Jersey

I am completely out of ideas guys. I really think i'm missing something logical and simple but i just can't figure out my Z's problem. I think it's been three weeks of troubleshooting now and i just can't find it. Here's the symptoms and what i've found: - No timing advance. Just sits @ 20BTDC. Looks like it slightly retards about 2 degrees when bringing up R's but that's it. VERY slight movement. - Runs very rich @ idle - Green LED on ECM does not flash, ever. Only time i see it lit is when key is in "run" position Any idea what could possibly have an effect on all these things to just happen all at once? It's an '82 L28ET in a '73 240, NPR I.C., Walbro Pump, 1G DSM BOV. Everything else on the motor is stock. No POV, EGR or AAC. Before whatever it is causing all these things to happen, the car ran perfect. Nothing was changed, i just noticed one day that she didn't want to basically hold an idle and was running real rich. Shoot any ideas that you may have, as simple or as weird as they may be. I am at a complete loss here and am open to ANY ideas. Thanks guys.

Don't want to get anyone pissed because this is the tech forum but, the F-14's are my favorite. They just look like they'd kick your @ss standing let along climbing up on your tail, aiming to gun your butt down!!! Wish i was near St. Louis this weekend, i'd be there. Cool. Take some pics and send 'em if you can.

No, not in the military. My cousins wifes uncle is the Commanding Master Chief on the UUS Reagan and he invited my cousin and me on the ship. They have what's called "family day" once a year and what it is is that the certain members of the crew are able to bring a couple members of thier familes onboard for this to see what the ship is all about. He just chose us this year. It was amazing being with the Master Chief. He is one of the top 3 men on the ship and everyone knew it. I guess being in the Navy for 34 years and doing the right thing gets you this status. Just awesome. Once in a lifetime oppotunity. He retires next year.

Bernardd - I did run the AFM through all the test as per the AFM. It was out a little bit - Off the top of my head, i think initial resistance is suppose to be 280-400K ohms and it measured 200K ohms. I also found out that this has an effect on the full sweep values. I added a 150k ohm resisitor in line which raised the initial value to 350k, which wouold also put all the remaining sweep values in spec as well. Didn't help one bit. I pulled the cover off and everything that i could see looked good and clean. Tonight, i think i'm going to swap the AFM with the one from my cousins 83ZXT just to see if it does anything. Thanks a bunch for the offer. And yes, i am REALLY ambitious...my Z's been sitting in the garage for over 3 weeks and it wont leave until i figure this out! Thanks again. 525 - sorry to hear about all your bad luck. It could only get better now, right? Good luck.

Hey all. Just got back from vacation yesterday- Went to Virginia, climbed aboard the USS Ronald Regan Aircraft Carrier, sailed 80 miles out to sea for 12 hours while F-18's landed, launched, did major maneuvers, breaking the sound barrier....talk about acceleration and agility!!!! One word - AWESOME. Anyway, I got back yesterday and started tinkering with my Z last night. It was to my understanding that the HTS didn't effect timing - only the ECM adjusted timing but, i decided to unplug the HTS while shooting the pulley and sure enough, the timing almost immediately advances near 10 degrees. So, i'm assuming, once the ECM received an open from the HTS, it adjusted injector pulse AND timing? What other sensors will make the ECM adjust timing? If i had a better understanding of exactly how all the sensors work in conjunction with the ECM and what the ECM does to adjust for the readings it gets from all the different sensors, i think i could figure out the problem i'm having. The FSM is vauge on some of the information i need. BTW - this is in reference to the problems i've posted here - http://hybridz.org/phpBB2/viewtopic.php?t=24962 - and here - http://hybridz.org/phpBB2/viewtopic.php?t=25052 . Last night i also swapped the ECM, Dizzy and Coil w/Transistor with known good ones and none of it helped AT ALL. Still rich at idle and no timing advance. I'm wondering if a leaky injector might be causing my problems. Running out of electrical/sensor ideas. Double and Triple checked all sensor values and they're all spot on. Also checked all powers/grounds and ripped apart half the harness, just to find everything was ok. Thanks in advance for any info.

