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Huge backfire, cutting out

Posted by Wasteland, Jul 22, 2020

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  1. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    Hope someone sees this.

    I have a 96GST That idles fine then a minute down the road it starts backfiring out the pipe and tries to shut off and sometimes does. But it will always idle ok. Revs up blow off does it’s job start going down the road plenty of power then starts cutting off then backfires over and over until you turn key on and off. If you wait about five minutes it acts fine again the the same thing?

    I have two for spare so I’ll try whatever. Already check the usual. Timing plugs Wired’s vac leaks coils.... pressures. . Please help I am loosing it. Lol


    Backfires out the pipe... not lip .... LOL

    Not getting any codes forgot that .... duh o codes
     
    Last edited by a moderator: Sep 2, 2020

    150  3

    1996 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
  2. Ludachris

    Ludachris Founder & Zookeeper

    7,258
    1,456
    Joined Nov 12, 2001
    Roseville, California
    I would suggest you create a vehicle profile for the car and list ALL the mods in that profile: https://www.dsmtuners.com/dsm-profiles/

    That info will help others see what you're working with so they can offer up advice. I'm assuming you've done a boost leak test. Was there any work done just before it started doing this? Was it driving fine up until a certain point?
     

    Street Build 9K  0

    1997 Eagle Talon TSi AWD (sold)
    manual · 2G DSM

    Road Race Build 8K  10  23

    1991 Mitsubishi Eclipse GSX
    435.0 whp · 399.2 lb/ft · 1G DSM
    Loading...
  3. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    Slowly learning site. Lol
    I have 5 2g spyders of them 2 are GST.The one with wide body kit was just given to me. Lots of new parts rebuilt head. Under the dash was a nightmare of wiring. That’s when I found an older MAFT 1.3.
    It’s doing something I have never came across in 30+ years of molding cars. It idles fine rev up fine then hold at 3000 rpm or drive for a couple of mins(time varies) and huge backfire and wants to cut out goes back to open loop then once it comes down it goes though same issue.
    Check everything the usual sensors vac etc...
    Any outside the box ideas..
     

    150  3

    1996 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
  4. steve

    steve DSM Wiseman

    13,543
    661
    Joined Feb 3, 2002
    Boulder, Colorado
    First idea, is to make sure that the BOV is routed back to the intake and not vented to atmosphere
     

    167  4

    2008 Audi TT 3.2 Quattro Roadster
    awd · manual · Misc Vehicles

    138  5

    2002 Audi TT Quattro Roadster 225
    awd · manual · Misc Vehicles

    148  2

    1992 Dodge Stealth RT/TT
    awd · manual · 3000GT/Stealth

    4K  12

    1991 Mitsubishi Eclipse GSX
    manual · 1G DSM
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  5. 95FullSend99

    95FullSend99 Proven Member

    240
    105
    Joined Dec 3, 2019
    ledyard, Connecticut
    Its been a really really long time but....
    First things first, verify that everything is installed correctly. With the maft you need the gm maf and if you want to vent to atmosphere then the maf needs to be after the bov. Make sure you have the correct gm maf. There is a list somewhere on the dsmtalk website I believe. Boost leak test test test test.
    Then i recommend hunting down some old instructions for the maft 1.3. There is a whole section in the instructions about how to tune using a maft. Also get a way to log. If you want to keep it old-school get a PocketLogger. I believe the maft has some dials and such on it used to dial it in.
     

    Street Build 780  12

    1997 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
  6. Ludachris

    Ludachris Founder & Zookeeper

    7,258
    1,456
    Joined Nov 12, 2001
    Roseville, California
    How is the car tuned, since it's using a GM MAF?
    What is being used to tune it, since it's using a GM MAF?
     

    Street Build 9K  0

    1997 Eagle Talon TSi AWD (sold)
    manual · 2G DSM

    Road Race Build 8K  10  23

    1991 Mitsubishi Eclipse GSX
    435.0 whp · 399.2 lb/ft · 1G DSM
    Loading...
  7. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    That’s one of the first things is when I got the car home I rerouted all vac lines. It ran better but same issue keeps occurring.
    UPDATE:
    Completely retimed and it seemed to work. Drove great pulled strong for about 30 miles hen next day it was like I had never touch it... ABOUT TO TAKE 44 mag and see if that fixes it... LOL
    Any advise even if it sounds dumb or even plain stupid if it worked at one time for you then you have my attention!!
     

