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

Z cars in general just rock! They are super easy to work on, and when something does wear out or break, it's usually pretty quick to figure out whats going on. And the bottom end is almost bulletproof within reason of course. I do wish that an affordable crossflow head was available, but I understand why they aren't. Palau is correct that the stock EFI can be cantankerous, but I have been designing a true plug-n-play drop in replacement called HellFire that will begin shipping in May that completely solves all the EFI problems. It's completely configurable as well so you can modify your engine all you want with cams, heads, exhaust, map, maf, ect. And finally, you can actually SEE what coolant temperature the ECU is reading on your laptop. (or isnt because of a corroded CLT sensor connector which is pretty common on these cars) I don't want to step on this build thread, but I'm exicted about the HellFire and thought I'd share a little. I think it will prove to be a nice addition to the Z car community's bag of performance tricks. Lenny

Strike, If you put new urethane bushings on your front tension arms, be sure to just one one poly and one stock rubber bushing. Many, (including me) have had the tension rod actually snap from have all polyurethane bushings. I think it's just too tight and the poly holds the rod very rigid right near the bushing. The steel fatigues right at the bushing, then....snap. You can google for more info. Others have had success, but I didn't. Lenny

+1 on your fuel system is kersplat. That's a looong time setting. -Start with dropping the tank and inspect/flush. -Next in line is a small filter in the inlet of the fuel pump. Just pitch it and splice a cheap plastic inline from the tank to the pump inlet. -The fuel damper I think may be ok, but check all the hoses back at the tank. -Don't put a new main fuel filter on it until you have ran the pump a while. Leave the old Filter on and just see what comes out. The old filter is trash for sure, but use it's last breath to save your new one. If you drop a fresh new one it at the first, you will just have to replace it in short order. -Once you get clean fresh fuel flowing to the rail, then check your pressure & confirm the FPR is doing it's job. -The fuel lines on the rail all need replacing & don't forget to put new vacuum line on the FPR to intake manifold connection. -The injectors will need cleaned/tested. - After all that you should have good fuel, next would be checking/cleaning the electrical connections on the EFI harness. Hopefully, the rats didn't eat most of it. Len

I think some of the KA24 TPSs have both an analog connection as well as a IDLE/WOT switch connection similar to the stock 280z tps. He may be running that. I'm not 100% sure on the dual connection but I think that is the case. FYI My HellFire digital ECU accepts the bone stock 280Z tps switch or an analog TPS potentiometer using the same wires/pins. Just plug whichever you have in. I actually read the stock switch as an analog input & it just shows up as 0, mid range, full scale emulating IDLE/OFF IDLE/WOT. Len

Comic, The amount of fuel is pretty sensitive to that CLT sensor. You noticed how it floods the car instantly when it comes off (you said it just dies, but it dies because the AFR tanks). This is because the ECU all of a sudden sees and infinitely large resistance which it determines to be a really damn cold engine & starts dumping lots of fuel to it. It will also run your car very rich if the connections are just corroded. The corrossion causes the ECU to read a higher resistance than is really there & then it thinks the engine is colder than it is, thus it dumps more fuel to it, not as much as when the connector fell off, but still too much. This could easily explain your poor mileage. Your plugs may be somewhat fouled now as well depending on how long it's been running rich. The fact that the mileage problem occurred right after the connector falling off and being reconnected is pretty smoking gun like. Pull that connector, clean & then see how it does. Len

