GM TBI on an AMC 360/401 motor FAQ Here I will try and address the common misconceptions and frequently asked questions in regards to upgrading to TBI (Throttle Body Injection) for your AMC 360/401 motor. www.gearhead-efi.com has a wealth of information RE GM TBI systems. They are knowledgeable and friendly. Read the FAQs. Ask questions. Once you have a good understanding of what’s going on and how everything works, your conversion will go much better. I will not try to rehash what is posted there, but will instead focus on the issues unique to the AMC 360/401 motor that is found in thousands of Full Size Jeeps across the US and the world. First, you need to decide what type of system you want. There are three different types. TURNKEY TBI SYSTEMS: Several companies make turnkey (ready to run, you simply install and go) TBI systems for AMC 360/401 motors. Howell and AFI (Affordable Fuel Injection) seem to be the most popular. Another “Custom” EFI seller is also out there, but he has a shady record of not delivering on promises and his product does not use the most popular GM ECM, the 1227747. PROS: Simple and quick to install. If you can install a stereo, you can install a turnkey TBI system. The only thing you might not be able to do is weld in the O2 sensor, but a muffler shop can do that for you inexpensively. You can install most of these systems in an easy weekend and be up and running with your TBI by Sunday afternoon. You don’t need any programming knowledge whatsoever. All you need to be able to do is turn a wrench and cut and splice together a few wires and hoses here and there. CONS: Friggin’ expensive!!! You get what you pay for, and in this case, you are paying for convenience and speed. Everything is done for you and you are paying for that service. Many of these systems do NOT control timing unless you pay (a lot) more money for that feature. Howell does now have one that is CARB certified for certain years, but it still does not have electronic timing control. DIY TBI SYSTEMS: Well, it’s really not a “system” if you are cobbling it together for yourself, now is it? If you are one of those folks who has more time than money, putting together a DIY system with junkyard parts is more inviting than paying lots of money for something you can (really!) do yourself. PROS: Cheap. Buying junkyard parts will save you tons of money. You can get a used TBI (just the throttle body injector unit) from a junkyard for about a tenth of the cost of a (usually) remanufactured TBI. CONS: It will take a lot of time and hard work on your part to round up all the parts. And some of the parts might be bad, but you won’t know until you plug them in. And by that time, your 30 day return might be up, so now you’re stuck with a DOA part that you can’t return or exchange. You need a good working knowledge of the GM TBI system to recognize the different parts so that you get the correct ones. If you are able to cannibalize one single donor vehicle, this is not as big of an issue. You will have to learn everything about the GM TBI system in order to successfully install a DIY system. HYBRID TBI SYSTEMS: If the whole DIY thing is too daunting, and the turnkey systems are too expensive, a hybrid system may be the answer for you. This technique involves sourcing some parts from the junkyard and some parts from retailers. The end cost might approach a Turnkey system, but your final system will be custom made for you and you can spread the costs out over time if you need to. PROS: Less work than a DIY approach, but cheaper than a turnkey system. You can select which parts you buy new and used. You can balance cost vs. potential reliability this way. CONS: More expensive than a DIY approach and you STILL have to learn about the TBI system. WHAT I DID: Since I originally purchased a turnkey system and then modified it after the fact, I consider my system a hybrid. Here is what I would recommend if someone asked me what type of TBI to install if they were thinking of doing the DIY approach. Your end result will be a TBI system with fuel AND spark control. Short Version: I would start out with a pre-made wiring harness and source all the other parts either from the junkyard or the parts store. Long Version: I would start out with a Chevy TBI Wiring harness. Several companies offer Chevy harnesses. You want the standard TBI harness WITHOUT electronic transmission control (usually 88-91) To start, you want one that uses the 1227747 ECM. When you order your harness, ask if it is labeled. That will be a huge help if it arrives with labels indicating which wire is which. Get one with the longest length possible. This will give you options when mounting the ECM in the cabin. It must be inside the passenger compartment as it is not weatherproof. PARTS: Here is a list of most of the sensors/parts you will need to buy new or from a junkyard: ALDL (Assembly Line Diagnostic Link) You can get this plug from the junkyard. ECM (Electronic Control Module) You want the GM ECM with Service number 1227747 on it. Any ECM with that number out of a V-8 equipped vehicle will work. The V6 vehicles have the same ECM, but use a different limp-home chip. It will work, but the limp home mode will be a little wimpy. Your engine will not have a lot of power in limp home mode. You can get your ECM from a junkyard. Before you leave with it, make sure it still has BOTH chips underneath the cover. A 10mm socket will aid in removing the cover to check this. The limp home chip (the smaller one on the right when you hold the