Thanks 327, Sleeper. Do either of you, or anyone else that reads this, know what sensors would tell the ECM not to advance timing because it's possibly sending a lean condition? Maybe all of them combined or, maybe if only one of them is out of spec, it would disregard all the rest? I'm not even sure if any of the sensors where sending a lean condition that it would stop the ECM from advancing the timing. Just guessing away now. I do know that the knock sensor will retard it. Maybe the knock sensor wires and picking up some kind of noise in the car and sending a signal to the ECM like it's knocking, even when the wires are unplugged from it? I thought all the sensors below send signals to the ECM so it can determine how much and how often to through fuel at the system, not mess with ignition timing, no? O2 HTS AFM ATS TPS Only thing left sensor wise on my Z is the knock, which is the only thing that i know controls ignition...in a retarded type of way Sorry. Well, at least i have my cousins '83 ZXT in my drive for a couple of days and can get some time to do some comparisons. Thanks again guys.

Bay - yes, i check first at each sensor, then go to the FSM and check the pins themselves. I'm not sure if the CAS is aligned right. It doesn't say how to do it in the FSM, although it does say it may become mis-aligned and may need to re-align! I'm doubting as this is it because Sleeper on my other post ahs suggested that the CAS has nothing to do with timing advance, it just tells the ECM where the pistions are. Thanks for the ideas. Keep 'em comin'! 525 - i will figure out what the h*ll is wrong with this thing. I MUST have overlooked something.....well...twice and i'm just not getting it. I will keep trying. It is easier to have a second vehicle. I just wish i had my Z back on the road and get her back to the track!!!! Like you, it pissed me off to apoint to where i put it in the garage and vowed to figure out what was wrong until she went back on the road. Keep trying 525, you'll get it.

It's just unreal that i haven't been able to solve this rich/idle condition. Now i'm going to focus on this no advance issue and i think it'll be the answer, or at least get me in the right direction. I mean, damn, i would have been easier if i spun a bearing or something! At least then i could diagnose and concentrate on THE problem. Unreal. I was told if the CAS was bad, she wouldn't run, and it does, and it is sending a signal of where the pistions are back to the ECM. So i'm pretty sure it's working properly. HTS resistor value at all different temps are in the curve as per FSM. Just not sure of what voltage should be going in and what should be coming out and what wire does what out of the two, but it is creating the right resistance at whatever temp the coolant is. Tried pulling knock sensor wires off, no help. Cap and rotor look fine. CAS looks clean and even blew a little air around in there just in case one of the 3 photo diodes was dusty/dirty - no help. Thanks for all the ideas and keep em coming!! ha. Maybe I keep looking at what i think is the cause and maybe it's actually the effect like...it's not budging over 20deg btdc because the 02 is sending a lean condition to the ecm and not letting it advance? Although the O2 voltage sits at about .4vdc at idle at the sensor and ECM so that should be fine. hmmm.....keep thowing ideas around...the answer's here somewhere! Thanks 327.

Hey all. What could be the cause of getting no timing advance on the '82 L28ET that's in my 240? As i understood it, the CAS (Crank Angle Sensor) sends a signal back the the ECM and the ECM sends the appropriate signal to the coil. It just sits at 20deg BTDC all the time. It will not advance even bringing it up into the higher R's. The car does run so i'm assuming everything is ok with the CAS and, i swappd out the ECM with a known good one last night and still, there's no movement off of 20deg, neither advancing/retarding, no matter where the R's are at. I also checked the TPS for operation and it is working properly. I disconnected it while the Z was running and watched the timing, no change - 20deg btdc. Any ideas? Please, i have a feeling this might be a simple problem i'm overlooking and if you have any ideas, please, bounce them off of me. Sincerely, Stumped

Yo, picked up my cousins '83ZXT last night ($800, been sitting in driveway since 1995, 80k miles) did all the usual to bring it back to life and had it running perfect by 11pm! Anyway, this morning i robbed his ECM, popped it my Z and NOPE, NO HELP! Damn. As much as i didn't want my ECM to be bad, at this point i just wanted it to be. So as of right now, i wont be needing yours. Thanks. Oh yeah, with his ECM plugged in, i figured i'd check timing just to see if it was advancing, and it wasn't...still rock solid on 20btdc. So, i think i'll start a new post about timing. Maybe someone else has had this problem and found it to be the power transistor or coil....SOMETHING. haha. Thanks again Yo.

