Fuel cut symptoms.....not fuel cut????

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Fuel cut symptoms.....not fuel cut????

Postby luvinmycel » Sat Sep 11, 2004 11:15 pm

I have a 1987 Celica convertible with a JDM 92 MR2 3SGTE in it. Okay, basically as soon as the car hits "0" on the boost gauge it starts bucking and jumping and whenever you do more than a light acceleration on the gas it feels like it just stops. However, if you can patiently get over about 2 psi in 5th gear it finally levels out, otherwise it keeps bucking and jumping. We've tried the fuel cut mod that plugs the map sensor and the vacuum line, it's still doing the same thing. We've checked voltages on the map sensor, ecu and the AFM and everything appears fine. The TVIS appears to be working correctly also. Unfortunately we are comletely dumb founded. It's been doing this for almost 2 years now and it's so annoying that I really don't like to drive it very far anymore. We've done everything we can think of. If anyone has any ideas, please post.

We decided to swap out my stock 3SFE fuel pump for the Walbro fuel pump to see if that would help at all. Dad said that it made the problem a little bit better. It didn't eliminate it though. We are now trying to hook up a secondary oxygen sensor since mine didn't have one on it. Any one have any other ideas???

Any advice is well welcomed.

Thanks
T
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Postby BraveUlysses » Sun Sep 12, 2004 12:59 am

Sounds like fuel cut to me. Time to buy or make a FCD.
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Postby Gary » Sun Sep 12, 2004 2:56 am

T,
Have you tried to pull the code or reset the ECU?
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Postby Trance4c » Sun Sep 12, 2004 5:10 am

Hi Talitha..

What you are discribing is definately infact fuel cut. You will need to put an FCD inline on your PIM wire off the ecu.

Good luck.

Clayton
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Postby saved_1992 » Sun Sep 12, 2004 1:27 pm

to me it doesnt sound like fuel cut, the gauge is only hitting 2psi, when you did the swap did you use the jdm afm/ ecu or a combination. the basics are the wires,cap,rotor,plugs good and are they toyota or cheap aftermarkets?
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Postby BraveUlysses » Sun Sep 12, 2004 2:13 pm

saved_1992 wrote:to me it doesnt sound like fuel cut, the gauge is only hitting 2psi, when you did the swap did you use the jdm afm/ ecu or a combination. the basics are the wires,cap,rotor,plugs good and are they toyota or cheap aftermarkets?


It definately sounds like FC to me, because the only way he's getting up to that 2 psi is in fifth gear, which is probably the only amount of boost that can be allowed by the wastegate for being in that gear.
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Postby alltracman78 » Sun Sep 12, 2004 2:42 pm

Sounds ALOT more like really bad misfire.
Does the cel come on?
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Postby saved_1992 » Sun Sep 12, 2004 2:44 pm

what, fuel cut hits at 10-12 psi, not 0-2psi :doh:

this is all stock unless the wiring in the conversion is wrong
mike
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Postby alltracman78 » Sun Sep 12, 2004 2:53 pm

Well, once you hit fuel cut, after that, it will hit at ~0psi, until you clear the ecu.

However, like I said, this sounds more like a really bad misfire, so check plugs/wires/cap/rotor, like Saved said.
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Postby luvinmycel » Sun Sep 12, 2004 8:16 pm

We found the problem. I have MAJOR intercooler leaks. It's not fuel cut, we already did the fuel cut mods and it had no effect on the problem. There are no ECU codes and the ignition system has all checked out, not to mention that the plugs, wires, and coil are BRAND NEW. The rotor and cap checked out fine. Later guys.

T

I know this it OT but, Clayton, are you going to NOPI? IM or email me man.
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Postby saved_1992 » Sun Sep 12, 2004 11:43 pm

and it took you 2 years to find that

:lol:

later
mike
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Postby luvinmycel » Sun Sep 12, 2004 11:55 pm

No, we actually had the problem fixed back in May, it was a combination of the boost controller not working properly and the MAP sensor being bad, the wrong AFM and prior IC leaks. But after about a month it started doing the exact same thing again and we didn't think it would be any of those other things we already fixed. Turns out that my IC had busted the welds out somehow where we fixed them before and instead of rewelding it again we're gonna look into getting a brand new one now.

T
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Postby saved_1992 » Mon Sep 13, 2004 12:13 am

:doh: my bad
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Postby etantshi » Mon Sep 13, 2004 2:24 am

I have seen the car and I know what the problem is. It is not fuel cut. The car bucks. Fuel cut will stop your car and throw a code. No such code comes up from the ecu. The best bet I can think off is incompatable sensors and wiring to the ecu. I have checked many of the voltages/ohm reading from the sensors. Many were within spec. Some were not. I recoment buying a new loom, or rewiring the current loom back to stock using the wiring loom diagram book (this means take out all your extra stuff you put in when you installed it like all the extra hks electrical goodies). Or you can go aftermarket engine management. That's pretty much what it is.

Sorry girl. That's gonna be it.
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Postby Gary » Mon Sep 13, 2004 2:36 am

and a boost/vac gauge would make it easier to detect boost/vac leak. :wink:
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