SDgoods
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Posts posted by SDgoods
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I'm just a rookie but the only thing that would "use" the RPM data would be the ECU. The CAS delivers that information, the ECU uses it. Seems like a map, or look-up table, issue in the ECU program, if it happens exactly at 3500 RPM no matter what (note that the stock tachometers are not super accurate, so 3500 may not be 3500). The map, programmed for the stock Z31 that the ECU came from, is doing something at 3500 RPM that your L28ET engine doesn't like. Maybe the ECU is expecting other information at 3500 RPM and it's not there. The ECU might be switching modes, and getting poor information from the sensors after 3500 RPM. Or it might be switching modes because it's getting unacceptable information from the sensors.
For example, one mode that switches at 3000 RPM is the injection mode, from group injection to simultaneous. Another one is EGR at 2700 RPM. Another one is RPM limiting to 2000 RPM if the MAF signal is bad, which doesn't seem to be your problem. These numbers are from the 87 FSM.
Of course, since you're getting a CAS code, it might just be that the CAS signal is consistently breaking up exactly at at 3500 RPM every time. They might be the same problem or two different ones.
Just offering a different perspective. Helps me learn. Good luck.
Thanks for the input! I have a speedhut revolution tach that's pretty accurate. And whether or not its exactly at 3500 rpm, its at that place on the tach everytime.
Regarding the CAS, I have 2 seperate sensors, one from the ET and one from the Z31, both of them giving the same exact symptom, which now that you say it, is probably too coincidental. Ill try and get my hands on another ECU. I suppose if it got fried and happen to be on the CAS circuit it would throw the same code. The circuit does recieve 12v and does have a ground but it could still be 'bad'
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Raising fuel pressure should have fixed a lean problem and possibly created a rich problem, assuming the same injector open times. The ECCS assumes a certain fuel pressure so it seems like that should have had an effect.
It was just a guess. As for timing, I didn't think through how the Z31 ECCS system works. It would probably be worth some study though.
If everything is working properly thats true. If its getting a bad signal from lets say, the CAS, it may not be compensating enough, even with the high fuel pressure, to run normal, or even rich.
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Did you install z31 CAS upside down?
Have you tested another working ECU?
Where is your MAF placement?
It needs to be at least 12 inches away from the turbo and not near bends to work effectively. The turbo will cause turbulence and the MAF will read wrong.
You say you have intercooler piping; are you running draw through(before turbo) or blow through (after turbo) with your MAF?
There's only one way to put the trigger wheel on I dont know how people manage to install it upside down.
I havent tested another ECU I need to find one and do that.
The maf is about 9 inches from the compressor but Ive been running this setup for a while now. it ran rich but physically ran great. Ill try and move the maf farther away from the turbo, however, the other side of the maf also greatly influences turbulence as the air needs to smooth out before hitting the hot wire. Ive tried a couple variations of piping before the maf but am very limited to room as I have a same sided intercooler.
Running draw through setup, its your typical ET setup.
is no one else curious about the fact that its at 3500 rpm every time, no matter of load? This means that no matter what volume of air (under boost or not), it's leaning out at that exact RPM. This and the CAS code really makes me think its CAS related.
What do you think?
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Raise the fuel pressure a psi or two and see if the problem goes away. You said it was lean at the problem point.
What's your timing doing when you rev? Have you checked vacuum advance centrifugal timing advances to make sure they do what they're supposed to?
I tried raising fuel pressure a lot more than that and it didnt fix it. This system doesnt use vacuum advance, it adjusts timing based on the crank angle sensor. Ill also check what its doing when I rev it tomorrow.
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Well I thought I knew the system quite well but I cant figure out this problem... I redid some intercooler piping and went as far as using a smoke machine to get rid of most of the leaks... (although even before with some the car run great)
Ever since the car never ran right.
73 240z with l28et, z31 300zx maf, ecu, trigger wheel.
Aftermarket FPR set per FSM. I can visually see fuel pressure raise when revving while standing still. Fuel filter is clean.
Car will drive mostly fine at low RPMs and idles great at 800 RPM. It lean surges once in a while but every single time no matter what load while driving (from letting RPMS rise slowly to WOT), it will lean and hesitate at 3500 RPM where I let off. with the car standing at idle I CAN rev past 3500 and the AFR's stay fine. This only happens when im driving.
I tested a known good maf that seemed to fix the problem, only to buy another known good one and the problem persists.
Ive replaced the CHTS that tested bad as well.
I am throwing a Crank angle sensor code and swapped it with the z31 sensor I got with the rest of the z31 stuff, doesn't change anything. It gets 12v and the other tests passed.
Straight Ohming out the sensor none of the pins have any resistance on either of the CAS's. Is this normal? Can someone ohm out a known good and let me know if this is the same?
I plan on cleaning connectors and such tomorrow and tinkering around but Im pretty stumped. I feel like its CAS related because of the competely RPM dependent symptom but cannot find any issues with it.
Any input would help!
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Which sensor did you replace? It would help if you explained a little more about what exactly is happening. So it stays on (drives? idles?) and then you turn it off and when you try to start it again does it crank? does it fire up? does it die right after it fires up?
If you take note of all these things it can help you and other members help fix the problem.
