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Discussion Starter · #1 ·
My 79 el camino has had a heart transplant. It was born with a 305, but now has a 305tpi and a 700r4 behind it. It idles fine in park, but when I am in gear and pull up to stop at a light, I get a surging happen. With my foot on the brake its like it wants to keep going forward. If I dont have my foot firmly on the brakes it would creep inch by inch. With brakes firmly on, it torques the front of the truck. Kinda looks cool really, like its got some big bad-ass cammed motor in it, but I know that aint what it should do.

Could it be as simple as a vacuum leak, or am I barkin up the wrong tree with this thought, and if it is vacuum related, would the old brake cleaner trick be the appropriate measure to test for leaks? And yes, I would have a fire extinguisher at hand if I do try it if its what you all would suggest to try.
 

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Darbysan will probably jump in here and give you some good info when he sees the thread. This will get it on top again.
 

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I'm kind of in the same spot Mike. I put a rebuild carb. from Mt. Man and trying to get the idle set correct. Warmed up in park I'm at about 900 RPM'S and every so often i think the choke kicks in up to 1100 rpm for a couple of seconds then back down. I gear at a red light it's at about 800. What should it be at in park warmed up? Got new plugs,wires,dist. cap/rotor,EGR,CO2 sensor ect. new 190 thermostat. inspected and changed most of the soft vacuum hoses and the hard ones look fine. Also theres a vacuum sensor that screws into the thermostat neck with two hoses. Does the bottom hose tee-off to the smog pump and the top one to a round thing'y next to the starter there solid vacuum hoses?
THANKS
ROBERT



 

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did you hook up your p/n wire to the correct terninal on the correct nuetral switch.that signal tells the ecm its in gear so the idle motor will control the idle?
 

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did you hook up your p/n wire to the correct terninal on the correct nuetral switch.that signal tells the ecm its in gear so the idle motor will control the idle?




where's that?
 

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the nuetral switch at the bottom of the steering column or on the floor shifter.i used a painless harness and it gave you instructions on this.the tpi looks for a ground signal to tell the ecm what gear it is in.been 20 years since i did mine.and dont remember if it looks for ground in gear or park.mine had the wrong switch and would idle crazy until i changed it.i will look for my book on it to see and will let you know
 

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the nuetral switch at the bottom of the steering column or on the floor shifter.i used a painless harness and it gave you instructions on this.the tpi looks for a ground signal to tell the ecm what gear it is in.been 20 years since i did mine.and dont remember if it looks for ground in gear or park.mine had the wrong switch and would idle crazy until i changed it.i will look for my book on it to see and will let you know

never tuched it. but i forgot i pulled my codes a week ago and 15 came up temp. sensor. DA!!!! CHECK IT OUT TODAY
 

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Discussion Starter · #8 ·
Did my thread get hijacked? lol I assume ccc was responding to me there, er at least I hope so. It is a painless harness too, and I have the book for it from the original owner who did the tpi swap, I will look for this and see if its hooked up right and let you guys know what I find. thanks!
 

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For a tpi setup to run correctly, besides the stuff normally needed like proper parts & not having vacuum leaks, Computer must be tuned for application sometimes, particularly when an engine is parted together. This is best done by a reputable tuning shop with a dyno.
Firstoff though, computer codes need to be pulled up from diagnostic port. Hope painless provides one. Think their harness is speed density, rather than mass airflow. Mass air adapts better to changes.
Robert, you don,t have tpi, this thread won,t help you.
 

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Discussion Starter · #10 ·
My apologies for not getting back to my thread here, weather has been horrible and I only have the great outdoors for a workshop right now. Today does look promising!

The 305 with tpi setup came out of an 86 Iroc I believe. Was a total engine swap apparently. A Painless harness was used to do the transplant by the PO. I have the Painless manual for reference, it covers all their harnesses, MAF, MAP, and TBI. It is mass airflow I think, but haven't confirmed by looking for the 9th injector.

I've bought new vacuum tubing and will start by replacing all vacuum lines today. If the problem persists, I will move on from there and check for intake leaks. If that still fails, I will be back here for more info as to where to check next. Thanks to all for their interest in helping me sort this out!:You_Rock:
 

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I would use some starter fluid, Propane, or carb cleaner and spray check for vacuum leaks. I've always had trouble getting the intake runners to seal properly. It might not hurt to re-set the IAC motor, as that controls the idle. Surging though sounds like vacuum leak.
 

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The ninth injector is just the coldstart injector,you will find the MAF if it has one in the incoming air supply to the throttlebody.If I was you I would pull the (IAC)idle air control valve passenger side of the throttlebody and it screws in into the throttlebody.Remove it and chech the seat inside for carbon buildup and the IAC for scoring of the valve.
Another possibility is the EGR valve not closing properly and of course the ever possibility of a vacuum leak.
Carburetor cleaner usually will take care of the carbon buildup in the throttlebody and on the IAC but if the solenoid in the IAC is bad it will need to be changed.
These are not the only possibilities for your problem but they are the ones I have run into the most.
The first is MAF and the other is the IAC.


 

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Discussion Starter · #13 ·
Well, after I got done watching the nascar race, I was rudely surprised to see it snowing! It's almost spring dammit!

I do have a MAF tpi by that picture, I remember seeing it. Will check the other do-ma-thingys when I change the vacuum hoses.

Too cold to work out there, so I went to the parts store and bought two new rotors and calipers just so I could feel like I did something! Had to do the same thing last week, but was inner and outer tie-rods and idler. Week before that was air-shocks.

Gonna have a lot to do when the weather finally warms up and stops snowing/raining! Or else I'm gonna have a huge pile of parts! I really need a garage! :???:
 

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Gonna have a lot to do when the weather finally warms up and stops snowing/raining! Or else I'm gonna have a huge pile of parts! I really need a garage! :???:
I have the same issue in Chilliwack with all the rain and no garage ,luckily my neighbour felt sorry for me and let me use his garage.


Chris
 
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