Joey J

They had sent me a vid when it was getting dyno’d. Sounded fine. The crud was dirt and gravel. No metal. Old belt actually looked good. No teeth missing. Didn’t appear to be old at all. I hope that’s not the case. I don’t want to have to deal with pulling the engine. I don’t have space to do all that. I’d have to ship it to a shop. I really want to avoid that. I got everything back on today but I ran out of time. I’ll check all the bolts next week end and refill coolant, check for leaks and give her a crank. I had replaced the water pump and thermostat since I was there. The gasket maker says it needs 24 hours to cure. I’ll report back next week. Thank you all for the responses. Much appreciated! I feel I’d be lost without this forum.

Balancer looks good. When I pulled it off the crank gear mark lined up with the timing mark on the block. Im assuming below is why the cams are both off by 4 teeth. Not sure. Between those 2 teeth was that crud had pretty much turned into a rock. I don’t know how the car was dyno’d at the shop and no one noticed the timing was off. Is it possible it was set like that on purpose? I don’t see why that would be done.

Working on fixing it now. Balancer is off and mark on crank lines up with tdc marker. I will update once done. Probably won’t finish untill tomorrow night.

Just verified that the balancer is marking tdc corrrctly.

On my previous post there is a video of me checking the timing. Which was wayyyy off. At 60 degrees adjustment on the gun it was still off.

So I’m replacing a few maintenance items and I noticed the cams are both off by 4 teeth. The car will turn on and run for like 30 seconds before shutting off if I don’t give it gas. i thought the issue might be the tune but now I’m not sure. Could there be damage to the valves?

i uploaded a video to YouTube. I have the dial set to 60 and the timing marks show up. In the video it’s a bit off. In person having it at 60 is almost dead on tdc. It fluctuates 5 degrees while idling. it’s idling rough but significantly better than before. You can also see my fuel pressure at the end of the video. It’s at 25 ish.

Gotcha. Yea I’ll probably just go with a stand alone. Ughhhh, didnt want to spend all that right now but w.e. On the bright side I messed with the ignition timing again and the car idles pretty good. No need to give it gas or anything. Kept it idling for a good 5 minutes. I moved it like 10 degrees clockwise at the CAS. Last time I moved it about 10 degrees as well and that fixed my no start issue. From my last post someone suggested that the harmonic balancer went bad and I need to set a new tdc mark to set timing. I checked it and the tdc mark is correct. I tried to use the timing light and marks are no where to be found again. I adjust the timing on the light and it shows up as I increase it. I moved it to 60 and it shows the tdc mark now. I’m super confused. I feel like it’s impossible the ignition timing is at 60 degrees and the car turns on at all. I attached a pic of the CAs. It’s pretty far clockwise. It’s idling significantly better. The engine doesn’t shake much either.

I just came across this on a guide how to set up a z32 ecu for an RB25 motor. “Z32 ECU uses a fuel temperature sensor and R33 RB25 does not. A Diagnostic Trouble Code (DTC) will be raised by the Z32 ECU if it senses that the Fuel Temperature voltage is out of range” I checked and I do have this fault code on the z32 ecu. Supposedly when you have this code the ecu makes that car run rich and rough idle because it doesn’t know the temp. Maybe that’s why I was forced to drop the the fuel pressure so much? GTSBoy, any other option I may have other than just biting the bullet and getting a haltech ecu and new injectors?

It is on a z32 rom tuned ECU. I was just looking up what the stock injectors are supposed to be and I saw it was 370cc. I'm not really sure what my next steps would be with the fuel system. If I get 370cc injectors I'm not sure how that would interact with the rom tune. Also, that will pump more gas into the cylinders which seems to be my problem. I've lowered the pressure in the rails considerably through the FPR and that's helped the car run. The only thing I'm thinking is get a standalone ECU and get upgraded injectors. I planned to go with Haltech eventually but not so soon.

