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My TBI computer chip programing thread/adventure.

Good news! My buddy was able to borrow a degree wheel from a guy at work! So i'll check the cam out and see whats up. If its spot on, then i will know that i have something else going on elsewhere. Unfortunately, im busy till after haloween...
 
Pic of the degree wheel,

IMAG0259-1.jpg
 
Ok, so, heres what transpired today. Had my buddy Scott(who's pretty much my best friend) come over and help me out with rotating the motor while i watched the dial indicator and we determined that the cam is 10* retarded! So, we pulled the timing cover off assuming that that amount of error would mean i was off a tooth when i put the cam in. Turns out it was right on. Then doing some calculations we determined that being off a tooth would give about 8* advance/retarded so naturally, we advanced the cam sprocket a tooth. Which SHOULD put me at 2*retarded. Im going to re check it with the degree wheel now. If it turns out it is in fact 2* i might just go ahead and get those bushing sets and advance it the final 2*. We'll see. I still have to re-adjust the valves and check the compression for the hole with the plug that looked like it wasnt firing. When all of that is done i'll put it all back together and fire it up. Going to be interesting to see what happens...
 
:eek1:

What kind of cam is it? Man that's not even close... :doah:

No wonder you have had issues?
 
Its the super common SUM-1102 cam.

Here's how it looked before,

IMAG0281.jpg


And after. I think this was the right direction to go to advance,

IMAG0285.jpg
 
Check for sure and see what cam timing is before turning motor over and possibly hit a valve!

Double check cam timing! I can't beleive it was that far out? :doah:That really sucks...
 
Yea I will be double checking for sure! And yes I will rotate it around by hand before hitting the key. If indeed it is correct now, I will have to assume that either cam is messed up or one of the sprockets is market a tooth off where it should be.
 
Do you have the/an old timing gear set sprockets? You could check where timing mark and keyway are?

The way cams are ground it's not likely any lobes are off. It's the keyway that makes all lobes off. Hence why instructions recommend checking cam timing.
 
I usually don't comment on engine building, but setting the cam / crank sprockets and chain is usually very basic. The real key to knowing if the cam / crank sprockets are correct is to absolutely know, with 100% certainty where TDC is! The piston will dwell at TDC for several degrees, and can quite often mislead someone to where TDC really is. From my experience, it's not very likely the cam / crank sprockets are incorrectly marked. From my experience, it's most likely TDC was not correctly known when the cam / crank sprockets were installed. Sometimes the valve springs will push down hard enough on the lifters to actually move the camshaft, if the lifters were adjusted before installing the cam / crank sprockets.

dave w
 
I don't actually "have" it and with my phone I can't link to it. But if you go to summit racing and search for the sum-1102 cam, there is a link to click for the cam card.
 
If you go down to instruction sheets you can see a better cam card.

Intake center line is 107 and the lobe separation is 112 so that cam already has 5 degrees advance ground in it.
 
Well, i sold the TBI stuff today. Bitter sweet really. I thought for sure that burning a chip was going to solve all my problems. But it didnt. I had great hopes that finally i could just forget about it running bad and could move on. That didnt happen. It was a fun learning experience trying to get there though! It was just a roller coaster of emotion! Hope dashed by disappointment over and over again. Oh well. On to bigger and better things now!
 
y5mgisi said:
Well, i sold the TBI stuff today. Bitter sweet really. I thought for sure that burning a chip was going to solve all my problems. But it didnt. I had great hopes that finally i could just forget about it running bad and could move on. That didnt happen. It was a fun learning experience trying to get there though! It was just a roller coaster of emotion! Hope dashed by disappointment over and over again. Oh well. On to bigger and better things now!
Click to expand...

I saw a post on my local CL, thought maybe it was your setup ... guess it was. I posted the CL post on another board, maybe that helped.

Chip tuning is a challenge! I think you have learned more than you have let on. If chip tuning was ever supposed to be supported by service personnel, the factory would publish a manual on how to do the chip tuning. Ultimately, nothing ventured / nothing gained, I think with your recent chip tuning venture, you have gained much!

Best wishes on the the bigger / better things!:waytogo:

dave w
 
Thanks Dave! I really think there was something internally wrong with my motor that was causing my problems. I just wasnt willing to try anymore after 5 years so i finally admitted defeat. The good thing about all this is that the truck is now receiving a 5.3 vortec motor!
 
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