you said misfire? when?
what were the test condition at that moment, exactly.?
The the 400 stall test (Forced) for sure is a huge normal misfire event. in fact the engine shakes like wet dog, all normal stall test, forced.
if it misfires parked, and you just open the throttle, did it misfire then as the EGR opens.???? or were real wheels off the ground spinning?
no code 51? after lots of driving hot.? (or during)
51 means the egrt sensor exhaust flow is weak but 51 is a very crude test, replaced in 96 to cure that with EGR map valve to find if EGR works then.)
all my tests on the page are mostly to find why a EGR flow is dead. not weak, as you know weak is the hard one to prove and find.
the smog test proves it is. (do not go to real calif smog test station until, get a non reported test so you dont get hit for gross polluter rules, and then more testing. CALIF is pain with rules endless.
what some mech would say is my test are not definitive,(partly) but is wrong on the dead,my test are very effective. dead;.
but yes I have no test for 1,2,3 quad ports plugged up with carbon.
other than doing Exhaust (EGT) gas temperature sensor tests (like on aircraft engines) on 4 exhaust tubes, finding some too hot it has no EGR, flow.
IR gun may do just this job , throttle at 2500 rpm are all 4 tubes same temp. reading, as they exit the exhaust ports? (theory me, not tired)
The hard part is the relation ship from the MOD valve, to CAT (3way)
The mod is tuned to that stock cats back pressure. (1600 cc sized CAT) normal pressure.
this sets the modulation rate to the EGR main, for load, (engine load) the barks are stronger under max load and then EGR shuts off at WOT (or idle) by design.
the other failure to flow is a too tiny a CAT that had way to much back pressure to the MOD and opens up too wide too soon and caused misfire.
the mod valve can be bad, (most are just the air vent clogged, as the diaphragm is real nice HT silicon rubber, very, top quality and lasting)
also know that the best running engine and best fuel mix, makes max NOX
NOX means the combustion is super hot and super powerful and perfect, but when perfect NOX is formed. (and vastly worse on DIESELS, ask VW how that works for them HAH)
so the EGR simply lowers that temperature to below the NOX generation point, that is all it does, (or in truth lowers it enough so the CAT gets the remainder)
but on this tricky car 93' the 4 ports mean there are 4 separate NOX generating cylinders. (we dont know if all 4 fail or just some ,and would be a super good clue)
The other problem seen is non stock parts, (or near)
the CAT wrong sized or the 3way NOX part missing.
the EXhaust manifold is custom and the EGR port is too small or has tube that just loves to clog with carbon fast or one exhaust sold has only slot grove (#3) cut in the mounting flange it that loves to fail and clog. (this car love to make carbon in LIMPHOME mode, and then packs all EGR paths with carbon, yours is not in LIMP)
The head tunnel clogs (not yours I bet is clean)
the egr main fits on the mount #4 tube and there is on the head side to here this NASTY "S" bend that loves to clog.
eg: (see these series of photos by me and others contributed,)
http://www.fixkick.com/sensors/EGR/90-95...age_3.html
conclusions?
if all is perfect EGR flow wises, EGR moves under load, and stall test does 400 rpm. (or even stalls)
or is just weak, EGR, the mod is bad or CAT problems (backpressure wrong (too big) or 3way missing nox section so is 2way cat.
or one egr quad port is clogged. (some)
tell me all facts on your stall test , how done and RPM
![[Image: egr-gas-profile.JPG]](http://www.fixkick.com/sensors/egr-gas-profile.JPG)