Chevy 4.3L TBI install onto a 2F
Fuel injection! It works in hot weather, cold weather, at 0Ft, at 10,000Ft, even upside down...well almost. I have run my 2F with the Weber 32/36 and a rebuilt stock 2bl. Both work pretty well, although the Weber definitely uses more fuel. Anyway, I wanted a little more power, more drivability on and offroad, and maybe slightly better mileage (if it is at all possible from something shaped like a brick). Fuel Injection is really the only way to get all that (besides I can't adjust a carb for my life - pathetic). Anyhow, I have seen a few kits most of them custom. Custom worries me. Sounds unproven, hard to get parts, and usually expensive. What I was looking for is something proven, inexpensive, off the self parts, and of a closed looped design. I heard of a kit from Downy that uses the Chevy 4.3L V6 motor TBI. Hmmm. Proven, check. Inexpensive (TBI), check. Off the shelf (heck out of the junk yard even), check. closed loop (uses an O2 sensor), check. Ok I was sold so I got the kit and here is how the install went:
TBI unit - A Chevy 4.3L one. Can be found in S-10, Astro Van,
and probably some other type of vehicles during 1978-87.
Chevy TBI/Toyota intake manifold adapter
Computer - GM computer #1227747
O2 Sensor (heated is three wires, non heated is one wire)
Water Temp Sensor
Fuel Pump w/ Filter
Check Engine Light - 12v light
2 x 10A Fuses
Ignition Module - GM #10482827
Electronic Spark Control (ESC)
Coil - GM # 1115315
Distributor - Toyota LC '78-87
Vehicle Speed Sensor (VSS)
This is what the kit fom Downey included:
The most important parts are the Aluminum cast adapter for the TBI to the intake manifold (at the very top of picture) and the VSS (lower right corner). Not as important but good to have is the metal plate that also mounts between the TBI and intake manifold. All the other parts are off the shelf Chevy parts.
Installing TBI Unit:
This went pretty smooth. I just had to make sure everything had clean mating surfaces. One thing I did find was that you have to use 12mm nuts, (wrench size) as seen in picture three. If you use 13mm they will hit the side of the cast adapter. Starting with the manifold I cleaned 'er up real nice w/ a 3M sanding wheel (I also did this to all the other surfaces). First the carb insulator goes on the manifold, next the Downey cast adapter, then the Downey steel plate, and finally the Chevy TBI unit.
I installed this in the glove compartment. I figure it keeps it out of the weather and is also fairly easy to get to. Right now it is being held in there with double sided tape.
Installing O2 Sensor:
Yea I know not the best place to put it. It would definitely fit better on top of the header collector as well as be protected up there. Since I did not have a welder I had to have a shop do it and they were not able to get at it from the top. This just gives me an excuse to get a MIG welder for home so I can fix it . :-) Drill hole, weld in adapter boss for O2 sensor, screw in sensor. The picture shows the one wire. During my post install troubleshooting time I changed it over to a heated three wire one. Didn't really help "the problem" at the time but seamed to get into closed loop mode quicker after start up.
Installing Water Temp Sensor:
I placed the FI water temp sensor (with its adapter) in the hole where the Toyota stock one went. I moved the stock Toyota water sensor over to where the water for the heater comes out.
Installing MAP Sensor:
The only rule here is to make sure it is above the TBI unit. I also heard that the outlet should be pointing down so condensation and other crap don't inside the sensor
Installing Fuel Pump and Filter:
I put the fuel pump as close to the tank as possible but also made an efferet to keep it out tof the way so it doesn't get damaged. I also put an inline fuel filter between the pump and the tank.
Installing Check Engine Light:
This is a little red 12v light that is connected between A5 of the computer and to 12v.
Installing ALDL Connector:
This connector is used to hook up a scanner so as to be able to read data from the computer concerning engine functions and status. In the Chevy vehicles this is usually under the dash board somewhere. I decided to put it over here in the corner of the engine compartment so I could hook up the scanner to it and see it while I am playing with stuff or troubleshooting stuff in the engine compartment. The scanner that I use has a wire that is long enough so that it can reach from the connector to inside the vehicle through the window.
Installing Fuel Pump Relay:
I placed this in the back of the glove compartment to keep it out of the weather. The relay is not in a waterproof holder.
Installing 12V on all the time Fuse & during start and run Fuse:
I installed these two 10 amp fuses in waterproof holders here so they would be easy to get to and to troubleshoot if need be. I figured if I put them in the glove box they might get buried with all sorts of other crap that I might put in there.
Installing Ignition Module:
This is in the HEI distributor.
Installing Electronic Spark Control (ESC):
I mounted this on the firewall right near the distributor which also has the ignition module in it.
This is also in the HEI distributor.
