1g Throttle Body on 2g now Idles at 2200rpm

[jrpmp69]

I installed a 1g 63mm throttle body on my 98 eclipse gst and now my idle is between 1800-2200 RPM. I already tried adjusting the TPS according to the manual and it idled at 2200 showing 4% throttle at idle on datalogger. I also tried screwing in the BISS srew all the way and that just brought it down to 1800. Anyone know what could be causing this?

 

[talon96tsi]

I would look into boost leaks, and then the isc.

 

[jrpmp69]

I did a boost leak test and found a leak at the BOV and J-pipe and fixed them with some RTV. It still idles at 2000 with the ISC unplugged, I am using the same ISC i had on the 2g throttle body and it was idling fine before. Do you think it could be the throttle cable that needs to be adjusted?

 

[fallenauthority]

I did a boost leak test and found a leak at the BOV and J-pipe and fixed them with some RTV. It still idles at 2000 with the ISC unplugged, I am using the same ISC i had on the 2g throttle body and it was idling fine before. Do you think it could be the throttle cable that needs to be adjusted?

Yea it could be the throttle cable is too tight, loosen the two bolts holding the throttle cable to the intake manifold and adjust the cable till it has no slack between the manifold and the throttlebody but not to where its pulling the throttle open.

 

[90blacktsiawd]

Make sure the throttle cable wasn't installed too tightly. If you tighten it into place when it's slightly pulled it will do exactically what your having a problem with. Think of it as lightly resting on the gas at all times.

 

[jrpmp69]

I'll try adjusting it, I dont know how it would get tighter since i didnt do anything besides port the IM and install the Tb. Do I adjust it at the cruise controll box?

 

[90blacktsiawd]

When you took off your old throttle body you on hooked it. Theres 2 bolts holding the bracket on the throttle cable on the back of the intake manifold. That is what i'm suggesting is too tight. Loosen it up and try to set it so it just closes the throttle plate.

 

[blcknspo0ln]

Start with the basics, like you did. Obviously too much air is getting through your new TB and it's causing this crazy idle.

Check & adjust: BISS, TPS, ISC as per manual.

BISS - ground your ISC and adjust BISS; replace o-ring

TPS - check voltage while adjusting

ISC - easiest way to make sure it's working properly is REMOVE the ISC from the TB and have a friend turn the car on and off. I believe it also works if you put the car in ACC. The plunger on the ISC should smoothly move in and out, if it just vibrates in place, you need a new ISC. While you have the ISC out of the car, refer to VFAQ of how to do a resistance check.

Tshaft - replace your throttle body shaft seals.

CLEAN your throttle body plate.

Last, but not least, block off your FIAV. This is probably the most annoying thing to do concerning a TB, but I would reserve this as a last resort.

Adjust your throttle cable.

 

[4G63 For Me]

Another vote for the throttle cable being too tight.

I had the same symptoms after replacing my throttle body and the cable was too tight.

Check this before doing anything else because this is REALLY easy to do (5 - 10 minutes).

 

[jrpmp69]

Thanks for the help guys, the throttle cable was too tight and was opening the throttle plate. I loosened it up and my RPM's came down to 900. Now all i have to do is adjust my TPS again.

 

[Kevin Jewer]

Looks like it is mostly fixed, but did you swap the 2g TPS over to the 1g TB? You have to use a 2g TPS with a 2g car, it's the only source for the throttle closed switch signal, whithout which the ECU will not attempt closed loop control of idle speed. The 2g TPS throttle closed switch will usually crossover around 1-2% TPS. It really pays to watch the percentage in the ECU itself (not AFC or similar) and get it as close to zero as possible (without going more than ~1% negative, which you can't see). Also log the idle switch and be sure that is being made when the throttle plate is closed. You could also achieve this last step with a meter on the IdleSW pin. Check the service manual, but I would imagine it is at grond when made.

 

[Smokin80]

Looks like it is mostly fixed, but did you swap the 2g TPS over to the 1g TB? You have to use a 2g TPS with a 2g car, it's the only source for the throttle closed switch signal, whithout which the ECU will not attempt closed loop control of idle speed. The 2g TPS throttle closed switch will usually crossover around 1-2% TPS. It really pays to watch the percentage in the ECU itself (not AFC or similar) and get it as close to zero as possible (without going more than ~1% negative, which you can't see). Also log the idle switch and be sure that is being made when the throttle plate is closed. You could also achieve this last step with a meter on the IdleSW pin. Check the service manual, but I would imagine it is at grond when made.

You beat me to it. I second this. Make sure you use the 2g TPS on the 1G thottle body.

 

[jrpmp69]

I did transfer the TPS and idle control from my 2g throttle body.

When i was trying to adjust the TPS to read .97 ohms closed it kept changing on me while i was tightening the screws down and ended up at around .94. When i pull it open it reads 5.04K. Does this sound correct?

