Drfterdan

I actually ended up with an sc300 a fellow member was selling, I am not mad in any way but in the post I found of my car on here he said new distributor, injectors, plugs and rebuilt ecu but anyways I think the person I bought it off of bought it from our fellow member and I’m not sure who did the egr delete but anyway guy said it needed an o2 so I disregarded that took it into my buddy’s shop and reconnected egr and now it has a pretty gnarly misfire in the 6th cylinder from an injector I believe I’ve listened to them and it’s the only one that sounds like it’s not working 100% so my question is how is that possible with “new parts”

KahnBB6

iTrader: (5)

If you listen to the injector #6 with a stethoscope and you hear it firing inconsistently even when the engine is revved then that would be suspect. Also you should want to do a voltage test on your injector wiring at #6 and make sure the terminal ends and wire insulation is not cracked or the copper strands exposed and frayed in any way. Also in *exceptionally* rare cases if the wiring is fully intact but you get inaccurate voltage readings on the positive wire and ground wire then that would suggest you just need to replace the plastic injector connector with a new OEM one.

The EGR port gets its cylinder gasses from cylinder #6 on the 2JZ heads just FYI. So if after reconnecting the EGR you suddenly start getting a misfire condition in cylinder #6 you may want to check that the EGR pipe, EGR valve and "Y" intake manifold EGR passage are all clean. Additionally the EGR vacuum modulator has to be in good working order as does the EGR VSV. If your ECU had begun throwing a CEL code 71 ("EGR malfunction or passage blockage") then that would be a clear sign of where to start.

However... only a few years back I had to do extensive diagnosis of my SC300's 2JZ-GE EGR system while it had a constant CEL code 71 due to a couple of failed parts *and* a blocked passage in my "Y" intake manifold that had to be cleared out and while all that was going on with clogged EGR passages I did NOT experience a misfire condition.

I DID have a misfire on one cylinder just after I swapped in my current GTE engine and found out the hard way that the wiring on the offending injector was in need of repair. It was also the case (for me... as the following would be exceedingly rare to occur) that I needed to replace my injector connector due to an electrical transference problem with that 25+ year old injector connector.

Once I fixed the wiring issue and replaced the connector on that injector everything was fine for me.

Now I also did have used OEM injectors that I sent off to Driftmotion to get sonic cleaned and re-balanced before all of that happened. All six of my injectors cleared testing and were in top condition when I installed the engine.

If you can't verify that the previous owner actually got those OEM injectors replaced with new ones or had them professionally re-balanced and cleaned then you'd have to consider the possibility that these things might not have been done. Unless you can verify from a service record that they did.

Being in CA you have two good options to get your injectors serviced (if needed):

1) You can call up Driftmotion. They will take in your OEM injectors and can do these services. Their shop is located in Montclair CA but you can also mail the injectors to them.

2) You can contact Fiveomotorsport and have them clean the injectors you send in... or... you can specify the original part number printed on the side of each OEM SC300 Denso injector and order an off the shelf cleaned and re-balanced set from them and send in your originals for a core refund.

Both companies will give you good results if you need injector servicing.

....

Further, just in general you should rule out anything being off with your spark plugs, plug wires (use new OEM or Denso aftermarket plug wires -- same thing and OEM spec) and a Denso/OEM distributor cap, Denso/OEM rotor (very important) and Denso ignition coil.

My guess is that you should check that questionable injector and its wiring and connector but am just covering all bases here.

With the list of things that have been reconnected and serviced with new parts, according to the previous owner, it's possible something is off with the injector wires for that one cylinder or that the injector in that location has an issue but also if one of the two front Denso O2 sensors was in need of replacement that means the car would probably be running a little too rich and burning more fuel than normal (granted the SC300 is not an efficient car to begin with).

If you have a 1992-1994 model your car takes two 2-wire Denso O2 sensors (non-heated). 1995+ takes two front 4-wire Denso O2 sensors (heated).

If the SC300 is a Cali-Emission spec model (all model years) then the #3 under-car O2 sensor (4-wire heated) can throw a CEL code but does not directly affect engine efficiency and performance. It is required to pass smog testing for sure but its function is to check the efficiency of the second catalytic convertor under the middle section of the SC300.

The previous owner having had the ECU capacitor serviced rules that out and that's a good future proof measure.

Check the offending injector out. Then also check to see that the EGR system is clean of carbon buildup and is otherwise functioning normally, including the vacuum modulator and EGR VSV and correct hose routing.

To me it sounds like those three issues are going on at the same time: 1) Cyl #6 injector misfire 2) EGR system clog or EGR component issue or mis-routed vacuum connections to the EGR parts 3) At least one bad O2 sensor that needs replacing... and if a front O2 sensor that would throw off the engine's air/fuel ratio and cause it to burn a richer mixture than normal.