I could use some help on my pickup, which is a 94 v6 5sp 4x4. I have two dead cylinders #4 and 6, but they have 175 psi of compression, I just finished rebuilding the motor. I have spark going to each cylinder and I swapped fuel injectors around to see if the dead cylinders would move with the injectors and they didn't. I also checked the connections for the injectors and they seem to be fine as well. Also changed the spark plugs and still no change. I'm really stumped and not sure where to look next any advice would be greatly appreciated!

 

What is code 71?
Timing set correctly?
Any bent valves?

 

Code 71 is related to the EGR system I'm not sure what all that involves. The timing is on the best I can tell and the heads where all redone when the motor was rebuilt so the valves should be fine. The motor has only 230 miles since the rebuild and I haven't been able to get it running right since I got it back in.

 

How did you find out two cylinders are 'dead'. if you have spark going, and you said you swapped injectors around, and you have compression... that's a working cylinder. So, why do you think they are dead?

 

That's what's got me so puzzled. The way I found the cylinders was a pulled the spark plug wires one at a time and the engine didn't lose any rpm. Also the plugs on those two cylinders were very black when compared to the others which were a nice tan color like they should be.

 

That means your not getting spark to that cylinder.

 

Assuming your swapping the injectors would prove no issues with the injectors, compression and presence of spark... it's most likely your timing. You could be a 180deg off on the distributor install, or much deeper problems with cam positions. Start with the easier to check items, make sure your distributor is not 180 deg off (or any other amount of course, 180 is common) then check your distributor's pickup coils for resistance. Use the FSM here http://personal.utulsa.edu/~nathan-buchanan/93fsm/ or you can search the forums, lots of info on how to do that. and go from there.

 

Thanks I'll try that!

 

Based on information provided. X2 on camshaft/distributor timing and position.

Rotate the engine to true TDC #1 Compression a verify timing.

 

I'm going to check the distributor timing this weekend. I'll let y'all know the results. Thanks for the help!!

 

as someone else mentioned code 71 should be egr.

1) bad egr valve (test per fsm)
2) bad vsv valve (test per fsm)
3) vacuum lines to egr clogged, or leaking vacuum
4) bad temp sensor in egr (test per fsm)
5) egr vacuum modulater bad (test per fsm)

http://personal.utulsa.edu/~nathan-b...77exhaustg.pdf