Timing a motor after tbi conversion and now my official tbi tuning thread.

[GsxrMike]

Can someone give me a run down on timing my motor? It is a mid 80's carbed motor converted to TBI using parts from a 95 chevy truck. I know to unplug the little brown wire but I'm not sure what to set it to since I don't have the emissions sticker.

 

[4X4HIGH]

ALL TBI engines are set to ZERO with the EST wire disconnected.

 

[GsxrMike]

Awesome thanks, any benifit from running a little more advance on these motors?

 

[82355]

Some will say yes, some will say no.

Mine runs better set at 4 degrees.

Martin

 

[jekquistk5]

Some will say yes, some will say no.

Mine runs better set at 4 degrees.

Martin

I was at 2 degrees was were my 350 was happiest

 

[GsxrMike]

Thanks guys, we set it at 4 but it didn't run so hot so we used the powerbrake method while out test driving and we think we got it dialed in where it runs best, not really sure where it is set though. Right now it runs well enough to go do some crawling but I wouldn't want to take it through a mud pit, it doesn't run very well in the upper rpm range. We have the fuel pressure set at 9.5psi which is what seemed best. We have tested everything but the water temp sender which may be an issue because it has a little trouble starting once warm. Any ideas?

 

[jekquistk5]

Thanks guys, we set it at 4 but it didn't run so hot so we used the powerbrake method while out test driving and we think we got it dialed in where it runs best, not really sure where it is set though. Right now it runs well enough to go do some crawling but I wouldn't want to take it through a mud pit, it doesn't run very well in the upper rpm range. We have the fuel pressure set at 9.5psi which is what seemed best. We have tested everything but the water temp sender which may be an issue because it has a little trouble starting once warm. Any ideas?

Bad water temp sender and having a bad connection to my o2 sensor was my warm starting problem.

 

[GsxrMike]

10-4, for $15 bucks I think I will change the sensor for piece of mind anyways! Thanks!

 

[4X4HIGH]

Thanks guys, we set it at 4 but it didn't run so hot so we used the powerbrake method while out test driving and we think we got it dialed in where it runs best, not really sure where it is set though. Right now it runs well enough to go do some crawling but I wouldn't want to take it through a mud pit, it doesn't run very well in the upper rpm range. We have the fuel pressure set at 9.5psi which is what seemed best. We have tested everything but the water temp sender which may be an issue because it has a little trouble starting once warm. Any ideas?

TBI likes 12-13 psi of fuel pressure and almost all come from the factory between those pressures.

The CTS will definately make a difference in how the engine runs.

 

[jekquistk5]

TBI likes 12-13 psi of fuel pressure and almost all come from the factory between those pressures.

The CTS will definately make a difference in how the engine runs.

isn't it like 9 psi at idle and 13 at WOT?

 

[4X4HIGH]

isn't it like 9 psi at idle and 13 at WOT?

Nope, I checked mine when it was stock and it was 12.5 psi and i've checked many others that were anywhere between 11-13 psi and that's at idle or higher.

 

[Jessie James]

The manual states it should be between 9 and 13 PSI. If 9 is the bare minimum, and you are running that, I bet that is why you lack power at high RPMs - you are running out of fuel. You may also be running lean which may lean to other issues.

 

[jekquistk5]

Nope, I checked mine when it was stock and it was 12.5 psi and i've checked many others that were anywhere between 11-13 psi and that's at idle or higher.

Good to know

 

[GsxrMike]

Yeah we turned it down from 12.5 to 9.5, we had tried everything between as well with no luck. I borrowed a snap-on scanner and found the CTS was bad (reading -40 which I believe is open). I changed that and power braked it and it ran better but surged so I turned the fuel pressure back up to 12.5 and when I power braked it this time the rear tires spun (38.5 boggers on concrete). I didn't get to drive it because I have no lights but I will tomorrow. The only other immediate error I see is after I cleared the codes I got a code 43 that popped up right away which on his scanner was ESC circuit problem so some thing of that sort. I'm not sure what to check with the ESC because it seems to work (I'm getting spark and the timing is changing as I rev the motor) but I don't really know what all it could be with the ESC. On the internet it said a code 43 could be a knock sensor as well but I have the knock sensor wire hooked up to a 5 vdc source coming from the computer which I was told would pretty much eliminate that from the equation. Any help with this one guys?