Failed emissions in AZ


Active Member
Friend of mine is trying to pass emissions here in Phoenix, AZ…but failed on HC…it’s an 87 GN…the car has a rebuilt engine with ported heads…no EGR...the test here in AZ is the dyno…used to be IM-240…now they call it IM-147…he has a Terry Houston cat on for a THDP…he put some denatured alcohol in with the 91 octane unleaded gas…the chip he is using is a stock factory emissions chip with the injector constant changed for 50 lb injectors
…I have passed a couple of times with my GN using the same chip…here are the limits and his numbers:

HC his car was 1.93….limit is 1.60

CO his car was 14.60….limit is 15.00

NOX his car was 2.16….limit is 2.50

…any ideas of why he failed HC?...any suggestions…really appreciate any help
I appreciate the advice but as for the stock chip not being able to do it as I stated in the original post I used the exact same chip...he is actually using my chip...I have used that chip with my GN twice now which has basically the same setup as his car except for the heads...mine has EGR...his doesn't and my car passed with flying you can see he passed on the NOX which I think has to do with the EGR so the chip isn't the problem...IMO...
If the failed car is burning oil,then it may throw it over the edge.I dont think there are 2 of these cars the same anymore,if ever.Try using the other cars MAF as well. Reset ECM.Both cars using same inspection site?
Usually a good Cat will let you pass. Some have used 2 bottles of ISO-HEET to pass.has O2 sensor seen racing fuels?You need to compare scanned readings of both cars and if you can lwr FP without car seeing a lean condition,try it.If not lowering FP will make HC readings worse.Can reclassifing your car under different plates end the emissions for you later on?
He's high on everything. Last time I did mine, I passed with: hc-.40, co-3.88, nox-.99. The only differance from my sig, is I had ported irons. I've never had an egr, and I have .623/.616 lift, 240/234 cam. I'm with suicide, turn down the fp, and get the car good and hot
The other thing I didn't mention...because I didn't know about it was he also used a colder set of plugs...think they were Autolite 24 or 25's...I always use the stock AC44TS plugs or comparable to pass emissions...not sure how much colder plugs would affect the numbers...maybe worth a try to also put in hotter plugs...
Just passed in IL.

I also have 50LB'ers , added the cat back in, turbotweaks emission chip. also a bottle of "All you need" emmision passing stuff, bought at my local parts store....
Scott when I used to run my through with emission I always used the hotter plugs , put a half gallon of denatured alcohol and turned the fuel pressure to 38lbs line off and never had a problem. This was with 55's and no EGR with ported heads and a 45A turbo. I've found the 55's to be easier to get through emission than 50's but you should be able to get it through.
I suggested he turn his FP down quite a bit but not sure he really did it... I think he should be able to get through also if things are set up right..."pitch black" what chip did you use to get through?...
I doubt any of you would make it through a Texas IM240, at least not Houston spec.EGR makes a big difference in everything. CO and HC are balanced, lower one, raise the other. What was the CO2? I agree, drop the fuel pressure, see what happens. I'm no expert, good luck!