Swervy and NewZed both have good suggestions. If the coldstart valve is leaking, or electrically malfunctioning and just spraying you will get obviously get a rich condition, and the coolant sensor is prone to crappy connections & it will cause a rich condition as well. You said you cleaned all the connections so hopefully that's not biting you. Pinching the fuel line feeding the CSV rules this out in just a few minutes. If it's not the CSV, then the only other thing that can cause the rich condition is the injectors spraying more fuel than needed and there are several possibilities there. Here's a quick list: 1. Fuel pressure to high. The stock ECU expects 36psi across the injectors. If your fuel pressure regulator is failing & you now have 42... well you're going to run rich. 2. The injectors are larger than 180cc/min. NewZed touched on this. If someone "upgraded" to larger injectors, again the stock ECU has no clue about this. Assuming your PSI & injectors are correct, then it's the ECU telling it squirt too long...why? Well, i'ts reading the sensors & making a calculation. If one(or more) of these sensors are faulty, you'll have issues. So how do we tell? With the stock ECU, sadly the only method to do this is to make measurements at the ECU connector with a voltmeter and compare to the values in the FSM. I got annoyed at having to do this and designed a digital ECU drop in (HellFire). I can read my sensors with my laptop. It won't be availalbe until late spring so for now, you'll still have to do the FSM test. Here are the sensors that can fail and make you run rich. 1. AFM This is the #1 control element to set the amount of fuel. More air -> More vane movement -> more voltage to ECU -> more fuel. The AFM was a great idea in 1975 & it can work well if it's in great shape (although it's restrictive as hell). Sadly, most have drifited all over the place & who knows what you're really getting. Additionally, the wiper inside can become intermittant and have dead spots. It's important to get a nice smooth voltage without seeing spikes/dips when testing these. 2. CLT sensor. The next biggest contributer to calculating the fuel pulse width is the coolant sensor. If the engine is cold, the ECU dumps more fuel until the engine warms up. You wouldn't think it was much, but it can actually be a massive amount if the ECU thinks it's really cold. This is where those crappy electrical gremlins cause problems. Unhooking the CLT sensor or a high resistance connection due to corrosioin will make the sensor read colder...sometimes really cold. The ECU responds with dumping extra fuel. When you test this circuit, make sure you test right at the ECU connector. That covers your wiring all the way from the sensor to the ECU. 3. IAT sensor. The intake air temperature will also control the pulse width, but much less so than the CLT. Cold air is more dense so it contains more oxygen and thus we can squirt a little more fuel. So if this sensor is reading wrong, you could get a rich condition as well. The IATs on the zcar are pretty reliable however, & with the conditions you describe I would check it just to rule it out, but I don't think it's your problem. Note: when you unplug your AFM you are unplugging the IAT at the same time. So teh ECU now sees the following: AFM is a really low number so meter way less fuel, IAT has went to extremely cold (meter more fuel).. Who knows what percentages each of these are, but I'm pretty sure the net result would be to lean the overal mixture. That matches what you saw I believe. The ECU it'self could also be failing. They are almost 40years old now. It's a wonder they still run. While designing the HellFire board, I've taken apart several of these. I'm amazed at well the Bosch engineers could implement the basic fueling requirments with opamps and multi-stable vibrators. Features and special conditions are easy to add with software, but when you're doing it all with analog parts that can/do drift with time/temerature, that's impressive. Apparently, the cold start feature couldn't be done with the technology they had or at least in the time frame they had so we ended up with 5lbs of wires, hoses, cold start valves, fuel lines and such on the intake. Hope the above is helpful. A spare ECU and/or AFM to swap in/out of your car would go a long way for troubleshooting. PM me if you have trouble coming up with one, particularly an ECU. I have a few known good ones (or at least goodish) that I don't mind trading for even an known bad ECU. I can still use the bad ecu as a core for HellFire as long as the case/connector isn't trashed. BTW, my gut instinct for your problem is your AFM(edit- i re-read where you tested the AFM - so I'd now guess ECU), at least if you have confirmed that the CLT sensor reading at the ECU is within spec & it sounds like you covered your bases pretty good there. Also adding a fuel rail (like you were planning) with the FPR at the end (not in the middle) along with boosting the fuel pressure from 36 to 42 should help hot starts a lot there in AZ.....plus they look cool. Lenny

