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Discussion Starter · #1 ·
Here's the scenario:
7MGTE Turbo Swap in a 1993 Mark II L-Model. Motor and car extremely well maintained.
Has developed a stalling problem:
Come up to a stop, put in clutch, rpm drops down below normal; go the next stop, rpm drops down to normal idle.
Rev the engine up to about 5,500 rpm, quicly let of pedal; rpm drops now below normal and motor will usually stall.
Very bad backfiring in between shifts.
Motor seems "dead" with foot just on top of the gas pedal
Acceleration not smooth.
Here's what we have tried:
Vacuum Leaks: No
Blow Off Valve Stuck: No
Blowing into the atmosphere: No
Throttle Body Cleaned out: Yes
Replaced Idle Speed Control: Yes, new
Tested Throttle Positon Sensor: Yes
Air Flow Meter: currently a used air flow meter; have tried putting in two other air flow meters (used), but problem persists.
Fuel Pump: A stock 5M Fuel Pump with 161,000 miles
Where do we go from here, fellows? All comments greatly appreciated.
Spoker Derek (Supra Derek)
Oakland, California
 

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The most common reason for stalling is the intake is open somewhere. If you haven't found any leaks, check again and one more time after that just to be sure. 7M's are picky bastards when it comes to that. Using MKIII IC pipes? the fender pipe likes to separate and cause leaks.

Your symptoms scream air leak somewhere.
 

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while I still think it's in the IC pipes. The below is the next thing I would be all about.

Fuel Pump: A stock 5M Fuel Pump with 161,000 miles <--- this needs to be addressed ASAP.

What's your fuel pressures running?

Get a MKIV or at least a Walbro 255 pump.
 

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Check inside the Cam Position Sensor... You're looking for:

Cracked/Heat Hardened and split insulation on the wires for the pickup induction coils
Oil Inside the Cam Position Sensor

Not really what I'm thinking is the problem, because if it were this it would present itself as breakup under higher boost/rpm's when the oil & cracked wires would create a poor input signal for the coils.
 

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I recommend you fit a new fuel pump,Walbro 255 is a better suited pump. If you leave the stock one on and fix the problem it could well lean out on you. It also might be that the pump is stuffed and not giving enough fuel pressure. JUST BECAUSE IT'S PUMPING FUEL DOESN'T MEAN IT'S OK. YOU CAN REV IT OUT WITHOUT LOAD ON THE ENGINE, APPLY LOAD AND IT DIES. A LACK OF PRESSURE WILL CAUSE INJECTORS TO NOT SPAY FUEL CORRECTLY,THEREFORE BUGGER ALL POWER UNDER LOAD. I'VE HAD A PUMP SHIT ITSELF BEFORE! :duh::32:
 

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If it's your CPS, it will cause the engine fire at the wrong time which will try to force the piston back down on the upstroke. You will probably feel it during starting, but I would thoroughly check for vacuum leaks by buying some PVC fittings, capping both ends at the TB and turbo inlet and pressurizing to about 20 psi. If you are backfiring badly, you are probably running rich, which will also occur with a vacuum leak. As far as the fuel pump, if it worked properly before the swap, it should be good for normal driving, but I would change it out before boosting heavily.
 
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