rcb280z

How about head light buckets...PM me with $$. Welcome to the club. Oh, fuel rail too $$

What was the 77 supposed to be? I mean besides a turdmobile. I don't get it. A twisted mind got a hold of that poor 77!

Hey everybody, I decided to look everything over before tearing into things. I noticed my idle was off... just slightly lower. I started to turn the idle set screw CCW to raise the idle and decided to take it further....curious how high it would idle. I could only get it to 1600 rpms (with set screw). Shouldn't I have been able to get it to idle higher with the set screw?

Cool, thanks for the valuable info everyone. At least I know for sure I have the right AFM or at least close enough. Oil.....I recall seeing some oily residue in the AFM where it mates with the throttle body boot. Thanks for reminding me. Will check this out next. Post results later

If you have the FSM you could probably repair it faster than finding a quality replacement....would be cheaper as well. I was looking for a EFI harness a couple years ago and found out mine was in better shape so I just made a couple simple repairs and it's good. You know there are 2 harnesses in the engine compartment right? There is the engine and EFI harnesses.

Yeah Capt Obvious, you got that right! I'm chasing my tail. I can put the AFM back to factory setting I believe. There is no "goop" but I did mark the original starting point. At least I hope it is the original point. I will actually have some time to spend on it tomorrow. I am going to attempt another adjustment before removing it from the car. I heard that the anti back fire valve only came on the 76 model. Couldn't understand why if it was such a good thing so I will assume I was misinformed. Hope to have good results to post tomorrow.

Just a quick run down for you Fastwomen, I started this thread because I was having an issue with the fuel pump running in the "on" position-engine not running. So found that problem corrected it and went into trouble shooting the issue with cold start not working. With help from this forum we found all sensors working properly and fuel pressure being correct. My Z would start after sitting over night but would have an unstable idle at around 900-1000 rpms. Long story short, when I rotated AFM counter weight CW the idle increased to 1300 rpms and she idled smoothly (AAR working). That told me I was running rich during cold start (AFM related). Now we are trying to fix the problem. Thank you for your continued support. How goes the move? I hate moving. Did it too many times in my life.

I am going to find the problem with my Z if it is the last thing I do! I can't walk away from something that is not working right. I won't let it beat me. So with that said as soon as I get time away from work I am pulling the AFM and will try Blues' calibration procedure. I know it's in the AFM. I also know this AFM was not for the 77 280 rather a 76. It has the anti backfire valve in the flap. Maybe that's why it never ran "perfect". Stay tuned for results.

Okay, I'm depressed now.:disappoin Started her up (cold start) and she is back to her unstable idle! I thought I had that fixed at least. There must be something seriously wrong with the AFM. Not sure if it is worth doing the "recalibration" do you? Sorry everyone, thought I was making progress.

I went to NGK's web page and my plugs look like there is a combination of 2 of the plugs displayed. Mine look normal and at the same time have "dry and wet" fouling look to them. Strange. ngk.com/tech_support/spark_plugs/faqs/faqread.asp

Maybe I should put the timing back to factory setting and run it and see if the plugs look different. Capt Obvious, glad I could clear things up. Back to researching..... I still need to figure out how to do Blue's AFM calibration.

That is actually the next plan of attack.....AFM clock spring adj. I think I understand what you are saying Fastwomen. Everything is getting a little complicated right now. Thanks for the continued help.

Here are the pics

That is all correct Captain Obvious. I'm not sure what you don't understand...you pretty much said exactly what I did. I probably didn't explain clearly. When I started the car (cold) and it had it's typical unstable idle I rotated counter weight CCW and it stumbled more saying to much fuel. Then I rotated it CW (leaner) and it perked right up and idled where it should on a cold start. Hope I was able to clear things up. The mechanic did what he did long before this. About 1 1/2 years ago. I pulled plugs and they look good, I think. I will post pics soon. I also ran a compression test this afternoon. Here are the results: 1-150, 2-170, 3-155, 4-150, 5-175, 6-175. This could be why it doesn't idle that smooth. I did last valve adj. about 4 months ago at the latest. 1,3,&4 are a little low compared to the other three. I will try adding some oil to those cylinders and test them again. Again...grasping at straws I know. Any thoughts? Capt Obvious, let me know that I cleared things up.

Well I tried adjusting the AFM and I can't find a happy medium. What is so strange is I ran a mileage test today, about a 100 miles, and she's getting 22.5 mpg. That's 90% freeway driving at around 65 mph. I expected a lot more because she really feels like she is lean. Plugs are almost white which would say lean. And seems to have less power. Am I expecting to much out of an engine with 120k miles? My vacuum gauge is showing 18-18 1/2" and sometimes 19. If it were low I would look for a vacuum leak as a culprit. Timing is set at 14% right now. I feel like I'm taking 1 step forward and 2 steps back always with this car. And Fastwomen, I tapped on the ECU a couple of times and didn't notice a difference. If I adjust the AFM right now for a smooth running engine then I will really be rich.

