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L28ET swap 240z runs rough won't take throttle


motomanmike

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Air temp sensor test in FSM= 1.99 ohms at 76 degress outside, same at unit, at the AFM itself, same at ecu plug. Lower than spec but really close. Insulation resistance OK at AFM too. Air flow meter test at Air flow meter. pin 33 and 36. has .202k ohm at AFM pins? Measuring pins 33 and 26 at the AFM 2.02ohm ? pretty sure thats not a good thing. Test 2 on AFM, partially open, .255k ohm at about half open. AT pins 33 and 31 at the ecu plug I get 145.00 ohm. If this is the actual AFM pin configuration - - - - On the left, to the second from left I get .257, third from left to far left I get .257, far right and far left I get 2.02 ohms. Its probably a dud

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They are spendy. Some people have been bale to clean up the carbon trace and contact switch and get them back in order.

 

Still not sure where you're getting pins 33-36 as an AFM test. By the AFM diagram, there is no pin 36 used on the 1982 turbo AFM, from what I get out of the FSM. Only 33, 26, 31 and 30. Are you using a turbo AFM or NA? They're different.

 

And you measured different pins for your "test 2 partially open" than you did for the first test. 33 and 26 first, then 33 and 31 for "test 2". Hard to tell what you're doing. Are you using the 1982 FSM or one of the Chiltons/Haynes manuals? Page EFEC-96 has the diagram and EFEC-98 has the AFM test and specs.

 

Looks like you might be on the right track, if you can get the right numbers in the right places.

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its the turbo suppliment from xenons130 site, I think that it references an 81 so I need to get some more info on it but I really think it might be my issue, something doesn't quite jive with it. Its hard to say the condition, posting the pins left to right measure at the AFM the numbers aren't really that close either to what reference material I have. When it all arrived the AFM was on top of the motor in a bag, with the ecu in a small box, all strapped to a pallet when it arrived at my work by truck freight. Its all second hand stuff. Popping the cap off of it the internals look new but looks can be decieving

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Here it is with everything hooked up, later i pull the plug on the CHTS and rev, you can definetly hear the difference, not a great change but a change none the less.

 

 

 

At one point you when you see me reach down, that is when i unplugged the CHTS, the car ran better. Not great but better so I think once I get some parts we might be good. At least all the connection plugs are brand new and I soldered them with heat shrink so its all done right.

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If I had your parts, I would confirm that they were 1982, then would use the 1982 FSM, EF&EC chapter, ECCS specs. They integrated the turbo stuff in to the FSM in 1982 from what i see, so the 1981 supplement isn't necessary, and may be the wrong document for your setup.

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Its an 82 setup with the 4 pin plug on the distributor, doesn't necessarily mean i have the right AFM either. I sourced one though. Probably going to try but they want quite a bit used, say its a reman, i have to price them at work and see if thats in the ballpark. Its adding up quick, by the time I get done fixing all the stock stuff I probably could have bought a MS lol

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Howler - be sure to get me info if and when you've got that engine management package together.

 

Motorman - With all the time (and now $$) you've got into that, it's a shame someone didn't steer you towards a Maxima / Z32 / M30 "A18" ECU (MAF, Coil, TPS, chopper wheel). Much better engine management than stock on the L28ET. It's rewiring the harness for sure, but the benefits (AND not having to troubleshoot the stock system) are immense...

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CGsheen, I appreciate the thoughts. If this AFM i've ordered doesn't make the car driveable, I'm definetly going megasquirt. I've emailed and researched quite a bit with Matt Cramer at DIY, those guys are more than accomidating.

 

 

NewZed, the post where you had asked if my readings were a typo, I figured that out, I have a self adjusting ohm meter and it went into kiloohm mode, hence the K ohms, i'm sure some knew what it was but I didn't, just multiply those values by 1000. Made total sense when the rebuilder here told me that.

