2002 4 dr 4x4 150k.... making me very very mad
 

Hey guys been a while...... Here's my prob I'll try to be short n sweet lol ........ Light throttle its got a very pronounced miss. After doing some digging under the hood I found I had no choice but to replace the lower intake gaskets for the 2nd damn time. I've done more than I can count so I can knock em out pretty quick. So I went ahead got new cap rotor plugs wires get fresh oil in it fire her up and its still doing the same thing ..... Hook my nemisys scan tool to it to watch the cylinders as and I get a miss on 3 and 5 luckily I recorded the data from before to compare miss was there w the old intake and alot worse but its still there .... The trucks throwing an engine light but nothing to do with a miss. I just put a tps in a while back and still get the low voltage code. Watching live data everything is spot on except that stupid miss I'm thinking its gotta be the actual distributor ..... That's the only thing I haven't replaced ...why ? I have no excuse lol .... But before I spend the money what am not seeing here? ThAnks n advance

whats the fuel pressure?

Check the distributor shaft play. Only had 93k on my '02 Blazer and had to replace the distributor due to shaft bushing wear. Good thing is that all aluminum housing distributors are only $50 or so and are easy to replace. If you do replace the distributor, will need to check the Cam Retard value; requires a better scan tool than what you have. Value must be between ±2°.

I've done everything on this truck .. I mean everything ......pump is new. Pressure is spot on at 60 and holds......... I'm going to put my meter on the tps and see for myself what its doing just to make sure my scan tool isn't lying lol

Are you using AC Delco plugs # 41-993 with a gap of .060"?

Are you using an AC Delco cap and rotor?

What DTC's are in memory?

A common mistake is incorrect wiring of the distributor cap. Make sure the cap is wired correctly, (notice cyls 1 & 3):

Attachment 31545

Next is fuel pressure: Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off. Your reading of 60psi is at the bottom of the allowable range, which means volume is also near the bottom of the allowable range. Check pressure and leakdown and post the results.

If you still have the original poppet style fuel injectors, they are known to fail. You can do a injector pressure check using a scan tool like a snap on bidirectional scanner. If you know your cap, rotor , crank sensor, tps and plugs are good, testing injectors and fuel pressure would be my next check. Its cheap to replace poppet injectors, but I like the upgraded injector kit from AC Delco or denso. Those cost 200 to 240 tho. My 02 zr2 had specific misses on 3 different cylinders, it checked out to be the injectors. + Hope this helps.