Hi Everyone
I have a 1995 4x4 4.3L Just installed a new engine and installed everything new including Spider injector assembly return lines and fuel pump,.now with just 20 miles on it i have a misfire #4 cylinder, I replaced the cap,rotor plugs and wires two times since and also the coil, reset the check engine light and the same problem is still there at idle. I cant feel it misfiring when driving it only at idle. I have been reading up on all the related threads here about this issue but i'm stumped! Do Ya think i need to break it in some more? or could my issue be with the Distributor? any suggestions would be helpful. Thanks
By the way i now have spent $2400 including the engine lol

 

The very first thing that you are going to have to check is for good spark at the #4 cyl.

If you have a nice bright blue spark there at both idle as well as at a higher RPM then we can move on from there.

 

yes it has spark but i noticed the spark "dances" around

gonna do a compression test on that cylinder and post results..Whats the chances of a reman engine having low compression?I'm hoping slim to none but at least its got a 3year unlimited mile warranty

ok its not a low compression issue 120 psi on all cylinders ..I dont have any computer diagnostic equipment so i guess off to see the man to run a full test tomorrow..what an annoying problem..Is it possible my new spider assembly has a bad poppet for #4?

 

A bad poppet is a possibility. Was it a brand new spider or a reman? You could pop the plenum off, pull the #4 poppet and direct it into a small jar. With the fuel pump on and primed, energize the injector momentarily, watching the spray pattern. Remember though, when you energize the injector, it will be supplying fuel to all 6 poppet nozzles at the same time.

 

I am thinking the spider assy. has an issue also. Looking at my receipts the spider assy. cost me $254. at Advance. Normal price was $296.99 i got a 15% discount lucky me ..one year warranty..I assume it was new but will check for sure.

 

One of the easiest free ways to eliminate the spider as the problem is to swap the legs of the spider around and see if the problem follows the bad leg.

On most of the spider assemblies there is a plate with a single nut that holds the legs in place. Simply remove the nut and swap out your suspect #4 leg with say the #1 leg. Reassemble and clear your codes and see if you now get a cyl #1 misfire instead.

If you do then you have your answer, if you don't then we'll have to keep looking. BTW, for future reference you can purchase just a single leg rather then the entire assembly for most model years.

 

This is on a 95 S10 Blazer 4x4 with the CPI unit and you Cant replace just 1 poppet, you have to replace the whole unit. I haven't been able to get it in a shop to get a full diagnostic check they are busy. Hopefully tomorrow..I personally think its a bad poppet in #4..just to refresh, this happened as soon as the new engine started and was assembled with all new parts.

 

With an old engine, this is a good way to open up a leak in the internal fuel lines where they are pressed over the fittings on the ends. They do not take kindly to being disconnected.

For the CPI motors ONLY, you can try just moving the poppet nozzle from the #4 cylinder to the #2 or #6 cylinder. There should be sufficient length to the line inside to make this possible.

 

Thanks swartlkk I was thinking the same thing. I still want the diagnostics done just to ease my mind tho. if it ends up being the injector unit i will first test it myself just to see. My parts guy has one on the shelf just in case lol . At least the parts are under warranty

 

I finally got in to have computer diagnostics done and was told the spark timing was all over the place and that the timing is off a tooth..Mechanic couldn't get back there to check it because the engine was too hot lol....Ummmm ??? any ways going to take it back early in the morning before they open so its cooled off. will post results as soon as i know.

Its kind of weird tho, Thinking back when i first tried to start it i was off a tooth and it wouldn't even run..Am i retarded or is the engine?