First time TBI tuner

[DOCBAWRENCHTURNER]

Well, I went to the local DQ to soak up some WiFi and got TunerProRT, also installed driver for my cable. Got home and acquired my first datalog! The first thing I noticed is this truck is idling at 19.7degrees of timing. Also the BLM is between 90 and 125, the integrator is around 120-128. And the 02 sensor sometimes just dies for a couple seconds then fires back up hovering between 700 and 815. I attempted to check the base timing, I unplugged the esc wire, fired it up and base reads 23 degrees. Shouldn't that read 0? Also it won't run and has zero throttle responce below 7 degrees As read on Tuner Pro. I would upload the file, but have no Internet at home. I think I have a problem to fix before I tune this thing. Suggestions? Thoughts, questions? Life advice?

edit: I failed to mention that I had previously set base timing with a timing light. Seems like it should have been right.

[EagleMark]

Just looked at a 5.0L bin but not yours. Post up your bin and the data log so we can help!

But base timing says 0 and it should be about 19 at idle.

Timing is set with bypass wire (a single wire with disconnect plug, not sure where it is on your truck) disconnected and set to 0. SO if your getting 23? Something is wrong? Idle timing could be that high with wire NOT disconnected... You sure the timing light was on number 1 cylinder?

The big swing in BLM could be the 5.0L chip and 5.7L engine.

[DOCBAWRENCHTURNER]

Just looked at a 5.0L bin but not yours. Post up your bin and the data log so we can help!

But base timing says 0 and it should be about 19 at idle.

Timing is set with bypass wire (a single wire with disconnect plug, not sure where it is on your truck) disconnected and set to 0. SO if your getting 23? Something is wrong? Idle timing could be that high with wire NOT disconnected... You sure the timing light was on number 1 cylinder?

The big swing in BLM could be the 5.0L chip and 5.7L engine.

I was a GM tech for nearly six years and have set the timing on more than one vehicle, however it seems the base timing should, with the esc wire unplugged, read zero on live data, it doesn't. I'll get a formal datalog posted when I get to WiFi again. I still haven't ordered my BURN2 as I am trying to make sure my first marriage anniversary (today) has sufficient funds first, so can't upload my BIN yet. I'm positive that the timin light was on the number one cylinder. Gotta be something strange going on here. Also I had an idea, the truck dies while idling at or below 5-7 of timing. Also the throttle responce is sluggish to say the least. Is it possible that I just need to reset the IAC, that it isn't open enough and retarding the timing is causing it to flood out? Or maybe that my underlying cause is an overly rich condition that the computer is covering up by advancing the timing?


edited due to lack of punctuation and many fat fingered misspellings. (Don't you just love typing on a phone?)

[Fast355]

Just looked at a 5.0L bin but not yours. Post up your bin and the data log so we can help!

But base timing says 0 and it should be about 19 at idle.

Timing is set with bypass wire (a single wire with disconnect plug, not sure where it is on your truck) disconnected and set to 0. SO if your getting 23? Something is wrong? Idle timing could be that high with wire NOT disconnected... You sure the timing light was on number 1 cylinder?

The big swing in BLM could be the 5.0L chip and 5.7L engine.

My experience with setting the timing on Vortec head motors is they will not run at all below about 10* even at idle. I give my Express 12* of cranking timing even and set the base timing at 10*BTDC at the distributor. Then account for the distributor timing in the calibration. Also I tend to start with the Hypertech 93 octane 1998 Vortec 350 timing map I have. I can post a copy of it soon if anyone needs it.

[EagleMark]

My experience with setting the timing on Vortec head motors is they will not run at all below about 10* even at idle. I give my Express 12* of cranking timing even and set the base timing at 10*BTDC at the distributor. Then account for the distributor timing in the calibration. Also I tend to start with the Hypertech 93 octane 1998 Vortec 350 timing map I have. I can post a copy of it soon if anyone needs it.

Yes if this is Vortec head, I must have thought these were both TBI head, this thread is about 2 vehicles now... I think? But I usually do the timing all in tables and leave distributor alone. Moving timing at distributor also moves injector timing, which is usually not a help until big cams are an issue.

Yeah I'd like to see the 93 octane Vortec head table!

[dumb_dog]

I didn't mean to hi-jack the thread but you are right two vehicles with similar issues base timing on vortec heads topped with TBIs. GM TBI computers expects 0° base timing and the spark tables control from there. For some reason it's very hard to get a vortec head engine to idle at 0°. I agree with fast355, DOCBA may need to start with 10° of timing at the distributer and set the initial timing scalar in the bin to match his distributer setting. Also if his bin is for a 5.0 (BJXP) and his actual engine is 5.7L his timing and ve tables will need some love or he should switch to different bin like BJYL as a starting point for his 5.7L engine.

[Fast355]

Yes if this is Vortec head, I must have thought these were both TBI head, this thread is about 2 vehicles now... I think? But I usually do the timing all in tables and leave distributor alone. Moving timing at distributor also moves injector timing, which is usually not a help until big cams are an issue.

Yeah I'd like to see the 93 octane Vortec head table!

I never liked using TDC with Vortec heads because my engine practically refused to start cold. It would windmill, almost flood itself out, and start very weakly. With timing it would fire right up.

I will have to dig up those tables, they are on my tuning laptop not my desktop.

[buddrow]

Welcome DOCBA! You have come to the right place for advice. Fast355 and Eaglemark are great guys and very knowledgable. I do agree with the concensus that u need more base timing. Havent fiddled with much vortec injection tuning but do have some exp with carbed versions and they always run better with more base timing. Just my 2 cents. Happy anniversary btw

[EagleMark]

I never liked using TDC with Vortec heads because my engine practically refused to start cold. It would windmill, almost flood itself out, and start very weakly. With timing it would fire right up.

I will have to dig up those tables, they are on my tuning laptop not my desktop.

Oh so cold start, like when timing is in By Pass... I think you may have just fixed a cold start issue I'm having on one that was perfect all summer!

[Fast355]

Oh so cold start, like when timing is in By Pass... I think you may have just fixed a cold start issue I'm having on one that was perfect all summer!

That is exactly when the issue shows up. When the temperature gets into the 30s and below. I altered the crank timing in my 0411 PCM as well. Really helped the cammed 5.7 Vortec startup as well.

One other place the advanced distributor timing helps is should the ECM ever fall into Limp Home mode. You have a better chance of actually being able to make it off the road with a little timing.

[tayto]

My experience with setting the timing on Vortec head motors is they will not run at all below about 10* even at idle. I give my Express 12* of cranking timing even and set the base timing at 10*BTDC at the distributor. Then account for the distributor timing in the calibration. Also I tend to start with the Hypertech 93 octane 1998 Vortec 350 timing map I have. I can post a copy of it soon if anyone needs it.

Post the Vortec timing map if you get a chance fast.