86IROC112

OK, I have ben battling this car for months and finally figured out it had bad heads. The PO rebuilt the bottom end and slapped the old heads back on giving me very poor compression.


Just got it all back together with my newly rebuilt heads. For the first time since I've had the car it fired right up just like it's supposed to do. First thing I did was time it. Then I adjusted the IAC. I got the car to idle wonderfully. It would even for the first time EVER idle in gear. It would restart right back up without excessive cranking like it did before. I was very happy!


Then about an hour later when my son got home I fired it up again to show him and it held a steady idle of 2000 RPM.?? I did another IAC adjustment and with it unplugged it idles just great. As soon as I plug it back in 2000RPM again. Frustrated I gave up for the day.


It has to be IAC related. IAC is brand new. Just had the TB rebuilt by Dr. Injector. CTS is brand new. I am wondering if the computer still thinks the engine is cold and after it got hot and sat the ECM doesn't know it's hot?


Or could Dr. Injector have changed the TPS adjustment? Just confusing that it was great before it got heated up.?? Ideas?

aliceempire

iTrader: (14)

Well, you've come a long way since you started. Did you ever find the clamp for the air cleaner you needed? I searched my stash and didn't find one.


What rpm was it running at when it was cold? How long did it run? Did it get to warm idle at 600-700ish the first time you had it running?

86IROC112

Nope, Haven't found a clamp yet. Least of my worries right now.


I had it running for maybe five minutes. Definitely did not get all the way to operating temp. But you know how they heat up after sitting. Going to start her up tomorrow after work and see if it's back where it should be. I've made huge strides and can now at least rule out mechanical issues.


I wonder if Dr. Injector removed the TPS and just put it back on without adjustment? Not sure if he dials them in before shipping them back.?

aliceempire

iTrader: (14)

He probably didn't.
5 min usually is enough to drop the idle to 'normal'. Depending on temperatures you have right now. I'd probably let it warm up before readjusting everything again. Things may be off if the temps aren't right. I like chevy thunder's write up, even thought there is a good one on TGO too. http://api.viglink.com/api/click?for...inimum%2520air

86IROC112

I will adjust the TPS and repost the results. The more I think about it, that might be it. Makes sense. But it sure ran and idled nice when I first started it up.. I will get her all heated up then do both adjustments again.


Can't wait to drive this thing!

86IROC112

OK, got it all warmed up and did the IAC, then the TPS. The TPS was out of adjustment and it idles at an acceptable RPM. However, after a minute or two it surged up to about 1200 and stayed here for a bit, then dropped back down to 550 or so and ran kind of rough. ??? WTF? It still idles in gear which it never did before which is a plus but....


AND, the fan won't kick on which it did before the heads were pulled off. AND my upper radiator hose is leaking where it attaches to the thermostat housing. The upper hose feels like it is under a tremendous amount of pressure like maybe the Tstat is not opening. (It's brand new too) Had to finally shut it off as it close to red on the gauge..

aliceempire

iTrader: (14)

Was the upper hose hot? That'll tell you if the thermostat is open. Possibly air in the system even though that's not a common problem for a sbc.

You can test the cts when warm too, that'll show if it's at spec for whatever given temperature.

86IROC112

Upper was hot as hell. Couldn't touch it for more than a second or two and could barely squeeze it. CTS is brand new with new connector.

aliceempire

iTrader: (14)

Hot upper hose means the tstat opened.

You'll have to check the circuit and find out what isn't working to find why the fan didn't turn on.

86IROC112

Seems there is excessive pressure. that hose shouldn't be leaking. It's a new hose and the clamp is good and tight. Is it true if I unplug the CTS the fan should come on automatically? Kind of an ECU failsafe? It comes on in diagnostic mode as it should...This crazy car is going to put me in the loony bin!

aliceempire

iTrader: (14)

Disconnecting the cts shouldn't turn on the fans as far as I know. The CTS gives less resistance the hotter the temp is, so disconnecting it would be the opposite of that. Diagnostic mode skips the cts circuit so that means little other than the ecu and fan circuits are functioning.

Are you sure you put the intake gasket on correctly? My thought is the coolant port is blocked...see coolant ports...
Just a thought.

86IROC112

Oh Jesus, I hope not. Doubt it but now you've got me scared...I specifically remember seeing the "this side up" stamped on the gaskets when I installed them though...

86IROC112

OK, good news. I guess I just wasn't patient enough yesterday. Ran it again right now and the fan came on. Going to chalk it up to the OEM gauge is not real accurate. Temp came right back down when the fan came on so everything is OK.


Going to take her for a test drive to let the ECM "learn" after setting the minimum air at the IAC. Wish me luck...