Thread #2 Thank you all for the valuable information in the last thread I posted. the motor cranks on just fine now. I'm trying to work out my new issue. The car turns on and and idles for 10 seconds before it stalls out. If I give it some gas through the throttle body. Just rotating it a tad keeps the motor running. I let it go it starts to lower RPMS to the point of stalling out. Even giving it some gas it feels pretty rough. The motor is in a Datsun 280z so i don't have a tachometer so I cant check where the RPM is at. Sounds really high when I give it enough gas to stay on I cleaned out the IAC just incase. Tomorrow I'm going to check the voltage for the TPS and make sure that's set up correctly. Then I'll set the ignition timing hopefully. I don't have the loop behind the motor. I have bought an inline spark tester so I'll use that on cylinder one. Also fuel the fuel pressure is confusing me. I had lowered it significantly to about 30 psi and that's what allows the car to run. Today i tried to raise it back up to 42 while it was idling and didn't make much of a difference. Once it stalled out. It only would crank and no start. I disconnected the injectors. It started up for a few seconds. Lowered the fuel pressure back down to 30 and the car started up. I looked at my emails from the shop and they used 330cc injectors from a 370z and bumped up the fuel pressure from 42 to 48. They said at the time that worked. I'm wondering if the injectors are the issue. Since the motor will only start up with low pressure maybe they're soaking the plugs at the regular pressure? From what i understand I cant upgrade injectors without getting a standalone ECU. Any ideas and tips are much appreciated! If i cant work it out I'll take a video, upload to youtube and post a link here. I'm sure that would provide more information than what I'm trying to say here.

That makes sense. Thanks so much for that. I was baffled on why I couldn’t see the marks. I’ll definitely start shopping around for a new balancer. I’m thinking if I’m gonna pull the balancer might as well get a new timing belt and tensioner. It looks like the hardest part about getting to the timing belt is getting that pulley off.

The voltage at the fuel pump was at 9.5v when it turns on. I tested all the wiring replaced the terminals and it’s still at 9.5v. I unplugged it and tested the voltage to the wiring only and it was over 12v. Not sure why it drops once it connected to the pump. i ended up lowering the fuel pressure to under 30 and it sounded like it wanted to turn on but still no dice. I didn’t know what else to do so I tried adjusting the CAS while it was cranking and BINGO! Turns out it was ignition timing. I adjusted the CAS a bit to the right and it started to idle. Turned it off once it stayed idling for a bit. I got everything hooked up to set timing correctly with a timing light. The marks are no where to be found on the balancer while the light is flashing. It’s definitely there because I checked to make sure they were visible before trying to set it but I see the marks at all once trying to set the timing. Is it possible the timing was way off to the point the marks don’t even show? I ran out of time so that’s as far as I got.

So I unplugged all the injectors to test for voltage and it started up for 2 seconds. Plugged them back in, car didn’t start. Unplugged again and it started for 2 seconds. Also on the Fuel pressure the gauge stays at 43 if I use a jumper on the pump relay. As soon as I unplug the jumper, fuel pressure falls by 20 psi. any ideas? Edit: I lowered the fuel pressure pretty significantly down to low 30s through the fpr and it would want to start when cranking but wouldn’t fully start. EDIT: I’m thinking it’s either the fpr is bad or the rom tune is bad telling the injectors to dump too much fuel.

