The Stovebolt Site Forums The Shop Area Engine Shop 235 running on fuel injection

My other thread was getting long so I will start a new one with the showing of the final product



all that is really left is to just load the tuning software onto my laptop and set the egr so that it will never come on. Currently it has a slight high idle, at about 900rpm. Im going to check for vacuum leaks as that can cause it to want to idle high.

If anyone is interested and as time allows I will post a list of everthing I used.

I think that we would all be interested. This is bringing the faithful 235 into the modern era.

you need to make a how to book with parts list and how its done it would be a best seller

I highly doubt that a book about it would be a best seller, but a Tech Tip on the Stovebolt pages would be well read. I'd appreciate you taking the time to write one as I'd like to do it to my '54 GMC when I get to the engine.

I would happily write up a tech tip for the stovebolt page, what do I have to do?

OK at the moment I'm working on a rough draft for the tbi conversion tech tip. During the process I took lots and lots of pictures and will have links to them in as many places as I can.

Nice demo Chris - thanks - what you're doing is really interesting to me and probably many others. It's a lot of extra work for you but a flight plan with pictures on that kind of a 235 mod would really help some of us get the most out of these great old in-lines. BTW - I really liked what was coming out of that muffler - looked pretty clean - Dale

Sounds healthy.

Nice.. Love the exhaust, You'll get the same thing I got with my flowmasters. Pull into a cruise or show, pop the hood and guys will be saying "wow that's a Six?" Great video look forward to the tech tip.
Mongo

Thanks guys



I worked on it a bit more today. Working out the bugs that come with doing something like this.

I believe its getting a bit more fuel than needed. It starts up nice, runs nice, revs nice but when I let it idle for a long period it starts to struggle. Nice thing about fuel injection is that it won't let the engine die. I took the air cleaner off and from the top you can watch the idle air control valve (IAC) coming to save the day. When the engine starts to see it struggle, it opens up the IAC and the rpms pick back up, then repeats and it continues to do this unitl I shut it off or rev it. Revs fine even when its doing this. Took the spark plugs out and they seem a bit wet, not horribly, but wet. The spark plugs are black, mostly because of the 4bbl. This week I'm going back to the u-pull-it yard and will pickup a 2.8L injector unit to see if it corrects the problem.

Also have to get a can of starter fluid to see if there are any vacuum leaks around the adapter plate I made to mount the TBI unit.

OK, have a question. Can't quite tell from just watching, but I was wondering if the computer fires both injectors at the same time or one after the other or ???

I was thinking, what would happen if I unplugged one of the injectors? I still plan to try the 2.8 injectors, won't get to the yard until saturday though.

Anything else I should try from the 2.8?


Did a bit of researching and comparing of my wiring diagram to a 2.8L V6 diagram from a 88-92 s10 and the wiring is the same, so when I go to the yard for the injector unit, I am also going to pickup a 2.8L computer.

This leads me to my next question, do I also need a 02 sensor from a 2.8 or will the one I have work and what about the map sensor, grab one too?

Ok did some more researching and thinking. The 3.1L which uses the same 2bbl tbi220 unit came in the 91-93 chevy lumina, 89-92 olds silhouette and 91-93 pontiac trans-sport. The wiring, like the 2.8 is also the same as the 4.3

I may buy at the yard 1 2.8 injector unit/pod, 1 2.8 computer, 1 3.1 injector pod and 1 3.1 computer and do some mixing and matching. A nice thing about the 3.1 computer is that it has a trigger wire for a cooling fan relay. Not sure if I should also get the 2.8 computer or not. The yard charges about $20 for computers. 3.1 is probably a bit closer than the 2.8 and the fan relay trigger is a plus.

I can try a few different combinations
4.3 computer with 2.8 injector pod
4.3 computer with 3.1 injector pod
3.1 computer with 3.1 injector pod
3.1 computer with 2.8 injector pod
3.1 computer with 4.3 injector pod
2.8 computer with 2.8 injector pod
2.8 computer with 3.1 injector pod
2.8 computer with 4.3 injector pod

anyone know or can get the specs on the 2.8, 3.1 and 4.3 injectors

not sure what sensors and that will interchange, I imagine the IAC, TPS and CTS won't make a difference, MAP might need to be changed and MAYBE??? the O2 sensor.

I also read somewhere that the vac port on the MAP must be pointing down. TRUE?

OK a little update

I changed out the 4.3 injectors for 3.1 injectors and the stumble/struggle at idle was less frequent. IAC still has to save the day and keep it from stalling, but not as much as before. BUT (and I found out something by using a computer tuner) when the engine starts to warm up and gets around 130degF the computer wants to start to lower the idle rpm from 1000/900 to 600. When it starts to do this, the engine struggles and stalls. Im still guessing to much fuel.

I have a few more things Im going to try and then Im taking the leap to MS. I want to try the 3.1 computer as well as the 2.8 injectors. Im not positive that these will fix it but I have to try.

Ive been talking to EFI-DIY about the MS system and will be buying the unassembled kit and the 746/747 adapter board if the above don't work. Nice thing about the MS is if I ever switch to a different engine (inline of coarse) the ms is adaptable. Total for the MS system comes to about $400.