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Like the title says need z31 300zx turbo OR NA
let me know if you have one!!
Im in San Diego CA, willing to pay for shipping if the price is right.
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Turns out it was a massive vacuum leak at the blockoff plate for my egr bung. I've fixed it and the engine has smoothed out a LOT. Now the fun is in figuring out what's causing this random grinding noise. The engine misses regularly sometimes around 2500 and up, but stays pretty close to stable at idle. It's so close to perfect I'm losing my mind. I've been running it without the filter, so now I'll be adding that to the mixture to see what becomes of it. I have to figure out how I'll plumb the CAI now, since the MAF doesn't sit as close to the hole as I'd like it to. I may have to take a hammer and smash it in. Has anyone come up with a reliable way of stuffing that in line with the hole in the radiator support wall?
The next issue that's popped up is a VERY random grinding noise, similar to the sound of someone engaging the starter while the engine is running. I can't seem to locate its origins, but I'm going to check valve lash and run a compression test just to see the state of this engine. I never got the chance to because it was dirt cheap and sitting in the back of someone's shed for several years. It's quite possible the block is bad, but I somehow doubt it since it feels like it wants to run right. Just a gut feeling. It's also running a bit hot according to the gauge, but I've yet to check the accuracy of the gauge now.
Is there a way to check a/f ratio without an emissions check?
Glad you got it figured out for the most part. I would just buy a wideband 02 sensor with the gauge... Theres a guy selling AEM Uego on here for 157 shipped brand new. I have the same one and I love it.. You can just run it straight on its own, I use mine every day I guarantee it will come in handy, especially on a modified/swapped car.
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I went through all this
Car sat for a couple months as I had a lot of other stuff to do but these systems are still relatively finnicky. Took me a while to figure out.My advice...
I made the mistake of leaving the air filter off the maf, make sure you put a filter on the maf/intake.... the maf does not like the turbulent air and after I put mine on it helped immensely as it did another member who did the same thing...
Make sure you have The constant + voltage to the ECU for the ECU memory. It was not in the right up I used and I discovered it just comparing the s130/z31 wiring diagram.
Were your guys cars running alread before the z31 stuff swap?
I'm running fine with no 02 sensor and no burn cycle on the maf (although I still plan to wire it in)... make sure injectors 2 and 5 are switched for batch firing. Make sure if you have 81, the dropping resistors are removed. Have you all verified fuel pressure? If you have a wide band are they running rich or lean?
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My 30 year old Hayashi Racing perrier 503's refinished by me and HRE wheels.... 15x7 +4 front 15x7 -16 rear on 205/50/15 on original center caps slightly refurbished by me
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Ive been thinking about someone swapping one into an s30 ever since i saw this, although its a built 5.2 L, it maxed out the dyno at 1700whp and they estimate it at 2200-2500 whp!
1:1 power to weight ratio anyone?
http://www.superstreetonline.com/features/sstp_1203_2005_infiniti_g35/viewall.html
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Looks great! Do you know if it will meet any SCCA requirements?
Officially Im not sure but like my last post said it seems to be designed better than the autopower scca so i assume it would
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Looks nice.
Since you had the Autopower bar before, what didn't you like about it that you had a new one built. I ask because I have a Autopower roll bar just like your old one that I haven't installed yet.
ritrebor
I didnt like how close it sat to my head in my bride seat that leans a little further back than most. The new bar sits slightly farther back but doesnt sit as high. Its also just designed a lot better as the autopower only bolts up to the fender wells while the new one utiliZes the strut towers, a bar between them, and an extra diagonal bar from the strut tower to the main hoop.
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just added pictures
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Since it is made from scratch, I suppose they need customer car present to bend it up? Or did they take measurements from yours and can reproduce it without a car present?
I can find out but for a tight and clean fitment depending on how intricate you want the bar it would probably be easiest for them to have the car. Ill find out and let you know
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Can you post a photo of how the front mounts are bolted to the car?
Ya ill post some pics tonight
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Would it work on a 280 with stock seat belts in place?
It should but its made from scratch so they can virtually make you anything you want
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How much did they charge you for it?
To duplicate it would be about $650. Its 100% bolt in other than drilling 8 holes in the fender wells.
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Hayashi racing 503's refinished by HRE , original center caps repainted on me on my dirty car!
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I recently sold my Autopower roll bar and had my friends over at SAE motorsports in Oceanside CA build me this utilizing the front mounting points on the fender well and a cool cup that bolts to the strut towers and connects all the points..
What do you all think?
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I have front and rear off my 73 in good condition, some surface rust specks
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^^ Thanks, I know what the JDM ones look like hence why I want pics of the MSA one to see how similar it really is.
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I couldn't find any angles other than whats on the MSA website.... Does anyone have some pictures of this spoiler from some different angles... Overall quality of spoiler? I had the victory on my last z and I was for the most part happy with it..
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Added some more photos!
Car sat for a couple months as I had a lot of other stuff to do but these systems are still relatively finnicky. Took me a while to figure out.
l28ET Z31 ECU/MAF leans out 3500 RPM on the dot, Any driving load.
in Trouble Shooting / General Engine
Posted
Yes its tight and Ill double check again.