[Toby Van Horn]

Hello - I am having an issue with a 94 Z28 - wont pass smog, running rich and the smog shop states the injectors are clogged and need cleaned or replaced. I had a couple questions - The car runs amazing,

1 - can clogged injectors make it run rich although run really good (low MPG but runs strong)

2 - what are the best value OEM size injector

should I try a pour in cleaner first? whats the best way to check injectors? or check other things?

I have new 02s and plugs / wires, knn air intake, pace setter smog legal headers still have EGR and everything stock

Any help would be great - I do not want to waste time or money if injectors are not an issue - 115K miles.

 

[Toby Van Horn]

I got a fuel pressure test tool today - here is what I got -

ignition ON - engine off - 39psi

35 psi @ IDLE
revving engine it jumps to 40 - then drops to 35 with moderate gas (3500 rpms in nuetral)

disconnect vacuum line - 44 psi

we have a 95 trans am (that passed smog and runs clean) and seemed to be similar but more like 33 - 34 at idle and once stabilized.

What should these run stock at?

Did not know if that PSI range is right, if the couple more in the Z28 could be caused by clogged injectors or a regulator that needs replaced?

 

[Karl]

The fuel pressure at idle - that may be due to your engine running slightly less vacuum at idle, or just manufacturing tolerances in the fuel pressure regulator. If plugged injectors are causing the car to run rich, it means they are not sealing fully so some fuel is leaking past when they are supposed to be closed. Throwing in a can of injector cleaner just might help. that's a cheap and easy thing to try. If that doesn't work, you can follow your mechanic's advice to clean or replace the injectors.

 

[Toby Van Horn]

Thank you - good insight I have injectors coming so I will keep my fingers crossed

Toby