Changed EVERYTHING, Still misfiring.... 97K1500-5.7vortec (stock)

[Stepside_fever95]

http://www.gmt400.com/index.php?threads/6884/

 

[Archer-97k1500]

Before you spend any more money, id check to see if your distributor is off by one cog. Its easy to do, and was my problem when i changed my intake manifold gasket. Theres a thread somewhere on properly setting the vortec distributor.

Thanks for the reply. The distrubutor has never been touched on either the old or the new motor. Also if it was out a tooth the pcm would throw a cam correlation code. These are very sensetive to timing changes.

 

[Archer-97k1500]

Be very careful of the big plug with a million wires going into the top of the spider injector assembly. Go over all the little connections with a fine tooth comb. I had a problem with it once after an engine swap. Took me awhile to figure out what the problem was.

This started right after the transmission was swapped in? Really sounds plausible that a plug or wire got pinched somewhere by accident.

I am assuming of course you used the same wiring harness from your truck after the motor swap.

Yeah it seems more and more like i pinched something sometime. Im in the middle of checking the wiring harness. I checked the spider inj plug. Its good. Thx for the suggestions

 

[Rusty Nail]

What happens if you remove the SES bulb, does it still "misfire"?

 

[magimerlin]

Im thinking the same thing.. only problem is ill have to goto the dealer. Ive tried those bluetooth dongle to ur phone apps but i dont think its good enough...

Check with the smaller shops first... most of the shop scanners can check each cylinder for misfires... unless they only bought the cheap consumer ones that is.

Odd question but....have you looked at your gas cap? reason I ask is i have seen the light blink when people have brought their trucks to my shop and it turned out it was from a loose or bad gas cap....lol... just a thought...

sent from what use to be a great country...

 

[slowburb]

It's definitely odd to see this from both engines. What parts went from old engine to new engine? When the MIL flashes, there are "P" codes stored in the computer. Without exception. Too bad you can't compare codes engine to engine. It might help with diagnosing the cause(s).

At least take it to the parts house next time the MIL is on so they can tell you which codes are stored. With a proper scanner, you can sit and watch misfires at idle in real time. The computer counts them.

When you replaced the fuel pump was there all kinds of trash in the tank? Did you replace the sock? What kind of replacement spider did you install...poppet or electronic?

 

[Supercharged111]

What's your cmpret value? Regardless of if you'VE not messed with the distributor, it may still be off and could be due to a worn distributor gear.

 

[Archer-97k1500]

Check with the smaller shops first... most of the shop scanners can check each cylinder for misfires... unless they only bought the cheap consumer ones that is.

Odd question but....have you looked at your gas cap? reason I ask is i have seen the light blink when people have brought their trucks to my shop and it turned out it was from a loose or bad gas cap....lol... just a thought...

sent from what use to be a great country...

Not a gas cap in this case. Replaced the entire fuel system from tabk pickup to injector. Thx for the reply

 

[Archer-97k1500]

What's your cmpret value? Regardless of if you'VE not messed with the distributor, it may still be off and could be due to a worn distributor gear.

This engine ran perfect before it was installed into my truck. Thats why i know its not that. If anything it could be the wiring to the dist. Im in the process of checking wiring

 

[Archer-97k1500]

It's definitely odd to see this from both engines. What parts went from old engine to new engine? When the MIL flashes, there are "P" codes stored in the computer. Without exception. Too bad you can't compare codes engine to engine. It might help with diagnosing the cause(s).

At least take it to the parts house next time the MIL is on so they can tell you which codes are stored. With a proper scanner, you can sit and watch misfires at idle in real time. The computer counts them.

When you replaced the fuel pump was there all kinds of trash in the tank? Did you replace the sock? What kind of replacement spider did you install...poppet or electronic?

New sock on the fuel pump. The injectors were wired. But that injector set is still in the old motor.