fl_799

Burn a chip and raise the injector constant to lean it out! Scan and see where the BLM's are and if they are close to 128 you got it!

Benny42

No it doesn't. NOx is 0.0 so it isn't EGR.

bjankuski

The car is running too rich at idle, the correct way to fix this is to burn a chip. Another way (not as good as burning a chip) is to add in an adjustable fuel pressure regulator and lower pressure to lean out the idle. You can buy on through summit racing, Jegs, TPIS. You should use a scanner and see where your BLM's are and adjust fuel pressure to get BLM's around 128 at cruise which will hopefully get your idle to a position where the PCM can correct for the rich condition.

chstitans42

He went in again and it failed both sections this time. So please explain this burning chip thing to me, I have no idea what this paragraph means above,

chstitans42

This is what I need?
http://www.pcmofnc.com/index.php/tun...ette-1986-1993
Will it tune the engine to compensate for the 24lb injectors? I guess I need to call them and ask.

fl_799

Hit up Moates.net. He will have the writable chips, the USB to ODB interface cable, and the piggyback adapter. You will need the software like Tunerpro RT and a Windows PC or laptop. The best was to do this....is to do it yourself and nail down your tune 100 percent. Plenty of people here who can assist.

aDigitalPhantom

OP Don't forget the programmer that was not mentioned ^

chstitans42

All that stuff sounds expensive, Ill check them out

fl_799

Yep, the programmer too! The Moates AUP1 is a really good all in one package but it is indeed expensive for a one time deal. At the very least, you can datalog the car yourself with TunerPro RT or Datamaster32 and buy the interface cable. You could send the datalog(s) to a tuner and they can burn a chip for you. 27SF512 chips are $5 and the G1 memory adapter is $35 plus whatever the tuner would charge for their work.

On the Harley forum, we had tuning FI bikes down to a science!

bassackwards

Put new 02 sensors in it before doing anything else. They are cheap and do wear out

bogus

whew... In summary... EGR is fine... HC's high...

I do agree, injectors are too much. Bring down the pressure or lower the lb rate.

I am also suspect of the cats. 140k miles on OEM cats is asking a lot from those pieces of crap.

This is what I would do:

1. Get rid of the pre-cats. They are doing nothing anymore. Period. Gut those bastards.
2. Replace the main center cat with a Magnaflow cat.
3. Get the ECM tuned to go with the injectors, or lower the pressure a touch.

I have never seen an OEM Corvette cat go much beyond the 140k mile mark.

straycat21

My 1991 initially failed too until a knowledgeable inspector told me that the cats were put more rearward in the early GM catalytic cars. You have to rev them up to about 2500 rpm before entering the booth for about a couple of minutes to get the cats hot. When I did this, my car passed. I had to go through 3 times before it passed though. Good luck.

bonvolait

From what I have read the same injector (size series) is rated anywhere from 19 to 24 lbs /hr dependent on several standard levels of fuel pressure and on the specific application that the injector is employed in. As long as the injector is NOT rated over 24 lbs /hr, it is the correct stock
injector size for the L98. The next size up, that actually has more flow capability beyond the normal calibrated input control range of the ECM (requiring re calibration), is going to have flow ratings that start at 30 lbs /hr.

aklim

From what I have read, the last post was 8/1/14

aboatguy

bonvolait

I realize the Original Post is several years old. I am wondering IF you were able to get the car to pass, since my 85 has the same problem of pass at cruise speed/fail at idle. I am wonder IF you were able to resolve the problem and what /how exactly it was done. Thanks

chstitans42

The resolution was wait another 6 months until the car turned 25, because in Texas after 25 years it is safety inspection only. Sorry that wasn't more help!

856SPEED

Problem solved.......

It's fun to see these old threads......brings back memories!

billschroeder5842

That really is your answer. Or you can swing by Southlake and I'll introduce you to "my guys." Safety only for me. Why are you getting the emission test?

chstitans42

This was back in 2014 when the car was not yet 25 years old.