DStegs Posted July 2, 2009 Share Posted July 2, 2009 I have a 75 Z with FI and I can't get the thing to idle worth a squat. Cold, it runs rough and back fires a bit but once it is warm and rolling down the road it runs fine but I have to play with the throttle when I am at a stop, or it is racing at about 1200 rpm at idle. I can't get the timing mark on the balancer and farther onto the scale for timing then 0. Do I have to pull my distributer and reset it in the next "slot"? I have tried moving the phase adjusting timer but can't get the marks to line up. Is my chain too sloppy to get the rest of it right? Car has about 141k miles on it and I think somewhere along the line it might have needed a new cam chain. I can deal with carbs on American Iron but this FI is baffling me. Maybe a small block will solve my problem but don't have the cash for conversion right now. Something simple has to solve it that I keep missing because it runs good when warm and rollin. HELP! Quote Link to comment Share on other sites More sharing options...
thetremendoustim Posted July 2, 2009 Share Posted July 2, 2009 check ur vacuums for any "sudden high idle" problem adjust ur IAS? this should help... http://atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf Quote Link to comment Share on other sites More sharing options...
thrustnut Posted July 2, 2009 Share Posted July 2, 2009 Whats your RPM when trying to set your timing? Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 2, 2009 Author Share Posted July 2, 2009 check ur vacuums for any "sudden high idle" problemadjust ur IAS? this should help... http://atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf Hey TTT. (The Tremendous Tim) Thanks for the literature to read. This will probably make me sound stupid but that is why I am asking questions. Will read before attempting much more. I have a couple of issues. Idle is about 11 1200 rpm and will not drop if you rapp the throttle nor go any lower without spitting and stalling. Sensors?? Well off to the garage with the literature. Thanks. Dave Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 2, 2009 Author Share Posted July 2, 2009 Whats your RPM when trying to set your timing? Thrustnut. Can't get the idle below a grand to 1200 rpm. Got the lit from TTT and will see if I can cypher a reason out of that. Might be vacuum or a sensor. Hope a simple fix will do but I am ready for the worst. Thanks. Dave Quote Link to comment Share on other sites More sharing options...
burninator Posted July 2, 2009 Share Posted July 2, 2009 There are 7 adjustment screws on my distributor ('72 240Z). I'm not sure if it's the same on the newer models. I did have the same problem as you with not being able to get the timing setup right even with both adjustments maxed out. I'm guessing the newer Zs have a similar setup where the distributor is driven off a spindle from the oil pump and I ended up having to pull the oil pump and re-aligning it fix the timing. Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 2, 2009 Author Share Posted July 2, 2009 Well, I went through and searched out most of the vacuum leaks, I think, and solved the ones I could find. Got it to idle lower and was able to set the timing (FINALLY). Don't know if it is because timing chain is stretched or what but I had to go into the distributer and adjust the "Phase difference adjuster" to get it so I could get the mark on the pully to even hit on the timing scale. After a few back and forths I was able to set it and move on to the next problem. It seems that with age everything gets brittle and cracks. Going to replace all the vacuum lines and assorted hose that attach to the many wonderfull things the lines attach to. Still unable to "adjust the idle correctly because the little adjustment screw for idle is retained by a small nut. Can't adjust it because the I cant release the nut to set the screw deeper because the housing is there. Sounds like another dissassembly to do a simple adjustment. It also runs a bit rough at idle and I am ordering a valve cover gasket to get in an adjust the valves. Also have to replace the pcv hose under the manifold. It fell apart like old dried cake when I went to touch it. Certain that was one of the major leaks I had. Plugged the pcv valve to do my timing. Also seems that the throttle switch does nothing. Unplugged and plugged it in and no difference when reving the engine and letting it idle. (see above where everything gets brittle) Going to follow the wires and see if they are broken any place. Have to study the circuit testing section and maybe can avoid a lot of dead end chases. Thanks to the tremendoustim and thrustnut for your suggestions. Seem to be leading me in the right direction. The electronic fuel injection manual also helps a lot. Now I am off seeking a 1975 280Z Service Manual. Anyone have one out there to download?? Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 2, 2009 Author Share Posted July 2, 2009 Burninator, You might try the same thing that I did and search out all the vacuum leaks and go from there. Dave Quote Link to comment Share on other sites More sharing options...
thrustnut Posted July 3, 2009 Share Posted July 3, 2009 Thanks for the props. The best way I found to check for vacuum leaks is with carb cleaner. Just spray down the lines you think are bad, and if idle speeds up, you found a leak. A couple things on your timing...if your not at 800ish RPM, you cant set it correctly, and did you disconnect the vacuum line to the dizzy before adjusting? I think the idle adjust on my 77 was the big screw on the top of the throttle body (as long as your not hitting the throttle stop on the linkage first). Check for vacuum leaks and get your idle set before setting timing, as long as it runs I think it should be close enough for now. Anyone want to correct me on the idle adjustment on the FI? I'm running a carb now so its been a while. Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 3, 2009 Author Share Posted July 3, 2009 Thurstnut, Thanks for the help. I followed a combination of Chiltons, old school and the EFI booklet I downloaded from TTT and after dinkin around with the vacuum leaks and weak brittle hoses, I got the idle down. FI had to have the thermotine switch pulled and jumped. It said nothing of pulling the vacuum line, but I had done that before with a couple of carbed cars before. I might still have a few leaks but at least it idles now. Next is the valve train and from what I found with the EFI booklet and the tests in the back, my throttle valve switch on the idle side is shot. That would contribute to my problem. Have been looking and I think Advanced Auto has one for cheaper than online. Looks like the right one and the pic matches the one I have. Also want to check the BCDD switch or valve but that is a bit more disassembly. Oh well, there is always tomorrow. Plus the switch won't be in for a couple of days. It runs good enough to drive so I am set for a while. Actually it runs better than before. This site and you guys have been very helpful and I will continue to use it. Later. Dave Quote Link to comment Share on other sites More sharing options...
