Allright put your reading glasses on
I have been having an air/fuel mixture (read: super fat) problem ever since I swapped my engine and upgraded to 24# injectors at the same time.
Vehicle in question is a 90 Mustang 5.0, naturally aspirated, 24# injectors, 302 cid, very mild cam (218/220* @ .050 and a 112* lobe seperation), long tube headers, no cats, AFM Power pipe to locate shorty ProM 77 in fenderwell, Cobra intake, AFR 165's.
Here is my summation of the problem thus far:
--The meter originally had a calibration by the the old MAF manufaturer that caused it to run extremely rich with an eye-burning fuel smell. Gas Mileage was never better than 13mpg. Driveability steadily declined, eventually to the point of sputtering itself out almost completely. A stock meter and airbox were substituted and although still slightly rich due to the incorrect calibration, power and performance improved dramatically.
--The original element/plug assembly was fitted for the EEC-V square plug setup but tuned for 89-95 5.0. I had to cut and resplice the correct plug to my harness (another long story why the meter was like that, please take my word for it).
--I had the meter recalibrated by Professional Mass Air Systems in November and was pleased with the results for a few weeks, but there has been a notable decline in performance over the past month or so. I made sure to point out on the recal sheet that I was keeping the EEC-V plug, but the application and ECU were '90 GT.
--The vehicle has run progressively richer over time and the "seat of
the pants" loss of torque is quite apparent.
--With all sensors in place, it has reverted back to the occasional surging and hang-throttle at idle that seems to accompany MAF sensor calibration issues.
--With the O2 sensors disconnected, driveability improves enough to get from point A to point B-- but while not as prevalent, the surging and occasional hang-throttle sometimes returns-- even on my relatively short work commute. Power does not noticeably improve, and the acrid fuel-smell remains at all times.
--When the vehicle was at its best, gas mileage was never better than 16.5 mpg on the highway, it is now back down to the 11-12 range
These are my conclusions so far:
--When the recalibrated meter was first installed, there was a rich smell at idle but part throttle power was very torquey. My suspiscions are that the meter is still giving a "rich" signal to the computer and this has caused my
O2 sensors to progressively foul out, aggravating all symptoms.
--I am using longtube headers, and while the O2 sensors' distance from the exhaust valves does not help the situation, I think the rich exhaust caused by the MAF cailbration or possibly the ECU's fuel mapping is the real culprit in preventing the 02 sensors from maintaining temperature, as I have seen many street-going 5.0's do just fine with longtubes.
--I did try a MAF tuner and have never been able to have any positive effect with it, regardless of where I set it.
--The EGR valve, IAT sensor, O2 sensors, Coolant temp sensor have all been replaced with Motorcraft units. Another ECU out of a running GT had no change.
I am prepared to replace the meter, switch to short-tube headers, or get a custom ECU program if necessary, but I was hoping for some guidance before I spend any more money. I don't mind ditching the Power Pipe or longtubes, but only if there is some hope of curing the problem. If it matters, I can have it recalibrated again and replace the plug with the old stlyle EEC-IV one.
I am very sorry for the length of this post, but I am completely out of ideas...
any input you guys can give me on this matter would be greatly apreciated.
I have been having an air/fuel mixture (read: super fat) problem ever since I swapped my engine and upgraded to 24# injectors at the same time.
Vehicle in question is a 90 Mustang 5.0, naturally aspirated, 24# injectors, 302 cid, very mild cam (218/220* @ .050 and a 112* lobe seperation), long tube headers, no cats, AFM Power pipe to locate shorty ProM 77 in fenderwell, Cobra intake, AFR 165's.
Here is my summation of the problem thus far:
--The meter originally had a calibration by the the old MAF manufaturer that caused it to run extremely rich with an eye-burning fuel smell. Gas Mileage was never better than 13mpg. Driveability steadily declined, eventually to the point of sputtering itself out almost completely. A stock meter and airbox were substituted and although still slightly rich due to the incorrect calibration, power and performance improved dramatically.
--The original element/plug assembly was fitted for the EEC-V square plug setup but tuned for 89-95 5.0. I had to cut and resplice the correct plug to my harness (another long story why the meter was like that, please take my word for it).
--I had the meter recalibrated by Professional Mass Air Systems in November and was pleased with the results for a few weeks, but there has been a notable decline in performance over the past month or so. I made sure to point out on the recal sheet that I was keeping the EEC-V plug, but the application and ECU were '90 GT.
--The vehicle has run progressively richer over time and the "seat of
the pants" loss of torque is quite apparent.
--With all sensors in place, it has reverted back to the occasional surging and hang-throttle at idle that seems to accompany MAF sensor calibration issues.
--With the O2 sensors disconnected, driveability improves enough to get from point A to point B-- but while not as prevalent, the surging and occasional hang-throttle sometimes returns-- even on my relatively short work commute. Power does not noticeably improve, and the acrid fuel-smell remains at all times.
--When the vehicle was at its best, gas mileage was never better than 16.5 mpg on the highway, it is now back down to the 11-12 range
These are my conclusions so far:
--When the recalibrated meter was first installed, there was a rich smell at idle but part throttle power was very torquey. My suspiscions are that the meter is still giving a "rich" signal to the computer and this has caused my
O2 sensors to progressively foul out, aggravating all symptoms.
--I am using longtube headers, and while the O2 sensors' distance from the exhaust valves does not help the situation, I think the rich exhaust caused by the MAF cailbration or possibly the ECU's fuel mapping is the real culprit in preventing the 02 sensors from maintaining temperature, as I have seen many street-going 5.0's do just fine with longtubes.
--I did try a MAF tuner and have never been able to have any positive effect with it, regardless of where I set it.
--The EGR valve, IAT sensor, O2 sensors, Coolant temp sensor have all been replaced with Motorcraft units. Another ECU out of a running GT had no change.
I am prepared to replace the meter, switch to short-tube headers, or get a custom ECU program if necessary, but I was hoping for some guidance before I spend any more money. I don't mind ditching the Power Pipe or longtubes, but only if there is some hope of curing the problem. If it matters, I can have it recalibrated again and replace the plug with the old stlyle EEC-IV one.
I am very sorry for the length of this post, but I am completely out of ideas...
