Ok,

I am new to engines, so please do not get mad at me for saying something stupid. I am stranded and living in South Carolina where no body knows anything about Japanese engines. If I had dropped a small-block chevy into a 240sx, I'd be fine, but as far as CA18DETs go, I'm all alone. This is long and painfully detailed because I want to help you help me fix this problem.

Here is my situation. I bought a 92 240sx coupe from a guy in Florida with the CA18 swap already done. He had a mostly stock setup with only four variations including an HKS FconV mounted piggyback to the ECU, an HKS AFR, a 300zx tt mass air sensor, and a manual boost controller. He also has a FMIC, and various other stuff, but I'm only including the details that pertain to this problem.

I drove the car back from Miami, which is an 800 mi trip, with no issues other than loosing oil and power steering fluid. I narrowed the oil leaks to the head gasket and turbo oil feed line. I took it to a shop that has experience with Nissans and although it took them 4 days to work me in and 2 days to fix them, they fixed the oil leaks. (I was too busy with exams to worry about it myself.) After doing some research, I found that the FconV was not doing anything, and could not be tuned in the US. So, I pulled it and planned on selling it on e-bay. I then took it to the upolstry shop to get the interior redone while I still had two cars. I drove it after it got back from the upolstry shop for three days with absolutely no problems whatsoever.

That night was the coldest night the car had ever seen with temperatures dropping to the mid 20s. I went out to start the car after work and it sputtered, wouldn't idle, and was running really lean (according to my narrow-band AFM). I dialed in my AFR more and more rich until it would run at all. At this point, I was running it at 9 out of 12 (vice 5 where it had been previously). Things got progressively worse over the week until the car left me stranded yesterday.

Here are the symptoms: -It doesn't idle worth crap (falls below 500 rpm and often stalls). -When you engage the throttle, it hesitates, and then maxes out at 2000ish rpm like it's hitting a rev limiter (goes up and down, while sputtering, having lean fits, and backfiring). -These symptoms are at any throttle position past idle -It blows grey smoke and some kind of black liquid out of the tail pipe. It didn't start out that bad. When it first started acting up, it would just hesitate under full throttle. Then, it got to where it would have several-second-long hesitations that consisted of surging and just slowing down (even under increasing throttle).

Here is what I have observed under the hood: -There is only one vaccuum line going to the BOV. -Vaccuum line comes from Intake Piping between turbo and fmic and goes to a 4-way splittler They go to the boost gauge, the wastegate, and the top of the BOV (I removed the m.b.c. and I have a new Greddy Profec B e.b.c., but it is bypassed at the moment for simplicity's sake). -Vaccuum line comes from intake manifold immediately after the throttle body and goes to a nickel-sized diaphram behind the engine that looks like a tiny little fuel regulator. -Vaccuum line comes from rear of intake manifold to a half-dollar-sized diaphram that appears to be the fuel regulator. -There is a liquid that has collected on the top of the block around the injector closest to the firewall. The liquid appears to be too dark to be fuel, but I'm not sure, I didn't smell anything. Nothing is literally squirting out up there. -Cam Angle Sensor is dialed completely to one side. If you try to dial it back to center, the car stalls. -Thottle position sensor was dialed completely out. I have since re-calibrated it to read 8.22kohm closed, 8.0kohm barely open, and 1.99kohm fully open. -There were loose connections on the Mass Air Sensor, and the wires had melted (run too closely to the exhaust), but I have replaced them checking and re-checking that I have them connected correctly.

I have been told it could be a faulty Mass Air Sensor, but at $680 retail, I'm looking for other options. I found a used J30 Mass Air Sensor, and the salvage yard claimed they were identical. The housing is different (plastic vs metal), but it has 4 wires like the 300zx tt one, so I don't know. I hooked it up and the car wouldn't even start, but I didn't think to check the wiring. I did a little research tonight and found out exactly which terminal gets which voltage, so I will try that tomorrow.

I have also been told it could be a vaccuum line problem, but everything seems to be going to the right places.

I know this is long, but I want to give as much information as possible so that you can help me without having to ask a million questions.

Please reply ASAP... this is my only car and a daily driver!!!

Thanks,Sam

Did you try resetting the computer after you fixed the jacked flow meter connection? It retains the error code until you do that.

If you can conform for sure it is the flow meter send me an E-mail with your address and I will mail you a stock CA18DET flow meter so you can get back on the road.

Madscientist,

You have mail!

BTW, how do you reset the ECU and/or read error codes?

Thanks,Sam

disconnect the battery negative and leave it off for a while, about 30 minutes should be more than enough.before you do that though I would zero any piggyback computers just to take out any variables, you can re-tune them once the car runs normal. While the battery is off check every single electrical connection on the motor, it kills time and you might find something else loose. If you have in fact fixed the problem it should start and run fine after you hook the battery back up.

i agree with checking all connections espesiacaly the MAF and O2 connects mositure might have built up in them or they could be looose my motor had loose wires an my motor wont start

Hmmm, bought the car here in miami? I don't know of many people who use this engine down here. I'm the only fool that has one in my sentra and I know one guy who has one in a starlet. Very important to do a compression test to see if this thing hasn't been dogged to the point of needing repair. Check the hose that comes off the valve cover by the butterfly valves' actuator to see if it has been split. If so, it means someone has been in there. Your crank angle sensor should not be cocked completely to one side. I bet it's cocked more to the left which would mean the timing is waaay to advanced. The crank angle sensor could be tired or it's connectors as well. Definitely check the codes on the computer to see what it reads. Or it could be a busted exhaust camshaft spline in which the crank angle sensor sits. Let us know what you find.

