How can I tell if my CAS is bad?
How can I tell if my CAS is bad?
Just what it says in the title. I've been having the same problem for a long time and I haven't been driving my car because of it. Pretty much the car idles rough, throwing out a lot of blue/black smoke at idle. When I drive it with new plugs I have no problems until about 5 min go by. Then the car starts to buck and surge around 3500-4000 rpm. If I drive any longer than five minutes the car won't idle and I have to feed it throttle just to keep it running. I'll pull the plugs right after and they smell strongly of fuel and are totally black. When I get on the throttle it feels like fuel cut because at the same rpm everytime the car stops accelerating and I'll back off the throttle and get back on and it runs rough. It's kind of like somone trying to learn to drive stick for the first time is the best way I can think to describe to bucking.I got the idea that it may be the timing by reading this forum. So last night I checked the timing and it was about 1/4" past the farthest right tick on the crank pulley. I have adjusted it this morning to the second mark from the right at idle, and let it idle for about 3 min but it doesn't sound any better and fuel is still pouring out the exhaust. (I'm sure that it is because the fouled plugs are still in there). I'm going to switch the plugs out after I get back from work today and see if this changes anything.I'm running a t28 on an s13 blacktop with a jim wolfe ecu, bkr6e plugs, newer O2 sensor, nismo fpr (didn't adjust it, just installed it), just replaced the fuel pump yesterday. I haven't driven my car for over 6 months because of this problem any help is greatly appreciated!
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rkreimer10
- Posts: 228
- Joined: Sun Aug 21, 2005 10:08 am
- Car: s13 240sx with sr20det
Re: How can I tell if my CAS is bad? (grnsilvia)
you have a fuel issue not a timing issue. sounds like injector/fpr problem. time to start testing.
Pick up a gauge from the local parts store and T it into the line between the fuel filter and the fuel rail and start the car.
You should see 34 psi.
Disconnect the vacuum line going to the fuel pressure regulator and it should jump to 43psi.
Using pinch off pliers clamp the fuel line exiting the regulator, pressure should jump to at least 80 psi, if not then the pump is bad.
Shut the car off.
Pressure should hold at 80 psi, if not the pump or injectors are bad.
If it is dropping pinch off the fuel line between the gauge and fuel line, if it stops, bad pump, if it keeps going leaky injectors. move the clamp to between the gauge and rail to double check, if the gauge is stopped it is leaky injectors, if it drops bad pump.
Take off the pliers, pressure should drop to 43 psi and hold. If it drops lower than 43psi the regulator is bad, as is higher.
To test injector flow...
install the gauge as above
build a harness with battery clamps on one end, install a switch inline with one wire (momentary push button is best) and a resistor(10 ohm or 10 watt from radioshack) for peak & hold injectors, and an injector clip at the other end.
prime the fuel system (shold hit & hold 43 psi)
clip it on to injector 1. hold the button down and count how long to drop to 20 psi. Round it off to an easy number.
Repeat the following for each injector until you get a consistant number for each.
prime the system
Watching a clock hold the button down for the time you figured out earlier, and record the fuel pressure shown after each try.
If one injector is exceptionally high or low it is bad.
Pick up a gauge from the local parts store and T it into the line between the fuel filter and the fuel rail and start the car.
You should see 34 psi.
Disconnect the vacuum line going to the fuel pressure regulator and it should jump to 43psi.
Using pinch off pliers clamp the fuel line exiting the regulator, pressure should jump to at least 80 psi, if not then the pump is bad.
Shut the car off.
Pressure should hold at 80 psi, if not the pump or injectors are bad.
If it is dropping pinch off the fuel line between the gauge and fuel line, if it stops, bad pump, if it keeps going leaky injectors. move the clamp to between the gauge and rail to double check, if the gauge is stopped it is leaky injectors, if it drops bad pump.
Take off the pliers, pressure should drop to 43 psi and hold. If it drops lower than 43psi the regulator is bad, as is higher.
To test injector flow...
install the gauge as above
build a harness with battery clamps on one end, install a switch inline with one wire (momentary push button is best) and a resistor(10 ohm or 10 watt from radioshack) for peak & hold injectors, and an injector clip at the other end.
prime the fuel system (shold hit & hold 43 psi)
clip it on to injector 1. hold the button down and count how long to drop to 20 psi. Round it off to an easy number.
Repeat the following for each injector until you get a consistant number for each.
prime the system
Watching a clock hold the button down for the time you figured out earlier, and record the fuel pressure shown after each try.
If one injector is exceptionally high or low it is bad.
Re: How can I tell if my CAS is bad? (rkreimer10)
Thanks alot. I'll hopefully be able to get all that done this saturday. I'll post up here if that was the problem.