Adaptive fuel limit... what is this??

jruppert · 10-09-2002, 05:10 PM

My car has been using a little more gas lately. I have 24lb injectors and also have a Pro-M calibrated to run them. My pro-m started acting up so I took it off and replaced it with my stock MAF. Once in a while my check engine light comes on. Today I went to check for codes and I had gotten 6 or 7 of them. The first two basically said that both O2 sensors were reporting a rich mixture. Which I thought was odd because of the mismatch in MAF. I assumed it would be running lean if anything. The next code said that the adaptive fuel limit reached at half throttle. Does anyone know what this is? I know that my MAF isnt right but I wasnt sure if I had something else going on. Any suggestions?

lx mike · 10-09-2002, 06:57 PM

It's running rich cause of the stock maf with the 24 lb injectors and the computer is trying to correct it but can only do this up to a certain point and that what it is doing in your case.

jruppert · 10-09-2002, 08:24 PM

Well thats what I thought but since it never threw out a actual MAF code I didnt know if I was dealing with a totally different problem.

srv1 · 10-09-2002, 09:30 PM

basically how much the computer can pulse the injectors for a given time. since you running so rich, the computer cant even lean it out correctly in order for it to run right. it also thinks that it is giving an A/F ratio of full throttle, and it is getting those figures at half throttle. basically injector "on-time" is very high. the computer cant do no more except throw a check engine light on and throw a code into memory. also, what is your fuel pressure at?

your running rich: too high fuel pressure. wrong MAF or defective. too big of a cam. fuel pressure regulator bad. myself, i think you have a MAF problem. try another 24lb MAF and go from there.

88workcar · 10-10-2002, 04:52 AM

Did it ever run good with the 24s?

mike72678 · 10-10-2002, 07:55 AM

when your eec is in adaptive mode , that means that is learning (closed loop only) .with a mas calibrated for 19 lb. running 24 lb. you will run very rich , and it is too much for the computer to adjust for unless you have a custom burned chip. i would try putting the pro m back in and make sure it is in the stock location , also if you have a cone filter clamped directly onto the mas , i would try removing that and putting some kind of tubing in front of the mas before the filter , also you can try actually rotating the mas about 45 degrees either way . these are just a couple of known problems that can disrupt airflow to the mas and cause false readings . hope this helps .

jruppert · 10-10-2002, 04:30 PM

At one point the car ran fine with my Pro-M installed. The car was getting around 24mpg. When the MAF went bad it started running so rich that the cats were getting real hot. They would get so hot that they cats would start smoking. Also, you could really smell the fumes in the exhaust. That is why I took the Pro-M out. I am getting ready to send it in to have it checked out. When it was installed, the computer threw out a code. I cant remember what number it was but it basically said that they MAF was running below minumum voltage. With the stock MAF installed it runs fine. The performance isnt up to snuff and I am getting around 200 miles per tank. Also, I have a custom chip installed and when I had it made I told them that I had 24lb injectors with a MAF calibrated to run them. I thought maybe the chip would run those injectors if anything. Is it possible that the chip could be bad? If the chip was bad would it make my Pro-M dump even more fuel into the system?

10-09-2002, 05:10 PM	#1
jruppert Registered Member Join Date: Jul 2001 Location: Reed City Mi Posts: 106	Adaptive fuel limit... what is this?? My car has been using a little more gas lately. I have 24lb injectors and also have a Pro-M calibrated to run them. My pro-m started acting up so I took it off and replaced it with my stock MAF. Once in a while my check engine light comes on. Today I went to check for codes and I had gotten 6 or 7 of them. The first two basically said that both O2 sensors were reporting a rich mixture. Which I thought was odd because of the mismatch in MAF. I assumed it would be running lean if anything. The next code said that the adaptive fuel limit reached at half throttle. Does anyone know what this is? I know that my MAF isnt right but I wasnt sure if I had something else going on. Any suggestions?

10-09-2002, 06:57 PM	#2
lx mike Undescribable Join Date: Sep 1998 Location: Ft Myers Fla Posts: 1,539	It's running rich cause of the stock maf with the 24 lb injectors and the computer is trying to correct it but can only do this up to a certain point and that what it is doing in your case. __________________ Rice Haters Club Member #101

10-09-2002, 09:30 PM	#4
srv1 Get down..... Join Date: Apr 2001 Location: Room 103 Posts: 2,095	basically how much the computer can pulse the injectors for a given time. since you running so rich, the computer cant even lean it out correctly in order for it to run right. it also thinks that it is giving an A/F ratio of full throttle, and it is getting those figures at half throttle. basically injector "on-time" is very high. the computer cant do no more except throw a check engine light on and throw a code into memory. also, what is your fuel pressure at? your running rich: too high fuel pressure. wrong MAF or defective. too big of a cam. fuel pressure regulator bad. myself, i think you have a MAF problem. try another 24lb MAF and go from there. __________________ Cobra brakes are on! Finally..... ------------------------------------------------

10-10-2002, 04:52 AM	#5
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	Did it ever run good with the 24s? __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
fuel pressure issues	mustang98gt	Modular Madness	3	07-05-2003 10:43 PM
Fuel Problems...I think	silver_pilate	Windsor Power	15	05-31-2003 08:36 PM
89 LX Fuel Problems	Ryan94GT	Small Ponies	0	08-19-2002 09:47 PM
Adaptive Lean limit in Fuel Control program?	Mad Horse	Windsor Power	3	09-18-2001 05:09 AM
Cartech/Aeromotive fuel system owners please read!!!!	Black306	Windsor Power	4	06-18-2001 03:39 PM

10-09-2002, 08:24 PM	#3
jruppert Registered Member Join Date: Jul 2001 Location: Reed City Mi Posts: 106	Well thats what I thought but since it never threw out a actual MAF code I didnt know if I was dealing with a totally different problem.

10-10-2002, 07:55 AM	#6
mike72678 MW Link Sponsor Join Date: Sep 2002 Location: rochester , ny Posts: 79	when your eec is in adaptive mode , that means that is learning (closed loop only) .with a mas calibrated for 19 lb. running 24 lb. you will run very rich , and it is too much for the computer to adjust for unless you have a custom burned chip. i would try putting the pro m back in and make sure it is in the stock location , also if you have a cone filter clamped directly onto the mas , i would try removing that and putting some kind of tubing in front of the mas before the filter , also you can try actually rotating the mas about 45 degrees either way . these are just a couple of known problems that can disrupt airflow to the mas and cause false readings . hope this helps .

10-10-2002, 04:30 PM	#7
jruppert Registered Member Join Date: Jul 2001 Location: Reed City Mi Posts: 106	At one point the car ran fine with my Pro-M installed. The car was getting around 24mpg. When the MAF went bad it started running so rich that the cats were getting real hot. They would get so hot that they cats would start smoking. Also, you could really smell the fumes in the exhaust. That is why I took the Pro-M out. I am getting ready to send it in to have it checked out. When it was installed, the computer threw out a code. I cant remember what number it was but it basically said that they MAF was running below minumum voltage. With the stock MAF installed it runs fine. The performance isnt up to snuff and I am getting around 200 miles per tank. Also, I have a custom chip installed and when I had it made I told them that I had 24lb injectors with a MAF calibrated to run them. I thought maybe the chip would run those injectors if anything. Is it possible that the chip could be bad? If the chip was bad would it make my Pro-M dump even more fuel into the system?