Problem since upgrade

[Ray@VSK]

I just finished my 93, everything I did see below, ever since I keep getting engine light come on & when it does it throws a code wich I looked up to be a air/fuel mixture problem, everytime the engine light comes on now my idle gets terrible & it likes to die till I reset it, do I need a different computer, any suggestions ?

Also I was wondering since I'm using stock fuel pump & 24lb injectors do I even need the fuel regulator I installed or should I remove it & put the stock non adjustable back on ?

 

[giddyup306]

Do you have the 24# maf?

 

[Ray@VSK]

Yep 76mm C&L with Tube.

 

[nito88stang]

A few possible culprits come to mind:

MAF - clean it or replace with a known working one to check it out.

TPS - Check the voltage and see that its within range when you open the throttle.

02 sensors - Are the codes ur getting 41 or 91 ?

ACT - clean it, might help.

Check your plugs too see if its a lean or rich condition.

 

[Ray@VSK]

Everything is brand new, the code is 91.

You think maybe the fuel regulator I put on fully open is not flowing as much as the stock non adjustable, do I even need a fuel regulator since I'm using the stock fuel pump & 24# injectors ?

 

[jrichker]

Code 41(Right O2 sensor) or 91 (Left O2 sensor) - O2 sensor indicates system lean. Look for a vacuum leak or failing O2 sensor.
The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel.

Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.
The O2 sensor ground is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than .4 volt. Remember lean = less voltage.

" When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than .6 volt. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage."
Charles O. Probst, Ford fuel Injection & Electronic Engine control

 

[giddyup306]

Also check for a missfire. This will also set a lean code.

 

[lxwants12's]

its always good to have and adjustable furl pressure regulator..i would def dump the stock pump though for a 190 cause stock pumps suck...and i would also buy a fuel pressure guage that screws directly into the fuel rail just to keep an eye on things...make sure all ur sensors are clean and in working order...ur maf sensor matches your injectors...and u should be ok

 

[jrichker]

I'll make it simple - you either have a vacuum leak or a bad O2 sensor.

With properly woking O2 sensors, a misfire will not set code 91. A misfire will pass unburnt gas out the exhaust, showing a rich mixture to the O2 sensor. That is the exact opposite of what happens with a code 91.

Got any doubts - read the Probst book. Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.

 

[Killer50stang]

I just finished my 93, everything I did see below, ever since I keep getting engine light come on & when it does it throws a code wich I looked up to be a air/fuel mixture problem, everytime the engine light comes on now my idle gets terrible & it likes to die till I reset it, do I need a different computer, any suggestions ?

Also I was wondering since I'm using stock fuel pump & 24lb injectors do I even need the fuel regulator I installed or should I remove it & put the stock non adjustable back on ?

You can't run 24lb injectors with a stock Mass Air Sensor. I went with a 75mm Grantelli and mine worked fine. The stock Mass air sensor cannot measure correctly with bigger injectors. I would recommend to go with a 255 intank Walbro fuel pump, After market Fuel regulator to adjust your fuel pressure and a 75mm Mass air of some kind. This should fix your problem and Your car will run 100% better. You should notice some horse difference as well. The mass air sensor should be top priority! Good Luck!