I will inspect it more thoroughly tomorrow. I' will be trouble shooting all day. When i pulled it out last weekend I was careful to not move the halfmoon key from the cam. I put it right back in how it was. I did realized during the week that the CAS affects timing which i didn't know when I was looking at it. 2 of the 3 bolts holding it in place were tight, but the bottom 3rd one was not even fastened all the way. Maybe the 4 hour shipping back from the shop caused the CAS to rotate a bit. I plan to check timing and adjust if needed tomorrow. Below is my to do list for tomorrow. If anyone has any other suggestions please let me know. I will update if i can get it running. To do list Look for all grounds and check them. Maybe replace battery terminals. Check ECU to see if we can run diagnostics on it. How to check the codes of the ECU in a '90-'95 Nissan 300ZX Check all fuses. Driver and passenger side. Is the alarm immobilizer making the car unable to start? Verify if fuel lines are correctly plumbed. Check whole loop (Tank, pump, rail, FPR and back) Fuel pressure should go to 43 PSI once ignition is turned on. Why does it bounce when starting? Adjust FPR? Is it damaged? Use a jumper wire on the fuel relay to test fuel pressure. Check voltage getting to injectors. Check injectors, maybe it’s flooding the engine? Try and air out cylinders, dry and clean plugs then use starter fluid with injectors unplugged. Prime pump then remove fuel pump fuse then crank for a bit. See what happens. Clean out idle air control valve. IAC is attached to backside of the stock manifold. Is mine deleted? Remove and clean if possible. To adjust: Unplug TPS. Adjust screw so it idles at about 750-900 RPM. Clockwise lowers revs. Counter increases revs. Plug TPS back in to set it. Check ignition timing with timing light. Inspect CAS again. Check voltage. Remove and spin with ignition on. Check TPS Voltage

I’ve heard the CAS is a big problem with these cars. I was hoping the CAS would not go bad until I can swap over to a trigger kit and have a standalone ecu. im gonna test a few things and I may have to look into replacing the CAS if I can’t figure it out. I pulled mine out and it looked okay. The fact that plugs sparked gave me a sense that it was okay.

I'll check the fuel lines going back to the pump then tank. I only checked what was in the bay. Inlet, fuel rail, FPR then outlet. Hopefully its something that simple. I'll make sure to check that out. Thanks for that. I'll have to look into how to check ignition timing. The one thing I really was hoping I didn't have to mess with was timing. I'll start my research on that. Not sure the reasoning behind rom tunned z32 ecu. The only mod on the motor is aftermarket front facing intake manifold and intercooler. Everything else is stock. Unfortunately I don't have the stock RB25 ECU. Thanks again for the help.

Thanks for your response. Idk what to say about that shop... they had done the swap multiple times. I just don’t know why they would let a car leave their shop that isn’t running right twice. It has a Z32 ecu rom tuned by them. I don’t have a wideband on it. Is that something I should get now to help diagnose the issue? The car won’t run at all it just cranks. Would a wideband help at all? ive been doing a lot of research on what my next steps should be as my mechanical knowledge if very limited. I’ll start looking into a wideband now.

Hello, I have an rb25det that I had swapped into my 280z by a reputable shop. Ever since I got it back it wouldn?t run right. Once it got hot it would shut off. It got sent back. They fixed it supposedly and same issue when I got it back. Ran a bit longer this time but once it got hot it would stall out. I lost the motivation in the project. I didn?t have the experience and bite off more than I could chew. Plus money was tight after the swap. This was like 3 years ago. Now I?m trying to get the car running finally. I?ve checked a few things and can?t figure out why it won?t turn on. Spark is good. I pulled out the plugs and replaced them just incase. I made sure they?re sparking when I turn the ignition. When I pull them out their wet so they?re getting fuel. I will say the fuel pressure regulator is showing odd readings. When I turn the key the pump primes and pressure jumps to 22 psi and holds. When I crank it the engine tries to turn and fuel pressure jumps to 40 and the needled jumps between 40-50 while its trying to start. Tested compression on all the cylinders and they all hold compression. I?m not sure if the tester I have is good because it?s old. I did cyl 1-3 and they were all 145-150. Then cyl 4,5 and 6 showed 180. I went back and did cyl 1-3 and it also showed 180-185. I assume it?s a problem with the tester. Not sure. I tried using starter fluid into the intake manifold and nothing. It?s almost as if it has no spark but the spark plugs are definitely firing when I pulled them all out and tested them. Any help is much apprecaited!