TBI timing problems (1 Viewer)

[bandy rooster]

hey all,


I have a TBI setup that i just put on my cruiser... stock 350 for the most part....


i disconnect the wire to the est or whatever that wire is they tell you to disconnect to set the base timing to 0 degrees.. but my truck won't run/idle long enough for me to get to 0 degrees, it runs great otherwise during idle but I just can't get it to idle at 0 degrees with the wire disconnected.. i think the timing might be advanced right now but i can't remember... either way its to far from 0 and the computer is not getting the right baseline to start from...

i'm not sure what to do ?

 

[bandy rooster]

it totally just bogs down and starts to have a rough idle when i get close to that 0 degree mark

 

[Rix86]

How'd it run before the TBI conversion?
Timing cover and crank pulley remained the same?

 

[bandy rooster]

ran good, strong engine...


didn't touch the timing cover & crank

 

[xjnation]

I had the same problem trying to put TBI on a 350 carbed motor. Distributor was off 180 degrees. Pull the distributor, set TDC on # 1 and reinstall distributor. After that she ran nicely.

 

[bandy rooster]

yeah but it runs real smooth right now, its hard to believe that its possibly 180'd right now... just not at 0 degrees timing... its hard to believe that the computer could advance/retard timing that much to compensate



i'll give it a try though...

 

[xjnation]

So it only runs rough when you disconnect the wire? If thats the case then you shouldn't be 180 out. Tells you how much I pay attention while I'm at work. If thats the case I have no idea. Sorry for the confusion.

are you disconnecting the brown wire while the truck is NOT running? Be sure to shut it down before disconnecting the wire.

**edit heres something I found: When you are setting the timing I assume that you are disconnecting the wire to disable ESC. Also for what it is worth, I have long not used TDC from static timing on TBI. I use 6 to 10 BTDC depending on fuel and vehicle. They will run much better this way with 89 or 93 octane fuel too. I generally find TBI's somewhat slug like with TDC and 87 octane fuel. I am not sure what roll that VS sensor plays in ECM management but it does watch it and this is a concern. Also, your Eprom may not be mapped properly for your engine because TBI engine have higher CR and a different cam profile than a carbed 350 from a few years earlier. This may not be total cause of problem but it is not helping it. Try this, set static timing to about 6 BTDC with wire disconnected then hook it back up and then pull ECM fuse for several minutes to clear its memory and place it back in learn mode. (this reboots ECM) see if it helps at all. EDIT**

 

[bandy rooster]

So it only runs rough when you disconnect the wire? If thats the case then you shouldn't be 180 out. Tells you how much I pay attention while I'm at work. If thats the case I have no idea. Sorry for the confusion.

are you disconnecting the brown wire while the truck is NOT running? Be sure to shut it down before disconnecting the wire.

yes, i'm disconnecting it prior to starting the engine. it only runs rough when i start to get close to 0 degrees TDC with the bypass wire disconnected. runs smooth with it connected and without connected. but it bogs down when i get close to TDC... i'll keep trying at other things

 

[TBIFJ40]

It may be that your distributor isnt 180deg off, but one tooth off. The CPU would compensate for that no problem, but only to a certain amount. How is/are the rest of the tuning components in the rig, such as wires ,plugs, etc? What RPM is the engine running when youre doing this? Have the stock idle plugs been taken out of the throttle body, (which usually messes up the Idle circuit anyway)? Did you take everything from the original TBI setup, or eliminate certain things? If it runs great with the tan wire hooked up, dont worry about it, The CPU will adavance the timing as far as it can without knocking, (provided youre using the knock sensor) it just may not retard it at slower RPMs, which could hurt torque a little bit. hmmmmmm

 

[Trollhole]

If you have installed a new distributor or manifold, you will need to set the timing. This is accomplished by disconnecting the single lead wire electrical connector breaking out of the harness near the distributor. With this wire disconnected, set your timing to “0” deg. for most applications. Big Block installations should have the initial timing set to “6” deg. BTDC. The ECM does all of the timing for you and uses the reference of “0” or “6” degrees to properly deliver the correct spark angle. With the set timing wire disconnected, your check engine light will illuminate and set a code “42” EST malfunction. After the timing has been properly set, reconnect the single lead wire and turn the vehicle ignition off. Wait for at least 10 seconds and restart the vehicle. The ECM will not control the timing until the vehicle has been turned off and restarted with the connector in proper position. If you choose you can clear the code “42” by disconnecting the battery lead to the ECM for at least 10 seconds.
If your system is equipped with a tach filter and not using the ECM controlled distributor set ignition timing to the factory specifications for your engine.

Have you tried adjusting the idle set screw?

 

[Big6ft6]

Hey everyone, just came across the forum, I'm having the exact same issue right now.

Just installed a rebuit TBI 350 essentially stock (has new cam but wasn't suppose to require adjusting ECM chip).

Wit the EIC wire disconnected (or connected) my truck won't start unless I set timing about 20 degrees advanced, once started I can just barely get it down to 0 BTDC, it will idle rough, but I can do it.

Then I shut off the turck, re-connect the EIC wire, and it will start if the truck is warm. But after I let it sit for 15 minutes, she won't start unless I advance the timing by turning the distributor.

The place where she seems happiest starting and running is about 20 BTDC with EIC disconnected or connected (doesn't matter).

Just like Bandy Rooster, the engine barely idles at 0 BTDC and connecting the EIC wire doens't help.

 

[too tall]

You guys might try to swap the two wires in the dizzy on the module from the pickup coil. I had this issue one time with an aftermarket pickup . Had to time it way too far advance . Once I reversed the wires the timing was set normally and ran good. Worth a try.

 

[Big6ft6]

Interesting...wonder what that does? This is my original distributor that ran fine in my last engine...(although I never checked the timing)

 

[too tall]

I read somewhere one time that pontiac or oldsmobile manufactured pickup coils carried the same part# when cross-referenced but the poles were reversed on those ones . Not as important for carburated vehicles but causes issues with GM FI .