 

[blcknspo0ln]

One thing I've learned about adjusting the 2g TPS is not not adjust via resistance between pins 1-4 and 1-3. Adjusting by voltage is much more accurate.

 

[jrpmp69]

What voltage should it be set at?

 

[flinguist]

I adjusted mine per the service manual, and it came out perfect.

1. Disconnect the connector of the TPS.

2. Connect an ohmeter between terminal 3 and 4. (1234)

3. Insert a feeler gauge with a thickness of 0.45mm (.0177 in.) between the fixed SAS and the throttle lever. The SAS is the screw that stops the travel of the throttle plate on the backside of the TB.

4. Loosen the TPS mounting bolts then turn the TPS body fully counter clockwise.

5. In this condition, check for continuity between terminals 3 and 4.

6. Slowly turn the TPS body clockwise until the point at which continuity between
terminals 3 and 4 changes to non continuity. Tighten the TPS at that point.

7. Connect a voltmeter between the TPS terminal 2 (sensor output) and terminal 4 (sensor
ground). You'll need to use some jumpers between the TPS and the connector (all 4
terminals).

8. Turn the ignition to on, but do not start the engine.

9. Check the TPS sensor out put voltage. Standard value between 400 and 1000 mV.

10. Remove feeler gauge, reconnect TPS and turn off ignition.

I didn't do the voltage check part, and the adjustment was dead nuts.

 

[fallenauthority]

As close to .63 volts as possible when the throttle is closed.

 

[blcknspo0ln]

I adjusted mine per the service manual, and it came out perfect.

1. Disconnect the connector of the TPS.

2. Connect an ohmeter between terminal 3 and 4. (1234)

3. Insert a feeler gauge with a thickness of 0.45mm (.0177 in.) between the fixed SAS and the throttle lever. The SAS is the screw that stops the travel of the throttle plate on the backside of the TB.

4. Loosen the TPS mounting bolts then turn the TPS body fully counter clockwise.

5. In this condition, check for continuity between terminals 3 and 4.

6. Slowly turn the TPS body clockwise until the point at which continuity between
terminals 3 and 4 changes to non continuity. Tighten the TPS at that point.

7. Connect a voltmeter between the TPS terminal 2 (sensor output) and terminal 4 (sensor
ground). You'll need to use some jumpers between the TPS and the connector (all 4
terminals).

8. Turn the ignition to on, but do not start the engine.

9. Check the TPS sensor out put voltage. Standard value between 400 and 1000 mV.

10. Remove feeler gauge, reconnect TPS and turn off ignition.

I didn't do the voltage check part, and the adjustment was dead nuts.

That's the crappy part of using the tech manual, sadly. .4V to 1V is a hell of a difference if you think about it. However, this is definitely the correct way of adjusting your TPS. The HUGE question is (I hope someone can answer this) do you leave the TPS at what point of continuity and non-continuity? Do you leave it so that its just slightly resistant, or not at all? I've always asked this question, but it seems that the slight adjustment really has a minute meaning.

 

[Kevin Jewer]

About the continuity/noncontinuity, I'm willing to get that is the throttle closed switch. Since that is all the ECU really cares about (absolute values mean nothing, the ECU is looking for relative changes for accel and decel pump functionality), setting it that way makes a lot of sense. On every DSMlink car I have adjusted it on the IdleSw crosses over around 1% TPS. It seems to be VERY consistent. So this should be a good way to adjust it. The large range given for voltage is just a reality check, not an actual adjustment.

The HUGE question is (I hope someone can answer this) do you leave the TPS at what point of continuity and non-continuity? Do you leave it so that its just slightly resistant, or not at all?

With the throttle plate closed you want that switch made, to provide the ECU with the ground signal it needs to enable IdleSw. So you would want it right at that cross over, but with continuity, unless my thinking is way off base. It would seem that the manual states to leave it at non-continuity, because there is a feeler gauge holding the throttle plate open slightly. When you remove that, it will close slightly and make the switch (continuity). Hopefully that makes some sense.

 

[Guzman08]

ok guys well i have a 1g throttle and i want to know where i could buy the fixed sas bolt that goes on the back.

 

[Black95TSIawd]

Take it off your old throttle body.

 

[Guzman08]

they are on both 2g's and 1g's? it is a 6 bolt in a 2g and it never came with it thats why i was wondering what i can get it off from

or buy it

 

[Black95TSIawd]

1g's have an actual switch in that spot and 2g's have nothing but an adjuster, but both have something there.

 

[snowborder714]

You can find a picture of the 1g idle position switch (equivalent to the screw on the 2g) in this thread, as well as a link for adjusting it properly.
http://www.dsmtuners.com/forums/new...ody-merged-5-8-idle-position-switch-stop.html