Hot start issue- car floods with bigger injectors

coupe9050lx

New Member
Aug 9, 2007
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I have a 93 coupe with a 306 trick flow heads, trick flow stage 1 cam, 30 pound injectors with a pro m, performer intake, 70mm throttle body.. And for some reason this car will start perfect in the morning first thing i can drive it no problem but if shut it of once it has reached running temp it doesnt like to start... i can sometimes get it to start by holding the gas pedal down before i turn the key but i do it wrong thats it, it wont start.. How can i fix this.. i really want to start driving the car but its not reliable.. ive been at this for 2 month now and yesterday when it wouldnt start i unplugged all the injectors and it started up.. these are the things ive done so far.. checked fuel pressure good 35 and it holds pressure when off, changed the relay under the hood for the fuel pump, changed ignition switch, tried 3 comp 2 A9L and 1 A3M same result, does it with 24 and now 30 pound injectors, by the way stock comp no chip. pulled the complete harness out looks brand new the car only has 61000 original miles the one thing i did was convert it from auto to stick, car has mean spark tried with and without msd, tried it and the coil cap and at each plug, put new wires and cap by the way. ive done a whole check list for this car with a volt meter checking voltages everything seems to be fine.. someone please help this is driving me crazy and i really dont want to go carb.:bang:
 
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I would take a hard look at your MAF. Your injectors are too big for that combo, but if you have a properly calibrated/functioning MAF for the injectors it should work good enough. Probe pin d of maf with KOEO and see if it reads voltage. It shouldn't as no air is moving past meter. Another thing to look into is your TFI module on the distributor. They seem to be a heat sensitive part when they are going bad. also check out the cranks but no start checklist sticky @ top of forum.
 
Too much cranking fuel. The puter is still thinking that there are 19# injectors but you're squiring over 50% more fuel (even 24's are occasionally balky, especially if something else is not quite right). When cold the engine can take the extra fuel but it's too much when hot. Flooring the gas pedal while cranking turns off the injectors and helps the issue.

This is generally fixed via a tune or self tuning.
 
i wouldnt mess with a tune seeing how the combo is pretty mild. i woild ditch the 30s and run the factory 19s, 19s would feed that combo with no problem at all.

get a nice C&L or pro-m for 19s and toss it back on there. the car will start better and get some drivabilty back. and gain some power. 30s are way too much fuel.

the factory 19 lb injectors go ALOT farther than people think. they can handle pretty much any basic HCI you can throw at them. if you add boost they wont be enough and will need an FMU or larger injectors with a tune.

i see people get away with putting on 24s with no tune but that isnt that much more fuel to cause severe issues.

putting on 30s or higher with no tune is asking for rich problems with no tune. a tune will be able to set them to run very good with the engine and will drive like stock. but without a tune the "calibrated" maf has to fool the eec by sending less return voltage to make the ECU think there is less air entering the engine and shortens the pulse width of the injector delivering less fuel through the bigger injectors to make the AFR more correct. not to mention that fooling the EEC also affects the load% and causes the EEC to use the incorrect spark advance curves.
 
One more thing to check is the ECT calibration when the car is hot. If it's telling the puter that your engine is cold, you'll really have too much fuel. Remember, just because you dont see an ECT code doesnt mean the sensor is calibrated.

Good luck.