ECM with the chips closest to you) is fairly expensive to buy new, so make sure you have one when you get your ECM. You can buy a set on eBay, however, but they are getting pricey. MAP (Manifold Absolute Pressure) Buy this used. They’re usually fine. New ones are semi-expensive. TPS (Throttle Position Sensor) There are two styles. You can swap the plugs if your throttle body doesn’t match your wiring harness. This may also still be attached to your junkyard throttle body. You can test it with an ohm meter. New ones are a little pricey, but not too bad. I recommend testing a junkyard version. Throttle body with injectors: Try and find one that will work with the stock throttle cable. If not, you can buy bolt on brackets from a parts store. Get this from a junkyard. New throttle bodies are EXPENSIVE. IAC (Idle Air Control) This may still be on your junkyard throttle body, but I recommend a new one. CTS (Coolant Temperature Sensor) Buy this new. It’s cheap enough. EST (Electronic Spark Timing) Buy this new. Used ones are iffy IMHO. ESC (Electronic Spark Control) and Knock Sensor: These are optional. Buy them new so that you know they are matched. The knock sensor is fragile and hard to remove intact. VSS (Vehicle Speed Sensor) This is semi-optional. It does have a CARB certification number, so it could help you pass emissions in your area! You can get one from Jaguars That Run. Click HERE. You want the # 2PRS. O2 Sensor: A single wire sensor is fine. New ones are inexpensive GM Ignition coil: You want the one with the two plugs on top. NOT the Ford style “TFI” coil. Fuel Pump Relay and Fuel Pump. You can get the relay in a junkyard. Get an intank fuel pump for a 1989 Chevy pickup. I referenced an 89 Chevy R3500 because I already own one. The Binder Plant Injection stickies have a link to an in-tank install that happens to show an FSJ installation! SES (Service Engine Soon light) aka Idiot Light. Any 12V light will work. I originally used an old side marker light and mounted it under the A/C ductwork. For a complete ECM pin-out list, CLICK HERE. (Page will open in a new window) Distributor Modifications: If you contact Affordable Fuel Injection, they will tell you that they can sell you a modified HEI distributor that will be usable for computer timing control. You don’t need to spend that kind of money. For probably less than $20 and an hour of your time, you can modify your STOCK distributor to trigger a GM ignition. No need for fancy and expensive HEI distributors. What you want to do is remove the centrifugal advance weights and weld the two shafts together so that the rotor will no longer turn independent of the distributor drive gear. Again, see the Binder Planet for pictures of how to dis-assemble your distributor. It is important to put the trigger wheel back on in the SAME orientation that it was originally installed. A permanent marker is useful for the task. Don’t have a small welder? No problem. Take it to a muffler shop or a welding shop and I’m sure they could do it for you fairly quickly. (That’s where the $20 comes in!) To get rid of the vacuum advance, you simply don’t hook it up. Problem solved. The stock AMC distributor uses a VR (variable reluctance) sensor which is perfectly compatible with the GM ignition module that controls the actual distributor timing. You will note that the Binder guys have to do all sorts of crazy modifications to their distributor. All we have to do is one simple weld and remove some guts. While you’re playing with your distributor, you will also want to change out to the larger Ford cap. This will allow your distributor to handle the computer controlled timing better AND will let you use the different plug wires required to connect it to the GM coil. I used MSD Streetfire plugs, Part # 5551. They are a universal set, so you can make the plug wires the exact length you need, not too long and not too short. MISC NOTES: From here on, the installation is just like any other TBI conversion. You can add the VSS at the transfer case. I tried to mount it behind the speedometer, but the connection is the wrong size. It fit perfectly on my NP-229 transfer case. I used the AutoProm from Moates to reprogram my chip and adjust the timing. I also have the G2X switcher which I intend to use to allow E85 (85% Ethanol, 15% gasoline). I plan on simply switching bins between three different tunes, one for regular gasoline (actually E10 in Colorado), one for a mix of regular gasoline and E85 and one for E85. There are several E85 stations in northern Colorado. The Moates AutoProm is easy to use. I bought the complete set with the TunerPRO license. One thing to make note of is that the 27SF512 EEPROM is a 64 KB chip. It is NOT A 512 KB chip as the name suggests. The 512 refers to 512 kilo-BITS!!! This is important when trying to set up a bin for stacking in order to use the G2x switcher! I was never good at hexidecimal, and it shows. I currently use the switcher during the tuning process. I load several different bin files with different settings. For example, if I’m adjusting timing, I’ll have 4 or 5 different bins with different timing advance on them in the area that I’m adjusting. I can simply switch between bins with the switcher and experience the difference. This works even BETTER than an emulator, as I can switch the bins with one hand while I’m driving. No need for a co-pilot! If you have any FSJ specific questions, head on over to the FSJNetwork.com forums and ask away! There are several of us who have GM TBI systems on our trucks.

