My TBI adventure...so far

[fyresq]

The E8153 was definately a mistake and I am replacing it - totally inadequate pressure. I will post an update on that as soon as the new pump is installed.

It's kinda weird that people have actually had success with them.....mine was so underpressured that it was ridiculous. And the Carter is worse! IIRC, the Howell Injection pump is a walbro rated at around 30-35psi and you can order it right off their site for about $125. A little pricey but you get the confidence that it has been tested and tried. Good luck!

 

[cruiser enthuiser]

Hey Fyresq...which Carter pump are you referring to? I've seen a couple different models recommended for TBI. I may have already purchased a Carter as a replacement. I'm reluctant to admit it though if it's the one you said you tossed.

 

[cruiser enthuiser]

Update

I have been trying to work out some of the bugs since I first got it started. It starts very easily, which is very satisfying but there's a few issues. For starters, the fuel pressure was totally inadequate. When running the E8153 I was getting only 10 PSI at idle and with the pedal down it dropped to 8-9 PSI. As a replacement I got the Carter P5001. It is rated for 20 PSI max, designed specifically for TBI supposedly. The cheapest I found it was $115 from Parts America (Kragen locally). Right out of the box it appeared to be a much higher quality unit. When I got it connected I was getting a strong 12 PSI. Not exactly where it should be, but better.

I also realized I hadn't made any arrangement for the oil pressure sender for the dash guage. I had to pull the distributer and install a tee that would allow me to run the TBI sensor and the sender. While I was trying to pull the sensor the brass fitting broke off in the block . Another trip to the parts store for an extractor kit and I manged to get it out. Now I have a functioning oil pressure guage .

 

[cruiser enthuiser]

So, what to do about only getting 12 PSI? I understand that TBI should run a strong 13 PSI. I just couldn't believe that the new fuel pump was not performing. After some reading I came to understand that the fuel pressure regulater on the throttle body unit can cause a drop in PSI with age and wear. Since my unit is 21 years I figured it was a likely culprit and due for a rebuild. I ordered a TBI rebuild kit from Ebay for about $40. The throttle body is very simple. It only took 2-3 hours to break down the unit, carefully clean it and reassemble. Notice in the picture the old, worn diaphragm from the pressure regulator next to the new one.

 

[cruiser enthuiser]

Here's a pic of the throttle body reinstalled. I primed the pump, fired it up and checked the fuel pressure guage....13 PSI .

 

[cruiser enthuiser]

Problems Persist

Unfortunately, all is not well. It runs fantastic for several seconds after start up and then begins to idle very rough. RPM's bounce all over and often it nearly stalls. I'm sure I've finally got the timing right. It is not throwing any error codes and I am seriously stumped. I'm wondering if it's the IAC - idle air control??. Anyone got thoughts? Just to help diagnose I am posting up this video. As always, any help is appreciated!

 

[eg40]

Sorry I don't have an answer but have enjoyed your post. also thanks for the links you posted last time for the wiring diagrams they helped out alot. any way I have mine all bolted on adn think I have it wired right but wanted to ask you first before putting power to it. 1) where did you connect the fat pink wire coming off the coil. 2) the orange and tan white wires that come off the oil sending unit. I put the org to 12v and the tan white to the fuel pump. 3) I put the pink black wire to a key on power sorce other than that I think I am ready to try and fire the beast up. thanks again for your help and your good write up.

 

[cruiser enthuiser]

Unfortunately, all is not well. It runs fantastic for several seconds after start up and then begins to idle very rough. RPM's bounce all over and often it nearly stalls. I'm sure I've finally got the timing right. It is not throwing any error codes and I am seriously stumped. I'm wondering if it's the IAC - idle air control??. Anyone got thoughts? Just to help diagnose I am posting up this video. As always, any help is appreciated!

I replaced the IAC valve with a new one last night. Found it on-line at Rock Auto for about $27. Much, much better now! Idle is very steady . However, I'm not convinced my timing is right. I'm go back and try to determine TDC and start over.

 

[cruiser enthuiser]

Sorry I don't have an answer but have enjoyed your post. also thanks for the links you posted last time for the wiring diagrams they helped out alot. any way I have mine all bolted on adn think I have it wired right but wanted to ask you first before putting power to it. 1) where did you connect the fat pink wire coming off the coil. 2) the orange and tan white wires that come off the oil sending unit. I put the org to 12v and the tan white to the fuel pump. 3) I put the pink black wire to a key on power sorce other than that I think I am ready to try and fire the beast up. thanks again for your help and your good write up.

