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2G Poor acceleration

Posted by Chris_Guthrie, Jul 30, 2019

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  1. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    So guys I had another thread about this car that I started a while back, basically had to out this thing together from scratch, 96 gst, 98 engine and ecu. Long story short, I've gotten it running but it has very poor performance. When I take off from a stop, it begs down so bad it almost cuts off, and when I'm moving it feels exactly like (best way I can describe it) I'm in my truck towing a loaded down trailer.

    From the research I've done on here, I've seen a lot of posts with similar issues of blogging, breaking up in the higher rpms and such, but nobody has posted their results of what the issues actually were. But I have narrowed it down to what I believe is the same symptoms of a decent boost leak. I'm going to hook up my boost leak tester my next day off, but was wondering if anyone has had similar issues after putting a car together, and what the cause was. The reasoning, so far every single little problem I've had with this car, has turned into a huge issue so trying to get some information on what to look at if the boost leak test doesnt fix this up for me.

    As far as the car, bone stock except the evo 3 16g, fmic, and full 3" exhaust (I am currently running a silencer due to restrictions here, but even if that's contributing it shouldn't be anywhere near as bad of a lack of acceleration as I'm getting now. I also have a boost gauge. Boost builds up to around 4psi, I've seen it go up as high as 9psi, but there really is no difference in lower seems to be lacking through the whole rpm range. Also, nothing to datalog. I need to get it drivable in stockish condition before I dump any more money into mods etc.
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  2. 2gmitsueclipse

    2gmitsueclipse DSM Wiseman

    2,066
    613
    Joined Jul 13, 2005
    Auburn Hills, Michigan
    You should report back after you perform the blt. I would mention that you have a bit too much turbo for a completely stock setup. I would keep boost under 11-12psi since the OE fuel system won't be able to supply enough fuel. If you can get your hands on a 14b, that would be my suggestion until you can get the parts/monitoring equipment necessary to run that Evo16g. Keep in mind your current turbo has a tendency to boost spike under load, so keep that in mind as you decide what to do.
     

    Autocross Build 18K  47

    1998 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 2K  0

    1999 Mitsubishi Eclipse GST
    manual · 2G DSM

    Autocross Build 3K  0

    1990 Plymouth Laser RS Turbo
    manual · 1G DSM
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  3. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    Really good info thanks for that I'll report back after I do the test, also I'm pretty sure it has a Wally in it not sure which one, but every Wally I've ever had has a very distinct ringing humming noise. Not sure if that makes any difference.

    Also, since we are on the subject, oem style turbos (ones with internal wastegates)are completely new to me. I boosted a 420a eclipse with a t3/t4 on 12lbs that pulled like a demon child in a haunting so this 4g setup is pretty new to me. But I did go with that turbo because believe it or not I got the motor with the turbo already on it for $500, and I know that a 16g is what I need for overall power goals so I figured I could always build up to that but original intention was keeping the boost stock wastegate pressure until I have all of the supporting mods. I'm almost 30, already did the mistakes before and definitely not trying to do any more LOL, so keep the info coming I'll soak it up like a sponge.
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  4. rabenne

    rabenne Proven Member

    1,001
    235
    Joined Apr 21, 2006
    Racine, Wisconsin
    BLT. You will have better results if you cover the most basic of basics before posting your questions. I don't want to guess at it if you haven't done a boost leak test. This should be your number 1 check when you have driveability issues in a DSM or other boosted car.

    If that doesnt solve your problem, continue through this list. Do not skip anything. Your first mod should be ECMlink or similar. Without data, everything you change is just a guess. While guess and check is a valid method (got Russians into space) it is time consuming and expensive.

    1). No boost, vac, or exhaust leaks.

    It is ABSOLUTELY VITAL that you have all boost and exhaust leaks fixed before doing anything with the ECU. Any leaks in the intake or exhaust (even small ones) will throw off the measured airflow and/or wideband, and will make the calibration and tuning process much more difficult.

