Hawk

Thanks Joel

Twisted

Hey, Joel, if his diverter or bypass valves were not working, wouldn't he be throwing a code that the thermactor system on both banks was not working?

5.0rick

From my post at Austin Area Stangs. Hope this helps.

Rick


Hi Everyone,

I decided to start working on the old Stang again. I have a Cartech SS -t-76 turbo intalled on my 89. I could not really get it tuned right for drivability so in order to simplify things a bit, I turned the boost all the way down and installed the stock MAF, 19# injectors, and the stock fuel pressure regulator (by the way, the stock fuel pressure is set to 47 psi without the vacuum attached and 40 psi with it attached according to my autometer mechanical gauge which is mounted on the cowl - Not 39psi as it is usually stated ). The cam is stock and all of the smog equipment is still on the car.

With all of the stock parts on the motor, I ran the key on engine running test and got 2 codes 44 and 94. The description in the manual as to what these codes are is very poor, basically Thermactor system is not working.

After doing a bit of research I found some specific information regarding these codes.

44 - Thermactor system is not working on the right bank (passenger side)
94 - Thermactor system is not working on the left bank (driver side)

I checked all of the thermactor components and everything appeared to be working.

The koer portion of the test that checks the thermactor system, introduces air into the cylinder head exhaust ports before the O2 sensors. At the same time, the EEC increases the fuel and reads the O2s for a change in the air fuel ratio. This got me thinking that maybe there was too much fuel and the thermactor system could not lean the mixture enough. I did some research on what the throttle position sensor should be set to and came up with .6volts at idle. That's right, not .980v like everyone says. I got this information from page 257 in "How to understand, service and modify Ford Fuel Injection & Electronic Engine Control" by Charles O. Probst. In order to achieve that voltage on my BBK 70mm TB, I had to drill out holes on the TPS.

I ran the koer test again and only got code 94 this time. Well, I figured the O2s were kind of old, so I replaced both of them and ran the test again and it passed! No more codes

I have been chasing the elusive perfect idle and part throttle for quite a while, and it has been a very frustrating journey. Now, I am going to install the 42# injectors and the Pro-M MAF and start tuning with the peace of mind that everything is as it should be with the emission control equipment.

I hope this information helps someone else out.

BTW, to set the stock idle of 675 rpm, open the TB until the motor will idle with both the AIC (air idle control valve) and the Spout disconnected. This will be the mechanical idle with no intervention from the EEC.

Regards,

Rick