As I recall all the pink wires go to an ignition-hot fuse and the orange to an always hot fuse. Sounds like you got the fuel pump wired correctly. Good luck starting it up! I have come to realize that installing all the componenets for TBI and getting it to run was only about half the work. The other half has been getting it to run right! I am considering ordering (or making) an ALDL cable and downloading WinALDL for my laptop so I can really see what's happening inside the mind of that little computer .

 

[terrx]

To make it run well, knowing what's going on in the ECM is a must. To make it run really well, eventually you might want to learn to tune (reprogram) the ECM. For now, take it one step at a time and get something to read the ALDL. There're different solutions out there. I started with a scanner (autoxray), and later got an XtremeALDL cable from moates.net. You can keep with the spirit of DIY and make a cable, but be sure to have a serial port on your laptop. The moates ALDL cable is already USB so no need for a serial-USB adapter if you don't have one.

 

[cruiserbrett]

I built my own ALDL cable, but that was before the days of the USB supported ALDL software, well free software anyhow.

I would get the moates cable, USB is better and the DIY serial port cables wont work the the USB to serial adapters reliably if at all.

The best source for anything DIY programming and tuning is hands down the ThirdGen.org website. So much info you will feel like a monkey trying to fly the space shuttle. Its the mud equivalent for third generation camaros... but has a cult following of all types of vehicles in the DIY PROM section and TBI section.

Did you do the IAC reset procedure? And adjust min idle speed, and TPS voltage? All of these will affect idle quality.

Timing can be an pain. making sure what the computer knows to be base timing is important. Some are set to 7 advance with the tan connector disconnected. this means the computer is factoring in the 7 advance as set by distributor position... Setting at TDC may not give enough total timing if the computer thinks base timing is 7 degrees advanced... youre bin ID Should start with "A" and be four letters will tell you what the computer expects once you look at it on tunerpro(free)

 

[Elbert]

Maybe I'm wrong...but ECM's on TBI engines are not tuneable to my knowledge... You have to get a new chip burned if you want the base parameters changed.... Timing should be easy to set... On my 92K1500 5.7 TBI..it was zero degrees with cable unplugged. If you get outiside of this the ECM thinkgs its at base timing and adjusts from that point witch could potentially buy you too much timing. The old TBI ECM's are not "smart" and take new chips to get small increases in power.

 

[fyresq]

How's it coming? Just got my motor, tranny, and t-case in so it's time for wiring. Couple questions...

Oh and that Fuel pump was not the same carter I got but it sounds like it's working ok now...

You took out your EGR right? I thought this required a different "new" PROM to basically "ignore" the fact that it isn't there?

What did you do about the Vacuum lines off your TB? Did you plug them or use the vapor canister from your donor vehicle?

Did you find the grommets for the holes you drilled? And what size hole worked well for you?

I'm sure I'll have more questions for ya...

 

[cruiser enthuiser]

How's it coming? Just got my motor, tranny, and t-case in so it's time for wiring. Couple questions...

Oh and that Fuel pump was not the same carter I got but it sounds like it's working ok now...

You took out your EGR right? I thought this required a different "new" PROM to basically "ignore" the fact that it isn't there?

What did you do about the Vacuum lines off your TB? Did you plug them or use the vapor canister from your donor vehicle?

Did you find the grommets for the holes you drilled? And what size hole worked well for you?

I'm sure I'll have more questions for ya...

Yeah, the fuel pump seems to be ok for now...I'm watching it closely though. I did take it out for a short test drive the other day and it did pretty good. I got a couple of error codes...one was related to the absence of a VSS (I believe) and the other said lean exhaust. I think I may have a vacuum leak somewhere. I'm gonna go through it very carefully this weekend and check for leaks and re-torque the intake manifold. If it's not a vacuum leak, then I don't know why I would be getting lean exhaust unless I'm still getting low fuel pressure . By the way, anyone know how much torque the gm intake bolts require?