    This can't be stated enough. It is way too common to get involved with helping someone on a tuning issue, only to find out days later that they didn't "really" test for boost and exhaust leaks. "No boost or exhaust leaks" has to mean "Zero boost or exhaust leaks...nadda...zilch...none.".

    One commonly over-looked vac leak is a VC breather vent that is not recirculated back to the turbo inlet after the MAF. This will not show up on a BLT if the PCV valve is doing it's job, but can cause problems when the engine is running in vacuum. If you have a breather hanging off the VC or it is running to a vented catch can, be sure to let us know this.

    2). Verify mechanical timing.

    This means making sure that all of your timing marks line up properly, and that you don't have any timing belt-related issues. Although problems with mechanical timing are usually fairly serious and obvious, minor problems or adjustable cam gears can affect tuning. If you are running adjustable gears, be sure to mention it along with how much advance or retard you have on each cam.

    3). Verify base timing

    Base timing on the 4G63 should be 5* BTDC. Don't guess at it; get hold of a timing light and verify it. It also wouldn't hurt to verify that the mark on the harmonic dampener still lines up with true TDC. Bring the #1 piston to the top of it's stroke, and make sure the dampener mark lines up with the TDC mark on the timing cover.

    4). Ignition system

    Make sure that your plugs and wires are in good condition. Plugs are normally gapped at .028", but may need to be gapped down to prevent spark blowout. If your plug gap is not at .028", tell us and let us know why.

    It also wouldn't hurt to test your coils and PTU, to rule out any potential problems.

    5). Motor health

    We're talking about a compression and leak-down test here. If you can't get more than 70psi in cylinder #4 during a compression test, or air goes screaming out of cylinder #2 when you inject it into cylinder #1, don't ask us to look at a log to figure out why your car doesn't have any power. :)

    6). Basic throttle body adjustments.

    This includes properly adjusting and setting the idle switch, throttle cable tension, TPS (Non-V3 adjustment and V3 adjustment), and BISS (1g and 2g). There is a specific procedure for adjusting each of these, and they are critical to getting the engine to run right. If you don't know how to properly adjust these, learn. Don't guess at it or assume they are adjusted properly. If you are experiencing idle issues, please make sure to test your ISC, and check out this page.

    7). Compression ratio

    If you are running a high compression ratio (9.0:1 or higher) or a stroker setup, make sure it is noted in your profile or be sure to mention it. Higher compression pistons have a big impact on what you can and can't get away with as far as tuning.

    8). Wiring and sensors

    Nothing is more frustrating than chasing down gremlins hiding in the wiring, or intermittent sensor issues. If you know you have broken connectors or old brittle wiring, fix it. If you know your O2 sensor "sometimes works and sometimes doesn't", fix it.

    9). No DTC/CEL codes

    This feels like I'm stating the obvious, but there are plenty of people who try to tune and have DTC/CEL codes thrown. Make sure to clear up any that are there (get them read via a scanner to see what exactly is going on) or let us know that they don't affect anything (i.e. you have your wideband in the rear o2 spot which is throwing a CEL for a missing rear o2 sensor).

    10). Electrical system

    Make sure your electrical system is in good working order. Low battery voltage affects many aspects of performance, including fuel pump output, injector response, spark energy, etc. You should see between 12-13v at the battery with the car off, and at least 13.5v throughout the operating range while running. Keep in mind that additional accessory loads such as stereo amps and aftermarket lighting can put a drain on your electrical system, so make sure your alternator and battery are capable of supporting them. Be sure to always log battery voltage whenever possible.

    11). Base fuel pressure and injector values

    In order for the ECU to know how much fuel to inject, it has to be told what base fuel pressure you are running and how big the injectors are. If you are running an aftermarket AFPR, tell us what pressure it's adjusted to. If you don't know what size your injectors are, find out.

