superlen

You can adjust the valves cold too...or at least check them cold to see if they are reasonable numbers. 2 thou less than adjusting hot. The AFM looks to be why you were running so rich. Weaker spring = more vane movement with less air = more fuel for less air than designed. Len

Yes. That's Blue's site and has a lot of good information. He's more active on classiczcars.com, but he may be on here too. If you follow his method of setting the spring tension using a known mass (beer can on a string), the AFM should be pretty close. It definitely won't be so far out that the car runs massively rich. The other usual suspect for highly rich is the coolant sensor connection. If that connection becomes corroded or disconnected, you will have an instant rich condition. I didn't bring it up earlier as you said you went through the EFI bible tests so you probably covered it already. The key is to measure at the ECU connector so you test all the wiring connections, not just the sensor itself. Len

Yes. The FPR is non adjustable. The only test is to compare the rail PSI to what it should be given the current manifold vac like your doing. Always there should be 36psi difference. If you have a vac pump like a mighty vac, you can attach it in place of the manifold and watch the rail pressure go up/down as you release/apply vacuum. You would need to make sure the fuel pump is running during this test either by holding the AFM vane open (simulating airflow to the engine) or by jumper wire, or by pulling wire to starter solenoid & having someone hold the key in the "start" position. BTW, if you just bypass the AAR with a hose you will always be in high idle mode. It's easier to just pinch the hose on either side with vice grips. That will take it completely out of circuit and you can test the rest of the system. Also, I watched the video more closely and it looks like your getting around 30psi with 10" in the manifold. Those match so your FPR is probably ok. Other sources of rich condition are of course the AFM and/or the ECU. I'm doing a bunch of tests on AFMs currently. PM me if you have any questions. Len

Ahhh...the plot thickens. LOL You're saying the actual connector that's supposed to stay with the AAR came off, right? That's another failure I haven't seen nor heard of, but if the AAR had any leak you would get higher idle and leaner burn of course. I don't think it's the cause of the rich condition. The rich condition is something else, again maybe the FPR. If you're engine is really as tight as indicated by your compression numbers and the valves aren't horribly mis-adjusted, your car will hold a pretty good vacuum at idle, 20" perhaps. Just judging by hearing your rpms on the video & watching that fuel PSI gauge, your fuel PSI is too high. I normally see around 26-28psi at idle, drop a little as you blip open the throttle and then climb to 36 when wide open of course.. Replace the small vacuum line from the FPR to the intake when you're checking it out next time, even if it looks ok. That little piece takes a fair amount of heat abuse and a small intermittent split might be causing a lot of your problems. Without that connection sealed and solid, your fuel pressure will definitely be too high at idle (which is what I think I see in the video). Len

Another strange possibility along the same lines as NewZed's is the AAR. If the valve inside it has somehow became loose/broken and is bouncing around that would be just like you blipping the throttle open/closed. I've never heard of this happening before, but it would make your idle erratic as hell. You can easily test by just temporarily clamping the hose leading to it with a pair of pliers. If the jumpy idle goes away that would tell you something. Len

Check your fuel pressure again. The FPR should hold the PSI at 36 above what's in the intake. At WOT the psi in the intake will be atmosphere which is where the gauge on the fuel rail is referenced to. So, at WOT your gauge should read 36. At idle it should read 36 - your vacuum reading in PSI, not inches HG. If your vacuum is reading 20" HG (around 10psi) your fuel psi should read 26. From the video, it looks like your psi is too high to me which would definitely cause a rich condition. It is hard to tell exactly & you may be ok, but it looks like you are reading 32 psi around idle, and you have around 20"hg vacuum at the same time. If that's true you have 6psi too much pressure on the rail. Lenny

Josh, Howdy neighbor! I'm in NW Arkansas and travel to Tulsa all the time to visit customers. I'm trying to map our 280z vane AF Meters & get a better understanding of their airflow vs output..particularly ones that have drifted due to weak springs. It's a tad difficult as you can imagine because so many have been messed with and adjusted, but each one I come up with gives me more data points. I still haven't messed with one from a known turbo car yet. I'm assuming that they max out at more airflow and have their springs a little stiffer, but I'd like to confirm that. Len

