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2G GSX Auto brake boosting problems.

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Kdouglas89

Proven Member
436
11
Jul 8, 2013
Davenport, Iowa
Hello guys, gonna give basic run down of relevant mods followed by the question. My profile is updated with a complete list, just naming only things relevant.

Built supertech head with HKS 272
Stock block
Stock tranny
Ported 16G, 1250 injectors, on 255
Dsmlink
Speed density
Running E85 on bpr7eix i think is the number.


I am unable to build more than 2lbs of boost at 2400RPM on stock converter at the line. My AFR is 13.2 during brake boost. Have been advised to drop it down to mid 12's, and swap my plugs to copper br6's.

Having a big debate between other DSM'ers about if I will have to swap out my converter to be able to build 10-15lbs off the time.

Have also tried to retard timing off the line to like 12 or so. I was unable to build boost after the change. Have been told retarding timing for a 16g would not do anything.
 
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I'm shocked no one has mentioned your cam setup. 272s are a great cam. I run a set of Comp 272s in my own car with a stockish 2.0 long block. Aside from that I have a 1g TB, EvoIII intake and a PR FMIC kit with supporting mods. Initially I was having problems building boost due to my wastegate flapper being slightly opened. I shimmed it out and still have the same issue. Since then I've tried all the different tricks for launch control- fat and retarded, lean and advanced and everything in between. In the end, the 272 shifts the power band too much for a stock stalled auto and will create the exact issue you and I both face. If it's not the tune, if it's not an exhaust leak, if it's not a wastegate issue or a boost leak, look into installing a set of adjustable cam gears and you may be able to get over the threshold.
 
I think the problem is the super tight 2G lockup converter. In a 1G I had no problems stalling up a 16G/sd/HKS272 combo even with a tired motor, and on pump gas. The only thing I can think of is try out a restall. Keep your stock converter though incase you don't like it.
 
I have to agree with Cracked, you need a stall converter to get to the cams power band. It's the same thing I would do for a SBC.
 
So how much better could you expect the results to be brake boosting the stock converter if the op had a 264/264 or 264/272 setup instead..I'm kinda curious
 
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I've known 1g's with 272's and an hx35 that could spool on a stock converter with a tired engine. A 2g with higher compression and a 16g should have no issues.

Boost leak, exhaust leak, wg blowing open. Theres something up.

Justin was selling modified holset wastegates for mhi turbos. I've got one on my car works very well.

The afr's are a bit lean while on the brakes at 13.2. That could be a contributing factor.

It also looks like he was only on the brakes for a total of 5 seconds. Try giving it 10 seconds and see if it gets over the hump.

Id try the afr's and 10 second build up first.
 
Waking this thread back up!

Still having issues with stalling past 2400rpm. I was low on fluid. I added some autozone fluid to top it off. This made no difference. I did an exhaust leak, and found nothing that would effect spool. I have messed with retarding timing quite a bit, with no luck in raising rpms or boost. I have tried using anti-lag, but build the same amount of boost "3lbs". No matter what I do, I cannot get it to rev past ~2400 RPM.

Could the TCU be affecting this at all?
Is there some sort of trans sensor that would affect this?

Could my torque converter just be going bad?
 
O wow, thread did not update for me right away.

The only exhaust leak I have is after the O2 housing "Internal wastegate". I have no major boost leaks as of a few weeks ago. A new test will be in order in the morning. A few days ago, I did try holding the pedal down for about 8 or so seconds with the timing being majorly retarded.

Was really hoping this issue could be solved without dropping the trans, but it's looking grim. Will be bringing it over to bigdnno98's house tomorrow to see if he can work some magic on the tune. :cry:
 
5100 is way too late to be hitting full boost on a 16g. Normal is 3100 - 3800 "ish". So find out why all the extra lag and you find out why you cant brake boost.

Have you checked the wastegate?

I am actually having a buddy come over tomorrow morning with his adjustable actuator to test it out. Thought about this earlier.
 
I'm shocked no one has mentioned your cam setup. 272s are a great cam. I run a set of Comp 272s in my own car with a stockish 2.0 long block. Aside from that I have a 1g TB, EvoIII intake and a PR FMIC kit with supporting mods. Initially I was having problems building boost due to my wastegate flapper being slightly opened. I shimmed it out and still have the same issue. Since then I've tried all the different tricks for launch control- fat and retarded, lean and advanced and everything in between. In the end, the 272 shifts the power band too much for a stock stalled auto and will create the exact issue you and I both face. If it's not the tune, if it's not an exhaust leak, if it's not a wastegate issue or a boost leak, look into installing a set of adjustable cam gears and you may be able to get over the threshold.
Seen this before also. Interesting.
Also what intake manifold you using Kdouglas89? Stock 2g?
 