duder280z Posted July 3, 2009 Share Posted July 3, 2009 I had high and inconsistent idle issues till I just removed the BCDD. I had to take the TB off, remove the BCDD valve and plugged up all the holes with screws and JB weld. Idles great and consistent now. Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted July 3, 2009 Share Posted July 3, 2009 I 100% agree with the BCDD reccomendation... It was a pain in my ass until I took it off... I'd start with that. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 5, 2009 Share Posted July 5, 2009 in all of this, have you verified that TDC on the pulley aligns with actual engine TDC? The L28 Dampeners are known to slip after 30+ years... Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 5, 2009 Author Share Posted July 5, 2009 I understand things slip and stretch with age (gee, that sounds familiar) but I haven't checked the pully/engine alignment. I also want to either check or replace the timing chain and gears because of the same potential problem. I did (prior to spending any money) open and check the throttle valve switch. I did that after the tests from the EFI PDF bookelet. It indicated the throttle valve working on acceleration but not decelleration. Well with nothing to loose, I cracked the baby open and lo and behold, no contact on the decell. mode so I took my needle nose and bent it till it made contact, and it now works as it should. A bit of silicone sealant in the corners and it is back in place functioning as it should. One more thing that you guys suggested is next on my list and that is the BCDD valve?? Guese it is under the TB. Any suggestions as to what it is and looks like. I can kindof see it from above but don't know for sure what it looks like. Someone else here said to take off all the extra garbage on the manifold and plug the appropriate holes. That is coming also. The car now starts, idles, goes, and stops like it hasn't in years. I do want the rpms to drop like a rock when I decellerate so I guese the BCDD will do that???? Thanks for the help, and suggestions from all. Hope you had a great 4th of July. Quote Link to comment Share on other sites More sharing options...
duder280z Posted July 6, 2009 Share Posted July 6, 2009 Glad to hear your making progress! If there are no other major vacuum leaks, the BCDD delete will cure the RPM drop issue for sure. It is pretty obvious what it is when you take the TB off. It is a roundish, cylinderish sort of thing that looks a bit like a starter solenoid. It is also the only thing hanging off the bottom of the TB, so get a new TB gasket (should cost $1 or so) and just dig in. Don't be shy, anything that is on the under side of the TB that can be removed, goes. There will be 3 or 4 air bleed holes that will need to be plugged. Plug them with anything that will seal the hole and not come loose. I used screws and sealed them in with JB weld. I tapped the holes (that I could) with threads for the screws, but that is probably overkill. After that you will probably have to adjust the big idle screw on the top of the TB when you get it back on the car, but that's about it. My car idles at a perfect 800 RPM now. Before it would go all over the place, up to 1300. Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 6, 2009 Author Share Posted July 6, 2009 Duder280Z, Thanks for the description of the BCDD and how to remove and plug it. Will get a gasket and tackle that next. I get this thing running any better and I won't want to get rid of it...... Still have to work on R and R ing the floors. Got an idea from Mull's videos on taking out and installing new floors. I think I can do it from the top down without stripping and flipping it over. Looks like the flat 18ga. with 2x3" rails is what I am going to do to it. Might lose about an inch and a half but can fit the seat rails to work at the correct level. Oh, to find a 2+2 floor system and just weld it in. Right now I have a patchwork repair job on it and the rails are still bad. Oh well, I didn't want to get bored this summer. Quote Link to comment Share on other sites More sharing options...
thetremendoustim Posted July 7, 2009 Share Posted July 7, 2009 DOODT i just figured out what the BCDD is last week its this son of a bitch boy is it ugly, i just straight up swapped the TB's out with another one I had. I can even tell you what four screws you need and how much of a pain in the ass they are to change since they have a hexhead btw, as for your earlier fsm question carfiche.com my friend it has helped me with EVERYTHING, you can even run to your local car shop and I got a ohmmeter in the $5 clearance bucket and when I ghettorigged it up to a 9v I am able to test the continuity of any wire in the car and test the resistance of every sensor, in fact tonight I just tested the character curve of my CHTS and the readings from my AFM :mrgreen: free FSM + $5 ohmmeter = THE BEST DEAL on earth i can go on for ages Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 7, 2009 Author Share Posted July 7, 2009 Man that is UGULY! No wonder it gives everyone a PITA! So where do I take it off at? Is it just the round thingy at the bottom with the 5 or 6 screws in the base of it or is it everything south of the TB? Quote Link to comment Share on other sites More sharing options...
DStegs Posted July 7, 2009 Author Share Posted July 7, 2009 carfiche.com my friend I either need stronger glasses or I have to blow it up a bunch larger. How do you read it or is it better if you download a page and print it?? Quote Link to comment Share on other sites More sharing options...
duder280z Posted July 8, 2009 Share Posted July 8, 2009 You pretty much remove everything that can be removed without cutting. That includes the round part on the bottom and the section in the middle. Quote Link to comment Share on other sites More sharing options...
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