Ok. I just rebuilt my LS engine and have been having idlie and start up problems. Let me say first that I have read the Write ups on this issue. The IACV write up is unclear in the part that I need to know.
So my idle started to suge about 500rpm when starting the car in the AM. I would crank the car and it would idle at 1500 like it should. Then as the car started to warm up or if I hit the gas and revved a little the idle would start to bounce. I checked the two holes on the throttle body and the FITV was sucking air in all the time hot or cold. So I took that a part and the plunger was in fact backed out. So, I screwed it back down and re installed the part. Not the IACV is always sucking hot or cold. The FITV valve is pulling in some air but not much at all when it’s hot (as it should stop when the engine is warm). If I cover the top hole (IACV) with my finger while the engine is warm the car sputters and dies. Is this normal? I suspect that it is not. If I unplug the sensor the engine stalls as well. The IACV is clean b/c I cleaned it when I put the engine together and cleaned it again just to make sure it was no built up from anything in the blocks coolant passages.
The IACV should be pulling in air if the engine is warm correct? Mine pulls the same amount of air hot or cold. Suggestions comments please.
The second problem.
I was driving the car on the interstate and about 10 minutes into the ride my CEL came on and the car performace was affected. I checked the codes and pulled code 4 and code 7. TPS and crank position. I turn the car back on and the CEL is gone. The ECU constantly flashes the red light even when I am not jumping the plug to do so. So I reset the ECU b/c I knew I started the car with out the TPS plugged in prior to my interstate drive. I took it back on the interstate and about the same time passed and the CEL came back on again. Could the IACV effect the TPS?
Third problem.
Now When I start the car from a cold start it dies immediatly. I have to hold the gas for about 20-30 seconds and then it will start to idle ok. I don’t have a surge anymore but like I said it will stall on me. I am going to check all my grounds to make sure they are in good shape. Could this be a TPS problem? I don’t get the check engine light unless I am driving for a while. Any help or suggestion would be appreciated.
I tested a spare IACV with a 12v source and ground and it clicked. So I was going to clean that one out and swap them and see if it helped. I have read that the stalling could be a vacuum leak by the throttle bodyand that has me thinking it is the IACV.
Thanks,
Ryan
First:
Note that the IACV controls idle when getting warm-full operating temp. The FITV controls idle when cold and first warming up. Based on what you describe it sounds like you still have a problem with both.
FITV:
You said that now when you start the car you have to press the gas to keep it running? I bet you turned the FITV screw too far. Try backing it off one or two turns. You will have to experiment with where to set the screw until you reach about 1500-2000 rpm when the engine is first started cold. The other option is just replace the FITV.
IACV: After trying the above then check the idle when warmed up. If it’s still not correct or bouncing then I would swap the IACV with the spare you have. Just be sure it is very clean before reinstalling.
Lastly, as far as the CEL coming on, I doubt is related to the idle unless the light is staying on all the time. Try checking the connectors at both the TPS and the distributor for loose/corroded terminals or loose/broken wires. If you don’t find anything with the connectors you can test the sensors. I’d recommend buying a service manual it will make your life much easier.
[QUOTE=90da9teg;2177189]First:
Note that the IACV controls idle when getting warm-full operating temp. The FITV controls idle when cold and first warming up. Based on what you describe it sounds like you still have a problem with both.
FITV:
You said that now when you start the car you have to press the gas to keep it running? I bet you turned the FITV screw too far. Try backing it off one or two turns. You will have to experiment with where to set the screw until you reach about 1500-2000 rpm when the engine is first started cold. The other option is just replace the FITV.
IACV: After trying the above then check the idle when warmed up. If it’s still not correct or bouncing then I would swap the IACV with the spare you have. Just be sure it is very clean before reinstalling.
Lastly, as far as the CEL coming on, I doubt is related to the idle unless the light is staying on all the time. Try checking the connectors at both the TPS and the distributor for loose/corroded terminals or loose/broken wires. If you don’t find anything with the connectors you can test the sensors. I’d recommend buying a service manual it will make your life much easier.[/QUOTE]
I have a haynes but I am going to look into the factory manual b/c it goes more in depth. Thanks for the response. I do have an update to add.
I swapped out the FITV with one I had laying around and changed the throttle body with one I had as well. The idle is sitting right under 1000 rpm when warm and doesn’t budge. Even when I turn my lights on it stays the same or move just slightly lower. I think I may have this one fixed. I will know tomorrow morning when I give it a crank from a long cool down. Thanks for your input it is appreciated.
Ryan