Nightmare, All you need to troubleshoot the fuel pump circuit is a multimeter, a jumper wire, and a copy of the schematic from the FSM. I've been designing an LJet digital/tuneable replacement ECU (HellFire) & have been wading through the FSM with regards to the ECU wiring/fuel pump workings so hopefully I can steer you in the right direction. First, The best page to find in the FSM is page EF-33. It's in the "Engine Fuel" section not the wiring diagrams section and it contains figure EF-45. If you have a paper copy, great, but if you are working from the pdf, search for EF-45 and you should come up with it. The fuel pump circuit for the early Zs isn't rocket science, but it's not straight forward either & it takes a bit of studying to get it clear in your head. All my notes below will refer to this page, so go find it first. For testing the FP circuit you can either have the ECU connected or not. The stock ECU does not control *any* part of the fuel pump circuit!! Strange isn't is? When you look at the schematic you will see a wire running to the ECU that *could* control the FP Relay but it's not even connected inside the stock unit. I think Bosch engineers had plans to use it, but never did. Anyway, don't get mislead by that wire. Just ignore it. FYI that wire runs to pin 20 on the ecu. Here are some key points to know: - The pump is only controlled by the FI Relay. - The FI Relay actually has two "relays" in it. Two coils, two contacts. They are both just housed in the same metal can and collectively called the FI Relay. - Two events can cause the pump to run. Either the key has to be in "start" position, or the key is on "run" and the AFM Vane is moved off of rest due to airflow. - Power to the FI relay comes from a fusible link which as we all know get flaky with age as the contacts corrode. It's always a good idea to verify your F' Links. Here's a cut/paste from a discussion where there are lot more details as we were troubleshooting the FI relay. There's more theory in that link, but the section below is a good easy first test procedure for you to follow. 1. With the key OFF. (note, it says OFF) 2. Jumper +12V to P74 (pump should run - as P74 is the actual wire going to + side of pump) 3. Jumper +12V to P36 (pump should run ) - tests one of internal coil/ contacts of relay 4. Jumper +12V to P39 & Move AFM flap off idle (pump should run) - tests AFM contacts 5. Now turn key ON & Move AFM flap off idle (pump should run) - tests the second internal coil/contact. 6. Now turn key to START (don't care about flap) (pump should run) - this tests the start switch it'self and the connection to the Relay. Hope this was helpful. Lenny

NewZed, Yes, I was referring to the EFI main relay inside. I wish Datsun would have named the whole package something with the word "dual relay" in it or similar. And Yes to clarify NZ is right if you just wired directly to the fuel pump and removed the EFI/FP relay you would lose power to a lot of components. Namely: the Aux Air Regulater, the ECU, the dropping resistors, & the cold start valve. One still needs the EFI relay or some external relay to provide power to these components. Len

For your car, the ECU controls NO part of the circuit that operates the fuel pump. The fuel pump control is completely external using the relay and the AFM switch. (75-77). If you're pump is running (either with the stock relay or with a bypass wire) then the ECU would be happy. Note: that the fuel pump relay also routes power to dropping resistors & the ECU it'self so if it has some issues you may still not have a car that runs correctly, but it's not because the ECU thinks the fuel pump isn't pumping. +1 on what others said about a pre-filter before you new pump. Also check the stock fuel filter. It is a fine particle filter and over time can get clogged with the fine rust that's coming out of your tank. (I know it looks clean when it sprays all over you, but over time it can still stop up). A partially clogged filter can give symptoms similar to what you're describing. Although usually you start noticing problems when you stomp on it and demand a large fuel flow....not just starting and trying to idle. Len

BA, When you turn the key to "on" and here the click. The following should happen: 1) Coil/Contact #1 in the Fuel Pump Relay (as you noted, there are two in there) turns on. That's the click you hear. 2) That should route +12V to your dropping resistor (via pin 43), +12V to a series switch inside the AFM via pin 39 (this is the switch that makes contact when air is flowing), & +12V to the ECU via pin 10. -- At this point if you push the AFM vane open manually, that internal switch should route +12V back to the relay on pin 36 & you should here another "click" & the pump should come on. Note: the wire coming back to pin36 also runs out pin20 to the ECU, but don't worry about it at all. The ECU does absolutely nothing with this signal & in fact it's not even connected inside the box. The ECU does nothing to control the fuel pump. It's all in that relay and the AFM switch. -- The second relay should also come on if the key is in the "start" condition. You usually can't hear that click though as the starter/engine noise hides it. If you pull the wire going to the starter solenoid, you can turn the key to start (the starter of course won't engage) but you should hear the relay click. I read again your post and you tried this but didn't hear the second click. (Check that pin 73 has +12V ALL the time even if key is off - its fed by a fusible link that lots of times gets really gunky and corroded so there's a good place to start). 3) Now, assuming you hear the second "click". That should route power from pin 73 (+12 from the battery via fusible link) to pin 74 (the actual wire going to the fuel pump) Hope this is helpful. Lenny