GM TBI on an AMC 360/401 motor FAQ

Here I will try and address the common misconceptions and frequently asked questions in regards to upgrading to TBI (Throttle Body Injection) for your AMC 360/401 motor.

www.gearhead-efi.com has a wealth of information RE GM TBI systems. They are knowledgeable and friendly.

Read the FAQs. Ask questions. Once you have a good understanding of what’s going on and how everything works, your conversion will go much better.

I will not try to rehash what is posted there, but will instead focus on the issues unique to the AMC 360/401 motor that is found in thousands of Full Size Jeeps across the US and the world.

First, you need to decide what type of system you want. There are three different types.

TURNKEY TBI SYSTEMS:

Several companies make turnkey (ready to run, you simply install and go) TBI systems for AMC 360/401 motors. Howell and AFI (Affordable Fuel Injection) seem to be the most popular. Another “Custom” EFI seller is also out there, but he has a shady record of not delivering on promises and his product does not use the most popular GM ECM, the 1227747.

PROS:

Simple and quick to install. If you can install a stereo, you can install a turnkey TBI system. The only thing you might not be able to do is weld in the O2 sensor, but a muffler shop can do that for you inexpensively. You can install most of these systems in an easy weekend and be up and running with your TBI by Sunday afternoon. You don’t need any programming knowledge whatsoever. All you need to be able to do is turn a wrench and cut and splice together a few wires and hoses here and there.

CONS:

Friggin’ expensive!!! You get what you pay for, and in this case, you are paying for convenience and speed. Everything is done for you and you are paying for that service. Many of these systems do NOT control timing unless you pay (a lot) more money for that feature. Howell does now have one that is CARB certified for certain years, but it still does not have electronic timing control.

DIY TBI SYSTEMS:

Well, it’s really not a “system” if you are cobbling it together for yourself, now is it? If you are one of those folks who has more time than money, putting together a DIY system with junkyard parts is more inviting than paying lots of money for something you can (really!) do yourself.

PROS:

Cheap. Buying junkyard parts will save you tons of money. You can get a used TBI (just the throttle body injector unit) from a junkyard for about a tenth of the cost of a (usually) remanufactured TBI.

CONS:

It will take a lot of time and hard work on your part to round up all the parts. And some of the parts might be bad, but you won’t know until you plug them in. And by that time, your 30 day return might be up, so now you’re stuck with a DOA part that you can’t return or exchange. You need a good working knowledge of the GM TBI system to recognize the different parts so that you get the correct ones. If you are able to cannibalize one single donor vehicle, this is not as big of an issue. You will have to learn everything about the GM TBI system in order to successfully install a DIY system.

HYBRID TBI SYSTEMS:

If the whole DIY thing is too daunting, and the turnkey systems are too expensive, a hybrid system may be the answer for you. This technique involves sourcing some parts from the junkyard and some parts from retailers. The end cost might approach a Turnkey system, but your final system will be custom made for you and you can spread the costs out over time if you need to.

PROS:

Less work than a DIY approach, but cheaper than a turnkey system. You can select which parts you buy new and used. You can balance cost vs. potential reliability this way.

CONS:

More expensive than a DIY approach and you STILL have to learn about the TBI system.

WHAT I DID:

Since I originally purchased a turnkey system and then modified it after the fact, I consider my system a hybrid. Here is what I would recommend if someone asked me what type of TBI to install if they were thinking of doing the DIY approach. Your end result will be a TBI system with fuel AND spark control.

Short Version:

I would start out with a pre-made wiring harness and source all the other parts either from the junkyard or the parts store.

Long Version:

I would start out with a Chevy TBI Wiring harness. Several companies offer Chevy harnesses. You want the standard TBI harness WITHOUT electronic transmission control (usually 88-91) To start, you want one that uses the 1227747 ECM. When you order your harness, ask if it is labeled. That will be a huge help if it arrives with labels indicating which wire is which. Get one with the longest length possible. This will give you options when mounting the ECM in the cabin. It must be inside the passenger compartment as it is not weatherproof.

PARTS:

Here is a list of most of the sensors/parts you will need to buy new or from a junkyard:

ALDL (Assembly Line Diagnostic Link) You can get this plug from the junkyard.

ECM (Electronic Control Module) You want the GM ECM with Service number 1227747 on it. Any ECM with that number out of a V-8 equipped vehicle will work. The V6 vehicles have the same ECM, but use a different limp-home chip. It will work, but the limp home mode will be a little wimpy. Your engine will not have a lot of power in limp home mode. You can get your ECM from a junkyard. Before you leave with it, make sure it still has BOTH chips underneath the cover. A 10mm socket will aid in removing the cover to check this. The limp home chip (the smaller one on the right when you hold the ECM with the chips closest to you) is fairly expensive to buy new, so make sure you have one when you get your ECM. You can buy a set on eBay, however, but they are getting pricey.

