Vince's TBI woes, progressive revelations, and tbi mods.

[Bextreme04]

i seem to recall a gentlemen who complained to me for about 35 minutes about how you needed a tech 2 like mine to perform a relearn when the distributo is changed or moved.
Is that relevant?

That's only a thing for Vortec engines that have a cam position sensor. You have to set the distributor to 0deg with a very small deviation to be able to even start the motor(which obviously makes it hard to figure out with a timing light). There are some good quality scan tools that can show you the right PID to do the adjustment without having a tech 2(which is really mostly for OBD2)

 

[AuroraGirl]

That's only a thing for Vortec engines that have a cam position sensor. You have to set the distributor to 0deg with a very small deviation to be able to even start the motor(which obviously makes it hard to figure out with a timing light). There are some good quality scan tools that can show you the right PID to do the adjustment without having a tech 2(which is really mostly for OBD2)

okay that explains a lot more. he was talking about it being a 96, so i thought okay later small block but prob not a LS yet. Prob for late obd1 and early obd2 to squeeze every last bit out of emissions allowance?
Just like my 96 f150 is the only year the inline 6 had a crank sensor

 

[Vbb199]

okay that explains a lot more. he was talking about it being a 96, so i thought okay later small block but prob not a LS yet. Prob for late obd1 and early obd2 to squeeze every last bit out of emissions allowance?
Just like my 96 f150 is the only year the inline 6 had a crank sensor

Who said 96?

 

[AuroraGirl]

Who said 96?

i said later. so a 94 probably has the thing i speak of?

 

[Vbb199]

okay that explains a lot more. he was talking about it being a 96

i said later. so a 94 probably has the thing i speak of?

Who said something about a 96?
The 30 minute rant guy?

My suburban is a 89?

 

[Bextreme04]

i said later. so a 94 probably has the thing i speak of?

96 or later for the truck(L31 350, or L29 454) have a 4x crank sensor and a 1x cam sensor. You have to set the distributor correctly to have 0 deg advance(+-3 deg I think) mechanically and then the computer will control ignition advance from there. If the distributor is outside of that +-3 degrees the engine won't run at all. The early 90's LT1's and TPI motors in the corvettes and F-bodies have a similar system. It mostly has to do with the Ignition advance and fuel injectors firing at just the right time. If the computer detects the Cam and Crank sensors too far out of phase it just panics, throws up the white flag(CEL) and shuts it all down.

 

[bucket]

96 or later for the truck(L31 350, or L29 454) have a 4x crank sensor and a 1x cam sensor. You have to set the distributor correctly to have 0 deg advance(+-3 deg I think) mechanically and then the computer will control ignition advance from there. If the distributor is outside of that +-3 degrees the engine won't run at all. The early 90's LT1's and TPI motors in the corvettes and F-bodies have a similar system. It mostly has to do with the Ignition advance and fuel injectors firing at just the right time. If the computer detects the Cam and Crank sensors too far out of phase it just panics, throws up the white flag(CEL) and shuts it all down.

I've seen some that other people screwed with that were way out of spec. They can be fairly far out of time and still run, they are just barely drivable and run like garbage. Iirc, anything past 2* and it sets the SES light.

It's also possible to get it within spec without any scan tool at all, but it requires a good eye.

 

[Bextreme04]

okay that explains a lot more. he was talking about it being a 96, so i thought okay later small block but prob not a LS yet. Prob for late obd1 and early obd2 to squeeze every last bit out of emissions allowance?
Just like my 96 f150 is the only year the inline 6 had a crank sensor

Also LS doesn't have a distributor at all. There is a 1x or 4x cam sensor in the timing cover and a 24x or 58x crank trigger wheel on the back with the sensor mounted near the starter. Anything after 1996 is OBD2(usually).

I've seen some that other people screwed with that were way out of spec. They can be fairly far out of time and still run, they are just barely drivable and run like garbage. Iirc, anything past 2* and it sets the SES light.

It's also possible to get it within spec without any scan tool at all, but it requires a good eye.

