Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Tied secondaires open now CEL

Trevor,

think of what you just wrote. All the air is metered, right? So the PCM knows how much air goes in, right? Where is lean condition coming from. Besides, it's not forced induction -- the amount of air breathed in is determined by the engine vacuum.

There are other reasons not to do things like that. See Blorton's thread for one. The other would be resonant frequency of the long/short runners at low/high RPM.

Ok alls well Its off,Went off by itself.Im sure its still in the memory,ill clear it out later.No worrys mate!

You could get a lean condition at startup because the computer is not in closed loop operation yet. If you race the engine, you could be in for trouble.

No, Sandman... in open loop the PCM still looks at the MAF readings.

-Lance

Right, but the computer still doesn't know if the engine is running lean. It uses the MAF reading and a pre-programmed table to determine how much fuel the engine needs. I would think that opening the secondaries at relatively low rpm's would significantly affect how much air is getting into each cylinder, provided the TB is not causing too much of a restriction.

In other words, at cold engine, open loop operation, normal driving should be OK as the TB is the restriction. Open the TB up all the way (WOT) at cold engine, open loop, low RPM's, and you may lean it out enough to do damage...

I understand that the computer can adapt, and that the MAF system works MUCH better at this than the old speed density (like on my 88 Mustang GT). However, if you get too far out of spec, the fuel tables need to be reprogrammed, kind of like the supercharged engines and how they need a custom chip burned. You could do more mods with the Mustang engines because they were bigger displacement, and the percentage of total airflow change was smaller than that for our relatively low displacement engine.

96 and 97 will also throw those codes, but I'm not sure if the newer contours will. I had my cel come and I hooked it up to a reader and it told me that my secondaries were stuck open. I turn out that the cable that controls it was frayed. So I put in a new IMRC, and no more cel.

Interesting, thanks Redracer. I don't think there are any provisions in the OBD-I equipped 95's.

I still don't think opening the secondaries at idle would cause a lean condition. The engine will only suck in the air it needs, the primary runners are long for the sake of airspeed velocity and better A/F mixing. You're right, however, with forced induction -- that's a different ball of wax altogether.

-Lance

Yeah, it could go either way. I just don't want to see anyone grenade their engine because of this, just in case it would cause harm. Anyone with an A/F gauge that wants to try this and report back to us? Then again, that might not actualy mean anything, as my intuition tells me that the problem will only be during cold engine (open loop) conditions, hence the O2 sensor data (and thereby the A/F gauge readings) will be off.

The computer goes into open loop at WOT also (I know the EEC-IVs did, what about the Vs?)? Could this be a potential problem even at warm engine WOT?

I was one of the first to do this mod and had the same problem. Who cares it's only a light forget about. It is on because of vacum issues (or a least thats what Iam guessing) pretty sure I talked to a ford tech about it. I dont think there is any harm but who knoes mod at your own risk!

Dude ... that statement was about as ignorant as this one: "It is on because the boogey man turned it on." Without an ODB-II scanner, all this speculation is nothing but that, speculation. If the computer has a possible 250 error codes to choose from, your guess has a 1 in 250 chance of being right ... think about that! The two could be mutually exclusive ... maybe the secondaries didn't cause the problem at all ... maybe his DPFE sensor is shot ... maybe you should use an OBD-II scanner to know for sure. Not trying to be an ass here ... just trying to keep things real.