Fuel cut issue
#173002
November 09, 2003 02:33 am UTC
November 09, 2003 02:33 am UTC
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Joined: Mar 2003
Posts: 274 hamilton
Jordan Markwith
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first let me lis my mods 1990 tsi awd, fully hacked can, k&n filter, lower comb removed, 2g exhaust mani, 2 1/2" turbo back exhaust w/test pipe, 255 pump (not rewired), curently running 15psi boost. I've done my research on this topic but every situation is different. I am just wondering if there is any method to fix the fuel cut aside from turning down the boost, keep in mind I have no money. I have checked for leaks and have found none any other suggestions would be appreciated. I apoligise in advance if this very same question has come up but I did many searches and didn't find what I needed.
1990 tsi awd- Big 16g fully ported, k&N, 2g mani, mbc@18psi, 255 pump, 3" turbo back exhaust no cat, hks turbo timer, datalogger, autometer a/f boost, unorthodox underdrive pully, big fmic, safc 2, JE 9:1 pistons, b/s removed, safc-2, 550cc's, 2g mas
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Re: Fuel cut issue
#173003
November 09, 2003 02:35 am UTC
November 09, 2003 02:35 am UTC
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Posts: 274 hamilton
Jordan Markwith
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sorry I forgot to mention that the cut pronounces itself at 5700-6000rpms in second gear
1990 tsi awd- Big 16g fully ported, k&N, 2g mani, mbc@18psi, 255 pump, 3" turbo back exhaust no cat, hks turbo timer, datalogger, autometer a/f boost, unorthodox underdrive pully, big fmic, safc 2, JE 9:1 pistons, b/s removed, safc-2, 550cc's, 2g mas
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Re: Fuel cut issue
#173005
November 09, 2003 03:05 am UTC
November 09, 2003 03:05 am UTC
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Posts: 274 hamilton
Jordan Markwith
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its like a back fire and all power is gone for a second fairly violent not like hitting a brick wall though. New accel wires and bpr7es plugs. I didnt have this problem until I installed my exhaust like a week ago but its hard to tell if its that or the colder air??
1990 tsi awd- Big 16g fully ported, k&N, 2g mani, mbc@18psi, 255 pump, 3" turbo back exhaust no cat, hks turbo timer, datalogger, autometer a/f boost, unorthodox underdrive pully, big fmic, safc 2, JE 9:1 pistons, b/s removed, safc-2, 550cc's, 2g mas
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Re: Fuel cut issue
#173008
November 09, 2003 07:42 pm UTC
November 09, 2003 07:42 pm UTC
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Posts: 274 hamilton
Jordan Markwith
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Well I think Im going to hack the maf. Please reply if you think I should not but from what I've read its either that or get a afc(can't tho no $$).
1990 tsi awd- Big 16g fully ported, k&N, 2g mani, mbc@18psi, 255 pump, 3" turbo back exhaust no cat, hks turbo timer, datalogger, autometer a/f boost, unorthodox underdrive pully, big fmic, safc 2, JE 9:1 pistons, b/s removed, safc-2, 550cc's, 2g mas
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Re: Fuel cut issue
#173009
November 10, 2003 12:01 am UTC
November 10, 2003 12:01 am UTC
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Joined: May 2001
Posts: 874 Toronto
Wesley Burke
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If you get an AFC you need injectors too or else what's the point. See if you have an eprom ECU and get a TMO chip.
2006 Jetta 1999 Ultra 150 18' Baja
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Re: Fuel cut issue
#173010
November 10, 2003 08:44 pm UTC
November 10, 2003 08:44 pm UTC
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Joined: Mar 1999
Posts: 1,704 Calgary, AB, Canada
Sean Costall
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Sure, hack the MAF. Let us know when you're in the market for a new engine, it won't be long. :rolleyes:
An AFC, by itself, will not solve your fuel cut problem. If you're fortunate, it may delay it very slightly.
Hacking the MAS will not solve your problem. That's a solution for MAS overrun, not fuel cut. Hacking the MAS will delay fuel cut - a lot - but it will also make your car run very lean. Engine-destroying lean. You then need an AFC in order to fix the lean problem, which puts you right back where you were before.
Installing bigger injectors and an AFC will likely solve the problem. The bigger injectors will make you run rich. You can then lower the airflow signal with the AFC. Net result is you are running the same mixture as before, but with an airflow / airmass signal that is low enough to avoid hitting the fuel cut threshold. You hope.
However, the only ways to eliminate fuel cut completely are a TMO-type chip, or a DSMlink. DSMlink is not really an option for you, since you're a 1G plus you're broke. That leaves the TMO. Fortunately for you, TMO knockoff copies can be had on eBay for cheap, and your ECU (being a 1990) almost certainly has the required EPROM in it.
