Changed Parts. Still Misfiring!! Help Please!

YakAttack · February 2, 2019

14 minutes ago, mjm-1957 said:

Did you check the injector connector with a noid light? The connector has 12 volts on one leg and the ecm grounds the other to fire the injector. The noid light plugs into where the injector would go and shows if the ECM is providing power and ground.

No just a regular tester light. Don’t have means to a noid light. So I assume a trip to the dealer would be the next trip before a tear down.

tbarn · February 2, 2019

Pull the valve cover. Connect what is necessary to run. Start the engine and slowly loosen the rockers on the bad cylinder. If the misfire goes away you have a lifter that is stuck in the "up" position. Only ever saw it once but was a bitch to find that first time. Noid lights are cheap on Ebay or Harbor freight.

riverbanks · February 2, 2019

110? compression,not good, carbon on valve seat?rings?and you just mentioned 300 code,so more to it,you wount get a 300 from 1 cylinder,it's "random",all over

YakAttack · February 2, 2019

37 minutes ago, tbarn said:

Pull the valve cover. Connect what is necessary to run. Start the engine and slowly loosen the rockers on the bad cylinder. If the misfire goes away you have a lifter that is stuck in the "up" position. Only ever saw it once but was a bitch to find that first time. Noid lights are cheap on Ebay or Harbor freight.

“Well it can't be stuck because when we rolled the engine over both rockers are rocking meaning the lifters are not stuck. If a rocker would be stuck all the way up then your push rod would be loose and probably fall out of place.”

Thats is what I got back from the person I had checking it.

YakAttack · February 2, 2019

1 hour ago, riverbanks said:

110? compression,not good, carbon on valve seat?rings?and you just mentioned 300 code,so more to it,you wount get a 300 from 1 cylinder,it's "random",all over

When he hooked up the compression gauge we only took out cylinder 5 plug. I just turned the key without engine starting. Just sorta clicked the ignition. Was that correct?

About the 300 code yes I did know it was random. Misfires sure throw the computer out of wack. I’m not sure what to do next. Had no visible play in the rockers when taking off valve cover. Could a collapsed lifter be possible with rockers operating as normal. Of course only pulled the valve cover on side of cylinder 5 where the code read.

riverbanks · February 2, 2019

If the motor was spinning shortly before,yes, proper test, two ways,dry,and wet,dry meaning sitting,so you said multiple scanners,what's the misfire count at? All one side or everywhere? problem you have is random"multiple misfire"so it's all ready been compensating,now the weak link shows up, compression test on all cylinders,fuel pressure test

O_J_Simpson · February 2, 2019

Take all the plugs out to rule out cross cylinder communication.

newdude · February 2, 2019

Cylinder 5 is NOT an AFM cylinder. Cylinders 1, 4, 6 and 7. A collapsed AFM lifter can be ruled right out for cylinder 5.

If its a mechanically caused missfire, it could be a bad cam lobe or bent pushrod. We've had a couple AFM and non AFM engines with bad lobes before on both AFM and non AFM cylinders.

Also, as some have mentioned, intake gasket leak.

As for checking cylinder 5 mechanically, you could pull the cover, pull all the rockers and the rocker support, and check the pushrods on that cylinder.

How did the spark plug look that you pulled out on that cylinder (the one pulled before installing the new one)?

Edited February 2, 2019 by newdude

YakAttack · February 2, 2019

4 minutes ago, newdude said:

Cylinder 5 is NOT an AFM cylinder. Cylinders 1, 4, 6 and 7. A collapsed AFM lifter can be ruled right out for cylinder 5.

If its a mechanically caused missfire, it could be a bad cam lobe or bent pushrod. We've had a couple AFM and non AFM engines with bad lobes before on both AFM and non AFM cylinders.

Also, as some have mentioned, intake gasket leak.

As for checking cylinder 5 mechanically, you could pull the cover, pull all the rockers and the rocker support, and check the pushrods on that cylinder.

How did the spark plug look that you pulled out on that cylinder (the one pulled before installing the new one)?

The spark plug didn’t look bad at all. The code that keeps showing on all 3 test are p0305 & p0300. Meaning misfire cylinder 5 and random misfire as you said. We didn’t check the pushrods. He just checked that when turning the engine that they were operating normally and when we stopped it he said he had it to where the cam lobes were sitting flat then pushed on the rockers and none could be pushed in

this is what he sent me when mentioning collapsed lifter.

Well it can't be stuck because when we rolled the engine over both rockers are rocking meaning the lifters are not stuck. If a rocker would be stuck all the way up then your push rod would be loose and probably fall out of place.

tbarn · February 2, 2019

Wow. I give up.

YakAttack · February 2, 2019

10 minutes ago, tbarn said:

Wow. I give up.

Sorry man.

For one I don’t understand how when I pull all connectors off they all seem to make a change in the engine except for the one on cylinder 5 but it has current going to it.

Secondly. If Cylinder 5 is the one getting the misfire to it. Would a lifter cause a misfire?

Third. When we did pull the valve cover off on the side of cylinder 1, 3, 5, & 7 and he checked the rocker arm position. Since 5 isn’t an AFM lifter would it be stuck in a position that would cause it to seem locked since is inoperable while idling?

newdude · February 2, 2019

34 minutes ago, YakAttack said:

Sorry man.

For one I don’t understand how when I pull all connectors off they all seem to make a change in the engine except for the one on cylinder 5 but it has current going to it.

Secondly. If Cylinder 5 is the one getting the misfire to it. Would a lifter cause a misfire?

Third. When we did pull the valve cover off on the side of cylinder 1, 3, 5, & 7 and he checked the rocker arm position. Since 5 isn’t an AFM lifter would it be stuck in a position that would cause it to seem locked since is inoperable while idling?

A non AFM lifter could cause a misfire, but if it is, I'd be checking the camshaft lobe for pitting and wear. If the lifter spins the bore at all, it would eat into the lobe. Is there any metallic squeak noises when its running at any RPM range? Something that would follow the speed of the engine?

Edited February 2, 2019 by newdude

YakAttack · February 2, 2019

53 minutes ago, newdude said:

A non AFM lifter could cause a misfire, but if it is, I'd be checking the camshaft lobe for pitting and wear. If the lifter spins the bore at all, it would eat into the lobe. Is there any metallic squeak noises when its running at any RPM range? Something that would follow the speed of the engine?

It’s more of a slight tick. Not really a squeak. We haven’t tore into anything more than taking off just one valve cover. It’s my every day driver to work so was scared to tear too far into it if I don’t have the parts ready to fix it before the week day. Any suggestions. I’ve still yet to bring it to the dealer and let them put on a diagnostic machine. Only used the hand helds.