+1 on condition, condition, condition.....of the body. Engines, trannys, & Interiors are easy for the DIYer with the least amount of outlay for welders and bodywork tools, ect. Body work isn't hard per se, but you need another set of tools and it is messy....very messy. You'll be angle grinding grit all over the place, torching panels perhaps, grating bondo, sanding bondo, spraying primer. It's fun but so is swapping engines and cleaning engine parts and you can do that with a good basic set of tools. If you farm out the body work, the less rust you have to start with, the less money you have to spend. All of this advise goes out the window of course when you find "the" car. It could be a pile of crap with most of the parts in totes, but if it speaks to you. Damn the torpedoes, full speed ahead. Congrats on the baby. My wife and I are expecting in April & I'm already planning on working from home three days a week all summer. Lenny

Just a quick bump. Anyone have an AFM from a turbo, or one known to have some skips/dead spots or otherwise flakey behaviour? Lenny

Bad Steve, no donut! No big deal. I'll PM you. Lenny

Hello, I just posted a link over in classifieds : http://forums.hybridz.org/index.php/topic/117203-wanted-old-afmsecus-for-testing I'm wanting to gather up several Air Flow Meters/ECUs to test & do some research on. I know this crowd has some that are being currently used as spider rent houses. Thanks. Len

Hello All, I'm working on a new project and need some donor parts so I can do some more detailed L-Jet research. With all the MS conversions, I assume that you guys have some of these knocking about under your feet. What I'm looking for are the following: AFMs They can be any any condition (this means the output is flaky/unknown/untested, not backed over by the wife's minivan when you left it on the garage floor. ) & I actually would like a few that you know are suspect in their calibration. ECUs 75-78 ecu, Again. Unknown condition is fine. Harness 75-78 FI harness. Can be rat chewed on, crusty injector clips, ect. Price? Well, I'm basically bottom feeding here for some test parts that I'm going to hack/cut/burn up & possibly destroy so free/cheap/reasonable in that order would be preferred. I would of course pay shipping. PM me with what you have. Thanks Len

The running conditions you state are not completely consistent with just a misadjusted or bad TPS. Definitely test yours before buying a new one and assuming that it will fix your problem. You can pop the cover off of it and watch the contact work as you move the linkage. There are basically two switches in the TPS. At idle, one is made, the other open. At WOT the opposite of course. When the throttle is inbetween those two extremes, NEITHER of the switches should be made. It's not uncommon to have to adjust the springs/contact arms in there with a pair of needle nose to get them to function correctly. BTW, when you unplug your TPS, the ECU simply thinks that the engine is NOT idling and it will turn off it's Idle enrichment. At Idle the ECU richens the mixture a bit to promote a better more stable idle. (Leaner mixtures tend to hunt around some at idle). There is also a slight spike in mixture right when you unplug the sensor while it's running. This is the ECU thinking you just came off idle and it wants to make sure the bit of extra air as you come off of idle doesn't lean you out a bit. It's time delayed so you only get this enrichment for a short duration. I dont know exactly how much extra fuel it delivers or how long the "short duration " is. So if you say the engine runs a bit better when you unplug your TPS, it's an indication that you're running rich now. My guess it that you're running quite rich for any number of common Z L-Jet reasons. Len

As a bonus design feature, the heat shield will conviently funnel any fuel leaking from your injectors toward the rear and drip/pour it on the exhaust manifold/down pipe connection. There's lot of hoses/clamps on that rail so check them all. If you have to pull the rail be sure to replace the small vacuum line from your FPR to the intake with a new one. It takes a bit of heat abuse there and doesn't have a particularly long life. New Orings wouldn't hurt either. Len

Haha... you guys are good. I think for what it's worth, most of the time the signal (whether you think of it as read or sent) is usually wrong due to that pesky connection. If one were customizing the engine compartment anyway, relocating it may be something interesting to do. Depending on where it moves, it may change the way your EFI behaves slightly. However, it probably would only affect hot start operation. Len