Very nice and welcome to the club!

Fastwomen, I sent you a PM regarding fuel injectors. That's a good looking Z you have there. Sometimes I wish my Z was all original. It is mostly, just exterior (minor) changes. I guess I would be happy with the one I have and one that was all original also. Wonder what my wife would say to that. Thank god she is understanding. I have spent quite a few hours lately trouble shooting the EFI. She knows just how rewarding it is for me to fix the problems though. I think I have it figured out now. Tomorrows AFM adjustment will tell. Again, I will post what I find.

Yes Fastwomen you are correct, I do have the best of the best helping me out. Even after reading as much as I have in this forum and the FI system being as simple as it is there still are so many things to consider. The "8 teeth" adjustment is just the beginning. I'm going to attempt a fine tune session tomorrow on the AFM. It was actually a mechanic friend of mine that messed with the clock spring...he adjusted it lean because he thought it would need it to pass CA smog (and it didn't). So after the smog he adjusted it to where he thought I would like it. So if what you say is correct about ECU drift then mine could be considered "drifted lean" right? If it was adjusted richer because that seemed right then that would mean a lean condition correct? I will tap on the ECU to see if there is a difference. I have read about all the things you speak of on this site. Which BTW I am so happy to be a part of. I am considering Blue's calibration technique if I can't fine tune the AFM. I will have to read it again. Will keep you posted. Thanks to all.

Okay, here is a promising update! Decided to start the car this morning and with my list of tests I wanted to run in front of me I started with #1. That being; as soon as she fired and started her low unstable idle I moved the AFM counter weight forward...stumbled more. Moved the weight back (CW) and she perked right up and idled where she is supposed to on a cold start! So she is running too rich on cold start up due to AFM. I tightened the spring about 8 teeth (sound familiar?) and she idled around 1300 until she started to warm up and then slowly dropped to around 800 which is OK with me. I'm going to run it for a couple times to see if she likes the adjustment. If not I will go from there. After reading several threads, posts I'm wondering if my ECU is "floating" so to speak. A positive step in the right direction huh?

I have a lot to learn also Captain Obvious! I have been able to fix everything else on the Z but this problem has been challenging. I like challenges and know that with the help of this forum we will find it. With special thanks to Blue for staying on this with me and everyone that has taken time out to help. I think I just found out that I have an AFM from a 76 280 on my 77. It has the anti backfire valve in the flap. I'm not 100% sure but I think the 77 and 78 didn't have that valve. Not that it matters but I know it's old and might be time to rebuild it or replace it if it warranted. The only thing I haven't checked out of your above list is the ECU drift. What are the symptoms?

I will try the AFM next. I was going to try that before and forgot to. I know with the cover removed you can rotate (ever so slight) the counter weight CW or CC to lean and richen it. Remember when I said I was going to remove the plugs to see if they were fuel fouling? That's because I thought I was running rich at start up (fuel fouling the plugs).

Hmm....funny you say that. I was just thinking the same thing early this morning. If I have a vacuum leak it is probably going to be hard to find because it goes away so fast. I know it takes longer than that for the intake to heat up enough for the metal to expand. I think you meant intake to head connection though. I'm contemplating a compression test. Looking for possible valve (s) not seating right because although it might smooth out after warm up it doesn't idle as perfectly smooth as it should. I did a cold adjustment about 2 months ago and didn't find anything out so....? My vacuum gauge shows a reading of between 18-18.5 in Hg so if I had a vacuum leak do you think it would show up there? Guess I should hook it up during a cold start and see if I get a different reading. Wish I had a spare good known AFM. I could easy change it out to see if there was a difference in fuel delivery when it's cold. I have a fuel gauge in line and the pressure is good. Guess I'm grasping at straws here. I will keep plugging away at it. I want to try Fastwomens vacuum leak test. I will have a buddy of mine blow smoke into the intake...he smokes I don't.

Damn Philip, I just read (again) in your post above where you asked me if I hit the brake when I started the car. The answer is no. I have been starting it from outside the car lately. I don't know why I didn't understand your statement "don't hit the brake". Must have been the lack of coffee this morning. Bob

Ok I will think about this as well. I know that if I disconnect BCDD the idle raises about 100 rpms. I'm pretty sure that it shouldn't raise the idle any right? So maybe there is something there. It didn't seem to make a difference when it was cold "cold start" though. Philip can you look at your throttle linkage and see if the linkage actually rests on the set screw....mine does and the FSM shows it resting on the dash pot shaft. FSM shows a 1.9 mm gap between the throttle linkage stop and the dash pot shaft. Sorry, not sure what you mean by "don't hit brake". Bob

Philip, In post #53 I mention the dash pot really doesn't seem to do much. After looking at ET-9 of the 77 FSM it explains that the dash pot is adjustable. But to me it seems that if I was to adjust the dash pot it would allow more air into the intake. On cold start with the throttle closed what difference does this make? I'm confused now. Oh, I took the dash pot off to see if there were any changes....none. You would think this would be something easy to find. Bob.