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Car hitting fuel cut 4500rpm

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jaharris209

Probationary Member
12
0
Oct 11, 2012
stockton, California
My 1990 Talon tsi is having a fuel cut issue or so I was told. My car use to run fine go through all gears with no problem, then all of a sudden it started having a serious issue where it feels like it hits a wall. When Im at wot it will pull to about 4500 rpm and then it boggs really bad and won't go past that rpm. I've done everything from blt to replacing injector seals, spark plugs and wires, but still has same issue. If I ease into boost it doesn't cut out or bog only if I'm at wot it does it. I currently have evo 16g, rewired 190 pump, 560cc injectors, fmic, full piping, 3 inch exhaust, 2g maf and running with a safc running at 15psi. I had a massive boost leak from throttle so replaced the gasket and used rtv as well. I'm not getting any more leaks coming from that area or any area for that matter, however even when it did have a small boost leak it didn't bog like it does now. My plugs are fairly new and every time I take them out they are completely black. I've changed the gap from .25 to .32 and even tried .20 as suggested by a fellow dsm owner. When at wot my afr is about 11.2 to 10.9 until I get to 4500rpm then it goes lean to about 14.1 and that's where it cuts out pretty bad. I have the fuel correction at +7, which is what I've had it at for a long time before this problem and it never did this. I'm at a loss on what it could be. I've tried everything I can think of. Also my timing is correct has anyone had this problem and if so what did you do to fix the issue. I don't have the money to get link at the moment so my only tune is off the safc.
 
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I think your still getting a boost leak that is occuring at or around 4500 rpm ( what is your boost at this rpm) ... I once had the same issue but it was only at / around 18psi ...... I adjusted boost controller thinking it was fuel cut from the 60trim, I changed to a larger fuel pump and took it to get tuned and the tuner found the leak under boost ( I felt dumb as hell ) ..... anyways it was fixed and I drove that car for many years just the way it was ...
 
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OGDSM1989 said:
I think your still getting a boost leak that is occuring at or around 4500 rpm ( what is your boost at this rpm) ... I once had the same issue but it was only at / around 18psi ...... I adjusted boost controller thinking it was fuel cut from the 60trim, I changed to a larger fuel pump and took it to get tuned and the tuner found the leak under boost ( I felt dumb as hell ) ..... anyways it was fixed and I drove that car for many years just the way it was ...
Click to expand...
 
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My boost stays steady at 15psi. I watch the boost when it does it. It doesn't creep or anything like that. I've been running the same set up for a long time now and it just started having this issue out of no where. I've tired turning the boost down but the problem doesn't go away. I checked all vacuum lines and used soapy water while doing the boost leak test and I'm not getting any bubbles or are escaping from anywhere. I'm just kind of stumped on what it could be.
 
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It's not a new set up or one I just put in the car. I've had the same set up for about a year and never had any issues until recently. I've been able to go to wot and it ran fine it just randomly started having this issue and haven't been able to figure out what the problem is. I checked all IC piping and clamps don't see any problems with them.
 
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Leaks under boost need to be tested with the boost leak tester that uses the compressor to fill the system ... water and soap wont do do it since there is no pressure in the system .....do you use a boost controller or just wastegate pressure. Here DSMtuners they show you how to build a leak detector .... I can try to find it ... fuel cut is triggered by to much air, which is another reason I think this is a boost leak issue. What about the throttle body shaft it maybe leaking from there which is kinda common for us DSM owners ....... maybe the J-pipe gasket.
I would get the boost leak tester that you make( only costs a few bucks) and then you can be sure .... and move from. also are you just using a SAFC and Wideband ..or do you have a MAF translator , egt ...... if you have the stock maf maybe its dirty or going bad
 
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OGDSM1989 said:
Leaks under boost need to be tested with the boost leak tester that uses the compressor to fill the system ... water and soap wont do do it since there is no pressure in the system .....do you use a boost controller or just wastegate pressure. Here DSMtuners they show you how to build a leak detector .... I can try to find it ... fuel cut is triggered by to much air, which is another reason I think this is a boost leak issue. What about the throttle body shaft it maybe leaking from there which is kinda common for us DSM owners ....... maybe the J-pipe gasket.
I would get the boost leak tester that you make( only costs a few bucks) and then you can be sure .... and move from. also are you just using a SAFC and Wideband ..or do you have a MAF translator , egt ...... if you have the stock maf maybe its dirty or going bad
Click to expand...
I know how to do a blt Not just spraying soapy water over everything expecting to find a leak this isn't my first dsm. I'm doing the blt correct
 
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I had the same problem on my 2g recently, It would cut out around 4500 and kinda sound like I was antilagging. I did plugs, no change. I did wires, no change. Fixed a boost leak, no change. I had a spare coil pack so I swapped them out and walla fixed. Im not saying this is the problem but it was in my case.
After fixing boost leak a retune is necessary. Ill use some random numbers to illustrate...
Maf sees an airflow of XX due to boost leak you are only getting say 90% of that air but the ecu doesn't know that so it bases its fuel on the assumption you are getting 100% of the air. You adjust fuel down because you are only getting 90% of the air. Now that you are getting 100% of the air you are still tuned for the boost leak so you will now be lean. You need to retune since you are actually now getting the missing air from the boost leak...
Hopefully that makes sense...
 
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Ok after doing another blt I found out my injector seals were bad. So I replaced them and decided to adjust the fuel from +20 correction to +10 and almost got rid of the fuel cut issue. My guess is I had to much fuel going to the injectors I wasn't getting correct a/f readings. Almost have it to where there is no more cutting out problems. Going to 0 out the fuel and see if maybe that will completely fix the issue. Basically update: car is running better with less fuel now that the boost leak is fixed.
 
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You should update your profile with all your mods. Injectors, fuel, pump, your safc, ect... It will help with any future hiccups you may have. People will be able to simply view your profile instead of having to ask... :thumb:

What injectors are you running?
 
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lasershark said:
You should update your profile with all your mods. Injectors, fuel, pump, your safc, ect... It will help with any future hiccups you may have. People will be able to simply view your profile instead of having to ask... :thumb:

What injectors are you running?
Click to expand...
Already says in first post what my set up is. Didn't change anything everything still the same
 
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What was the problem in the end???
 
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