As some of you know I have recently started for the first time my rebuild LT1. I am having some problems with a few things and have a Datamaster file for those of you interested in seeing it. Download it HERE Now on to the questions. First off my IAC is going between 119 and 160. HOW in the hell do I get that under control. Second the TPS is showing almost 25% at idle and only .16 v. I realize you are all going to tell me I need to hog it out. Problem is I have never seen any write up with pictures on doing this, and I really dont understand what I need to drill out. The sensor or the TB. AND where exactly do I need to do the work on it. For some reason I just dont understand what you all mean. Call me stupid. Anyway, those seem to be the only problems I need to tackle right now. Once I have it to where I can drive it I can take it to the dyno and have the real tune done on it. But it needs to be driveable to get it there without destroying anything. All help is GREATLY appreicated.

Q

 

Sorry, I'm desperate....Back to the top

Q

 

with the high MAP readings im gonna guess you have a vacuum leak somewhere. but then the IAC reading should be lower so i dunno what to say about that. what cam do you have?

you also have and EGR code and low TPS code. i will say your TPS might need replaced. some times it was reading say .51 volts and 7% while it would read .16 volts at 26% so thats definitely not right. also your idle is way high causing the car to stay in cell 18 when it should be in 16. did you mess with the throttle stop screws any?

 

Were you holding the throttle open at any time during that log? Why was the TPS changing? Do you have the valves adjusted correctly? Stock TB?

 

During the run I did hit the gas a few times to help smooth it out or prevent a stall. I have not touched the stop screws yet, I did the vent mod to the IAC via a hose to the bellows. That is how I got it to idle finally. The cam is a custom grind, I can dig the specs up if you need them. The TB is a Holly 58 MM. Valves were adjusted by my engine builder, and he is no rookie. Certified builder. I would hope he adjusted them right. I knew I would have a EGR code, and a Trans code, and a AIR code. All three were removed this past winter. Any suggestions?

Q

 

You need to elongate the screw holes in the TPS so that you can move it. You need to see at least .3v from the TPS when the throttle is closed. Your log indicates you are getting less than that.


Elongate the holes, mount the TPS and leave the screws a little loose, so the sensor can move. Turn the key ON (no need to start) and observe Datamaster. Rotate the TPS until you see at least .3v, tighten TPS screws. Turn key off for a moment or two, then start and check operation.

 

Thanks Rob, that is crystal clear. I will try it tonight after work and post the results. But what to do about the IAC? I think I know what the vacumn leak was, I had the hose off the FPR while I adjusted it. Other then that all ports on the intake were pluged or in use.

 

I would re-evaluate the IAC counts after you get the TPS squared away. Hight counts mean that you are letting more air in because of a sensed rich condition.

 

makes sense, I will post the results tonight. Thanks again!

Q