Thanks for the reply and info 525.

You are the man Yo. I'll keep you posted. Thanks.

Got it Yo/Sleeper. Thanks. Yeah, the CAS & TPS are working correctly. I don't know. Guess i'm at a brick wall now with this thing. I swear i've gone over everything...twice! Only thing left is ECM. My cousin's buying a '83ZXT this week. I'll steal his brain and try it. 99% sure the '82 and '83 ECM's are the same. Should be plug and play, right? We'll see. Thanks again guys.

Got it. Thanks bud....and thanks!

Thanks.

Can't really hear my 240ZT. I have all 3" stuff waiting to be fabbed up and installed as soon as i can figure out what the heck is going on with my Z. I also bought one of those 3" in/out straight-through mufflers just to see what she'll sound like The exhaust i currently have on is a 2 1/2" 45deg downpipe to 2 1/2" mandral to a Dynomax turbo. You can hear (not really) and see it if you click HERE with this setup. Yo, send me the clip if you can.

Sleeper - yes, sorry i didn't mention about the TPS. I pulled the connector off when it was running and watched timing - no change at all. I did meter it and it does have continuity between the two pins when the throttle is closed and breaks when throttle slightly touched. Also, after the Z is warmed up and goes into it's "warm" mode, the injectors go into their slower pulse mode and soon as i touch the throttle and the TPS connection gets broke, the injector ticking becomes fast. So it seems to be working correctly but it does not change timing one bit plugged or unplugged. 525 - have you confirmed that these ECM's can be reset?

525 - i put it right between the fuel filter and the hard line, on the passenger side of the engine bay. I still can't figure out how the ECM advances timing. I know it has to send some sort of signal to the CAS but not sure how and/or if there's any way to measure or test it. If the CAS was bad, i would think that the Z wouldn't run at all, right? Need to figure out if one of those photo diodes are just for advancing....or something like that My cousin just found a '83ZXT that i'll be picking up this week to get it running for him. If i don't get this figured out by then, at least i'll have a chance to see if all my problems really IS the ECM. Until then...back to the drawing board!

Yo - not exactly sure what you mean. Take the dizzy completely out, keep it still plugged into the ECM, rotate the shaft and what will click per revolution? Sorry, just not following you - cob webs in brain @ 35 I know i'm geting signal (i think that's what your having me test) because the car does run, it just doesn't advance. You say the ECM advances the timing...so i'm assuming it sends a certain voltage down one of these 4 wires going to it to make it advance/retard? If so, do you know which one and what i should see on a meter? Boy my L28 w/SU's was so easy

How does timing advance work on the '82 L28ET? I understand the CAS inside the dizzy and i know it has 4 wires going to it, two of which are power and ground. The others go back to the ECU. The problem i'm having is that i cannot get the timing to move off of 20deg BTDC. What i mean by this is, i know can physically adjust the dizzy and set the initial timing to whatever but, when i bring the R's up or down or wherever, it shows 20deg ALL the time. Never moves, never advances or retards, ever. I've been having a rich at idle problem for the last week if anyone hasn't read my recent babbling posts. Is there a certain wire from the CAS to the ECM to tell it to advance? In closed loop mode (or open loop, the one when it's not up to normal operating temp) does the timing just get a default value and stay there until the HTS gets to certain value? Doesn't sound right but who knows. I'm shooting in the dark at anything lately but i do know my advance was working, and no it's not. I did read about how the CAS works in the FSM but it's a little too vauge in which wires actually do what and if there's a way to test them, or the CAS itself. It also says the CAS can be adjusted in the FSM but for the life of me, i couldn't find the "how to" anywhere! Can you tell i'm frustrated Anyway, any help in advance is appreciated.