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Re: Fuel cut issue
#173011
November 10, 2003 10:16 pm UTC
November 10, 2003 10:16 pm UTC
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Posts: 274 hamilton
Jordan Markwith
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thanks for the info guys I'll post when I have figured out what I'm going to do
1990 tsi awd- Big 16g fully ported, k&N, 2g mani, mbc@18psi, 255 pump, 3" turbo back exhaust no cat, hks turbo timer, datalogger, autometer a/f boost, unorthodox underdrive pully, big fmic, safc 2, JE 9:1 pistons, b/s removed, safc-2, 550cc's, 2g mas
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Re: Fuel cut issue
#173012
November 11, 2003 02:19 am UTC
November 11, 2003 02:19 am UTC
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Joined: Nov 2002
Posts: 91 Cambridge
Mark Spittal
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Jordan, I posted a couple of weeks ago about this exact problem, as did other people. I just fixed my problem yesterday but it may not apply in your 1g. My problem was my o2 sensor housing to downpipe gasket. It was leaking very badly to the point that it sounded like crap. 2gs have an o2 sensor on the exhaust that is after the cat. Under 18lbs of boost there would be a lot of air escaping through the gasket. Air that is not counted by the second sensor. I put in a new gasket and voila! No sputtering! My EGTs are still high but that is another problem. Cold air, not enough fuel = LEAN.
Later TSI! Rollin' slideways in my RX7.
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Re: Fuel cut issue
#173013
November 11, 2003 09:08 pm UTC
November 11, 2003 09:08 pm UTC
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Joined: Mar 1999
Posts: 1,704 Calgary, AB, Canada
Sean Costall
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Originally posted by Mark Spittal: 2gs have an o2 sensor on the exhaust that is after the cat. And 1Gs do not.
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Re: Fuel cut issue
#173014
November 12, 2003 04:14 am UTC
November 12, 2003 04:14 am UTC
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Joined: Mar 2003
Posts: 78 Ottawa ON
Rich Padulo
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Jordan
I had the same problem, I followed some inscructions from the site(hacking themaf bleeder screwetc.), I'm running 15 psi with a stock pump its been a year very reliable could be sheer luck.
stock turbo, 2.5 inch custom downpipe w/heavy duty flex, 3 inch stainless exhaust, tappauto man boost controller, hacked mass air flow
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Re: Fuel cut issue
#173016
November 13, 2003 05:51 am UTC
November 13, 2003 05:51 am UTC
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Joined: Apr 2002
Posts: 1,449 Toronto/LA
Steve Marton
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If you hack the maf you'll need at least the pot mod http://www.ecanfix.com/~mdhamilton/fuelmod.html Not sure if this will cure your fuel cut once you tune it back to a proper mixture again, but at least you have some tuning ability and aren't running way lean. I'd say get a logger though to really know what's going on and make sure you're not running lean. Knock led won't tell you anything cause pre-fuel cut will make it blink even when there's no knock (that's what I get). If you have a logger all you need to do is get something like a b&m rising rate fuel pressure regulator (or a c-clamp on your fuel return line ), then add fuel and hack the maf (and/or tune the pots if the ecu cares) to delay fuel cut. You can probly get a b&m for not much over 50 bucks. Basically what you want to do is make the ecu see less airflow, while you compensate with more fuel. If you just make the ecu see less airflow (hack the maf) you'll run lean. That's it.
Black 91 TSI FWD
"DSM: Making mechanics out of normal people since 1989"
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Re: Fuel cut issue
#173017
November 13, 2003 09:06 pm UTC
November 13, 2003 09:06 pm UTC
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Joined: Mar 1999
Posts: 1,704 Calgary, AB, Canada
Sean Costall
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Originally posted by Steve Marton: If you hack the maf you'll need at least the pot mod http://www.ecanfix.com/~mdhamilton/fuelmod.html Not sure if this will cure your fuel cut once you tune it back to a proper mixture again, but at least you have some tuning ability and aren't running way lean. Won't do anything for fuel cut, unfortunately. Fuel cut is based on air mass, not air flow. If you reduce the air flow signal and "make up" for it with the temperature signal mod, the ECU will "see" the same total air mass. Of course, you could lean it out slightly and delay fuel cut - slightly. The adjustable regulator is a good one I forgot about. However, the 255 (depending on the model) might already be overrunning the stock regulator. Ideally, you may want an adjustable FPR that allows you to turn *down* the fuel pressure - and they're more expensive. You could just turn your boost down a few pounds for the winter.
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Re: Fuel cut issue
#173018
November 15, 2003 09:56 am UTC
November 15, 2003 09:56 am UTC
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Joined: Apr 2002
Posts: 1,449 Toronto/LA
Steve Marton
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Yeah the rewire would be a bad idea for the 255 cause it will most likely start overrunning the regulator if it's not already, and it will cause more problems than it will solve. Rewire is only useful if the pump is running out of breath at high revs, which the 255 will not.
What I'm saying is if he's got the fuel flow, he'll be able to lean her out with the pots or hack the maf more. Pots are nice for fine-tuning still, as I mentioned. So either he has the fuel now because of the 255 and can just lean it out as is, or he'll need to up the pressure to get the extra fuel. Either way he needs a logger to be sure.
Second, and I'm not 100% on this, I think upping the pressure will help things even if he's overrunning already. This stands on the assumption that the fpr will maintain the set pressure and not cause more overflow at a higher pressure setting. Theoretically it shouldn't.
Let's say you're overflowing at idle and get 45psi of base pressure instead of the stock 38. At higher rpms the pressure will level off at 38. Well things get complicated by the boost reference (subtract with vacuum, add with boost), but I think we can talk of a theoretical "base" pressure which should be constant, but is not constant when you have overrun.
Now if you set your base pressure to 45psi, you'd get the same 45psi from idle on up to redline, making tuning nice and easy. You can lean it out evenly across the board and delay fuel cut.
Somebody correct me if you have experience to the contrary.
Black 91 TSI FWD
"DSM: Making mechanics out of normal people since 1989"
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