The GM Computer and Ignition module will take care of retard and advance functions of the distributor. Thus we need to remove the stock Toyota vacuum and mechanical advance. Remove the cap and rotor. Mark the breaker plate (arm connects to it) to the outer ring so that at the end you can assembly the plate back to its resting state. Remove the VA arm from the breaker plate and then the whole VA unit from the distributor. Dig out the rubber plug on top of the distributor shaft and then remove the philips screw underneath it. Remove the upper distributor shaft and then the weights and springs. Place the upper distributor shaft back and install the philips screw and rubber plug back on the top of the shaft. Finally tac weld the breaker plate to the outer ring so it doesn't move. I guess you might be able to use JP Weld instead of the tac weld.
During my troubleshooting stage I feared that this mod to the distributor might be causing problems because there was just a little bit of slop between the rotor and the gear. I heard through the grape vine that that there was a shop (Performance Distributors) that made an HEI w/ mechanical retard/advance that had been modified to fit in the Toyota block and came with the proper metric gear. Not real big news since Mudrack Custom Cruisers has been selling this item for a awhile. What caught my interest was a thought that maybe Performance Dist could make a HEI with the stock Chevy ignition and pickup sensor still installed but would also fit in the Toyota block and come with the metric gear. No problem they said.
This item I got from Downey and it installed very easily. I have now heard that a VSS can also be gotten from JTR. According to others, that are more knowledgeable in this then myself, the computer is not very touchy about the speed signal. Just as long as it is getting a 2000 pulse per mile speed signal so as to show that the vehicle is moving or not moving.
This is were the real work went in. I had a heck of a time getting the harness out of the vehicle without ruining it. I ended up just cutting all the sensors and computer out with 6 to 12 inches of wire leads on them. I got a Chiltons manual for '82-'92 GM S10 Pickups and just followed the schematic. Using the maunal I spliced in the wires to make the harness in the vehicle. I soldered all the connections hit them with some liquid electrical tape and then shrink wrapped them. In retrospect I should have just ordered a whole new FI harness from Painless Wiring. Splicing in all those wires and making sure all the connectors were ok and correct took a long time. Everything usually seems to come down to time or money.
Hmmm what to do with this. I had an old canister filter from an early 70s cruiser as well as a HJ60 one. Well the HJ60 just didn't fit in the engine compartment but I really liked the dust collector it had. What I need is a combination of the HJ60 one and the early 70s one. A quick trip to Butch Built and the problem was solved. I also added an ARB Snorkel to complete the air intake system.
Post Install Problems:
First time I turned it over it worked! I then got in and drove it around a little. Eeeek! It started to sputter and even backfired a little. What the F. It ran a little better when the motor was fully warmed up but really ran like crap while it was warming up.
Well it took me a little bit of troubleshooting (replaced the modified toyota dist w/ a HEI, switched the the O2 to a heated one, these really didn't fix the problem) to find out that the problem was in the EPROM. What the heck is in the EPROM that is so important? Well inside the PROM are tables for just about everything the FI does. How much fuel and spark it delivers at different pressures, temperatures, throttle settings etc. All this are in maps so to speak. Great how the heck I am supposed to read them?
Well I found a mailist (diy-efi), they got one for just about everything I guess, the deals with do it yourself fuel injection. I logged in and asked a whole bunch of questions and found out that even though the Chevy V6 4.3L motor is pretty close in size to the Toyota I6 4.2L motor their fuel and spark requirements are very different. Face it the Chevy is a later and more efficient design then the Toyota I6. Just look at the intakes for each of the cylinders on the Toyota. Cylinder 3 & 4 are way shorter then 1 & 6.
Anyhow I got a scanner (GM OBD-I) to hook up to ALDL connector to see what the heck the computer was seeing while it was running. I hooked up the scanner drove around and took a whole mess of readings at different speeds and throttle settings. One of the more important readings the scanner provides is for the block learn codes. In a nut shell these codes reading tells if the computer is having to adjust for a lean or a rich running motor. Well all my codes indicated weather the motor is running real lean or rich. Ah now we are getting some where. Now I needed to read what was in my EPROM as far as the "maps" are concerned. I found a company (Tuner Cat) that makes a nice windows viewable package for decoding the "maps". Great now I needed a way of getting the program out of the PROM and into a format ( .bin) that the Tuner Cat program could read. The Pocket Programmer seemed to fit the bill so I got it. Now I can read and program PROMs as well as decode and modify the program that goes in the PROM. Well I took some readings, modified the maps, programmed the PROM and tested then test drove it. I repeated this over and over again. The motor got better with every reprogram but it was not just right yet. Luckily I found someone on the diy-efi list who had already gone through all this testing and reprogramming and he gave me a copy of his to try out. I did and wow! Now it drives great. If you have problems with programming your PROM let me know and I will give you a hand.
So there you have it. If you try this and get different results or make a better PROM let me know and I will update this page. Good luck.