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No fire on #3 cyl, injector problems??

G

gplostinnd

New member
Car Fixed!! WOOT! No fire on #3 cyl, injector problems??

Wow, I don't know if this was the only problem or not but.......it was an f'in rocker bolt. I pulled the front valvecover tonight and one of the rockers on the #3 cyl was off center by about 3/16"..hmmm...the rocker was completely loose[:o]. So, I took the bolt off and examined the rocker and pushrod and they looked fine. I cleaned out the hole with q-tips and put threadlocker on the bolt and put her back in. I checked the rest and they were fine. I put everything back together and voila! I guess I should have checked it earlier but hindsight is 20/20 I guess[&o]. If nothing else this post will give someone who is having problems a good list of what to check (if they know how to search). I want to thank everyone for their help, especially biggie for standing over the car going WTF? with me the last week.
Now I need to work on the damn GTO grilles.
Thanks again,
Matt


***Update 1/8***
Well, on a hint from dubob I unplugged the ICM and took out the fuel pump fuse and cranked the motor. When cranking I could hear a noticeable miss/drop in the cranking every rotation. So I plugged the fuel injector fuse back in and cranked it again with the ICM unplugged so I could see if there was fuel on the end of the injector, it still had the miss or drop too. Upon unbolting the fuel rail it looked like there was fuel on each injector. So I cranked the motor with the fuel rail pulled up a couple inches to see if fuel was coming out and the miss every rotation or so was really evident, I put my finger over the injector holes in the head and I could feel pulses of air coming out when the cranking dropped. The pulses felt strongest on the #3 cyl but I could feel them on the other front cyls. This makes me think there could be a loose rocker or somthing not seated right or maybe a bent pushrod. I will take the valve cover off tomorrow and report back. Does this sound possible?

Thanks again!


Update 1/6, compression was good in cyl 3 at 150 psi and the injector wire has continuity.



Well, I decided to make a new post about my mis/no fire problems. Long story short I installed a VS cam, the car was running perfect then it started misfiring. It was running rough and died and wouldn't start again for a couple days. We got it started finally and now it doesn't fire at all on cylinder #3. Here is a list of what has been checked...
Swapped ICM
Swapped Coils
Swapped Wires
Swapped Injector
Swapped PCM
Changed CPS sensor and went over wiring
Spark plug was pulled out and sparks
Changed spark plugs a couple times
tried unplugging MAF sensor
Only codes are misfire and egr codes
I took a test light to the electrical clip that connects to the injector and it is receiving power(I just used a test light).
Checked ALL fuses
Everything else works fine, it will run but obviously not very well without the #3 cyl.
Car ran perfect after the install. We took it on a short 15 minute drive and it ran fine, I got into the throttle once to about 50-75 percent and ran fine, then we drove down the highway a little ways and turned around and then it started misfiring so I took it home and it hasn't ran right since.

After getting the car to run yesterday I pulled the #3 plug immediately and it looked clean but there wasn't any fuel on it. I would think that after running for about 5 minutes and not firing once that the plug would have fuel on it but it didn't. The oil still looks brand new and doesn't smell like fuel or coolant.

Could this be a valve problem or is this wiring related? I plan on doing a compression test tomorrow and possibly swapping another injector in.

Thanks for all the help,
Matt

old thread...

ClubGP Message Forum troubleshooting
 
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i would think injector from what you said about no fuel but i am no expert . pull the injector and see if you can see anything inside of it or swap it out with the injector next to it and see if the other cylinder starts to misfire . like i said though i am no expert just what i would try .
 
Here's something to try.......crank the motor without fuel and spark (unplug the injector fuse and unplug the ICM). Listen to see if it cranks "smoothly". If you hear a pulsing or un-even cranking, then you may have a valvetrain issue, like a bad lifter, an issue with the valve springs on that cylinder, or a bent pushrod. The fact that it's cylinder 3, you should be able to see what's going on with those rockers through the oil fill hole on the valve cover.

The fact that you don't have any fuel on your plug leads me to think that there's something wrong with the injector/wiring though......but the above may help rule out valvetrain.
 
Reading over everything you did, the last thing I would suspect would be bad wiring to the injector, like Dave suggested. I know you said it is getting power, but I would check over the wiring real well.
 
do you have a injector wiring code? I can't remember exactly if its a P0203 for cyl. 3. I had this problem on a venture van, I ended up running a new wire from the pcm straight to the injector that was having problems on that van and it fixed it. As I said though it had a code saying injector fault #2 or 3 I don't remember now.


My other thoughts that I hope are not the case is that cyl#3 is the popular to chip a piston, but alot of times the plug will be smashed with that.
 
I did a compression check today and cyl 3 had 150psi, and I checked continuity on the injector wire and it was good. Any other ideas guys?
Thanks again,
 


Yeah I actually swapped it with another injector from biggie's car, I might just swap another one in. I would find it hard to believe that we had 2 bum injectors between our cars.
 
hmm...


a wild idea, perhaps -- disconnect the ICM (or the plug wires, either way) so you dont have spark (dont want to try and start the motor at this point) instead of swapping injectors, swap two of the injector connectors on the harness. turn the motor over a bit, enough to push fuel thru the injectors. (if you push too much, you'll flood the motor, will be harder to start later) then check the injector in question and see if it is wet from fuel (or plug, i suppose) if you have fuel in the problem cylinder, then you've narrowed the issue down further to the wiring to that particular injector.
 
I have a set of Noid lights for Ford, GM and Dodge and I can tell you they are invaluable tools in troubleshooting something like this.
 


it's possible that it's one of those. i'd suspect, that if the rocker bolt was loose, you'd have heard a racket while stepping on the gas.

i had a collapsed lifter and bent pushrod on cyl 3 last year on my gtp, and it was misfiring, etc.... but it was a pretty easy diagnosis after i found it was cylinder 3 and it had fuel and spark there. --- while idling, i could look in the oil filler hole and see that the rocker wasnt moving!
 
it did make a tapping sound for a little while before it stopped. The rocker was moving when we looked at it a while ago too.
Thanks for the help.
 
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