I'm going to chime in on this... I've been following this thread and others like it about launching an auto since I recently completed an auto swap. From my limited experience I believe that to stall the auto you need to build torque to load up the converter. To do this you need to have high timing and lean afr's... That being said, this last weekend I ran into the same problem...
I just installed my td05H 20g and after doing some tuning I tried to brake boost and launch. I couldn't Rev past 2800 rpms and was only building 3 psi of boost. After reviewing my logs I saw that I was running really rich when I was trying to load up the converter, so I adjusted the tune and tried again. After my tune was adjusted I brake boosted and loaded up the converter easily to 4000 rpm and 20 psi! I was pretty stoked especially since I was heading to the track the next day...
I made it to the track the next day, but to my dismay, again, I couldn't build boost at the line. I tried adjusting my tune but it didn't make any difference. Then I did a blt... I found a major boost leak on my new Manifold - it was cracked on the 4th runner...
If the OP isn't building full boost with a 16g he must have a boost leak or there is something terribly wrong with his turbo...
 
I'm going to chime in on this... I've been following this thread and others like it about launching an auto since I recently completed an auto swap. From my limited experience I believe that to stall the auto you need to build torque to load up the converter. To do this you need to have high timing and lean afr's... That being said, this last weekend I ran into the same problem...
I just installed my td05H 20g and after doing some tuning I tried to brake boost and launch. I couldn't Rev past 2800 rpms and was only building 3 psi of boost. After reviewing my logs I saw that I was running really rich when I was trying to load up the converter, so I adjusted the tune and tried again. After my tune was adjusted I brake boosted and loaded up the converter easily to 4000 rpm and 20 psi! I was pretty stoked especially since I was heading to the track the next day...
I made it to the track the next day, but to my dismay, again, I couldn't build boost at the line. I tried adjusting my tune but it didn't make any difference. Then I did a blt... I found a major boost leak on my new Manifold - it was cracked on the 4th runner...
If the OP isn't building full boost with a 16g he must have a boost leak or there is something terribly wrong with his turbo...
Could you add some info for us all here. What converter are you using? What intake manifold? What cams? Engine 2L or 2.3/2.4L?
I tend to disagree that a 16g will spool so easy. Just one wrong part and it throws the low end torque out the window and will not stall on tight converter IMO. But anyone with this problem should double and triple check for intake or exhaust leaks I agree. And get into the tune for sure.
 
Could you add some info for us all here. What converter are you using? What intake manifold? What cams? Engine 2L or 2.3/2.4L?
I tend to disagree that a 16g will spool so easy. Just one wrong part and it throws the low end torque out the window and will not stall on tight converter IMO. But anyone with this problem should double and triple check for intake or exhaust leaks I agree. And get into the tune for sure.
My setup is in my profile, but yes, I do have a restalled 1g torque converter, forced power sheet metal intake manifold, Crane 264 cams, built 2.0L with wiseco 9:1 Pistons and Eagle rods, and a JAM rebuilt 1g head with 1mm oversized valves.
It is true that I'd be able to stall up better with my restalled converter, but a 16g should be able to stall up and build boost with the stock converter. There are many people that have and that do. The point that I was trying to make is that the OPs innability to build boost at the line is either due something off with his car. Considering that he doesn't reach full boost until 5100 rpms with a 16g proves that there is something wrong with his setup - either the tune is way off, a major boost leak, a pre-turbo exhaust leak, or his wastegate is stuck open. It also be a combination of those things. I don't think that his cams should play a major part of the problem even though they do make more power in the top end. Basically, he should concentrate on getting his turbo to reach full boost between 3000-3500 rpm and then try launching his car. He will have much better results.
 
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My setup is in my profile, but yes, I do have a restalled 1g torque converter, forced power sheet metal intake manifold, Crane 264 cams, built 2.0L with wiseco 9:1 Pistons and Eagle rods, and a JAM rebuilt 1g head with 1mm oversized valves.
It is true that I'd be able to stall up better with my restalled converter, but a 16g should be able to stall up and build boost with the stock converter. There are many people that have and that do. The point that I was trying to make is that the OPs innability to build boost at the line is either due something off with his car. Considering that he doesn't reach full boost until 5100 rpms with a 16g proves that there is something wrong with his setup - either the tune is way off, a major boost leak, a pre-turbo exhaust leak, or his wastegate is stuck open. It also be a combination of those things. I don't think that his cams should play a major part of the problem even though they do make more power in the top end. Basically, he should concentrate on getting his turbo to reach full boost between 3000-3500 rpm and then try launching his car. He will have much better results.
I agree full boost would be great at 3000-3500 but the cams will move that up some. IF the cams are off some that could contribute to the issue. You can move that boost curve some with cam gears. I am not the first person to see this happen on a 16g with no mechanical problems. Post 26 agrees with me. It will be interesting what he finds for sure. To fix this issue on the 16g I seen it happen with he changed his whole set up and now the car acts like you think it should on a E316g on a stock 2g converter. So I have no hard evidence on what really helped. That's why I am trying to gather info on this subject.
 