    12). Properly calibrated and configured wideband sensor

    If you are trying to tune without a wideband sensor, you might as well be tuning blind. This is a critical part of a proper tuning system. This sensor is one that needs to be properly calibrated (if applicable) and configured inside your tuning software to have the logged input match what is displaying on your gauge. Please make sure both of these tasks are taken care of before you start tuning.

    13). Type of fuel

    This is often over-looked, but with all the alcohol blends these days, it's important to know what type of fuel you are really flowing through your injectors. Unless you know for a fact that you are running pure gasoline, it wouldn't hurt to pick up a cheap ethanol tester and check what comes out of the pump every now and then. At the very least, be sure to mention what type of fuel was used for the log in question.

    see here for more info
    https://www.dsmtuners.com/threads/w...r-receive-no-replies-from-the-wisemen.443297/
     

    Street Build 232  5

    1996 Mitsubishi Eclipse GSX
    awd · automatic · 2G DSM

    Street Build 178  12

    1997 Mitsubishi Eclipse GST
    fwd · automatic · 2G DSM

    Street Build 7K  9

    1995 Eagle Talon TSi
    awd · manual · 2G DSM
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    Chris_Guthrie likes this.
  5. 2gmitsueclipse

    2gmitsueclipse DSM Wiseman

    2,066
    613
    Joined Jul 13, 2005
    Auburn Hills, Michigan
    Keep in mind that the Evo III 16g will flow much more air than the stock setup at any given psi. If you still are going to run it without supporting mods, I may recommend keeping off WOT (as stated, it will spike). It is a great street turbo and was my first turbo upgrade some time ago.

    Good advice given from Rabenne.
     

    Autocross Build 18K  47

    1998 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 2K  0

    1999 Mitsubishi Eclipse GST
    manual · 2G DSM

    Autocross Build 3K  0

    1990 Plymouth Laser RS Turbo
    manual · 1G DSM
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  6. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    This is all fantastic info, thanks guys. I just got off work and am going to run the BLT when I get home. Although, what rabenne mentioned that I did have a funny feeling about is when I did the first BLT and fixed all the leaks before, with the VC breather hose disconnected and (new) PCV hooked up, there was air coming out of the breather port on the VC. Is that supposed to do that or is there issues there?

    I'll report back tonight after the test. Thanks again for this info.
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
  7. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    Okay so boost leak test went not so great. Theres a screw on the throttle body that has a small leak, there is also a leak on the fpr, I'm almost betting that's where the driveability issue is. But the bad part is I'm hearing bubbling in the engine, assuming hg is shot and air is bleeding into the coolant passages. I'm not sure if the boost leaks are the main culprit or if it's the hg but I'll have to do a comp test on it and see how bad it is and go from there. But I think that's where the problems are. I'm going to work on getting those fixed and I'll report back once I have all that sealed up. Might be a while, I have a very limited amount of time I can work on this every week. But I've got a good place to start, so I'll let you guys know what happens.
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
  8. 2gmitsueclipse

    2gmitsueclipse DSM Wiseman

    2,066
    613
    Joined Jul 13, 2005
    Auburn Hills, Michigan
    The screw on the TB that is leaking may be the BISS screw if so, it is cheap to replace. There is also an o-ring on it that will need replaced as well. The bubbling may not be a HG leak. Air is likely passing through the seals on the turbo (normal) and/or PCV leakage. Two things to try:
    1: Try the blt after the car has warmed up.
    2: Try blt after the turbo.
    3: Ceck operation of PCV.
    4: Try a compression test.
     

    Autocross Build 18K  47

    1998 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 2K  0

    1999 Mitsubishi Eclipse GST
    manual · 2G DSM

    Autocross Build 3K  0

    1990 Plymouth Laser RS Turbo
    manual · 1G DSM
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  9. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    Copy that I'll get on that on Saturday. But I do believe my pcv is bad, brand new but bad. Reason why that is because I can hear the air going through it when trying to do the boost leak test, then comes out the breather tube on the valve cover. Pretty sure it's definitely not supposed to do that but I'm not a expert at pcv valves.
     
