1987 V10 with 1974 engine- need TBI Help

[YakkoWarner]

I experienced the same thing except I needed the big block version - mine needed to be replaced because the shaft bushings were badly worn (to the point you can easily wiggle the shaft around in the hole). All the normal parts suppliers have a listing and part number for a rebuilt throttle body - it seems the actual supplier for those is out of Canada and nobody every has it in stock.

I found and bought a somewhat more expensive one from a company in California who had it in-stock, shipped in 2 days and I had it in just over a week. I'd buy again without issue if I needed another one - it came complete with injectors and regulator, correct fuel and return ports - an easy bolt-on replacement. Also a phone number that people actually answer when you call (I had some questions prior to ordering).

Unfortunately I just looked at their site and the unit for the small block is marked "sold out". The big block unit is still in stock. Might be worth contacting them though to see if they have anything coming down the pipeline...

The company is i-five automotive ( i-5automotive.com ). I have no connection to them, but they had what I needed when no one else did.

 

[JT58]

Ok- update. Everyone has been so helpful. And I was able to look up other threads on taking the gage cluster out to access the instrumentation and SES bulb. The good news is that everything behind the dash is in excellent shape for a 40 plus year old truck. The great news is that the SES bulb was simply burned out. I replaced it and it works! I also replaced other burned out bulbs while I was in there. And here's what I found the other previous owner(s) did. The SES plastic piece that states Service Engine Soon and 4WD was both painted out black and it had a perfectly cut piece of black masking tape over it on top of the paint. I removed the black tape and was able to carefully scrape off the black paint and saved the piece. So the SES is functional now. Hopefully the scanner I bought can give me the error codes and I can now troubleshoot further. I also bought a 195 degree thermostat- had to order it as it was not in stock at my local Autozone.

I'll be back working on the truck tomorrow.

To YakkoWarner- I'm very afraid of my shaft bushings being worn out on the TBI. I will next see if I can find someplace that has one available. Still waiting for others to chime in and if there is anyway to save mine and replace of seal off the worn bushings.

 

[bucket]

With the older OBD1 GM stuff, you can just jump the A and B terminals in the diagnostic port, then turn on the ignition. The SES light will flash in a sequence that will tell you the code numbers.

 

[Ricko1966]

Thanks for the replies. I am not sure if the scanner port works. I have an ODB2 scanner and it does not fit the port. It may be an ODB1 port or what is it? There are no lights on the dash other than the bulb when I turn on the headlights, so check engine light is inoperable. I tried jumping the two ports to reset the idle and they seem to be dead. The truck has the factory exhaust manifolds with the stock cross over pipe and it has the two O2 sensors installed. After the cross over pipe it goes into a single 4 inch exhaust which then splits into dual 3 inch exhaust pipes out the back. No CATS. All factory wiring under the hood is there and in great shape. It does seem to run rich, the exhaust does smell rich.

Would it be worth getting a 195 degree thermostat? Maybe purchasing a complete new TBI unit? I'm afraid after investing in that it still will not idle or run worse. Just getting it diagnosed I'm looking at about 1K at least so a new TBI unit and thermostat is much cheaper and I can easily install them. Vehicle work is horrible crazy expensive where I live. So I do as much work as I possibly can.

Is there a way to check for leaks at the throttle shaft of the throttle body?

The ALDL on that is not OBD 1 or 2, OBD1 came out 1991 in California OBD 2 Came out nationwide in 1995. Your truck is GM proprietary cccs.(computer control command system) using ALDL port. Best bet is an aftermarket patch cable and a laptop. Squirt your throttle shaft with carb cleaner or starting fluid,do not use brake cleaner, listen for the idle to change. If the idle changes the throttle shafts are worn.

 

[bucket]

The ALDL on that is not OBD 1 or 2 OBD1 came out 1991 in California OBD 2 Came out nationwide in 1995. It is GM proprietary. Best bet is an aftermarket patch cable and a laptop. Squirt your throttle shaft with carb cleaner or starting fluid,do not use brake cleaner, listen for the idle to change. If the idle changes the throttle shafts are worn.

I think you are about to learn me something...

I had always considered all the pre '96 proprietary stuff as OBD 1. Because when I got into the industry in the late 90's, that's what all the people I worked around called it. So that is not correct terminology?

 

[Ricko1966]

I think you are about to learn me something...

I had always considered all the pre '96 proprietary stuff as OBD 1. Because when I got into the industry in the late 90's, that's what all the people I worked around called it. So that is not correct terminology?

Early stuff was proprietary GM had cccs,Ford had EEC then in 1988 California said hey we need to standardize this so any garage can work on anything. So OBD1 was officially born in California for the 1991 model year. Then the rest of the United States said hey that was a good idea and OBD2 was born for the 1995 model year. GM if you look in the service manual on cars through 90 they say ALDL assembly line data link not OBD port. Naturally people started calling anything that wasn't OBD2, OBD1 by default, but that is inaccurate. And you might buy an OBD1 scanner and it will work on a 1992 model something,but it won't work on an 80s GM product. There are scanners that have specialty programs or cartridges to read early Ford,Chrysler,GM but they are reading manufacturer specific protocol no OBD1.
I had a few things wrong,here's probably better more accurate info. I was justbworking from old memory.

