89 5.7 one side engine not firing - Third Generation F-Body Message Boards

stalford88 · 02-19-2010, 11:17 PM

i just switched my 5.7 from one trans am to another. now im having a problem the passenger side of the motor is not firing.It has spark from the cap to plug.the fuel injectors are getting voltage.The engine idles fine but just dosent have a lot of power.any suggestions???

C-Titan · 02-19-2010, 11:27 PM

If the engine is running and idling fine, why would you think half of it is mis-firing??? I'm sorry but that makes no sense to me... Check all your vacuum lines and make sure you didn't leave anything disconnected...

stalford88 · 02-19-2010, 11:44 PM

i did notice there wasent hardly any vacum at the pvc valve.but when i take a plug wire off the cap on the passenger side the engine dosent change.but when i take a wire off the drivers side the engine loses power like it should

Rolling Thunder · 02-19-2010, 11:49 PM

Well if you truely have lost your passenger side i suspect a fuel injector issue. If your sure youve got power than you probably have a bad wire back to the ECM or the ECM has failed. Use a noid light to see if the injectors on that side are firing.

stalford88 · 02-20-2010, 12:03 AM

ok ill try that thanks.still up for other suggestions from anybody thanks

stalford88 · 02-20-2010, 12:35 AM

i took my fuel injectors off a 305 would that matter?wouldn't it do it in both sides?

Rolling Thunder · 02-20-2010, 12:37 AM

yea it does kinda matter the 305 injectors are 19 pound and the 350s are 24s i believe although it shouldn't cause this problem no.

stalford88 · 02-20-2010, 12:45 AM

if i fix the problem will it hurt to have the 305 injectors?

Apeiron · 02-20-2010, 12:50 AM

Did you try the noid light yet?

Rolling Thunder · 02-20-2010, 12:52 AM

Well it might be and it might not be. The problem with putting smaller injectors on is even if they max out with 100% duty cycle they may not be able to supply enough fuel. If that will happen i cant say for sure never tried it but it should atleast run well enough for u to decide for yourself how big of a deal it is.

stalford88 · 02-20-2010, 12:57 AM

no i did not try the noid light.i need to buy one ill prolly try 2mrow ill post when i test it

vetteoz · 02-20-2010, 01:02 AM

Quote:

Originally Posted by Rolling Thunder

If your sure youve got power than you probably have a bad wire back to the ECM or the ECM has failed. Use a noid light to see if the injectors on that side are firing.

If a whole bank is down you have lost the injector pulse

stalford88 · 02-20-2010, 01:04 AM

what exctally is injector pulse? i kinda no but im not sure.thanks

Rolling Thunder · 02-20-2010, 01:12 AM

Well the way injectors work is like many electrical things the work when there is a complete circuit from +V to ground. In this case the 12V is supplied to the injectors and to control the injector the ground is switched on and off. This brief period of time when the injector is grounded is considered the "pulse" like a heart beat. The "injector pulse" is in this case would be in reference to the ECMs rapid grounding and un grounding of the injectors ground again like a heart.

Apeiron · 02-20-2010, 01:13 AM

It's the electrical pulse that actually fires the injectors. All the injectors on each side are wired in a chain. If an entire side fails, it's because of a problem in the wiring for that side, or because one of the two injector drivers in the ECM has failed.

Rolling Thunder · 02-20-2010, 01:18 AM

Also seeing as how you just replaced the injectors with used ones did you ever ohm them out? If you had a bad one it could be shorting out the whole bank. Usually there are other symptoms as well but just a thought.

stalford88 · 02-20-2010, 01:21 AM

ok thanks ill let u no how it turns out

stalford88 · 02-20-2010, 01:30 AM

where is the ecm?

Rolling Thunder · 02-20-2010, 01:32 AM

behind the dash on the passenger side. If you remove the plastic interior cover underneath the dash on that side and look up under the dash you wont be able to miss it.

stalford88 · 02-21-2010, 04:33 PM

how do i use the noid light?thanks

bcmag · 02-21-2010, 05:48 PM

plug into injector connect and check for flashing light cranking or running....indicates injector driver/circuit integrity. i agree w/ rolling thunder probably shoted injector winding pulling whole bank down

taman86 · 02-27-2010, 02:40 PM

350's had 22lb injectors.
I had similiar issue.
Turned out to be 3 clogged injectors on passenger side.

You need to verify with noid light, if inj. are getting power.
I got loaner set from Auto Zone.
Pull off Inj wire from Inj. then put Noid light onto wire.
Then start car and see if light flashes a pulse.

C-Titan · 02-28-2010, 05:11 AM

Did you ever change your prom in the ECU when you did the engine swap??? The car would still run if you didnt, just not at its peak...

VincentZ28 · 03-01-2010, 08:39 PM

First thing first. Make sure that all the ground wires are grounded in back of the engine. 3 on passenger side and 2 or 3 on driverside.

A stock L98 has 22lbs injectors.

Why did you change injectors anyway?

Did you swap the 350 into the car that had a 305 in it? If so, the you need to swap the chip.

Question, what years are the cars? 87-88 MAF, 89 MAF with VATS, 90-92 MAP with VATS. swapping ECMs or chips may not work depending on the years.

Black'92 · 11-02-2010, 12:11 AM

I am having this problem with my 92 305, just wondering if you fixed this and what it was?

stealthroc89 · 11-04-2010, 06:42 AM

Try checking the fuses, theres 2 fuses that are in the box. I don't know if each one does a seperate bank or not, try the easy stuff 1st.

Black'92 · 11-04-2010, 11:04 AM

Quote:

Originally Posted by stealthroc89

Try checking the fuses, theres 2 fuses that are in the box. I don't know if each one does a seperate bank or not, try the easy stuff 1st.

Great thanks I will check it out!

stealthroc89 · 11-04-2010, 10:46 PM

I also noticed when I changed the plugs one time that the even bank plugs were black and the odd bank was almost white. I thought they weren't firing, did the usual checks and everything was working right, come to find out there was a piece of rubber blocking the crossover tube, this is on a HSR set-up using braided hose, but its something to check out. I've seen where fuel filters fall apart and clog little holes before so thats something to think about.