350 TBI sometimes hard to start. - Third Generation F-Body Message Boards

ggenovez · 03-16-2009, 01:40 PM

Hi all,

I have a 90 Burb with a TBI and sometimes it's hard to start. when this happens, I need to just barely give it some gas and hold it there while i'm crancking, then leave my foot there for about 30 seconds. then she runs rough until she goes into closed loop.

I've replaced the temp sensor and using winaldl it reads 57' and the ambiant temp is 62.

Any help would be greatly appreciated.

If this helps, here's some data from winaldl not running key in the on position.

IAC 145
temp 57.9F
map 4.8V
TPS .59V
int 128
O2 .004V

No error codes

Thanks

Fast355 · 03-16-2009, 08:14 PM

Quote:

Originally Posted by ggenovez

Hi all,

I have a 90 Burb with a TBI and sometimes it's hard to start. when this happens, I need to just barely give it some gas and hold it there while i'm crancking, then leave my foot there for about 30 seconds. then she runs rough until she goes into closed loop.

I've replaced the temp sensor and using winaldl it reads 57' and the ambiant temp is 62.

Any help would be greatly appreciated.

If this helps, here's some data from winaldl not running key in the on position.

IAC 145
temp 57.9F
map 4.8V
TPS .59V
int 128
O2 .004V

No error codes

Thanks

Have a copy of the .BIN you are using and/or a log of the problem?

ggenovez · 03-16-2009, 08:31 PM

Hey neighbor,

Looks like I'm gonna owe you a case pretty soon

I don't see an upload option and I did not bother logging any data since it was not running. how do you want me to log anyhow? while cranking, just on...?

Thanks

Fast355 · 03-16-2009, 08:57 PM

Quote:

Originally Posted by ggenovez

Hey neighbor,

Looks like I'm gonna owe you a case pretty soon

I don't see an upload option and I did not bother logging any data since it was not running. how do you want me to log anyhow? while cranking, just on...?

Thanks

Log the whole startup from Key-on to running. That will atleast give you some idea what sensor reading is flakey.

I am just assuming you have been playing with the .BIN since you posted in the DIY prom area.

I will also private message you my email address. That way you can send it directly rather than attaching it.

I have always had trouble with the early TBI ECMs on startup, the 7747 included. They seem to either not deliver enough fuel or flood on startup. They start eventually, but nothing like the later 93-95 PCM setup. Which BTW is a plentiful fairly simple swap.

This is a startup on a 20ish degree day a few years back, when I was still running TBI.

http://www.youtube.com/watch?v=FmS1m3zlqHo

I converted a 2.8 TBI powered S15 Jimmy to run a 3.1 and a PCM from a 94 Astro with a 4.3. Custom chip work on that one too.

http://www.youtube.com/watch?v=gNVs-_RzwFo

Compared to the original 92 model 299 ECM I was running, startup with the 7427 was a breeze. All that cranking was for a warm start, it took even more for a cold start.

http://www.youtube.com/watch?v=_3eiS...layer_embedded