Does anyone want to help?

[Unofficial]

As some of you know, I replaced my 305 TBI with a 350 TBI over the summer, and I never changed the injectors or ECM to fit the 350. However, I recently got some 350 injectors off ebay and installed them. I ran into a few problems, but everything is running smoothly. One of the o-rings was bad and causing fuel to be dumped into the engine. Just about every single spark plug was fouled, so I changed the plugs and wires. Should I run some cleaner through my engine to clear up and built up crud inside, or will combustion clean all that out. Also, I'm getting code 24 from my engine light. My speedometer and odometer are broken, so I'm not sure if that has anything to do with it. I've been getting code 24 long before the 350 injectors were put in, so I know it's not them. Is it hurting anything to have the 305 ECM with the 350 injectors? I'm getting the new ECM this weekend, so I won't be running it like this too much. Can anyone help out? Sorry about the lengthy post...

EDIT: I forgot to ask, what do I have to unplug on my truck in order to time it? I thought it was something to do with the ESC module. Do I unplug the ESC mounted on the intake next to the TB to time it?

[joesgarage71]

 What year system are you working on?
 Assuming you are working on a 87
http://www.troublecodes.net/GM/87-90_50Y.shtml
or 86-88
http://www.troublecodes.net/GM/86-88_50G_c.shtml
 Not sure about the ESC, but there is a harness that runs along the right side valve cover that you disconect the weatherpac time it and reconect it.

I was told by my tuner that there was no need to do anything to a 305 TBI system to make it work on a Stock 350, BUT turn up the fuel pressure. I was going to do the TBI swap on my 78.

[Captkaos]

Running the 350 ECM ins't going to hurt you.
the plug for the timing is at the back between the valve cover and the fuse panel.  It is black/white.

[Unofficial]

So is code 24 basically saying that my TPS is bad?

[DnStClr]

Not according to my 1987 emissions Service Manual. A code 24 indicates that there is no vehicle speed being indicated. That would match your info about not having the speedo work, since the speedo works off the VSS.( Vehicle speed sensor)

[Captkaos]

That is what I have, no VSS signal. 

[Unofficial]

Ok, so since my last post in here I put in a 350 ECM and now I'm getting code 13. According to the link given above somewhere, it's saying "Oxygen sensor voltage stays between 0.35 and 0.55 volts for 60 seconds. Engine was at normal operating temperature and had been running for at least 2 minutes after start with a throttle angle above 5%." Is that what you guys have in your books too? Because code 24 is different in your books than what it is on that site. Is that saying my oxygen sensor is bad or what? Also, I still get code 24, which is something to do with the speed sensor. My speedometer AND odometer don't work, and I can't really tell if I have any bad connections, so I don't know where to start. Any suggestions?

[DnStClr]

Hm.. the o2 sensor compares the oxygen level in the exhaust to the oxygen level outside the engine- and it should be normal if it sends a voltage to the computer that's lower than 1 volt. I would reset the ecm by disconnecting the battery + cable for 30 seconds or so and hooking it back up. start the engine and run it again for a few minutes, shut it off and see if the code has gone away. The o2 sensor is pretty hardy- it lasts a long time. It could be telling you that the fuel mix is too rich. Higher voltage signals from the o2 sensor means there's too much fuel not getting burned..

[Unofficial]

Ok, I'll see if I can get rid of the o2 sensor code. Any ideas on my VSS?

[VileZambonie]

Check the gear on the VSS. If it's damaged there's your VSS signal problem. No code will tell you if a sensor is bad, so clear the DTC's as Don suggested and see what comes back. If the O2 sets a DTC again, you'll need to check the sensor output voltage. If it's less the .500v and staying there that means there is a high level of O2 in the exhaust or the sensor is lazy. If it's over .500v and staying there that indicates a lack of O2 in the exhaust and again could indicate a degraded sensor. See what returns and let us know.

[Unofficial]

Where exactly is the speed sensor? Is it a plug-in or is it where the speedo cable meets up with the tranny?

[Unofficial]

I no longer get code 13, but I STILL need help on the VSS. All I need to know where it is. I asked in the above post. Any help?

[Captkaos]

It is in the tailshaft of the transmission, screwed in where the Speedo would be...