What do tuner shops actually do ????

[stuntinoutlaw]

ok so i was going to take my car (newly powered sr20det s14 on s14) to a shop to get tuned and i was told it wil run me from $280 to $500....what is it that they do for those $280 - $500 ??? cant i just take my money and replace some parts that i think is making my car run rich and maybe firing off 3 cyclinders??? like O2 sensor or new injectors or spark plugs and coil packs ??? my question is what do they do ???

[Ligouri Rd]

What you are paying for is the dyno and the technicians time. Dyno time alone is $250/hr. What they will probably do is put the car on the dyno with a wideband o2 sensor in the exhaust and watch your air-fuel ratios through the rpm range. If the car is missing (running on less than all cylinders) they will prolly try to diagnose the ignition system first: plugs, wires, coils, etc. Otherwise it could be a clogged or leaky injector, you can diagnose that by individually pulling the injector leads the one that doesn't cause the motor to change rpm at idle is the problem injector.

You could do buy yourself a wideband to verify that you are actually running rich . It is just basic process of elimination to figure out what is wrong. Try sheet until you fix the problem.