Rough Idle... Still

So it idles rough. I've searched on this, but haven't seen this same issue unless I searched with the wrong keywords. In general it runs great since I put the new motor in it. Today I rechecked timing, reset base idle and adjusted the TPS which was off and I was getting a code for it. Now it idles right at 1000 instead of 1100-1200 like is was before. KOER I get no codes except for system pass. I did a visual check of my vacuum lines and replaced the one from the tree to the brake booster which was not in great shape, but it didn't help. Fuel pressure is good. Only thing is vacuum at idle still reads 14in. Hg. on my vac/boost gauge. I'm going to have to pressure test the whole system, but while I am doing that is there anything else I should be looking that would cause this rough idle? It drives fine and runs real smooth above 2000rpm.

Brian, still sounds like a vacuum leak to me. I agree with having a pressure test.

Brian, still sounds like a vacuum leak to me. I agree with having a pressure test.

Yeah pressure test it. That will find any vacuum leak that may be hiding somewhere.

Another thing that is good to do is hook volt meter up to TPS and open and close the throttle a dozen or so times with engine off key on. Make sure open and close voltage is the same every single time. I had an issue where once out of a dozen times the TPS would stick and read a little high throttle closed. ECU really does not like it when that happens.

Pressure tested it... Found air escaping the valve cover. Seal had slipped apparently when I initially put it on. Fixed it, but no change in the amount of vacuum I am getting and the thing is not running any better. I let it idle for a while while I sprayed brake cleaner around all of the hose connections, but I didn't get any results from that either.

I don't know where else to look for leaks. Could it just be that the piston rings are not seated yet? This engine has only about 8 miles on since the rebuild. I have my boost controller disconnected and the vacuum line runs straight from the compressor outlet to the wastegate so boost won't go over 8 psi. I just did that in case I forgot I'm still breaking the engine in and decided to floor it. Anyways, what I'm getting at is it seems to have the power it should, but when I took it out for a test drive tonight it definitely had a miss during acceleration too so I'm thinking there's more to it than just a vacuum leak at this point.

The idle doesn't fluctuate very much. Maybe 100 rpm at the most. I just sounds like it's missing or something. I don't know - like I said it's been a long time. When I reset the idle I did check the TPS for consistency throughout the entire range and it did return to the same voltage every time I closed the throttle.

Haven't driven the thing in 10 years and when I finally get it back together it wastes no time in trying to frustrate the hell out of me!

Check your EGR. Even brand new, those effen things leak. I sealed mine with epoxy to dummy it out. It passes visual inspection but it's completely sealed inside. Now I have no leaks.

Where did you hook up the pressure tester, at the TB? or at the turbo inlet? What I'm getting at is have you thoroughly looked over the IC hoses and the VAM hose for leaks. Leaks there won't change the vacuum reading but will affect the A/F ratio

I hooked it right up to the turbo inlet so the IC hoses and everything were tested as well.

I'll have to check the EGR when I get home.

I'll do another pressure test tonight. Maybe crank up the psi to 18 this time. Another thought though, The Dizzy including the PIP and TFI are olllddd. I know it has nothing to do with the vac issue, but if the dizzy has excessive end-play could it be causing/contributing to this idle problem? I'm not sure what is normal for end-play, but I'd estimate on this one it's about 1/8th inch. It seemed like it was a bit much, but when I was driving the car several years ago I don't remember it ever being a problem.

what are the specs on the cam you have in it?any cam larger than stock will effect vaccum....