I agree full boost would be great at 3000-3500 but the cams will move that up some. IF the cams are off some that could contribute to the issue. You can move that boost curve some with cam gears. I am not the first person to see this happen on a 16g with no mechanical problems. Post 26 agrees with me. It will be interesting what he finds for sure. To fix this issue on the 16g I seen it happen with he changed his whole set up and now the car acts like you think it should on a E316g on a stock 2g converter. So I have no hard evidence on what really helped. That's why I am trying to gather info on this subject.

There are too many issues though. Full boost at 5100 is a major red flag.

Secondly in his log, he starts brake boosting at 23 seconds, but doesn't go wot 100% until 28 seconds and at 28.5 seconds hes off the brakes and rolling.

Then his afr's are 13.2 while on the brakes, killing his torque.

So theres multiple issues here. Problems need to be fixed before you start parts placing or adding anti-lag and whatever else.

With full boost that late, there is most definitely a boost and/or exhaust leak. Fix that then retest.
Fix the tune under load and probably across the board
Check the wastegate.

I wouldn't touch anything until those three are corrected otherwise you're just chasing your tail.
 
There are too many issues though. Full boost at 5100 is a major red flag.

Secondly in his log, he starts brake boosting at 23 seconds, but doesn't go wot 100% until 28 seconds and at 28.5 seconds hes off the brakes and rolling.

Then his afr's are 13.2 while on the brakes, killing his torque.

So theres multiple issues here. Problems need to be fixed before you start parts placing or adding anti-lag and whatever else.

With full boost that late, there is most definitely a boost and/or exhaust leak. Fix that then retest.
Fix the tune under load and probably across the board
Check the wastegate.

I wouldn't touch anything until those three are corrected otherwise you're just chasing your tail.

I appreciate all the responses guys!

1. I have done an exhaust leak test "Put BLT at end of exhaust tip, and pushed air through." Only leak was turbo to o2 housing. "Im internal wastegate".
2. I boost leak tested up to 20lbs, there is not even a small leak.
3. I just tried my friends 16g wastegate with same results. I also tried adding a couple washers to the wastegate to tighten it, same results.
4. Friend and I messed with the tune, and was able to build max of 4ish psi with anti lag. I always thought you wanted to richen fuel to boost, not lean it out?
5. I was not going 100% wot on the line because I was building same rpm / boost regardless.
6. I am on stock intake.

I am starting to think it actually is my torque converter unless somehow my tune is wayyyy off, but I don't see how.

Also, the turbo was rebuilt / bored / clipped from forced performance about a year ago. There has been maybe 150 miles on it since. Absolutely no shaft play. I would be extremely surprised if the turbo would be causing the issue.
 
My 1st gear launch seems to be the only thing holding me back. Once I actually get into boost, its kicks like a damn mule and holds the boost all the way through. Even with the slow launch, I was able to reach an 85 trap speed with a 9.5 on only 18lbs of boost "1/8th mile".
 
There are too many issues though. Full boost at 5100 is a major red flag.

Secondly in his log, he starts brake boosting at 23 seconds, but doesn't go wot 100% until 28 seconds and at 28.5 seconds hes off the brakes and rolling.

Then his afr's are 13.2 while on the brakes, killing his torque.

So theres multiple issues here. Problems need to be fixed before you start parts placing or adding anti-lag and whatever else.

With full boost that late, there is most definitely a boost and/or exhaust leak. Fix that then retest.
Fix the tune under load and probably across the board
Check the wastegate.

I wouldn't touch anything until those three are corrected otherwise you're just chasing your tail.

I have to say I did not look at the log. Sorry for that. I am not a tuner so I did not look at it.
But I do agree with you that there are multiple minor issues. Need to fix them all and post another log for the guys smarter then me to diagnose.

Even lean though the way some talk in here he should get more them 4 psi right?

But I still think even with a small stock 2g intake which helps make some major low rpm torque the cams are causing an issue for his set up. And IF the cams were thrown in "straight up" and not degreed there could be a problem there also. Need to be able to move the power around with the cams. I think the cams are one reason the max boost is at 5100. Seen that before on 2 E316g's before with bigger cams then the OP. Don't think it was quite that high rpm but higher then most other E316g I have seen for mas boost. And I think it some of it was the cams. Autos with small turbos and tight converters are sensitive to cams IMO.

Also another thought I have is to try stalling up with only the downpipe hooked up and see what happens.

Not trying to argue with anyone I just have seen this issue first hand on at least 2 dsm's and want to understand what is going on. Both changed to much for me to say this will fix it.
 
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