2G 1g TB on 2G high Idle

[Bedicine]

Hello,

Just recently switched from a S90 TB on my 2G as it was constantly whistling and had a leak. I picked up a 1g NT TB, replaced the seals in it (metal inserts), new BISS screw, bypass plate, new TPS and capped the 4 lines on the top. Did the adjustment as per the guide with the feeler gauge and such but when i started the car it is idling at 2k then climbs up to 3k. I screwed the BISS in all the way and that didnt help, loosened the TB stop and it made no change. Also when stepping on the gas then letting off the car drops idle quicks then picks it back up.

Wondering if this is because i capped the 4 lines on top of the TB instead of looping them or if its something else. Did a quick log i can upload but screenshot below. Appreciate any help.

Thank you

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[dwb]

I only see three nipples that are capped. What about the missing one on the back side (A2) - is it plugged too? No harm capping them rather than looping, probably better to cap each one individually anyway.
Does the throttle cable tension have slack when on the stop?
Did you do anything to block off the FIAV?
Is this a stock MAF/MAS and if so, have you performed a boost leak test?
Anything else change other than the TB?

Your pictures don't jive with "currently no mods" listed on your profile.

 

[Bedicine]

Haven’t had a chance to update my mod list . I do have a build thread going on. This tb only had 3 nipples on it, no 4th.

Running gm maf and iat sensor. Tuning the isc which is new on the tb but fiav blocked off. Only change to the car is the tb swap and the methanol injection which I just plumbed in. Don’t feel like that would cause any issues though because when the throttle is closed it’s still having the same issue and the sprayer is on the other side.

The throttle cable doesn’t have slack, it’s not tight but somewhere in the middle. Should it be loose? ECMLink shows throttle at 2% when idling, tps adjustment maybe?

 

[Bedicine]

Just tried loosening the throttle cable and no change

 

[dwb]

Cable doesn't need slack necessarily but it should not be holding the throttle open.
Do you see ISC movement on your logs?
IDK about a 2g since 1g has an idle switch, but 2% throttle with the plate closed is suspect. I'd try to adjust the TPS manually (preferred) or use ECMLink TPS adjustment to get it to zero and see if it changes anything.

This tb only had 3 nipples on it, no 4th.

Oh, yes, NT TB.

 

[Bedicine]

Discovered the isc was unplugged for whatever reason. Plugged it back in and made zero difference. Gonna have to play around with the tps tomorrow. Unless there is a leak at the gasket

 

[DSMPT]

Did you already fix this?

https://www.dsmtuners.com/threads/nt-tb-rebuild-question.545236/

 

[99dsmer4g63]

You said you did the adjustment per the guide. You then said your log is showing 2% at idle. You’re not doing something right.

You said you loosened the throttle stop. You must redo the entire adjust per the guide. The throttle stop must be set correctly and not touched first before anything.

Do the adjustment. Turn the biss screw out 2 turns. Make tps adjustment in link. I prefer not to simulate the idle switch and you don’t need to if done correctly. Warm the car up and after target 30 in the isc position with the biss screw.

This is after you boost leak test of course.

-Daniel

 

[Bedicine]

Did you already fix this?

https://www.dsmtuners.com/threads/nt-tb-rebuild-question.545236/

Yes got the correct one on this week

 

[chrisman287]

Are you using the 2g tps? It has 4 pins vs 1g that has only 3.

 

[Bedicine]

You said you did the adjustment per the guide. You then said your log is showing 2% at idle. You’re not doing something right.

You said you loosened the throttle stop. You must redo the entire adjust per the guide. The throttle stop must be set correctly and not touched first before anything.

Do the adjustment. Turn the biss screw out 2 turns. Make tps adjustment in link. I prefer not to simulate the idle switch and you don’t need to if done correctly. Warm the car up and after target 30 in the isc position with the biss screw.

This is after you boost leak test of coarse.

-Daniel

For the throttle stop is there a guide for a baseline on it. With the throttle closed should the stop be touching it so it’s snug but not pushing it open?

When you mention target 30 in link is this for the isc position?

Link adjustment is that the tps adjustment tab?

Are you using the 2g tps? It has 4 pins vs 1g that has only 3.

2g tps being used

 

[DSMPT]

I screwed the BISS in all the way and that didnt help, loosened the TB stop and it made no change.

This is telling you. If you couldn't lower the engine speed by the BISS all the way in, then probably the throttle plate opens too much or you have vacuum leak. If closing the throttle plate more didn't make any difference, then look for vacuum leak.

 

[Bedicine]

Will check tomorrow. Side bar the reason I’m going with a 1g throttle body is because my s90 was whistling like crazy. Was going to send it out for rebuild but looking at it even with the butterfly closed you can see a gap all the way around it. No wonder if whistled.

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[99dsmer4g63]

For the throttle stop is there a guide for a baseline on it. With the throttle closed should the stop be touching it so it’s snug but not pushing it open?

When you mention target 30 in link is this for the isc position?

Link adjustment is that the tps adjustment tab?

For a 2g TB is 1 1/4 turns after the stopper makes contact with the throttle plate.