    150  3

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

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    Pretty much stock maf trans not connect. One thing I forgot to add is it is now coding EVAP Control or sending unit I think 4660 code have to check but it’s my bday and down cracking my brain for now!!! Great day for a ride taking the Ducati out a little 3 digit cruising... thanks for you time. We can do this....
     

    150  3

    1996 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
  9. Ludachris

    Ludachris Founder & Zookeeper

    7,258
    1,456
    Joined Nov 12, 2001
    Roseville, California
    So what is being used for the tuning? Stock MAF, injectors and pump? I don't see any of the fuel system or tuning tool mentioned in your profile. See if you can fill in more details about your set up.
     

    Street Build 9K  0

    1997 Eagle Talon TSi AWD (sold)
    manual · 2G DSM

    Road Race Build 8K  10  23

    1991 Mitsubishi Eclipse GSX
    435.0 whp · 399.2 lb/ft · 1G DSM
    Loading...
  10. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    It’s pretty much stock. I’m looking at it now. On the last few times it did it it has gone longer as far as it didn’t backfire after only a few minutes I went about 30 then it happened. Was bummed out. I did a reset and when it backfires it is throwing a cam senior code. I had a new one so I changed it even though that one was new, just in case, but didn’t change the issue.
    *** Now, what would cause it to throw that code without that being the issue?
     

    150  3

    1996 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
  11. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
     

    150  3

    1996 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
  12. Ludachris

    Ludachris Founder & Zookeeper

    7,258
    1,456
    Joined Nov 12, 2001
    Roseville, California
    So stock 2g MAF, stock injectors, stock pump, stock regulator, stock ECU, stock everything except a GM MAF installed but not hooked up? And just to confirm, you did do a boost leak test? Do you have photos of the engine bay? Is the O2 sensor new? What are your plugs gapped at?

    See this post about the BOV having RTV in the hole:
    https://www.dsmtuners.com/threads/popping-backfires.197577/#post-1646360

    What BOV is it?
     

    Street Build 9K  0

    1997 Eagle Talon TSi AWD (sold)
    manual · 2G DSM

    Road Race Build 8K  10  23

    1991 Mitsubishi Eclipse GSX
    435.0 whp · 399.2 lb/ft · 1G DSM
    Loading...
    1990TSIAWDTALON likes this.
  13. KYLE JORGENSEN

    KYLE JORGENSEN Proven Member

    100
    33
    Joined Sep 22, 2018
    Spokane Valley, Washington
    check the cam sensor magnet is probably bad, this will cause backfiring and misfiring and sputter dying, this was the same problem my GSX had when I bought it from a kid, he did not know why it was doing it and ripping his hair out trying to figure it out instead sold it and it took me 10 mins to figure it out and 1 hour to replace the part, it's running like a champ now.
     

    Street Build 297  19

    1995 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 1K  20

    1998 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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    1990TSIAWDTALON and Ludachris like this.
  14. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    Ok
    Stock MAF. Stock Ecu it it’s a 99 and I did the firing order and all that. Did a leak check and that was ok. Plugs gapped at 28. They were at 45-50 so not sluggish at at. Pulls hard up the back firing. Cam sensor just replaced. No vac leaks....
     

    150  3

    1996 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
  15. JeffwithaG

    JeffwithaG Proven Member

    111
    23
    Joined Nov 30, 2017
    Flemington, New Jersey
    How is your fuel pressure? Maybe pull and test the pump?

    I've read that a bad PTU can cause similar issues, noticeably worse when engine temps rise. That could explain why your issue gets worse when the engine is warmed up and tends to go away after you cool down for a few minutes. I saw you have several DSMs, maybe you can pull a PTU from another one and swap it?
     

    Street Build 518  6

    1996 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Loading...
  16. Wasteland

    Wasteland Probationary Member

    10
    0
    Joined Jul 22, 2020
    Pioneer, California
    Yeah I have plenty spares. Lol
    Going to start again in about an hour and a half.
    BOV Some aftermarket one. Do have to check pressure of fuel. I have AEM reg new in he box. Still coding EVAP and cam sensors. Cam code kicks in during/after backfire. I’ll add some engine pics or vid when I get home.
     

    150  3

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

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