 

So that makes my readings for my air temperature sensor tests in my current AFM very low, its 80 degrees outside and the car thinks its hanging out with polar bears. Tomorrow I get parts, we shall see. I ordered a MSA downpipe, that way I have it installed before I go get my custom exhaust done and can do it right with as few welds as possible. I will have to block of the stock EGR valve. Eventually i'll put on this non EGR intake I have but I wanted to wait until I get it driving to do too much more to it.

 

Will blocking off the EGR now affect the stock computer system enough to cause issue, should I hold off on putting this downpipe on and get the exhaust done using the stock set up, I have 2 good stock downpipes with the egr provision, one of them I have about a foot and half of the exhaust that bolts to the 3 bolt portion of the downpipe so either way its easier for me to get exhaust made up.

Edited by motomanmike
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Blocking off the EGR won't have any negative effects on how well it runs. Just make sure you block off both ends. You don't want a any unmetered air getting in behind the AFM. You also don't want an exhaust leak in front (upstream) of the oxygen sensor.

 

The engine sounds lean to me. When my car would start and I'd try to rev with the bad ECU it would pop and crack and backfire like gunshots. It was actually kinda scary.

 

It also sounds like you have a dead miss. Not sure how well you've checked the engine health, but you don't want to be chasing your tail on the input signals to the ECU if your outputs (injecrors/spark plugs/wires)aren't in good shape. From what I've read you may be onto something with the CHTS, but that should in theory cause a rich condition.

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I think i'll just need a cap for the tube out of the manifold using the msa downpipe, i'm pretty sure the MSA unit doesn't have any other bung other than for the o2 sensor. The car will run great if you mist fuel into the intake so I know its not missing. I've also verified with just laying each plug wire on the cylinder with spark plug attached and can visually see spark. Hopefully my AFM will be here today and we can see which direction i'll be headed. Thanks for input on the EGR, I wasn't sure how much they actually affected the stability of the system. I've read they can be beneficial by lowering combustion temperatures but it seems marginal at best the advantages it would have on this set up.

 

I may have a bad ecu, there are a lot of test in the FSM that following the flow charts end at replacing the ecu. If the AFM I get doesn't change things, and after some more testing I conclude it "may" have a bad ECU i'm not sure which route I will go. Sinking more money in a very dated setup when I could go with a nice MS2 seems like a no brainer.

Edited by motomanmike
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Yea, most of the time manufacturers will have you test the component first(AFM for example), then make sure the harness is ok, and then last but not least they'll tell you to replace Engine Control Unit.

 

Have you searched any local junkyards to swap an ECU or CHTS on the cheap? I think I have $90 in my Z31T ECCS swap...

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Update, I think I found the problem or part of the problem doing some testing really quick this morning. On 2 of my front injector plugs, I have 12v on both sides of the pigtail plug. Seems my problem may be deep in the bowels of this harness somewhere, they have to be rubbing or broken at a similar spot to pass through. I hope this hasn't ruined the ECU. Whats the easiest way to find it? Just dismantle all the loom and check, or ground one end and probe around with a meter at both the other end or what? I only had about a half hour this morning before work to test but eventhough i'm bummed about it it is very encouraging that I found an big issue. Wierd thing is it will fire my cheap ebay noid light so i think the ecu will be ok.

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I thought they all shared ground signal? I don't have the diagrams in front of me, but I thought I remembered mine sharing a common injector ground...?

 

To check the harness disconnect the ECU connectors and the injector that you're testing. Then go from one pin on the injector side and find the other end of the wire at the ECU connector, test resistance. To check for shorted wires just measure resistance at both pins of the same injector connector. It should be OL/OFL/infinite resistance. If you get resistance between them that means either you forgot to disconnect the ECU connector or the wires are touching.

 

Sounds to me like a bad ECU...

 

Before I read your latest update I was gonna remind you that (I know you said the fuel tank was cleaned out) just because you have fuel pressure doesn't mean you have enough volume.

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