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Built Auto
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1,167 Posts
Discussion Starter · #1 ·
Okay in the past few months I've been having a sporadic issue with my car that has become very annoying and when it happens it leaves me stranded because the car wont crank. I'm lost on ideas and I desperately want to figure out the problem.

The car is a 97 auto with an OBDI conversion running vpc/safc combo on 525cc injectors and walbro fp. PT61 turbo, FMIC, iridium plugs, stock fpr.

The car normally runs just fine in and out of boost, I run about 14psi daily on pump. Now whats happening is the car will randomly stall out and just die. Always happening with no warning and when I'm at idle/coasting with no throttle, no cel's come on before hand or any thing to indicate a problem, it just stalls.

Now this is where it gets funny, after stalling I try to crank the car back up and it wont crank. The car sounds like its on the verge of cranking but I give it a little or a lot of throttle but it wont ever crank back up. Nothing, acts like its way too rich or flooded to turn over. When its done this in months past, I could jump out the car and pull the EFI fuse, quick reset of ecu and I could jump back in and the car would fire back up. Lately, when I do that it still doesnt help. The only way I ever get the car back running is to fully disconnect the battery, let the car sit a while (atleast 15-20 mins, sometimes more) and try to start it. Even then, I can get the car cranked and sometimes its struggling to run. I have to give it lots of throttle and after a few seconds, something will "click" and the car acts like it leans out and revs up fine and away I go.

Now this has been happening TOTALLY random to me and lately it might happen once every 3 or 4 weeks. The rest of the time, the car runs fine, I get good gas mileage, boosts fine, hauls ass. Sometimes it acts like it happens after I've been driving the car for a while during the heat of the day but even that isnt always a given. I ran the car pretty damn hard the other night on the highway and it never acted the slightest bit wrong.

If anyone has any suggestions or what not, i'm all ears. This has gotten to the point where I'm timid to drive the car sometimes for fear of it stalling out in a busy intersection/road/etc. Because now its not a simple fix and the car has to sit there with nothing I can really do besides wait....
 

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Built Auto
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1,167 Posts
Discussion Starter · #3 ·
I dunno, the car ran 100% fine for atleast 6 months after the ecu's were swapped
 

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Registered
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421 Posts
Perhaps there is some sort of electrical short. That may also cause the car to totally shut-off. There were times my car did that with bad battery terminals where the car would just shut off. hope that helps
 

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Built Auto
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1,167 Posts
Discussion Starter · #5 ·
I understand what you're saying and its not completely shutting off, its stalling/dieing. All the lights on the dash light up and stuff when it does it and the battery is brand new.
 

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Edge On The GE-T Epidemic
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575 Posts
Mine did somthing like this when my battery terminals had bad contact, check your terminals. It also maybe one of your grounds. I remember i had similar issues last year.
 

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Built Auto
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1,167 Posts
Discussion Starter · #8 ·
Battery terminals are good, battery is brand new. I am unsure on the fuel pump part as I see good normal fuel pressure that I've always seen since the pump was installed.
 

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Registered
1997 Black Hardtop Supra
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643 Posts
My supra is doing the exact same thing right now as well!! This is what Im told.. What is your safc fuel rating set at?? im supposivley running rich so when I let off the throttle too hard it drops leftover fuel which creates a stall.. Thats what im told.. Still trying to figure out what the hell... It might because im lean? because I dont think so.. Battery is perfect, fuel pump is brand new, safc wired perfect, etc..
 

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Registered
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2,189 Posts
Wow, sounds like a fun little grimlen you have. I remember a somewhat similar problem I had with my Ford. This is actually kinda funny, when I made right hand turns the engine would cut in and out making the truck lurch. I just kinda shook my head and said "f'n Ford" but I eventually found the problem. A ground wire wasn't secured and was very close to my altinator and wore the insulation down to the wire. When I made right turns, the wire would lean over and caused a short. I secured the wire and no more problems. Another problem with my old Mazda, it took me a few months to figure out that the plug that supplied 12v to the ecu wasn't clicked down completely.......I felt real dumb when I figured that one out.

Point of all this is that you probably need to go through your wiring harness from beginning to end and look over everything. Unbolt all the grounds and make sure there's a good connection. Unplug and replug all the connectors. I'd pay special attention to the wiring for your VPV/AFC!
 

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Built Auto
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1,167 Posts
Discussion Starter · #11 ·
Yeah thats really what I plan on doing, checking all my grounds and connectors. I've checked my VPC/SAFC wiring and all seems good. I did have a problem with a loose wire on the VPC in the past causing it to completely lose power and cause similar problems, but now is not the case.

As far as my safc goes, I know the car is tuned just fine for normal driving (Lo map is -12% across). Batlground Engineering in Atlanta did the OBD1 conversion for me and dyno tuned the car.
 

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The Boost Machine
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490 Posts
Just a shot in the dark here.
Try putting a load tester on your battery to see if the battery is charging properly.
Ever notice your headlights dim recently?
I had a bad "New" battery that was reading fine as far as output volts.
Under load "sometimes" it would crap out on me. Car would act all bonkers on me.
Not all the time but once in a while. Finally just had it replaced and ran fine since.

Hope this helps.
Good luck,

David
 

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Built Auto
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1,167 Posts
Discussion Starter · #13 ·
I really dont think its a battery/loose connection issue. I've never seen my HIDs or any in cabin lights dim before. I did have a battery that went bad on me after less than a year recently and I got a new one with a 3 yr warranty on it. I've never had a problem with cranking power, when it gets screwed up the ignition is working but the car seems at the wrong a/f mixture to run or something. It always gives a good crank but wont fire or stay running. Then its like after the car sits a while with the battery disconnected, it gets reset fuel map wise and then will crank.
 

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Registered
1997 Black Hardtop Supra
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643 Posts
I think you need tune your safc I think.. Sounds like your rich
 

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EFI Certified Tuner
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1,877 Posts
i hope ur crankshaft isn't damaged from a bad clutch install or low oil pressure
 

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Built Auto
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1,167 Posts
Discussion Starter · #16 ·
Okay but the SAFC IS tuned and I see good numbers 99% of the time. I get 260-280 miles on a tank of gas normally with 525s.

The car is an auto and I've never ever seen the low oil pressure light come on.

Damn this is so frustrating, I dont even want to drive the car now for fear its going to leave me stranded. Almost to the point I want to sell it...
 
G

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You need to pull a spark plug after it stalls to see if your getting any fuel. Sounds like you have a bad main relay/fuel relay/fuel ecu. Do you hear the pump prime when you go to start it back up?
 

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BoostAddict4Life
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2,012 Posts
check your altenator. when mine went bad it was doing the same thing. also just check for corrosion on the battery lead from the alt.
 
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