I got my custom TPI conversion done-update- distributorless ignition

[Blue85]

I haven't been on the boards for a while because I have been busy .

This post will seem long, but it's actually a very quick run-down of my project.

I started collecting parts months ago to run Tuned Port Injection with a DIY engine management system - Megasquirt. If you don't know what Megasquirt is, head on over to http://www.megasquirt.info/index.html. It's basically an open source project to build your own ECU. The schematics and source code are all readily available so you do everything yourself to run a K5, car, lawnmower, whatever. This was much more complicated than a standard TPI swap, but in the end it gives me the flexibility to do whatever I want in the future and it was actually low-cost.

I built the ECU to do fuel and spark, including idle speed control. The TPI hardware is from an 85 f-body that I got cheap off ebay. I plugged off the cold start injector stuff because it is lame. I built the harness from scratch using TXL wire and Delphi connectors/terminals/seals. I had the whole system including the ECU, harness, electrical center, intake, sensors, fuel tank, fuel pump, etc., running in the garage before I ever yanked the carb off.

I locked the stock HEI distributor down so that it doesn't have any advance at all. The ECU calculates timing and drives the coil directly, so there is no module in the distributor.





For fuel delivery, I used a 90 Blazer fuel tank, sending unit and fuel lines. However, the throttle body lines snake up the back of the engine and the TPI fuel rail connetors are on the front, so the last section of fuel line was replaced with SS braided teflon flex hose. The TPI lines were cut off and flared to make this work.





The fuel lines adapters at the front were very hard to get on and are not very pretty. Since then, I pickep up some fuel rail to AN-6 adapters from Earls, so I will eventually change this over.



A few weeks prior to doing the changeover, I installed this electrical center, to hold all of my under-hood fuses and relays. Before going MPFI, it handled only the electric fans and the A/C. I built a sealed 8-way connector into it so that I could simply plug the ECU harness into it when it was swapped in. Now it handles the fuel pump, the ECU, the O2 sensor, the injectors, the fuel pump and even the stereo. I thought it was messy before when I had 3 relays and 1 fuse mounted to the firewall. I can't imagine how messy it would be with the FI setup without an electrical center like this. I holds 7 relays and lots of mini and maxi-fuses. I think I got it out of a mid-90's Ranger, but I re-did all of the connections inside to suit this application. It's mounted near the passenger side fender, in front of the blower motor.





Here is the ECU and the mostly-finished harness. The harness feeds through the firewall via the hole originally used for the ESC harness. The ECU connector is a DB37 and there are connectors coming off for the 8 injectors, TPS, MAT, CTS, and the electrical center. The VR distributor pick-up coil is done through shielded twisted pair and the ignition coil drive is with coax.



To make tuning easier and allow fuel savings, I used a wideband oxygen sensor from Innovate motorsports - the LC-1. In case you don't know, a standard (narrowband) oxygen sensor is almost like a switch, indicating rich or lean, but not really by how much. A wideband sensor tells you the actual Air/Fuel ratio from <10:1 to >20:1, so you know what is actually going on. I also added an A-pillar triple gauge pod and there is an A/F gauge in there. I measured the response of the gauge on the bench and calibrated the second output of the oxygen sensor to match so that I can read true A/F ratio while I drive.



Here is the lower intake installed where the carb and cast iron used to be.



Here is the system mostly installed. I am using all of the stock accessories (non-serpentine), so I had to modify the alternator and A/C brackets to fit it all together. You can also see the WBO2 controller mounted on the evaporator box. I may fabricate a cold air intake system later, but the open filter was by far the easiest way to get things going.



I won't even go into all of the things I had to solve to get it running now. There are still a few bugs to work out, but I am driving it to work every day and it runs pretty good. When I get the higher load part of the fuel map done, I will adjust my new throttle cable so that I can get more than 80% throttle.

Here are some screen shots of the tuning software. Not only can you set it up to control anything via a laptop (assuming you know what parameters to set), there are even algorithms to automatically improve the tuning of the car while you drive. You can set these gauges to display ANY engine parameter that is measured or calculated. You can also log the data to analyze later what was going on. You can do that with OBDII or OBDIII cars with Autotap, but that costs more than this whole ECU and this software is free (plus open-source).

The three main tables are Volumetric efficiency, Spark advance and target air/fuel. Each is 3-D with manifold pressure on the y-axis and rpm on the x-axis. The idle control, warmup enrichment, acceleration inrichment and basically everything else imaginable is all tuneable.

 

[PeteH]

i wish i had the balls to do megsquirt. i made one of those hook up deals to read with my laptop/the realtime data logging, but i wish i could program stuff. your stuff is looking awsome!

 

[GillBill]

very cool. I am researching TPI for my 1st gen. I am building a 388ci stroker. How difficult do you think it will be to dial in a TPI setup for that motor? I am building it for low to mid-range power. very Cool post though.

 

[sled_dog]

what is a MAT sensor? I just can't place it...

 

[dyeager535]

what is a MAT sensor? I just can't place it...

Manifold Air Temperature also known as IAT, Inlet Air Temperature.

Car TBI and TPI use that, TBI trucks didn't. (at least our trucks)

 

[sled_dog]

Manifold Air Temperature also known as IAT, Inlet Air Temperature.

Car TBI and TPI use that, TBI trucks didn't. (at least our trucks)

Thought so but wasn't sure...


so you are tuning purely off of Inlet Temperature and O2 readings? Seems an after the fact style of tuning. What about an MAF or MAP? Megasquirt doesn't use either?

 

[Blue85]

You can get TPI to work on a 388, but it will require tuning no matter what. You can burn PROMs for the stock setup if you have the right stuff, but you will have to learn how or get somebody who knows. If you did Megasquirt, tuning would be as easy (or as hard, depending on your viewpoint) as with any other engine.

