I have recently swapped from a 305 to a 350 tbi. I changed the injectors and computer to match up with the 350 and 700r. After running it and a couple hundred miles, it idles real bad like it has an aggressive cam in it and it has a really bad skip around 1500/2000rpm's 55/60mph after running about 10 min, but when you give it full throttle it seems to have plenty of power. I have replaced the idle control sensor, map sensor, and distributer module, including swapping back to the 305 computer. It is almost like one of the injectors inst firing, but it is. I have worked on TBI a lot and it has me baffled along with every one of my friends that are mechanics. I have also checked my fuel pressure and it is in the upper 20's, and the 350 was rebuilt about 6 months ago and ran fine with a carb on it. It's a 4 bolt main. Has anyone ever run into this before?http://coloradok5.com/forums/images/smilies/dunno.gif
CK5
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OK, Need a little help with tbi 350
- Thread starter K5Cobb
- Start date
TBI fuel pressure should be 13ish PSI...
Jessie James
1/2 ton status
Are there any errors on the computer? Jump the data port and see what comes up. It should tell you everything.
Went back and checked it running, and it was 14, off is middle to upper 20's. I made the pump run while it was off just to see how how much it was putting out. Any reason for such a difference or normal?
It wont idle long enough to get the comp to throw up a code, But i got it to run for 20 mins or so on the open road and it throws up 42, which is losing connection with dist module, but its got a new ignition module (which was tested and came back good). I have also put a new computer in it with new chips that came from hypertec, and ran same with them as the factory chips. I also checked the wires and cant find any breaks or bad connections.
Jessie James
1/2 ton status
The two main issues that I know of are the coolant sensor in the intake being bad, and the O2 sensor being bad. If you recently replaced the O2 sensor did you use thread locker that is safe for the O2 sensor?
There is a long list of things to check in the TBI manual. Off the top of my head the PCV valve, the IAC, the MAP, the EGR, the injectors (test by unplugging them and then turning on the truck - if fuel flows you have a leaking injector or o-rings) or have wired them backwards (I just posted about that in another TBI thread, would you mind searching?
) or have the wrong injectors (while they look the same, there are different injectors for each engine).
There is a long list of things to check in the TBI manual. Off the top of my head the PCV valve, the IAC, the MAP, the EGR, the injectors (test by unplugging them and then turning on the truck - if fuel flows you have a leaking injector or o-rings) or have wired them backwards (I just posted about that in another TBI thread, would you mind searching?
) or have the wrong injectors (while they look the same, there are different injectors for each engine).The two main issues that I know of are the coolant sensor in the intake being bad, and the O2 sensor being bad. If you recently replaced the O2 sensor did you use thread locker that is safe for the O2 sensor?
There is a long list of things to check in the TBI manual. Off the top of my head the PCV valve, the IAC, the MAP, the EGR, the injectors (test by unplugging them and then turning on the truck - if fuel flows you have a leaking injector or o-rings) or have wired them backwards (I just posted about that in another TBI thread, would you mind searching?
I actually just found the other thread you posted in.
the injectors are right for the engine, and Brand new from advance. I looked at them run this morn and the one on the passenger side didn't have a fog patten, it's jus shooting out a stream of gas. The driver side has a fog pattern, but dribbles gas. I didn't have time to trouble shoot past that point b/c my father believes in my tractor cranking up with the lights on and it shutting down with the lights on. 
There's no reason for differant fuel pressures. That along with differant looking patterns from each injector are both issues that need to be dealt with.
So how do you get a fuel pressure with vehicle off?
So how do you get a fuel pressure with vehicle off?
63chevyll
1/2 ton status
You could have possibly torn an o ring around the injectors. What about the map hose, engine ground or timing, air leak etc..
It's very possible, but it did run good for a day after the engine was put in, as far as the map hose, its new along with map sen.
Engine is grounded, and timing was checked by a friend of mine that is a mechanic at the here, and i have been all over it looking for a vac. leak. I have even done a vac. test and no leaks...... I am thinking I might have gotten some cheap injectors.
I am having to do this from my phone, but when i get back Im going to pull the injectors and see if i messed up the o-rings. I didnt realize they were so expensive, Napa is 145 each and advance was 73 each.........
Jessie James
1/2 ton status
I think this is the issue you have, which is what I had. Remove the injectors and there are 2 o-rings and one washer. You should have a small o-ring at the base of the injector (I didn't, flooded the engine), then a super-thin metal large o-ring/washer thing (DON'T LOSE THESE, I can't find anyone who sells them!) in the TBI housing, then the other large o-ring goes on top of that one.
You put the metal ring in first, then the large o-ring, then the little o-ring onto the injector, then place the injector into the housing paying special attention to the pin on the injector which must fit into the opening at the base of the TBI housing where the injector sits. Mine is facing the rear of the truck, yours probably is too. Then put the cover plate on and slowly tighten down all the screws and you should be good to go.
I'd replace the large gasket and the small rear fuel line gasket while you were in there...
This is what you need: AC Delco P/N 217-1426
http://www.autopartswarehouse.com/d...apwcid=P1135867996W43b3f85c7ab9e&apwidvwd39jK
Advance Auto sells that but it's hard to find sometimes, I got mine included with the new injectors I bought.
ok, update. I had 2 bad injectors and the harmonic balancer had slipped, so timing was off a considerable bit. took #1 plug out and got it to the top and got it timed that way. After getting that straight, it idles good, has a little studder on acceleration sometime, but is alot better. Heres the thing I am having to run it off the 305 computer, the 350 computer makes it run rough, and i have tried to swap chips but nothing is better. I had to give my cuz back his hypertec chips, so i have nothing to compare to. So progress but not perfection.
i dont have a code reader and i have a check engine light on all the time. after i jump the connector and it gives me (Flash-FlashFlash--Flash-FlashFlash--Flash-FlashFlash--) it flashes the engine light 4 times, pauses then 3 more times. It flashes that sequence 3 times be for it gives me (Flash-FlashFlash--Flash-FlashFlash--Flash-FlashFlash--) again. I take it this is code 43, but cant find its meaning.....
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43 ESC - electronic spark control ESC module not receiving knock sensor signal.
From this page: http://www.cfm-tech.com/gm_tbi_trouble_codes.htm
From this page: http://www.cfm-tech.com/gm_tbi_trouble_codes.htm
At the fuel pump relay, I made a jumper and had a friend of mine put power to it while I watched it on the gauge, but come to find out, after looking into what you said, the gauge I bought was faulty and took it back to napa. The second one they gave me read around 14. I can try to draw up some schematics if you would like to see how I did the wiring at the relay.
I have been chasing wiring gremlins and have narrowed it down to the wires with quick connectors around the engine. If I un hook all the wires including spark plug wires, and re hook them the light will stay off for a while (sometimes a week, sometimes a few miles). Does anyone have an idea which wires around the top of the engine would affect the the knock sensor or code 43. I have have traced them but can't find the one not making connection.
