Hello.. My name is Andrew and I am new to thirdgen.org although I have been coming to read forums about problems I have had.. Thankfully have fixed them thanx to all of you. I am sorry I bring my Blazer into a Camaro forum.... BUT I did install a TPI into it because I love all the good things I have read about them.. expecially the torque and fuel economy compared to a Qjet carb..

The vehicle - 1984 Chevorlet K5 Blazer w/1991 350 origially TBI purchased engine with Holley 750cfm carb which is way to much for the 350. swapped the carb with 1992 Camaro TPI w/ custom harness.

Problem I had and fixed - went through alot of problem solving to find out the #2 injector was sticking open and fully fowling out the plug in less then a day. Ran like crap and could not do more then 35mph without it boging me down. I swapped the stock 21lbs injectors with LT1 24lbs. The engine runs better as far as the bogging goes..

Problem I have now - My truck idles VERY high.. I have a 1500 stall converter in my 700R4 with less then 20 miles. This is spoken about because the idleing is so high that I can let of the breaks and 5 seconds later im doing 20 mph. I have checked for vacuum leaks, spark plugs (ACDelco 45TS), TPS voltage (.62 @ idle & 4.54 @ full throttle w/ the key in the on position) wires and connectors. I have also checked the IAC valve under the TPS... wire are fine... Need a new IAC? Idle screw is all the way out... I have not unplugged the negative cable from battery yet to reset the comp.. ill try that today..

ANY ideas? Thank you for all the help!

if you need anymore information from me about anything.. please say so.. I need all the help I can get.. this is my first fuel injection swap!

 

Hi Andrew. Welcome aboard, hopefully you'll find all the help you need.

I'll refer you to this article to start: https://www.thirdgen.org/tpimod2

Just make sure your IAC is set correctly before you do anything else. It doesn't sound like you did this yet.

 

for the adjustment page..


Today (3/22) I tried the negative cable on the battery to reset my Comp.. there were numerous problems today.. I do not know if it had anything todo with disconnecting the battery or what.. my engine would start and run... turn it off.. fiddle w/ some sensors to try and lower the idle.. shut it off.. fiddle w/some more with the sensors and battery.. then I would try to start the engine.. it would turn over but not start.. I did not hear the fuel pump at this time.. the relay would switch on and off but the pump would not.. 5 minutes later.. the engine and pump would run.. IDK whats going on.. I will try the adjustments on the IAC and see what happens..

ok... today (3/23) I followed the IAC adjustment instructions.. didnt change a thing.. ???????????? Did I mention my 350 had a different cam then TPI spec? Could the cam be changing the vacuum that much? Its not very big.. I do not know what its specs are.. I bet my IAC is sticking open.. could that be it?

 

I am going to try replacing the IAC and TPS today..

 

I don't think a small cam change would drastically change the vacuum to change the idle.
1. Is your base timing set right? Roughly 6-8 degrees btdc. Check with ALDL disconnected.
2. You said you checked for Vacuum leaks. Does this include the intake manifold and vacuum lines?

Just a little more food for thought

 

I'll bet your timing is off, mine is too. Modified EPROM is doa on mine so i put the one with 5 degrees less timing in, same thing! Mine idles at 1300 RPM.

 

I believe my timing is set to 10 degrees.. how do I check my IAC to see if it is working properly? I have a new TPS and IAC.. should I install them anyways to see if that will fix the problem too? Thanx for your replies!!

 

I just purchased a ported plenum and BBK 52mm throttle body with new TPS and IAC.. I am hoping I can install the throttle body and everything will be better.. My chances are good I am hoping!

I have also heard about taking the IAT out of the plenum and installing it into my airbox for a really good ready of cool air.. is this true?? is this a good thing??

I am also runing dual 3" exhaust with 50 series flowmaster.. is this a bad thing for TPI and the OXY sensor? More torque is a 3" single exhaust.. but will the single be better for the TPI or no difference?

 

I changed the timing today... idle went down alittle.. but is still high..