My 261 with TBI from a 91 astro van with the 16144288 ecm and 5.0 throttle body runs fine with stock chip. It sounds like you have a vacume leak or a bad IAC. How does it run after you go closed loop ? is your O2 sensor in the exhaust from 3 or all 6 cylinders ? I'm running a 195 theromstat wich shows about 180 on my new tempature gauge and a heated O2 sensor. The unheated sensor would drop it out of closed loop at iddle.

I looked for a vac leak around the intake using starting fluid but didn't find any. Ive been thinking of the IAC and plan to grab a few the next time I go to the yard again.

Well all I know is when the engine gets warmer, and the computer tries to lower the idle rpm and it stalls.

28chevys, you got me thinking, maybe my problem isn't that Im getting to much fuel but Im actually not getting enough. A 261 should be close to a 4.3L V6 262ci but you said you have a 5.0L throttle body on it with a 4.3L computer and it runs fine with the stock chip. Did you try it with the 4.3L throttle body and it did not run quite right? Maybe I should also try a 5.0 throttle body with the 4.3L computer?

But before I do, Im going to check all the sensors and make sure they are within spec.

I picked up a 3.1L computer and plan to see what happens when I mate it with the 3.1 injectors. My plan now is to also try it with the 4.3L injectors.

oh yeah, the O2 sensor is mounted after the rear header.

Set the timing to zero (pointer and ball bearing on flywheel match up)

Installed the 3.1L computer and left in the 3.1L injectors. Let it idle until it got up to around 190 degrees and actually did better than I expected. Has a slight fluctuating idle but not bad. Idles around 800. The next time I have a chance Im going to experiment a bit more. Plan is to try both the 4.3 and 2.8 injectors with the 3.1 computer and see how it goes. Still wondering about the 261 running better with a 4.3 computer and 5.0 injectors. Maybe I will have the same outcome with the 3.1 computer and 4.3 injectors.

will see!!!

The 4.3 and 5.0 tbi injectors should be the same flow. The 4.3 tbi that I started out with had a problem with the IAC so I used a 5.0 that I had. You never know if the used parts you pick up are good. Did you set the timing with the bypass open ?

yes ive been setting the timing with the bypass plug disconnected.

The Throttle position sensor checks out fine, the map sensor I'm not quite sure on. I get 5.1 volts across terminals A (sensor return/ground) and C (sensor 5v reference), which seems correct. Across terminals A and B (sensor signal to computer) I get like 4.2 volts. Across terminals C and B I get about .3 volts. All this is with the key ON and engine OFF. From the testing procedure that I got off of a automotive repair site, this is backwards.

I have to test the IAC valve yet.

More than likely I will just end up purchasing a new MAP sensor anyways and getting a few IAC valves at the local yard.

Actually according to this TBI swap, the 5.0 injectors have a 5 lb/hr less rating than the 4.3 injectors http://www.rowand.net/Shop/Tech/SlantSixTBISwap.htm

the table itself
http://i175.photobucket.com/albums/w124/rockfan1815/injectorratings.jpg

I've seen the injectors listed at the same flow and at higher flow 40 for 4.3 and 45 for 5.0 but never lower for the 5.0 . I tried the 5.0 injectors and a diffrent IAC in the 4.3 throttle body and still had iddle problems. I think the throttle body in was bad inside. I might try the 4.3 injectors in the 5.0 throttle body some time and see how it runs. Most of the diffrence should be at warm up before closed loop and at wide open throttle.

UPDATE... I believe I'm getting closer, a computer tune may be needed still but I'm a bit more satisfied. I am now using the 3.1L computer with the 4.3L injectors. Seems OK

:::A run down of what I'm using:::
-Clifford 2/4bbl aluminum intake
-custom made TBI adapter
-4.3L TBI unit off of a 88-92 4.3L V6 w/ Throttle Position Sensor and Idle Air Control Valve
-Manifold Absolute Pressure sensor
-Coolant Temp Sensor
-O2 sensor (1 wire)
-Knock sensor
-Electronic Spark Timing module (for use with Knock Sensor)
-GM 250 Inline 6 modified H.E.I. distributor (vacuum and mechanical advance removed and locked down)
-Electronic Timing Control module (wired to distributor for computer controlled timing)
-3.1L V6 TBI computer from a 88-92 Chevy Lumina Van (or similar)
-External mount electric fuel pump (Using a Carter P5001 pump made specifically for TBI conversions, and is a siphon type pump meaning it can pull the fuel and not just push)

Some good links for those looking into going this route
http://www.bustedjeep.com/projects/junkyardtbi.asp - this link was very helpful to me and is a good how-to

http://www.championparts.com/tbi_applications.pdf - this link would be good for those wanting to use multiple tbi units. For instance using a dual carb manifold with two 1bbl injector units.

http://chevythunder.com/gm_throttle_body_injection_pg_1.htm - a link with a list of different TBI computers and their applications

http://chevythunder.com/1227747_ecm_198892.htm - a very useful wiring diagram

http://forum.ih8mud.com/hardcore-corner/106273-where-start-gm-tbi-conversion.html - another TBI conversion thread

A bit of a update on this. I have not given up on this, I just recently in the last 3 months started working on my truck again after taking a break for about a year it seems. Othe hobbies took over, almost to the point of complete lost of interest in the truck and going as far as listing the truck for sale. After I listed it for sale I started working on it and decided to keep at it.

