one way to test injectors

[ejXa q45]

someone once told me, for injector testing, if i rum propane in to a vacuum line the idle will smooth out and the miss will disapear. i went to a firend of mine to fix my car and tride to get it on the computer but i gess that the computer won't pick up injector or a miss in the cylnders because it obd 1 and is not showing a code . so i ran propane thru the brake vacuum line. i didn't work but maybe its not an injector........or maybe he's a retard .i dont know .

[Rex]

Here's the best way to test for a bad injectorhttp://q45.org/ohminjectors.html

A miss/rough idle can also be many other thigns in the fuel system, including the MAF before the fuel system (air intake side). Try wiggling the MAF connector when it's idling and see if it effects the idle at all. BTW, has the MAF ever been cleaned?

[ejXa q45]

i cleaned the maf... but still have a miss. i have also have ohms the injector . this was just another test that i thought was help full.

[Rex]

Have you changed spark plugs? If not, there's a chance leaky valve cover gaskets can allow oil to get on/around the spark plugs causing them to not fire correctly.

May post more detail, inclduing maint history, in the Infiniti Online Mechainc.

[ejXa q45]

i have new plugs and new coils, i think...... the person that put them was not that reliable and i have not checked.

[goody90q45]

Have you changed spark plugs? If not, there's a chance leaky valve cover gaskets can allow oil to get on/around the spark plugs causing them to not fire correctly.

Could also be a leaky injector. I replaced a lower o-ring and it solved my miss, stumble, gas odor and slow throttle response that I'd had since I bought the car.

Is your miss accompanied by the smell of raw gas (that you've determined is not a leaky fuel hose)? Fuel mileage drop recently? Since last May when I bought her, my Q ran great as it warmed up, with a slight smell of gas, but always had a miss at operating temp.

Spark plugs can tell you a lot if you can get your hands on the old set or have the time to remove the installed set (easy job, just takes time and tools). Checking fuel pressure is another way to tell if you have leaky injectors. In my case #8 plug was black and the rest looked normal. Removed #8 injector (glad it wasn't #7) and replaced the o-rings. All is well.

Good luck.

[Q45tech]

another way to tell if you have leaky injectors.

Please use the correct term the injectors usually don't leak! The o rings leak gas/air around the injector!

A misfire is usually caused by excessive lean [no gas, too little gas] in the cylinder. If double/triple the amount of idle fuel is sent to a cylinder some of it will still burn. A leaky injector will quickly instanteous fill the cylinder.......there is no half way here with 35 psi pushing the fuel.

The carbon deposits built up on valve stems can absorb/block/deflect the miniscule amount of gasoline injected at idle.

[goody90q45]

Could also be a leaky injector. I replaced a lower o-ring and it solved my miss, stumble, gas odor and slow throttle response that I'd had since I bought the car.

?

[ejXa q45]

Could also be a leaky injector. I replaced a lower o-ring and it solved my miss, stumble, gas odor and slow throttle response that I'd had since I bought the car.

Is your miss accompanied by the smell of raw gas (that you've determined is not a leaky fuel hose)? .

the car had a strong smell or gas and i fix the hose between fuel rail and one in the back near the acc valve. the Q have no gas smell anymore, but she still have a miss. how bad did your Q miss? mine start to stumble then into a shakes. it feels like a washing machine.

[goody90q45]

...the Q have no gas smell anymore, but she still have a miss. how bad did your Q miss? mine start to stumble then into a shakes. it feels like a washing machine.

Never had the shakes until a couple of weeks ago when the injector lower o-ring gave out, and then the gas smell got real bad at the same time. My symptoms were: after the engine warmed up, a very slight miss at idle accompanied by a minor gas smell when sitting in traffic. Engine idled steady at 650 rpm, accelerated well, and ran smooth at operating speed, but gas mileage was always about 14mpg city. Once the o-ring gave out completely it started hard, shook bad at idle, acceleration was poor, gas smell was nearly overwhelming, and mileage dropped to about 9mpg city. Now that I've fixed the problem (a 50 cent o-ring) all symptoms are gone.

Your car is not a lemon (I looked at your bio) it just needs a lot of attention. Keep reading posts and asking questions and you'll eventually be able to solve all of the problems you're experiencing and have a great car. Good luck finding your gremlin.