I guess the TPI is kind of restrictive for the high end. I opened up my plenum to help, but with a 388, you might consider aftermarket base, runners and maybe throttle body. Of course, that costs about as much as an aftermarket EFI system. If you don't plan to rev the engine high, it might not be a big deal.

 

[Blue85]

so you are tuning purely off of Inlet Temperature and O2 readings? Seems an after the fact style of tuning. What about an MAF or MAP? Megasquirt doesn't use either?

Megasquirt has a MAP sensor built into the ECU. Typically installations run speed density (like I do), but if you have a radical cam, it can run Alpha-N, where it looks at throttle position and rpm to estimate air flow through the engine.

 

[sled_dog]

Megasquirt has a MAP sensor built into the ECU. Typically installations run speed density (like I do), but if you have a radical cam, it can run Alpha-N, where it looks at throttle position and rpm to estimate air flow through the engine.

Seems like a very after the fact way of tuning... hmm said that twice now. I mean you wouldn't see problems until they are well into existence and wouldn't see the fix until it too was well done.(though this is all over ms not long term).

How does the Megasquirt have a MAP sensor built in? You pipe a vacuum line to the ECU?

 

[Blue85]

How does the Megasquirt have a MAP sensor built in? You pipe a vacuum line to the ECU?

Exactly.

This eliminates electrical noise picked up on the harness. The response of the vacuum signal is also very fast, even if you have meters of hose.

There is also a provision to add a second MAP sensor, so that you can do continuous barometric correction. This one wouldn't even need a vacuum line.

 

[shepdog]

That seems complicated unless you are some sort of mechanic or engineer. Do you think a stock set up with a burnt chip from S+P would be less complicated?

 

[dyeager535]

Seems like a very after the fact way of tuning... hmm said that twice now. I mean you wouldn't see problems until they are well into existence and wouldn't see the fix until it too was well done.(though this is all over ms not long term).

What do you mean by this? All tuning is "after the fact", no engine is the same, all benefit from individual tuning, and you have to see what the engine likes to know how it needs to be tuned. Again, maybe you meant something else and I don't understand. MAF or MAP are this way.

Kind of like setting timing by advancing until it pings, then backing off. That doesn't really "tune" the timing, it just gives you maximum advance. Timing "under the curve" is ignored, as is the fact that running as much timing as possible doesn't mean best performance.

 

[Brians89K5]

im getting ready to do this to my TBI truck but I don't think Ill need to run the mega squirt setup. Nicely done. I look forward to hearing how it runs once you work all the bugs out of it.

~Brian

 

[dyeager535]

That seems complicated unless you are some sort of mechanic or engineer. Do you think a stock set up with a burnt chip from S+P would be less complicated?

You need to learn about the system, how it operates, and what needs changed to get where you want to be.

The only other option is to pay someone else to do the same thing for you. I guarantee that not everyone who sells "chips" on the internet is an engineer.

Having someone randomly burn a chip based on engine specs is a recipe for disappointment. (dyno tuning or sending datalogs before/after a chip are better)

 

[GillBill]

How much did it cost you to set up your engine (outside of the cost of the initial tpi setup)

 

[sled_dog]

What do you mean by this? All tuning is "after the fact", no engine is the same, all benefit from individual tuning, and you have to see what the engine likes to know how it needs to be tuned. Again, maybe you meant something else and I don't understand. MAF or MAP are this way.

Kind of like setting timing by advancing until it pings, then backing off. That doesn't really "tune" the timing, it just gives you maximum advance. Timing "under the curve" is ignored, as is the fact that running as much timing as possible doesn't mean best performance.

true, see I wouldn't be happy only knowing what the engine is puting out. I'd want to know MAF readings or Vacuum readings as well. I like the idea of the MAP mounted in the ECU. Makes sense, everyone just mounts the MAP sensor close because its easy I'd say.

There are MAP sensors with built in BARO sensors, maybe you could use one of those inside the ECM.

 

[dyeager535]

My understanding of the MAP sensors is that they ARE baro sensors, they compare ambient pressure with engine pressure, thus they adjust to altitude changes.

The O2 sensor (especially wideband) allows you to know that what the ECM/PCM is doing to control the engine, is happening correctly, and at the right times. That's where the software previously mentioned comes in...it essentially roughs in the tuning for you. Tuning (and fine tuning) over the whole curve takes time.

 

[Blue85]

My understanding of the MAP sensors is that they ARE baro sensors, they compare ambient pressure with engine pressure, thus they adjust to altitude changes.

Remember, MAP = Manifold Absolute Pressure (i.e., not relative).

Yes, an ECM can compensate for altitude changes with only 1 MAP sensor, but you have to turn the engine off to do it. As long as the engine is running, atmospheric pressure is unknown. You store one value for atmospheric pressure during start up (after the ECM has power, but before the starter is engaged) and use that value for all of your calculations to follow. If you have two sensors, you have both baro and manifold in real time for your calculations.

I don't think this is a major problem unless you drive up and down mountains everyday. I suppose it's only critical if you are racing Pike's Peak or something . It could also be a problem if the ECU is resetting while you drive, or maybe if you push start a vehicle with a manual transmission because the battery is dead. The ECU can come up very fast, but who knows what pressure it measures while doing it.

 

[sled_dog]

screw it Blue85's explanation is better, ha.

Like I said, I know there are MAP sensors that also contain BARO sensors, but don' know of any examples. Its likely more common than I realize at this point.

 

[lamberthkp]

that's some good work im still working on all this tbi mess on my blazer be glad when im done.