hi. i own 95 basline neon its borderline 1996. i got custom CAI,lite port smoothing and intake manifold port matching,UDP,gutted cat,nitrous. i recently done head gasket all new seals as i put everything together. also done the rod bearings. its and atx. i have a plx r 500 wideband controler and i noticed that it idles at 13 to 14.7 and at WOT it runs at 11.7 witch i think is good but AT LOW SPEEDS when i get off the throttle it goes to max richness 19.9. when im driving it drive normal at 12.7 cruizing but sumtimes jerks but i saw the jerk was caused by it going rich. now when i drive on the hiway and try to cruize it wont let me it goes super rich and bogs then makes this loud bang(not a backfire)like sumthing snaping kindA sound. if im cruizing on the hiway i have to constanly punch the gas to get it from not going to 19.9 super rich to 11.7 at WOT. sumtimes it does this on the side roads but alot of it happens on the hiways. im realy geting pissed off and need a car. iv changed all intake seals and got a new upstream o2 but no egr no evap and no rear o2 after the cat. thats where my wideband is right now. iv got codes 12 32 21 and 21 again dont no why twice then ovously 55. i dont no wat is causing this sudden richness then sumtimes its fine it feels like a sensor is bad maybe cam sensor is bad i silconed it on kuz i didnt have a new o ring. it doesnt leak at all.it once had a map and intake temp out of range but when i put new intake mani gaskets in they went away and for the longest time my temp sensor for coolant was bad and the 02 and egr codes never showed up untill i fixed the colent temp sensor please help some one

 

wow thats a lot of problems did u try changing ur computer?

 

i havent changed the computer,but who makes and pcm for 95 96 borderline atx neon that is a porformnce pcm? im just goingh crazy with this sudden excessivness of fuel when i try to cruize at 70 at low speeds it drives tehn swtudders but doesnt do that banging noise when it gets realy rich. everything is new the car is only got 60,000 on it i did the headgasket and alot of new sensors except i didnt do the cam and crank sensor and down stream o2 sensor and i never changed map, tps, iac, or iat. i dont no what to fix

 

modernperformance sells performance computers for 95-99 neon and so on.can u check the voltage at the map sensor? if the cam sensor is bad it wont run at all same with the crank. it almost sounds like my freinds problem but hit starts running on 2 cycl on and off and its the wiring harness that is bad so that may be ur problem or u may need a fuel regulator to control the flow but if u havent changed the fuel pump to a high flow. I would try the computer or the harness go to junk yard and fins a 95 and try it.

 

ok i called howwell auto. talked to tech he sed change the pcm might solve it he got the af x race. im realy going to make my self sound like and idiot but 19.9 ratio equels LEAN pinging and the pistons melting thats the bang i was hearing. so everything i wrote swtich it around im talking lean conditions im realy sorry i thought 19.9 was rich not lean but it is lean an 9 is rich

 

sounds kinda werid maybe it could be related to the removalof the of the rear o2. but i guess the first thing i would check would be the injectors. Using an ohm meter test the resistance accors the injector terminals should be approx 12ohms at 68F. If thats good attach a tests 12voltlamp acorss injector electical connector terminals and crank engine to test the signal from PCM. After you know thats good then i would hit sensors

 

wow if u hurt ur pistons ur not going to go far but the computer will probibly help like he said. so if ur running lean get a bigger fuel pump and probily a regulator

 

if it runs its getting asignal so are u thinking its getting to much voltage?

 

since fuel pressure is constant the amonut of fuel injected into the manifold is incrased or deceased in proportion to the time electric current flows to the injector. Based on PCM signal.

 

ok i gotch ya. that sounds right. was the rear o2 eliminated? if so get and emulator ive never had a problem with mine.