Ok, i have read through 5-6 threads and countless pages on all the injector data. I have a question about using the neon injectors on a 91-95 HO 4.0L.

As stated in the post on the AUSJEEP web site and elsewhere on this site:

'94-'95, ...53030343 flow 248cc/min @ 43.5psi - so at 39psi dont they flow 234.8 cc/min ??

'96-'98, ...53030778 flow 228cc/min @ 43.5psi and 243cc/min @49psi

Neon Injectors, ...703 flow 238cc/min @ 43.5psi - and 252cc/min @49psi

So wouldnt the Neon injectors flow 250cc/min @ 48 psi ?? Wouldnt that be closer to stock for the 91-95 ??

Cause at 39psi the Neon injectors are only going to flow 225cc/min. Is that going to be adequate flow for a 91-95 ?? It seems a little lean and 252cc seems a little rich for the 96-98.

Thanks for the help on this.

 

I have the HO motor. The Neon injectors run a little rich as it is. I looked at the plugs. Anymore and they would be too rich. I can smell it now when I "wot" now. Stick with the Neons "703". Your good. Remember, these are more efficient. I posted my smog specs too. It passed like a new car. Noticeable more power.

Make sure you replace the FPR.
http://cgi.ebay.com/ebaymotors/ws/eB...m=400072369275

 

You changed the fuel pressure regulator and the injectors.

That is my point: that in a 91-95, you should change the FPR and the injectors together.

It would seem from your experience that one should get the Neon Injectors and an adjustable FPR to dial them in at around 45psi +/-.

Does this sound about right?

 

aaaauurgh the never ending thread lol.

 

Correct. Do them together and rebuild them. My injectors were dirty and the filters were bad.

I am happy with my setup.

 

good luck with it.

 

ok i have a 91 xj with a 98 motor. every part is from a 98 grand cherokee except the head. the head is a 95 off a cherokee. i have a set of the blue top injectors out of a 93 cobra should i put these on my jeep or are they too much?

thanks

 

703's & stock fpr will work.
no idea about blue tops.

 

This is why mine runs a little rich then. I used the 49 FPR on my '93. Which is 8% difference. What does that mean? Not sure. It passed smog with flying colors. Runs good. Plug is half brown and half slightly black. Real light. I can smell fuel on WOT in the exhaust slightly. Better slightly rich than lean I guess.

 

well if anyone knows about the blue tops let me know

 

Yeah thing is the 91-93 computers aint that smart, I have been told that the ability of the computers in those years to shorten up the injector pulse is more limited than in later years.
Also at %80 wide open throttle the computers stop listening to feed back from the oxy sensor and read off fueling maps stored in the memory. or the fuel management system switches from closed loop to open loop to use the correct terms.
So having a slightly less flowing injector that is more efficient works well. my 95 runs a touch richer than absolutely ideal with 703 and stock fpr @ wide open throttle.


Using the 49 psi fpr and 703 injectors will cause overfueling at 80%+ wide open throttle, below that, it would appear that at 15 mph and 25mph your computer can compensate (by shortening injector cycle) for the increased fuel pressure, in closed loop it is listening to the oxy sensor and making adjustments accordingly.
in open loop (80%+ wide open throttle) some of the unburnt fuel ends up in your engine oil, the oil looses its ability to lubricate and the longer this goes on for the worse it gets, then your engine dies.
that is why coas suggested to put the stock fpr back in and change your oil quick smart.
Its your heap, whatever rings your bell.

 

After reading this complete thread and all the ones linked in it, I'm 99.99% sure I know what I need.

Neon 22.5# 0280155703 (oem 5277739). These use the clip nut and are plug-n-play, correct?

 

if it is pre '99 then yes

 

It's a '98. Thank you

 

OK i get it, better to be a bit lean at WOT or open loop. And yes 4% is not worth the time or effort to dial in, especially when the Hesco adjustable FPR is $200. I will just go get the Neon 703's and leave the rest alone.

Thank you again for clarifying.