When I stopped, I had the 3.1L computer, a 4.3L throttle body unit and injectors and was quite happy with how it ran. Truck never seen pavement yet so I can't say much more about that. At startup the truck idled ok, started with a bit of a high idle (about 1000rpm) and as normal would start to drop the idle to about 700rpm. Problem was when the idle dropped and the computer started to lean it out at idle the computer would have to give it a bit of a jult (Idle air valve would open and idle would increase slightly) to keep going.

Just recently I picked up a few things to try out. I grabbed a TBI unit off of a 3.1L at the local u-pull-it yard. The 3.1L TBI unit has smaller throttle openings then the 4.3L (1-3/8" compared to 1-11/16") and also a lower flow rating for the injectors (33lb/hr to 40lb/hr).

First I tried the 3.1L computer with the 3.1L TBI unit and 3.1 injectors. Result - would not idle at all. Started fine but if throttle left unattended it would die instantly. Guess is too lean of a mixture.

Then I tried the 4.3L computer with the 3.1L TBI and 3.1L injectors. Result - same as above but not as bad, but still would not idle. Probably because the 4.3L computer has a longer injecter pulse width then the 3.1L computer so it wasn't as lean.

Next I left the 4.3L computer hooked up, but instead used the 4.3L injectors on the 3.1L TBI. Result - much much better, idles very nice, starts at 900rpm and as the engine warms up and the computer starts to lower the idle rpm and lean out the fuel it goes down to about 650rpm.

This time around I'm getting technical. Using a ALDL to usb cable and diagnostics program called WinALDL loaded on my laptop so I can monitor the computer and see whats going on. From reading different forums online about tuning I know I can find out if I'm running lean or rich by monitoring the BLM table, a number above 128 means the O2 is seeing a lean mixture and below 128 its seeing a rich mixture.

I've also come to realize that the stock computers tune just isn't going to do. So from doing some research on thridgen.org (camaro forum), they have a few computer tuning forums. http://www.thirdgen.org/techboard/diy-prom/ & http://www.thirdgen.org/techboard/dfi-ecm/ I found a few options for tuning. First option (which is what I'm going with) is an adapter from moates.net, since the eprom thats used in the earlier GM computers require expensive equipment write to, this company has came up with an adapter to use a later flashable chip. A little solder work is required but for $135 for all thats required its probably the cheapest option out there. Parts needed:
http://www.moates.net/g2-memory-adapter-060-leg-spacing-p-36.html?cPath=64 - adapter gets soldered onto the board after the old 24 pin socket is removed
http://www.moates.net/s2-aries-28pin-zif-socket-p-44.html - 28 pin socket
http://www.moates.net/c2-sst-27sf512-chip-p-39.html - new flashable chip
http://www.moates.net/burn2-chip-programmer-p-197.html?cPath=64 - used to burn or write the program to the new chip

The other option, also requires a bit of soldering is the EBL flash.
http://www.dynamicefi.com/EBL_Flash.php
It replaces the part of the GM ecm where the eprom or memcal and calpak reside with a new board that allows you to flash a new program through a serial data cable, so no need to remove the chip to program. Also includes datalogging and the way I read it the ability to have multiple tunes that you can switch back and forth using the software or a switch. This option was a bit more at $350. I liked this the most but wanted to keep this project as low cost as possible. I have not read any negatives with either route so I shouldn't have a problem.

I also came across a program that will take a saved datalog file from WinALDL and make the changes to the bin file(ecm file that is burned/written to the eprom/chip) for you. That program is called ALDL to BIN

On top of that I am using another program called TunerCATS to edit the bin file to disable the egr valve and maybe a few others. I can also use this program to burn/write the new bin file to the chip.

To also help I purchased a Innovate Motorsports LC-1 wideband O2 sensor kit so I can monitor the air/fuel ratio more closely.





The thing I need to figure out is what TBI unit would be better. I'm thinking I should switch back to the 4.3L TBI unit so everything matches. 4.3L computer, TBI unit and injectors then start tuning. When I open the throttle when using the 3.1L TBI unit just the sound of the air rushing in sounds restrictive.

I'm going to post a picture soon and ask were would be best to mount the O2 sensor. Im not certain the location I have it at now is the best place for it. And I may end up changing the narrowband O2 sensor to a heated version. I don't know if its OK to always run using the LC-1 wideband kit.

This is currently where I have the narrowband O2 sensor. Just a stock GM replacement that goes to the ecu.
http://i175.photobucket.com/albums/w124/rockfan1815/final%20tbi%20conversion%20pics/100_0862.jpg

I was wondering if it would be better to mount it closer to the header or in the header at the collector.
http://i175.photobucket.com/albums/w124/rockfan1815/engine/100_0094.jpg

Anyone have a part number or a car I can use a heated O2 sensor from.

Thanks