There's actually a special procedure for initial setup that I found on one of the LTswap websites I think, it works pretty good. I think it's only meant to get you within that window to start the vehicle and then use the tech2 or other scanner to get it to zero. You then have to do a crank relearn afterwards for the computer to learn the cam/crank offset and knock sensor sensitivities.

 

[AuroraGirl]

Also LS doesn't have a distributor at all. There is a 1x or 4x cam sensor in the timing cover and a 24x or 58x crank trigger wheel on the back with the sensor mounted near the starter. Anything after 1996 is OBD2(usually).



There's actually a special procedure for initial setup that I found on one of the LTswap websites I think, it works pretty good. I think it's only meant to get you within that window to start the vehicle and then use the tech2 or other scanner to get it to zero. You then have to do a crank relearn afterwards for the computer to learn the cam/crank offset and knock sensor sensitivities.

i had to do a crank relearn on my 3800. annoying because i had to fix evap code before it would let me do it

 

[bucket]

There's actually a special procedure for initial setup that I found on one of the LTswap websites I think, it works pretty good. I think it's only meant to get you within that window to start the vehicle and then use the tech2 or other scanner to get it to zero. You then have to do a crank relearn afterwards for the computer to learn the cam/crank offset and knock sensor sensitivities.

You can get it basically perfect without the use of any scanner equipment at all. You just have to have a good eye when it comes to lining up the marks. I’ve never had any issues getting them set up properly using this method:

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I've done it too many times to count. As long as it's within that 2* spec, the light will not set and the engine will run as intended with no driveability issues. The scanner just makes it easier for those that prefer to lock down a distributor when a computer says it's good.

 

[82sbshortbed]

That's why I got a square. **** a crank sensor, **** a cam sensor and for the SES light **** you most of all! I've got no use for any of that. Especially when that gay SES light popping up and ******* up your inspection.

 

[AuroraGirl]

That's why I got a square. **** a crank sensor, **** a cam sensor and for the SES light **** you most of all! I've got no use for any of that. Especially when that gay SES light popping up and ******* up your inspection.

I mean mechanical controls such as advance weights arent that much more trouble free an require knowledge that is only easily gained today as opposed to the past while a modern one can tell you what failed. pros and cons. Learning how ot fix a 1980 gmc has been a journey comapred to my 1990 olds 88 which was my first car. largely different, despite tehe 1990 being light years behind my 1999 which itself is. yeah it keeps going

 

[Vbb199]

K, somehow we got off on far more technical garbo than TBI with cam and crank triggers (lol)


So, as an overview, ive done ignition box, a 30k volt coil, regapped to .060 on my plugs, added a performance PROM chip (changed many things but namely added 3° to timing), I turned base timing up 2 more degrees BTDC, and adjusted TV line pressure.
Truck runs like a ******* scalded dog.
shes HAWT.
Uncomparable power against previous setup for a big heavy bitch from 1989. No pinging at WOT, and she feels like she wants a couple more degrees in base timing, but im not ******* with it because i want to do towing as well, which will pull the engine under load.


MOVING ON!

(I will rename this thread to something more appropriate)

My next move is to upgrade throttle body's.

Was riding along this morning, and i got to thinking.... i could really use a larger throttle body.
Im still running the stock 500 cfm unit (apparently flows lower than 500) on vortec heads!

How preposterous! My immediate first thought was to upgrade to a 670cfm 454 throttle body, but it would require mods, possibly machining to work on my small block, AND id need maybe a tad smaller injectors.


The second option is, i buy a new modified 46mm throttle body from NPR performance (650 cfm).

The 3rd is, i just machine my spare unit and make it 650 cfm.

One of those 3 ill decide on, but theres where i am.

 

[Vbb199]

Getting back to this -

This weekend im thinking i may teardown the spare tbi i have, and maybe go ahead and bore the barrells to 46mm (1.811") vs the factory 1.6875 (1 11/16).

I got lots o **** to do, but i can begin with boring it out, maybe making a riser to (or buy one) to lift the whole unit up off the intake so the larger butterflies can clear!


On another note, my idle keeps randomly going high out of no where? And sometimes the truck almosy chokes out and dies (only at idle)

Was thinking maybe the IAC i replaced has went bad, or the CTS is defunct now.

 

[Vbb199]

The victim

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