Nathan - i did pull the FPR diaphram up enough with about 30hg vacuum to get the pressure down to about 32psi but it never ran better, still rich as heck. Maybe my pressuse is a little high due to the Walbro pump i have in. That's the way i'm writing fuel pressure off right now anyway since i found this NEW problem - TIMING. I'm going to start troubleshooting in that direction to see what i come up with . Thanks a bunch for the suggestion.

I AM STUMPED AS WELL 327! Power is good and yes, driveable, but i know something is wrong because she just stopped idling correctly one day out of the blue and is running real rich down low. I cannot believe this is getting the best of me. I has to be something stupid. Ok, newest update, as of 2:30am last night - So i get my vacuum pump and try to pull the pressure down close to 30psi. With as much vacuum i can apply to the FPR, the lowest i can get it is around 32-33psi and guess what, no change at all! Unreal. I let all vacuum go to the FPR, pressure rises to 42-43 and still no real change in idle - still rich as a pig. Mind you, this is all with one port of the intake manifold uncapped, only because she'd crap out after a minute of idle due to running super, super rich (burning eye syndrome) Ok, so THAT'S NOT IT. I then start playing around with everything AGAIN and just for kicks, decide to re-check timing. Yep, dead on 20deg BTC. Then checked to see what she advances too...NOTHING. I get no advance, actually no movement at all...just a steady 20deg BTC ALL THE TIME. Rev it up, idle drops below 800 when throttle slapped closed..still 20degrees. HUH? I figured maybe it runs at a default value of 20deg until it's warmed up (closed or open loop mode) and made sure it was up to normal operating temp and it still didn't change..always 20BTC. It's just one thing after another right now. I don't get it. Must have stepped in the wrong Now i'm thinking ECM again, but i'm still not convinced that's it. I'm really betting it's something simple. That's usually how it is when i run into this much trouble with something..like a ground or something! Anyway, that's where i'm at now. Guess i need to make a new post about '82ZXT dizzy and Crank Angle Sensor operation to figure out what could possibly be the reason it's not advancing. Maybe THIS is causing all my issues. Man, i wish this on noboby. If any of you guys following my dilemma have any info on the CAS other than what the FSM says, please post it. Guys, thanks a lot for all the help and time you've taken to think and post about what could possibly be wrong. I will not give up. Thanks again. The saga continues....

Man, i am hoping Dale. Home now. I put the gauge in line, between the filter and hard line and yup, 38lbs @ idle. Vac gauge showing 20hg. If i pull the vacuum reference off of the FPR, the pressure jumps up to something like 45lbs. 327 - aren't you running 370 injectors? I would think 43.5 @ idle, it would be rich. Ever check what voltage your O2 is sending? Damn, if your Z is basically built like mine and you have a rock solid idle with 43.5lbs @ 850rpm, i guess getting this thing down to 30lb @ 20hg isn't going to solve my problem. I wish my buddy would show up with my vacuum pump! He's on his way and if i can manually get the pressure down by applying more vacuum than 20hg to the FPR, we'll see if it does the trick. Hoping so. 525 - here's a cheap way to check your pressure. Go to a Home Depot, or whatever you have near you and pick up a 0-100lb gauge ($10), then go get a couple of brass fittings ($1) for your fuel lines to hook to and have some teflon tape ($1) so it wont leak when you put it all together. If you dont have any small clamps, that'll cost maybe another $1. All in all, it shouldn't all cost more than $15 and you will always know what your pressure is. Me, on the other hand had all this and didn't want to permanently install it and THOUGHT it was suppose to 36-38lbs @ idle. DUH. We'll see soon if this was my problem....

