Haltech Control of the A442f (1 Viewer)

[moremazda]

So I've been struggling with an engine rpm flare on hot start. It is related to IAC function. The IAC shows that on start the engine state is in "Decel Mode", my guess is that the IAC is full open since without a time based rev limit it runs straight to 3k rpm. And that's basically the only issue that I have. So if y'all have any ideas, the tech help at Haltech USA said call Austrailia.

The transmission functionality is just fine. The haltech base map is only 5%-10% rich and the LTFT are coming in nicely. Starts with the base coolant corrections, and cranking maps. Tonight I'll leave out side and see how starts when gets into the 20's.

Since the timing solenoid is the primary reason I started this it worth mentioning what I found today. That is running the A442 timing solenoid with the A342 default settings for the A342 accumulator solenoid (which is PWM duty cycle of 50% at 5% throttle tapering out to 0% duty at ~40%) takes the rough edge off of the shift turning more into the stock shift characteristic. I'm not sure if that is actually how the stock solenoid runs, or if there is a true timing aspect and it simply opens during the shift. Not knowing I disabled it until I learn how it's actually supposed to work. The shifts without feel more firm but that is totally subjective measure of function with out knowing how these were designed. Anyway, you could probably do what several people here already mentioned (and do), at not use it at all.

 

[ThreeEyedBandit]

Can you see in the software the IAC being commanded to step open? It should be in the last position otherwise. I'm also guessing there isn't a setting to disable iac moves in decel mode?

Don't forget there is a vacuum operated dash pot that opens the throttle when no vacuum is applied. Opens the throttle when engine is off, and fairly quickly closes the blade once the engine is alive. Mine had a similar start flair(2500rpm) when it was mis adjusted.

With a modern ecu I would disable it.

 

[moremazda]

I do want to post a summary of the parts used. My rig is a '94 and I made everything completely plug and play.......other than having to trim the back of the glove box to clear the ECU header plug, no other modification where made to the rig. There are three parts to un-plug and three stock parts to put back in order to return the rig to stock; the transmission ECU, the engine ECU, and air flow meter.

I 3D printed a TCU box to hold the solid state relays (Hella P/N 931774031) the header pin and the Haltech PRNDL converter.
I 3D printed a box to hold the ECU header and provide strain relief to the soldered pins. I used a haltech basic harness to graft to the ECU header
I 3d printed an AFM delete pipe to hold the Haltech supplied GM air temp sensor......and delete the AFM
I bought the seven pin plug linked in this thread to build a connector that uses the AFM plug as a fuel pump relay pass through and connect the air temp sensor to the Haltech.
I used the dual channel CAN Wideband controller from Hlatech.

I'll probably get the 2" Haltech CAN gauge........once the turbo goes in. But that will be a little bit further down the road.

Also there is a big difference in the drivability of the rig now, like night and day for those weirdos that pay too much attention to how the cars work. It is clearly quicker at full throttle and still runs in the low 12's for AFR. I plan to map knock threshold against 87 and 93 and figure out what timing it really wants. I also have fuel milage data for the 3500 miles that I've gotten on it before this and plan to use it as my daily to capture the effect on milage of adding the Haltech.

 

[moremazda]

Can you see in the software the IAC being commanded to step open? It should be in the last position otherwise. I'm also guessing there isn't a setting to disable iac moves in decel mode?

Don't forget there is a vacuum operated dash pot that opens the throttle when no vacuum is applied. Opens the throttle when engine is off, and fairly quickly closes the blade once the engine is alive. Mine had a similar start flair(2500rpm) when it was mis adjusted.

With a modern ecu I would disable it.

I did not know that. I'll go look for it now.

 

[moremazda]

I did not know that. I'll go look for it now.

nope that's not it.

This seems like the IAC running to full stroke at cranking, and then the ECU going into a decal cut state that disables IAC control and then it just sits there. While it's happening I can put in a different value for the IAC step count and it kicks the ecu out of the decal state everything starts to work. this it only on starts.

 

[ThreeEyedBandit]

That makes sense, how long does it hang at the higher RPM?

 

[moremazda]

That makes sense, how long does it hang at the higher RPM?

Sometimes it won't come off of it until I do something.

But I have found a thing. Haltech has the number of IAC steps in the base map ( and their 1fz setup page) set to 240. Well it looks like the IAC logic puts the IAC at that full position during cranking. It doesn't care too much about the max percentage number in the IAC settings.

So I played with two settings moving the decel rpm higher and that didn't do anything. And I played with the number of steps in the IAC configuration. So far a step count of 120 keeps the rpm low enough to not get into the decel cut trigger and still give the controller enough authority to actually control the idle. The min allowed position needs to go to zero for this steps setting (or at least that is where I have it right now) or it will just bottom out on that min setting and not reduce the idle further.......so far it is working pretty well.

I did a 177 miles this morning on the free way at 70-75mph and got 11.7mpg, I was secretly hoping for at least a little bit of an improvement right out of the box, but I have to remember that it is basically a rolling brick

 

[Speedytech7]

@moremazda Are you using a factory gauge cluster in your 80?

 

[moremazda]

@moremazda Are you using a factory gauge cluster in your 80?

Yup, bone stock other than the things to make the haltech plug in.