For a 1g I seen most doing about 15/16 of turn after making contact with the throttle plate.

As I stated this must be done first. Disconnect the throttle cable and do not hook it back up until you are done in the engine bay.

After setting the stopper follow the guide for a 1g TB with a 2g TPS. RRE has a good article for this. Also I don’t get caught up on the .63 v for the TPS output. I’m focused on getting the correct switch point for the IPS.

Hook the throttle cable up not too tight not too loose. Hook up ECMLink and calibrate the TPS in while logging KOEO. Log the ISC position. If the TPS is set correctly you do not need to simulate idle switch.

I run the BISS at 2 1/4 out from closed as a starting position but I’m a 2g TB. So maybe start with just 2 turns out.

After a warm idle target 30 ISC steps while logging. No boost leaks is important as well as a car without other underlying issues. Without the FIAV I imagine you will always have cold idle issues. I personally kept mine and intend on keeping it.

-Daniel

 

[Bedicine]

Thanks for the reply. I did all of the above this morning. Throttle position is now showing 0% when closed which is good and a 100% when the pedal is to the floor which i didnt have before. Car is currently idling at 2700 rpm, photo attached of current log. Didn't get change to let it warm up to adjust the biss but figured that wouldnt correct the issue at this point on where it is sitting.

I just did notice that my throttle position will stay at zero for majority of the time but then later in the log it is showing it at 1-2%

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To add, when I had the s90 throttle body on I had the fiav and isc block off plate. Now I’m running the bypass with a new isc, would this change anything in regards to my ECMLink or could the isc sensor be causing the issue?

 

[99dsmer4g63]

I have no experience without the fiav however it seems cold idle is a problem but it wants to die not idle high.

Cold start sometimes I can see a slight spike but comes down close to normal within a minute or so and then eventually settles where it should be.

I think you have a leak or other issue allowing unmetered air to bypass somewhere.

-Daniel

 

[Bedicine]

We did two seperate leak tests before the new tb went in and no issues past 30psi. At idle if there was a leak wouldn’t it be isolated to the tb then?

Last night I took apart the fiav housing and added silicone along with the gaskets in case it was leaking but still not sure where else it would be. Be curious if I put the s90 back on if it goes away

 

[dwb]

Can you upload your latest captured log file please, not just a screen snip? Use the 'add photos' button and select your .egl log file.

 

[jdxnc]

High idle like this is pulling in air somewhere, period. Either there's a boost leak or the throttle blade is not adjusted correctly. Did you mark the orientation of the throttle blade when you took it out? They're tapered on the edge and need to face a certain way.

 

[SixBolt_16G]

Maybe something wasnt right with the new shaft seals you installed and its still leaking internally?

 

[Bedicine]

So i took off the FIAV/ISC portion and did the full block off and put the TB back on the car. Car is no longer idling high, sitting at about 1200rom but i havne't done adjustments. It was a brand new ISC so is there a possibility thats leaking?

Issue i'm having now is when i touch the throttle the car hesitates and then feels like its going to stalls and catches itself. log attached, i think i'm going to have me S90 rebuilt in the meantime but was really hoping to run the ISC to help with some of the idle issues when i drive. Before the car would stall out with the clutch in it going around a corner and had a loud whistle coming from the TB which is why i was aiming for the rebuild.

 

[DSMPT]

So i took off the FIAV/ISC portion and did the full block off and put the TB back on the car

look for vacuum leak.

This is called vacuum leak...

It was a brand new ISC so is there a possibility thats leaking?

ISC and FIAV has a seal. The air was sucked through there. Can't tell without seeing but I have seen some people installed the ISC not straight and got vacuum leak and damaged the ISC. Also leaking from FIAV is kinda common.

First double check everything you did for this throttle body swap and adjust the throttle body properly. And then run a boost/vacuum leak test. Then go next.

BTW, it seems your alternator is not working well. Should inspect and fix if necessary.

 

[Bedicine]

Alternator is brand new, is there something on the log that’s showing a concern?

For the fiav I have the bypass plate installed which blocks those holes out and I have vacuum caps over the two line locations. Would have to be the isc then, brand new gasket with it but they don’t fit in that well when you replace the factory portion of it

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[DSMPT]

Alternator is brand new, is there something on the log that’s showing a concern?

New doesn't guarantee anything, especially if it's a reman alternator. Sometime just a few mins is enough to stop working. Yes, I see it's not charging well. Even while the engine is running, it's showing below 12v. Should check all wirings and connections, too.

For the fiav I have the bypass plate installed which blocks those holes out and I have vacuum caps over the two line locations. Would have to be the isc then, brand new gasket with it but they don’t fit in that well when you replace the factory portion of it

We can't be sure about this until you actually run a vacuum/boost leak test.

 

[Bedicine]

i'll re run a vacuum test but had done 2 before the TB change so i know the piping and everything else isnt leaking. Only leak could be at the throttle body. Will try it again this week.

When you're refering to the alternator is that the battery section on the log? I'm running a motor cycle AGM battery, voltage was low when i started it as the car has been sitting for 2 weeks and hasnt been on charge.