how does efi advance ignition without vacuum
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how does efi advance ignition without vacuum
hello, i am working on a project with an 1989 460 from a f250 and i was wondering how the ignition system advances and what sensors in the engine it uses to do so, im new to the electrical side of things and so im looking to get a little more info on it. i am planning on doing a carb conversion but want to keep the original distributor and coil wiring so i want to see what i can do with the old one before i can justify spending the money on aftermarket ignition distributors and systems. Im pretty much asking what makes the efi distributor advance without vacuum advance and what i can do to retain such a system with carb. thanks!
Hotshot
Joined: Jun 2015
Posts: 12,885
Likes: 2,448
Why? What is wrong with what you have?
I believe you need to do more research. There are multiple threads on here that explain (by much more knowledgeable people than myself) what is involved including fuel and ignition items that need to be changed.
Tuned
Joined: Sep 2014
Posts: 358
Likes: 7
From: Ky
The MAP sensor responds directly to engine load reading vacuum.
PIP coil in distributor advances timing.
The learning curve is too great to ask questions of this nature on a carb conversion, until you have read through the multitude of carb conversion threads in the archives on this site.
Go into the search forums, plug in 87-97 trucks, and search the titles.
Absorb that info first.
PIP coil in distributor advances timing.
The learning curve is too great to ask questions of this nature on a carb conversion, until you have read through the multitude of carb conversion threads in the archives on this site.
Go into the search forums, plug in 87-97 trucks, and search the titles.
Absorb that info first.
Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
Likes: 116
From: Saskatchewan Canada
Well, sorry to do this to you, but combine these answers with your other thread and maybe you will start to see what we're talking about.
https://www.ford-trucks.com/forums/1...on-wiring.html
Now, you do pose a good question and it's true, the advance is controlled by a signal from the PCM called SPOUT. The SPOUT signal is complex and it is calculated by the PCM using input from the MAF sensor, the PIP sensor, the TPS sensor, the ECT sensor and quite possibly other sensors that I have missed. All this info is calculated as engine load factor and that information is used internally by the PCM to create the SPOUT signal which is applied to the ICM. There are different versions of the ICM dependent on application and this module fires the ignition coil with the appropriate amount of advance. One term you may run into is removing the SPOUT jumper to set initial timing. This removes the SPOUT signal from the ICM which now runs in a default mode, usually 10' BTDC.
I have a collection of documents and comments that I have saved over the years. It may be helpful to read these to understand how the Ford TFI ignition system works. There's a lot of cut and paste in here and I hope the various authors are correctly identified.
https://www.ford-trucks.com/forums/1...on-wiring.html
Now, you do pose a good question and it's true, the advance is controlled by a signal from the PCM called SPOUT. The SPOUT signal is complex and it is calculated by the PCM using input from the MAF sensor, the PIP sensor, the TPS sensor, the ECT sensor and quite possibly other sensors that I have missed. All this info is calculated as engine load factor and that information is used internally by the PCM to create the SPOUT signal which is applied to the ICM. There are different versions of the ICM dependent on application and this module fires the ignition coil with the appropriate amount of advance. One term you may run into is removing the SPOUT jumper to set initial timing. This removes the SPOUT signal from the ICM which now runs in a default mode, usually 10' BTDC.
I have a collection of documents and comments that I have saved over the years. It may be helpful to read these to understand how the Ford TFI ignition system works. There's a lot of cut and paste in here and I hope the various authors are correctly identified.
Fleet Owner
Joined: Aug 2005
Posts: 23,668
Likes: 301
From: Easton,Ks
The PIP is generated by a switch and amplifier in the distributor.
There is no coil involved. In other words there is NO coil inside the distributor.
There is no coil involved. In other words there is NO coil inside the distributor.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Which is no advance, it would be the same as using a vacuum distributor with no vacuum line attached, the motor will start and run but won't make much power.
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Temporarily Deactivated
Joined: Aug 2003
Posts: 1,859
Likes: 2
I don't remember if you said why you hate efi and love carburetors?
The computer has a memory map of timing and injection values for any given rpm and throttle opening. It modifies the timing and injection based on the sensors (input). The computer adjusts the timing, injectors and idle speed, etc by sending a signal to the actuators (output). Don't be skeird. It's a simple system.
I still drive my thirty year old trucks thousands of miles from home and they bring me back again.
Learn to test things without destroying them and don't throw money at problems.
The computer has a memory map of timing and injection values for any given rpm and throttle opening. It modifies the timing and injection based on the sensors (input). The computer adjusts the timing, injectors and idle speed, etc by sending a signal to the actuators (output). Don't be skeird. It's a simple system.
I still drive my thirty year old trucks thousands of miles from home and they bring me back again.
Learn to test things without destroying them and don't throw money at problems.
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Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
Likes: 116
From: Saskatchewan Canada
By the way, factory gauges are not integrated into the EFI system and may be the only parts on the truck that you can use.
But, staying on topic, John, I hope I answered you question on advance. If you really want a carb, it's your truck and do as you please. I hope you will see that there are way more pitfalls here than you may think. Keep the EFI.
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