I did remove the EGR and blocked it off. I thought the same thing about reprogramming the chip. I emailed the guy that posted this website: GM TBI Conversion Tips and asked him about it. He says he got an error code for about two weeks after installing his TBI and then it just stopped. He claims it runs great and he has never messed with the chip. So far I have not had any error codes related to the EGR. However, I am planning to order the cable which will allow me to run a diagnostic program like WINALDL or Tunerpro on my laptop. Then who knows? I may look into having a chip burned.

If you look at the picture of the throttle body just above this post you will see that I just capped all the vacuum lines except the one on the back going to the MAP sensor. Also, because I don't run power brakes (yet) I capped that very large port on the intake right under the throttle body (the brass plug).

The holes I drilled were 1 3/4". This was the smallest I could do and still fit the ECM connectors thru. I found an on-line source for some nice grommets, however, they're sold in packs of 20 for $19.95. Haven't ordered yet. If you find some cheaper let me know.


Good luck!

 

[eg40]

Another thanks for your tbi post, I just started mine up last night for the first time and it went with out a hitch. I was just about ready to buy a whole new kit till I found your post which was very helpful thanks again

 

[cruiser enthuiser]

Another thanks for your tbi post, I just started mine up last night for the first time and it went with out a hitch. I was just about ready to buy a whole new kit till I found your post which was very helpful thanks again

Congrats! It's a great feeling when it starts up that first time .

 

[cruiser enthuiser]

Tuning Update

Been a little bit since I updated - I've had some household chores lately that have kept me from logging much cruiser time. Finally got some hours the last couple days so I figure it's time for a report.

After I got her fired up the first time I realized I was still a long way from getting it to running really well. Idle quality was lousy even after I tried several fixes such as re-timing, replacing the IAC, checking for vacuum leaks, etc. I finally decided to pony up and buy the ALDL cable and download WINALDL. I got the cable from these guys: ALDL OBD1 OBD cable OBDI OBD2 engine codes. I got the USB cable which allows me to connect my laptop directly to the ALDL connector. It set me back $60. WINALDL is free software that enables you to monitor and log data from the ECM. The program came configured for a 7747 ECM (which I'm using), so set up was reasonably easy. Once I configured it to the correct com port on my computer and started it up I had more data streaming from my ECM than I could shake a stick at. I confess most of the information displayed in this program is greek to me, but I'm learning .

 

[cruiser enthuiser]

In an effort to fix my idle problems I took CruiserBrett's advice and followed the IAC reset procedure as described here: s-series.org. The IAC (idle air control) moves a plunger in and out of the throttle body to control the flow of air. The reset procedure does not require the use of a scan tool or software for setting the minimum idle speed with the adjustment screw but I found that adjusting the idle while WINALDL was running made it very simple. I would say it is as easy or easier than adjusting idle on a carb. I set my idle speed to a comfortable 600 rpm.

With this finished I checked the TPS voltage. I understand this should always be done after adjusting the idle speed screw and a scan tool or software is needed (though I think it's possible to do with just a volt-meter). If the voltage reading is too high the ECM may not go into close loop and idle correctly. It turned out that my TPS voltage was high and the sensor did need to be adjusted. Again, very simple to do with WINALDL running. It shows the TPS voltage in real time, right there on the screen.

I can tell you these two steps made a huge difference! Now it starts up perfectly and drops into a smooth, comfortable idle.


Not much for pics...just one of the TPS while I was adjusting.

 

[cruiser enthuiser]

And finally for tonight...After some consideration I still wasn't comfortable with the weak 13 PSI fuel pressure. So I replaced the stock fuel pressure regulator with an adjustable one. It is basically the stock component that has been modified with an adjustment screw that increases/decreases compression on the spring therby increasing/decreasing fuel pressure. The screw mounts on the bottom of the regulator cup and is rather tricky to adjust once installed on the throttle body. I found this one on ebay for $40. If anyone reading this decides to order this part (the guys sells a bunch of em) I would not recommend using the spring in his kit - I dialed it down to it's lowest pressure and it was maxing out my guage way over 15 PSI. Instead I used the stock spring from my throttle body and set it to 13 1/2 PSI for now.

 

[cruiserbrett]

glad to hear its getting better!

Little neglected items like IAC and TPS make a world of difference once you dial them in.

obviously there is lots of data in the ALDL stream. most important is BLM, its basically telling you whether its running rich or lean. 128 is optimal, above that is lean and below is rich. If you increase Fuel pressure higher than the 13-14 psi, expect to see BLM show rich, and a tad different starting characteristics.