On-board diagnostics - Wikipedia

en.wikipedia.org

 

[bucket]

Early stuff was proprietary GM had cccs,Ford had EEC then in 1988 California said hey we need to standardize this so any garage can work on anything. So OBD1 was officially born in California for the 1991 model year. Then the rest of the United States said hey that was a good idea and OBD2 was born for the 1995 model year. GM if you look in the service manual on cars through 90 they say ALDL assembly line data link not OBD port. Naturally people started calling anything that wasn't OBD2 OBD1 but that is inaccurate. And you might buy an OBD1 scanner and it will work on a 1992 model something,but it won't work on an 80s GM product. There are scanners that have specialty programs or cartridges to read early Ford,Chrysler,GM but they are reading manufacturer specific protocol no OBD1.

Yeah, I know what you mean about the different programs. Used to have a scanner at work that did OBD2 as well as the older stuff. The older stuff needed the correct connector attached to the cable and it needed a separate 12v power source to operate. The OBD2 connector needed different chips inserted into it for the correct vehicle manufacturer.

 

[Ricko1966]

Yeah, I know what you mean about the different programs. Used to have a scanner at work that did OBD2 as well as the older stuff. The older stuff needed the correct connector attached to the cable and it needed a separate 12v power source to operate. The OBD2 connector needed different chips inserted into it for the correct vehicle manufacturer.

https://en.wikipedia.org/wiki/On-board_diagnostics I edit my last post to contain this.

 

[JT58]

OK Todays update. Got all the dash lights working Yay!! Even the emergency brake light works. The SES works too and it does not stay on after it is running. I have not checked for codes yet. I changed the thermostat to 195 degrees. Same high and low idle issue. Will there be codes if the light does not stay on?

TBI needs to be replaced next. I suspect the throttle shafts are worn out. Will check that next tomorrow with carb cleaner. I need to source a new TBI. Rock Auto or Autozone show they have stock.

I did order one through Walmart through Mad Hornet Monday. They don't have it in stock and want me to wait 40 days plus for them to get one- communicated only through E Mail. They won't return my money and won't return my calls. I'll have to have the bank deny payment. One thing after another to deal with.............

 

[YakkoWarner]

Codes will still be stored for a while even if the SES light is off - unless you have disconnected the battery or otherwise interrupted the power to the ECU. There is no NVRAM type storage in the computer, so if it has had its power disconnected long enough for the internal capacitors to draw down, the memory is cleared (usually takes around 5-10 minutes).

Disconnecting the battery for 5-10 minutes is a fairly common and easy way to reset the ECU back to default values; but removing the fuses that power the ECU or unplugging its wiring harnesses can also reset it.

 

[bucket]

But if you haven't disconnected the battery recently, or at all, there may be codes stored from previous issues. Any current codes should be taken with a grain of salt, unless you were the last one to disconnect the battery and know when that was.

Save the old thermostat, because you may need it. Modern thermostats tend to be very unreliable.

 

[Scruffy49]

Have a tbi 350 that is getting carb swapped. 1979 block/heads, 1992 exhaust manifolds, redrilled intake, 1992 factory tbi unit, 1992 computer/wiring/fpr/fuel pump. It never ran right on modern gas, ran great on ethanol free 90 octane. Fuel economy however was always horrendous, as was seat of the pants power output.

Swapping to a newer style pre-heater equipped Bosch O2 sensor helped. A LOT. Ditto a 195* thermostat. Truck that is donating the engine was a “cataclysmic perverter” delete, true dual exhaust with glasspacks. 700r4 transmission, bad habit of snapping flexplates. Was slated for a Th350 conversion and older style flexplate. Going back to a Qjet when it becomes my wife’s 85 C10 swb engine.

IF I was to stay fuel injected would swap to a squarebore 4bbl intake and newer tbi. Holley, Aces or similar. Better parts availability and actual manufacturer tech support still available on them. I need to do an mpfi to tbi or carb swap on an OBD2 Vortec 350 that is even worse than your truck is acting.

Try ethanol free fuel after you change the fuel filter. Try adding about 16oz of ATF or Marvel to the tank, along with a can of Berryman B12 or Seafoam. Usually cleared up the tbi stumble within 3 miles, the orifices get dirty/gummy and the truck runs terribly. TBI basically went away after 1995 on smallblock GM engines, factory support by 2005… Good luck, you’ll get it fixed if you are patient (I’m not).

 

[Ricko1966]

Codes should stay stored until battery is disconnected or designated number of drives or key cycles with no fault. I do not remember the number but it's high like 50ish. If it's a hard code it will be there until the battery is disconnected and come back on the next drive. Soft codes certain conditions have to be met and it's helpful to look them up for diagnoses andvtesting. I don't remember a specific example but it's something like. (Soft code) x will set if engine is between 205 and 230 degrees sensor y has been low voltage for more than 20 seconds and the vehicle has Been driven 2 consecutive trips exceeding 15 miles.

 

[JT58]

I got the new TBI and my new fuel injectors. Is there anything I need to do after I install it? Just install and start it? Then let it warm up and reset base idle?

 

[gmbellew]

I got the new TBI and my new fuel injectors. Is there anything I need to do after I install it? Just install and start it? Then let it warm up and reset base idle?

I’d probably not mess with the base idle until after you have a peek at what the ECM is seeing and doing with fuel. But otherwise,yeah, just hook everything back up and fire it up