    Last edited: Jul 31, 2019

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
  10. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

    4,559
    1,995
    Joined Nov 14, 2013
    Independence, Kansas
    Plug the pcv valve and see if you can get it to hold the test better. I am one of the guys that runs a check valve in the pcv line and the brake booster line to keep boost from getting back into the motor or popping the diaphragm in the booster.
    https://www.ebay.com/itm/2Pcs-8mm-5...178485?hash=item3b092f8075:g:wooAAOSwbxhazvT9 for 5/16"
    or 3/8" here
    https://www.ebay.com/itm/3-8-8MM-Pl...=3830399224348936d2796c9d4eeebc76b8bd4c80dad8
    @ThunderChild runs the metal units, I run the plastic. He may use 3/8", I can't remember but maybe he can get on here and straighten me out!! :thumb:
    Marty
     

    Street Build 3K  27

    1992 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

    528  14

    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    446  18

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

    Street Build 642  4

    1998 Eagle Talon TSi
    fwd · manual · 2G DSM

    Street Build 5K  11  25

    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM
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  11. ThunderChild

    ThunderChild Supporting VIP

    2,540
    714
    Joined Jan 5, 2012
    Rathdrum, Idaho
    Marty's on it! Mine are 3/8". Since I've put my check valves in, all of my little piddly oil leaks stopped completely, and I'm getting much more consistent boost numbers and AFR readings, highly recommended add-in.
     

    Street Build 247  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    346  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 890  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 1K  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 2K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  12. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    That is the simplest, easiest solution to what I have going on with the pcv for sure. Great suggestion guys!! I'm going to see if I can find one at my local parts store tomorrow. Going to try that, replace those loose hoses, run another BLT and do a comp test hopefully Saturday and I'll report back then. I also have a timing light but I'm going to try this first and see where I'm at because although I've had thing for like 10yrs, never had to use it. But thanks guys, all of your suggestions and advice are giving me hope again!
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
  13. ThunderChild

    ThunderChild Supporting VIP

    2,540
    714
    Joined Jan 5, 2012
    Rathdrum, Idaho
    You might be hard pressed to find a parts store piece that will hold up, I couldn't. Hence why I looked online, bout some plastice ones that should've held by specs, didn't, then I got the metal ones. I would order the kynar ones at minimum, since soooo many members have used them with great success.
     

    Street Build 247  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    346  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 890  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 1K  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 2K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  14. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    Just ordered 2
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  15. Chris_Guthrie

    Chris_Guthrie Probationary Member

    21
    2
    Joined May 19, 2019
    Yale, Virginia
    Update, so finally got the correct check valve in today, ordered 3/8 first ended up needing the 5/16. So anyway did another boost leak test, found one and fixed that, went to go for a test drive and all of a sudden the car would start, run like 3-5 seconds, then cut off. Even when hitting the throttle it just died. So did a little research, found that was a common CAS issue. Luckily, mine wasnt bad, I had used these 16ga quick connectors so I didnt have to cut any wires and could run both 96 and 98 CAS plugs... well, they work absolutely amazing on wires they fit, but not so well on a dsm. Had to go back and rewire the plug. Plugged it back in and bam, started right up, idled great, took it for a test drive and low and behold, problems are fixed. Thanks guys. Boost leaks seemed to be the issue, although could have been the CAS wires loosening up but fixing both took care of the poor acceleration. Runs so much smoother now too, I believe that's mainly due to the check valve, best cheap mod I've ever done.

    Now I do have another issue, well a couple but one I know for sure is the water pump is leaking I believe out of the weep hole as it slowly drips down the timing cover (no biggie I shouldve done the timing belt etc anyway when I got the motor but I can knock that out with the wealth of info on that topic) but I noticed when doing the boost leak test I was still getting air being pushed out of the breather tube on the valve cover even with the check valve in line with the pcv out arrow pointing away from the valve cover. Is that normal?
     

    Street Build 115  4

    1996 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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