MAP (Manifold Absolute Pressure) Buy this used. They’re usually fine. New ones are semi-expensive.

TPS (Throttle Position Sensor) There are two styles. You can swap the plugs if your throttle body doesn’t match your wiring harness. This may also still be attached to your junkyard throttle body. You can test it with an ohm meter. New ones are a little pricey, but not too bad. I recommend testing a junkyard version.

Throttle body with injectors: Try and find one that will work with the stock throttle cable. If not, you can buy bolt on brackets from a parts store. Get this from a junkyard. New throttle bodies are EXPENSIVE.

IAC (Idle Air Control) This may still be on your junkyard throttle body, but I recommend a new one.

CTS (Coolant Temperature Sensor) Buy this new. It’s cheap enough.

EST (Electronic Spark Timing) Buy this new. Used ones are iffy IMHO.

ESC (Electronic Spark Control) and Knock Sensor: These are optional. Buy them new so that you know they are matched. The knock sensor is fragile and hard to remove intact.

VSS (Vehicle Speed Sensor) This is semi-optional. It does have a CARB certification number, so it could help you pass emissions in your area! You can get one from Jaguars That Run. Click HERE. You want the # 2PRS.

O2 Sensor: A single wire sensor is fine. New ones are inexpensive

GM Ignition coil: You want the one with the two plugs on top. NOT the Ford style “TFI” coil.

Fuel Pump Relay and Fuel Pump. You can get the relay in a junkyard. Get an intank fuel pump for a 1989 Chevy pickup. I referenced an 89 Chevy R3500 because I already own one. The Binder Plant Injection stickies have a link to an in-tank install that happens to show an FSJ installation!

SES (Service Engine Soon light) aka Idiot Light. Any 12V light will work. I originally used an old side marker light and mounted it under the A/C ductwork.

For a complete ECM pin-out list, CLICK HERE. (Page will open in a new window)

Distributor Modifications:

If you contact Affordable Fuel Injection, they will tell you that they can sell you a modified HEI distributor that will be usable for computer timing control. You don’t need to spend that kind of money.

For probably less than $20 and an hour of your time, you can modify your STOCK distributor to trigger a GM ignition.

No need for fancy and expensive HEI distributors.

What you want to do is remove the centrifugal advance weights and weld the two shafts together so that the rotor will no longer turn independent of the distributor drive gear. Again, see the Binder Planet for pictures of how to dis-assemble your distributor. It is important to put the trigger wheel back on in the SAME orientation that it was originally installed. A permanent marker is useful for the task.

Don’t have a small welder? No problem. Take it to a muffler shop or a welding shop and I’m sure they could do it for you fairly quickly. (That’s where the $20 comes in!)

To get rid of the vacuum advance, you simply don’t hook it up. Problem solved.

The stock AMC distributor uses a VR (variable reluctance) sensor which is perfectly compatible with the GM ignition module that controls the actual distributor timing. You will note that the Binder guys have to do all sorts of crazy modifications to their distributor. All we have to do is one simple weld and remove some guts.

While you’re playing with your distributor, you will also want to change out to the larger Ford cap. This will allow your distributor to handle the computer controlled timing better AND will let you use the different plug wires required to connect it to the GM coil. I used MSD Streetfire plugs, Part # 5551. They are a universal set, so you can make the plug wires the exact length you need, not too long and not too short.

MISC NOTES:

From here on, the installation is just like any other TBI conversion. You can add the VSS at the transfer case. I tried to mount it behind the speedometer, but the connection is the wrong size. It fit perfectly on my NP-229 transfer case.

I used the AutoProm from Moates to reprogram my chip and adjust the timing. I also have the G2X switcher which I intend to use to allow E85 (85% Ethanol, 15% gasoline).

I plan on simply switching bins between three different tunes, one for regular gasoline (actually E10 in Colorado), one for a mix of regular gasoline and E85 and one for E85. There are several E85 stations in northern Colorado.

The Moates AutoProm is easy to use. I bought the complete set with the TunerPRO license.

One thing to make note of is that the 27SF512 EEPROM is a 64 KB chip.

It is NOT A 512 KB chip as the name suggests. The 512 refers to 512 kilo-BITS!!! This is important when trying to set up a bin for stacking in order to use the G2x switcher! I was never good at hexidecimal, and it shows.

I currently use the switcher during the tuning process. I load several different bin files with different settings. For example, if I’m adjusting timing, I’ll have 4 or 5 different bins with different timing advance on them in the area that I’m adjusting. I can simply switch between bins with the switcher and experience the difference. This works even BETTER than an emulator, as I can switch the bins with one hand while I’m driving. No need for a co-pilot!

If you have any FSJ specific questions, head on over to the FSJNetwork.com forums and ask away! There are several of us who have GM TBI systems on our trucks.