Have you checked the fuel pump & fuel filter?

erich

No it hasn't busted the drive spine for the CAS, that is instant off. I did it in one of my Skylines, boy did that suck! I got your E-mail, AFM will be in the mail Monday on my end. With the holidays it will probably take two weeks minimum.

i had a problem with the low idle/die and the low "rev limiter'' before on my KA, but i dont think it would be too different. the MAFS and one of my 02 sensors where bad.i replaced them and it ran just fine.

again, that was my KA. i dont know about the rest, i would just check whatever the rest of the guys on here say.

Thanks for all of your suggestions, but I am still not getting it to run. I reset the computer and checked its error codes. First of all, the computer was in "diagnostic" mode, which supposedly would mean that it wouldn't run at all?!? Anyay, I was getting "3-4" as a code, then I reset it again and got "5-5" which means "no error" Car still won't start.

I have had two offers for stock CA18DET MAFs and both are on the way. Thanks guys. I am hoping that is the sole problem, but I doubt it. My wideband hardware arrived today from Australia(everything but the sensor itself), so once I swap the O2 sensor, I will have replaced that variable and will also have a much better idea what is going on inside my engine. Speaking of which, where can I get a wideband O2 sensor? Lots of suppliers list them, but few have them in stock.

My search for more bad connections has revealed a broken butt connector in a wire going to the ECU. I haven't determined what it was, but it is properly connected now.

As for being stranded, I gave in and bought a beater. It's an 87 Honda (I know, I know) Prelude Si, but it was 900 bucks, costs $250/yr in insurance and gets 30+mpg, so whatever... Most important thing is that it runs, which I cannot, unfortunately, say for my Nissan at the moment.

Please keep the ideas coming!

Thanks,Sam

Have you ever considered that the ECU was bad or if there was an electrical short in the AFM circuitry, that ECU is probably in need for repair (been there and done that). That's why I went standalone! No more dramas from crank angle sensors, AFM's and all that JWT shipping back and forth. And it will most definitley eliminate the mystery as to why the car doesn't start. Be wary of the ECU and good luck.

Is you computer reprogrammed fore the z32 mafs?If so the two stock mafs will do you no good.the mafs is what you problem is my car did the same thing.take a multi-meter and check continuity between the mafs and the ecu.And dont go switching wires around i have found that a few diagrams on line have been miss leading becuase they dont tell you which side you the plug you are lookin at.if you keep having the problem give me an email and ill help you throw it

[email protected]

IT'S ALIVE!!!

I have finally made some progress. Seems that the wiring diagram I found on the internet was inaccurate. Pin A is a feedback from the ECU and is a calibration of sorts. Pin B is a 12V power supply. Pin C is a ground. Pin D is feedback to the ECU.

I found that the ground was floating. I assumed a loose wire, bad connection, but it turns out the ECU was fried. That sounds bad, but I figured since it was fried, I might as well try to repair it. So, I cracked it open and soldered a wire from pin 10 to pin 37 to complete a ground. My electrical engineering training tells me that there may be too much current through pin 10 now, but theoretically, it would run.

So, I reinstalled the ECU, and the car started for the first time in weeks!!

Next, I took off the timing belt and realigned the OHCs, they were 16 degrees off. Now it will actually idle. Not very well, but it ran.

This is where Doug from EFI Systems came in. He immediately recongized that the engine temperature sensor was faluty (?!?) and had extras on hand. We swapped that and now the car idles smoothly. The problem now is that it is running lean under throttle.

My wideband and display arrived last week and the sensor comes in tomorrow, so I will use it for diagnosis. I think the HKS AFR is faulty because it is not varying the voltage to the ECU from the MAF. Luckily, I now work for EFI and can get our awesome AFR for practically nothing.

The only other option is that the fuel is not under enough pressure. The engine was hot and I didn't want to check that today. If the fuel pressure is low, I already have a new fuel filter and pressure regulator to replace those components. I pray it's not the fuel pump!!!

Quote »Have you ever considered that the ECU was bad or if there was an electrical short in the AFM circuitry, that ECU is probably in need for repair (been there and done that). That's why I went standalone! No more dramas from crank angle sensors, AFM's and all that JWT shipping back and forth. And it will most definitley eliminate the mystery as to why the car doesn't start. Be wary of the ECU and good luck.[/quote] Congratualtions! I guess part of my theory was correct! If you ever come across some excess money, you can always remove that factory set-up and rid yourself of a wiring nightmare.

EC you still need a AFM? the post office here will be reopened Monday.

Madscientist,Thanks, but the original maf for the car is supposed to be coming this week. -Sam