics and TPS zero percent throttle perimeters. Before beginning this procedure, the throttle body and IAC seat and motor pintle MUST be free of carbon deposits and thoroughly cleaned to enhance proper airflow, this is commonly done with carburetor cleaner and a rag. The following instructions will assume a scan tool is being used to access ECM data.

1) Warm up engine to operating temperature, then shut it off.

2) Put ECM in diagnostic mode and turn the ignition to the run position, diagnostic mode can be confirmed with the check engine light flashing code 12.

3) Wait 45 seconds, and then disconnect the IAC motor 4-pin connector.

4) Put scan tool in open mode (road test) and start engine.

5) Confirm closed loop status.

6) Put Emergency brake on and or block tires and put shift lever in "DRIVE".

7) Using the throttle blade adjustment screw on the throttle body, set the idle speed to 500 RPM +- 50 using only the scan tool RPM display.

8) Put shift lever back in the PARK position.

9) While the engine is still running, adjust the TPS to .046. If your TPS was well above or below this setting, it might be a good idea to recheck step #7 once more.

NOTE: It's suggested the idle TPS setting be done while charging system is operating.

10) Turn the engine off and reconnect the IAC wire connector, turn key back on to the run position and set maximum TPS value to at least 4.7 volts with throttle blade at WOT, recheck step 9 and 10 back and forth till both settings are obtained.

NOTE: To obtain 4.7 volts at WOT, it may be necessary to remove the TPS and trim off enough material from the banana shaped tabs to allow the sensor to shift closer to the front of the vehicle, this shifting will move the TPS throw arm closer to the throttle shaft throw pin changing the fulcrum point increasing TPS voltage output.

11) It is now necessary to clear the ECM memory. Disconnect the ECM power supply and wait at least 10 seconds then reconnect.

12) Test drive car and sustain 45 MPH for 300 yards, the ECM will now command an IAC reset and update its counts so the ECM will now know where the IAC is in relation to its seated position.

Text (c) John Pearcy

 

[leroy]

Re: Plenum Butterfly Adjustment

The ECM can auto-zero the TPS, if closed throttle voltage is less than 1.25 volts. There is no need for adjustment. TPS can easily be checked with a scantool. Voltage should vary smoothly as the throttle is applied from below 1.25 volts to above 4.5 volts at WOT. I have seen a TPS with a dead spot that caused a hesitation problem.

If you have an adjustable TPS and a different ECM, then the adjustment tips may apply.

There are lots of other things that can cause hesitation....timing, fuel pressure, ignition problems, vacuum leaks, low voltage, bad grounds, etc.

Jim

 

[Jimmy]

Re: Plenum Butterfly Adjustment

Just jump the A&B pins on the ALDL connector with the key on to run the IAC all the way in. Give it 30 seconds. Then remove and restart. The ECM should find its own idle.

 

[Bill Z]

Re: Plenum Butterfly Adjustment

Little tricky to put ECM in diagnostic mode when trying to use the TurboLink cable. It hogs the connector. However, I came in the back side with a paperclip and it worked fine.

So, I compleated this exercise and my truck does idle and run better.

It didn't fix all of my problems but I am working the list down.

Everyone, Thanks for your advice and your help.