View Full Version : Hesitant motor fuel, spark or air issue ?

06-13-2015, 03:49 AM
Sup guys just finished my swap but im having some issues, im not sure if its fuel, spark or air related.

Gen 2 93 usdm sw motor

Symptoms: revs hella slow. advancing timming and opening up throttle doesnt do much for the rev. also doesnt increase idle.

idle isnt too rough, and no air leaks seam to be present.

also i noticed that after turning off the motor today, i attempted to turn it on once more and it wouldnt even crank, so i tried like 15 min later and it did turn on.

having idle screw fully open or closed doesnt change the behavior
but the screw on my AFM is the only thing that makes a diff on it. having it all the way closed makes it run better but thats set all the way on rich.

i am new to turbo engines so diagnosing a problem is a bit different.

running no T-vis and still on my 5s stock fuel pump. also gas is from nov and yes its 91 oct. but againg im not sure if old gas can be a cause of it

06-16-2015, 05:50 AM
Well, running a 5s pump on a boosted application sure isn't going to help.

Honestly, if it were me, I'd pick one type of problem and attack that first and see if it helps. If not, move onto the next.

Any funny colors on the spark plugs?

06-16-2015, 05:59 AM
Yeah that fuel pump is gonna be changed out once i get some money to buy a turbo fuel pump, kinda narrowed it down to fuel, fuel because i think two of my injectors are probably clogged, havent had time to swap them out with another set i have. I have a misfire on the cylinders closest to the front of the motor

06-16-2015, 09:37 PM
Sounds reasonable. Keep us posted.

06-16-2015, 10:52 PM
It isnt the fuel pump. You wouldnt even tax a 5S fuel pump until balls deep into boost.

When you say youre not running TVIS what does that mean? You didnt install it? or you installed it and didnt connect it?

06-16-2015, 11:10 PM
My tvis is gutted

06-17-2015, 04:47 AM
Well i swapped out the other injectors and two are giving me problems again im gonna witch the good injectors from the other rail and see what happens. Spark plugs are dry dry dont even smell like gas, thats for the cylinders that have that miss fire

06-17-2015, 06:01 AM
Check the injector connectors for a signal using a noid light.

06-17-2015, 06:18 AM
Noid light is something i dont have

06-17-2015, 10:54 PM
You can build one. It is a very simple circuit.

Here is the first example/walkthrough I found on Google.

06-17-2015, 10:56 PM
Also, if your injectors are completely dry, jumper B+ and FP on the diagnostic port and ensure that you hear the fuel pump running.

Like Luni said, a 5S pump won't run out of steam until you get into mid-high boost so for the purposes of getting everything checked and verified, it doesn't matter.

06-17-2015, 11:46 PM
Thanks for the link ill make im sure i have the stuff laying around to make one

06-24-2015, 12:59 AM
Well i made my own had to improvise since i didnt have the right plug and yeah the buld would not light up. The bulb is in working order. Assuming that the bulb should turn on if the plug had current right ? Now where could the issue be in my wiring?

I dont think i got inj.1 and inj.3 mixed up. All plugs ground to the ecu and then go to the resistor pack. Then the O/B cable goes to the resistor pack. Since two injectors work it wouldn't be the resistor pack right.

07-01-2015, 04:07 AM
Well i swapped out the injectors with the other pair that worked before and that did the job jaja
Test drove it and fuel delivery is certainly an issue after 3k

07-01-2015, 04:07 AM
But i can atleast say my swap is finished so id say about a year that it took me to so my first swap

07-03-2015, 11:25 PM
Glad you made some progress on it man. I think there are threads around here about the fuel starvation issues over 3k. Tim may know as I think he dealt with it too.

07-04-2015, 12:47 AM
Feels nice to have accomplished it. It took me about 1 year and 2 months sounds like a decent time for my first swap. Ill try to find the threads. I need a diff fp for sure