ut oh. Why do i have a 36-38psi @ idle as being the correct # in my head? And i just went right by this after i checked because i thought that was what it was suppose to be??? Maybe i'm thinking of my old '77 280? If it's suppose to be around 30 with 18-21hg vac @ idle, then the 38psi i'm getting is probably, hopefully, causing my problem! And when i checked the pressure, i did it twice with the return line hooked up and then again with a hose going into a open tank just to make sure the 5/16" return line wasn't too small for the high pressure Walbro pump or if it was clogged or something. It didn't change the pressuse either way and i blew the return line out just to make sure it was clean anyway. So, if it is suppose to be 30 and i'm at 38, then basically the only "logical" thing left is the FPR. When i pulled the vac line off of the FPR and it did nothing to the idle (stayed rich and no change in idle) i put 20hg's of vacuum on it and it did hold, but it also didn't effect idle/rich problem. Wonder if it's just stuck closed? I also thought this may be the problem and did tap it a few times when i had the 20hg's on it but it didn't make any difference and i just figured that it all must be right and fuel pressure was right @ idle anyway (so i thought) so figured all was fine. hmmm. Now i need to go home and re-read the FSM and re-check that pressure. Moby, thanks a bunch. If this is it, i'll owe ya one.

Hey guys, thanks for the replies. I changed the O2 last night and it didn't help. It does give much better readings - .4v @ idle, .9v running @ 2k rpm for 5 minutes, but it still runs rich as heck at idle and the LED on the ECM still won't blink, EVER. It does light when i turn the key into the ON position so i know it's not just blown out. Hey, i'm trying to think of everything So then i start digging around again last night until about 2am and still haven't figured it out. Unreal. What gets me now is the Head Temp Sensor readings. With the sensor unplugged, key in the run position, i'm getting 5 volts on the yellow/green. The resistance across the head temp sensor is right in the curve as per the FSM at all different temps so it is working properly. Just for argument sake, the water temp is at about 110 and the resistance across the head temp sensor at this temp is right about 1.1k ohms. When i connect the plug back into the sensor, i now get a 2.4v reading on the yellow/green wire and a .02v on the black? Then i cut the black wire off of the back of the head temp sensor and measured both again, still plugged in - now it's back to the 5v on the yellow/green and it also shows 5v on the black! Then, I traced and ohmed out both wires back to the ECM to make sure neither weren't shorted to ground or each other, which they both tested fine. I also ohmed out both pins from the HTS to the head to make sure it was not grounded internally, and it wasn't. Does this sound right? In the FSM, it seems to only list what the value of the resister should be at, at certain coolant temps, not what the voltages in or out should be at certain temps. At least i can't find it in there. Also in the AFM, the air temp sensor inside the AFM shares the same curve as the HTS so, i checked that just for the heck of it. Maybe it would explain how the HTS circuit should work, i thought, anyway. With the harness plugged into the AFM, one wire on the ATS had 8v on it (figuring in) and (at the time, whatever air temp it was reading) 5v on the other wire (figuring return value) Then i put both legs of my meter on each of the pins and it gave me the 3v - the voltage drop across the resistor. Fine, that seems to measure correctly. I would think the HTS would be somewhat the same....something like 5v in through the yell/green, across the variable resistor, and back to the ECM with the new lower value, like 2-3v. Not on mine and maybe this is just how it works. i don't know. I also took off all connections, cleaned them all with a dremmel/wire brush, ran ground legs all over the car and none of it helped. One thing i did find strange, if i pull the vacuum line off of the FPR and plug the hole in the intake, she runs exactly the same. I thought at idle, if i did this, the FPR diaphram would drop, clamp off most of the return line and drown her in fuel? I checked fuel pressure last night and @ idle (gauge between filter and fuel rail) and it reads perfect - 38psi. Makes no sense but i'm all out of sense with this rich idle problem now anyway! If anyone has any suggestions or has ever read voltage in thier HTS, please, post away Thanks so much for all the info on the sensors and info you supplied guys. Helps me understand how the whole system works in conjuntion with each other better. I'm also glad i'm not the only "older 35 yr old" married with children guy here and can share my pain Actually, my wife has really been great about it all. Never know what next month will bring 525 - i went to Pep boys and picked the O2 up - made by bosch, $20 for the one without the male end and $30 with it. Thanks again guys.