5.7 Vortec missfire issues

[CreekSquad8485]

Is the scan tool a dealer specific thing? My regular shop told me I have to take my 98 5.7l vortec Z71 4x4 to a dealer to get the P1345 code fixed. This is the first fuel injection truck I've ever owned. Im out of ideas on how to fix it. I had to replace the intake gasket and I put it back on TDC on the compression stroke and it is throwing the code. Im so frustrated. And every dealer I've called said that they can't do it. Any help is greatly appreciated thanks

 

[SUBURBAN5]

Is the scan tool a dealer specific thing? My regular shop told me I have to take my 98 5.7l vortec Z71 4x4 to a dealer to get the P1345 code fixed. This is the first fuel injection truck I've ever owned. Im out of ideas on how to fix it. I had to replace the intake gasket and I put it back on TDC on the compression stroke and it is throwing the code. Im so frustrated. And every dealer I've called said that they can't do it. Any help is greatly appreciated thanks

Dealer must have a policy for not working on anything older then 10yrs.... that's bull. Yes you should be able to get it done with a fancy scanner. Its obd2 for crying outloud and a gas 350. Parts dont get any easier then that. If you dont have the obd2 fancy scanner then that's where there's an issue. All you do I believe is commute with the distributor and you turn it by hand which way. Never physically done it myself so I might be wrong with that. All I know is you dont use a timing light.

 

[CreekSquad8485]

Dealer must have a policy for not working on anything older then 10yrs.... that's bull. Yes you should be able to get it done with a fancy scanner. Its obd2 for crying outloud and a gas 350. Parts dont get any easier then that. If you dont have the obd2 fancy scanner then that's where there's an issue. All you do I believe is commute with the distributor and you turn it by hand which way. Never physically done it myself so I might be wrong with that. All I know is you dont use a timing light.

Yea I know that you don't use a timing light lol. It's definitely a load of bull that the dealers won't work on it. My buddy has the obd2 scanner. The only code its throwing is the P1345. He reset it and moved the distributor some but it still throwing up the code. Im just frustrated and have no idea what else to do cause idk anything about fuel injection and the type of distributor it is you can't just do it old school.

 

[SUBURBAN5]

Yea I know that you don't use a timing light lol. It's definitely a load of bull that the dealers won't work on it. My buddy has the obd2 scanner. The only code its throwing is the P1345. He reset it and moved the distributor some but it still throwing up the code. Im just frustrated and have no idea what else to do cause idk anything about fuel injection and the type of distributor it is you can't just do it old school.

I hear you. Gm had to reinvent the wheel. Btw are you using a ac delco one?

 

[CreekSquad8485]

I hear you. Gm had to reinvent the wheel. Btw are you using a ac delco one?

Honestly idk what kind it is. Its what was in the truck when I bought it. My truck was an absolute beast until I had to replace the intake gasket. I've thought about replacing the distributor but it doesn't look like it is bad

 

[SUBURBAN5]

Honestly idk what kind it is. Its what was in the truck when I bought it. My truck was an absolute beast until I had to replace the intake gasket. I've thought about replacing the distributor but it doesn't look like it is bad

Distributors do go bad eventually and most come with the cam position sensor I believe

 

[CreekSquad8485]

Distributors do go bad eventually and most come with the cam position sensor I believe

That's going to be my next step after my buddy from work tries his scanner tomorrow. He has an obd2. He also knows way more about fuel injection than I do lol.

 

[CreekSquad8485]

Distributors do go bad eventually and most come with the cam position sensor I believe

That's going to be my next step after my buddy from work tries his scanner tomorrow. He has an obd2. He also knows way more about fuel injection than I do lol.

 

[SUBURBAN5]

Make sure the plug looks good and the wires aren't shorted or messed up. I would follow it to the harness to make sure it's good and not a bad connection

 

[CKVortec]

Now here's my second question... if you plug in the scanne . Read live data and drive around. Nothing pops up with like cylinder 1/3/2/4. Either like spark jumping or fuel pressure dropping or anything that's stands out... I understand you have great pressure and I also know you've been reading the motor with the scanner. I'm just curious what all live data can show while your driving and see what it shows.. may be small but could be a factor.. btw i dont own a fancy scanner that's why I'm asking. Kind of like this. Say it's a spark or volt tiny difference. At least in norrow to electrical. Say its fuel pressure same thing. I just dont know if a scanner can read fuel pressure on each cylinder. Like I said never had a fancy scanner.. I just feel like something dropping for a few minutes hints the misfire. But going up to speed or idling no misfire detected because of the demand... maybe I'm wrong or you covered it already just trying to think as if it was my truck....

It's been a while since I was able to dig back into this, but here's some information for you about scan tools, on these trucks there is no way to read fuel pressure at all without a manual gauge on the fuel inlet test port. Also, there is no way to read fuel injector voltage without a volt meter and back probing the big connector on top of the intake. You can read the ignition voltage at the computer or voltage signals from many sensors, just not injectors. Without connecting the vehicle to a scope (oscilloscope) you won't be able to "see" anything about the spark at individual cylinders.
I am using a Solus hand held scanner and all of the readings seem good, I'm just not very savvy when it comes to performance diagnostics.
I have no codes and going by the missfire counter on the scanner to determine what cylinders are missing and when along with my "assometer".
What I am seeing is missfires coming from the front half of the engine, mostly from #2 and #3.
Since the front 4 cylinders have longer plug wires I assumed that I was getting a weak spark, but I am running out of things to check/replace.