One step closer to a carb!!!!
 

i posted about 2 weeks ago about a stumbling bogging prob, my car was running super rich and wouldnt hardly idle. every time i would start it, it would die in 2 sec unless i gave it gas. well. last friday i replaced the o2 sensor and it changed the prob 100%. yesterday i get in my car and start it and it dies in like 2 seconds just like before the o2 sensor. get to my buddies, and hang out for awhile, and get ready to go home and BAM it does the exact same thing before i changed the 02 sensor, bucks stumbles and wont idle worth a crap. what would cause an o2 sensor to go bad? thats what i am assuming is happening. something is messing up the o2 sensor and thats what really needs to be addressed. fp is fine, but i do drop to zero when the car is shut off. and the pump only primes the rails half ***. but the fp is perfect while running and under load. i am seriously thinking about throwing a carb on my car and not looking back. please help:(

Is the wire (or wires) to the O2 sensor touching the exhaust manifold or Y-Pipe? It could maybe be melting against it. Also, I'm not sure if there is an O2 sensor relay, that may only be for the heated oxygen sensors which I don't think (could be wrong) your car has.

the wire is in good shape and mine is not a heated o2. i just drove it around and it didnt act up one bit. wtf:confused:

Sounds like the injectors are leaking.

The ECM could care-a-less what the O2 sensor is doing until the eng warms up and the ECM enters closed-loop mode.

i hope they arent leaking:( they were sent off to rich at cruzin performance 23k miles ago... of course that was 5 years ago, so leaky injectors may be a possibilty. whats the best way to test em?

Not sure if there's an easy way to test them for leakage on the car. You mentioned the fuel press dropped to zero pretty quickly after shutdown. That fuel is going somewhere.

It has to be doing one of the following things:

1. leaking past the injectors

2. leaking back through the fuel pump past the checkvalve (never actually seen that happen, but I guess it's possible)

3. leaking past the regulator and back to the tank.

(It also could be leaking externally, but you probably would have noticed that. :) )

I've heard of clamping the return fuel line with smooth jawed vise-grips (where it is rubber) to check if the regulator is leaking internally.

A bad coolant temp sensor can make it run rich also, but that should have sent a code.

i pulled the vacuum off the regulater and it had plenty of vacuum and no fuel was present. this thing is driving me crazy man. when i cut the key on the rails only prime to like 15psi, and when i let it set 15 more seconds and try again it goes to around 30.

convince me not to sell this trash port injection and throw a carb on:(

sometimes when i cut the key on to prime the rail i can hear a wire shorting out somewhere on the driver side fuel rail. i cant find it yet, but would a injector shorting/gronding out cause it to stick wide open? that would explain the o2 going bad because of raw fuel getting near it. also that would explain the immediate drop to zero in fp when the pump quits priming or i shut the motor off after letting it run. tomm i am going to pinch off the return line and see if in fact an injecter is sticking open letting fuel get through. btw wich one is the return line? thanks

It seems like I did read somewhere that the ecm does provides a ground to open the injectors.

Try unplugging the injectors and letting the fuel pump run for a bit.
See if the fuel press drops quickly after pump stops.

is there anyway to check for shorts in the wires that run to each injector? also, what should be the correct resistance on the injectors? and this is measured in ohms right? thanks for all the help man!! im still kinda leaning towards a carb though, especially if there are shorts in my injectors wiring harness.:(

On a tpi system, all 4 injectors on each side fire at the same time. If you can feel all 4 of them all chattering at the same time with eng off and key on, there's definately either wiring problems or ECM is no good.
If you can catch the injectors chattering, start wiggling wires to see if you can make them stop.

My 24 lb/hr injectors all measure exactly 12 ohms.
I imagine your injs should read somewhere between 12 and 16 ohms.

didnt get time to check it today, been swamped at work. i will shoot for tommorow and give you some feedback. btw how would carb be for a stock L98? i am not interested in gas milage, but reliability is a concern since this is my daily driver (7 miles a day) to work and back. thanks man:D

You'll lose some bottom end and mid range torque with a carb.

Depending on your area, you may have problems with emissions testing.

You can gain some top end to make up for the decrease in mid-range by replacing the cam.

For any serious increases in top end power, the heads will need to be modified or replaced. The exhaust will need attention too.

Unless you want to do a lot of drag racing, I'd just stick with the TPI if I were you.

my buddy said i can take a spray bottle and spray the wires and if they are shorted he said it will light up like christmas since moisture will make them ground. is this ok to try an find the short i hear?:confused:

i say carb it!

your about the only one besides me that thinks that...lol
i am just getting so tired of this tpi stuff, its hard to work on and even harder to trouble shoot!! i dont know what to do:confused:

:hail: carbs

The spray bottle trick works on spark plug wires, not regular electrical wiring.

I suspect that you're hearing the injectors. They normally have a ticking sound. That's why I asked you if you could hear/feel them chicking with key-on, eng-off.

i can hear the inj ticking, but what i hear is a short somewhere. when i first turn the key on or when i shut it off sometimes. doesnt do it all the time. put a new o2 sensor in again today, and it runs alot better like it did before. im still stumped:confused: