madkiwi

I am not going to start celebrating yet, but I may have solved the "random and unpredictable going into safety boost" problem. Looky here- That is the EFI harness connector for the knock sensor. The black wire is the shielding ground wire. Completely broken. I have talked to 2 different people who believe an unshielded knock sensor sub-harness may indeed result in spurious noise causing the ECU to interpret it as knock signals from the sensor. And being completely random.

I had to send the USB Consult tool I purchased back to the seller due to the weird stuff it was doing to my car (HICAS error, not reading the speed etc). I am going to buy a new one, just waiting to get it. Then I will get the Nistune software and get those maps. How can you measure the AFR? IS this one of those deals where you either install a wideband O2 sensor or put it on a dyno with a sniffer attached to the exhaust? Here is where someone in Denver mentioned a bad JWT ecu- http://www.twinturbo.net/nissan/300zx/forums/technical/view/1146182/No-issue-in-Denver-doing-14psi-on-stockers.html Thanks

So here is the latest on my progress (or lack thereof). I had the compression tested, high was 171 and low was 148 psi. Like a new engine. Verified that the mark on the crank pulley lined up with 0 on the advance indicator when #1 was at TDC. With the plugs out for the compression test my mechanic inspected the cylinders with a borescope. Apart from normal carbon deposits, nothing to report. I can report that the FSM manual has an error in the testing protocol for the MAF. On page EF & EC 174 it says that voltage from b to ground with the key ON should be about 0.8 volts. I purchased a used N62 sensor last week and installed it, it has a voltage of 0.45 volts and my old one was 0.44. Both show the expected voltage at idle (1.216 and 1.245). And it did nothing to solve my safety boost problem. I just ran a tank of gas with a bottle of Redline Si-1 fuel system cleaner in it to clean up the injectors/valves. Happy to report that it has already helped my fuel economy a bit, just got the highest mpg in mixed driving in a long time (17.59 mpg, or 13.37 l/100km) but still getting the safety boost issue. I have not changed the base timing to 12 degrees (or lower) as suggested yet because I have been doing other things and seeing if they help first. Don't want to change a bunch of things at once and not know which one made the difference. Is there a way to examine the fuel maps programmed into the JWT ECU without spending a fortune on software? Because with the lack of anything else I am wondering if there is something wrong in the ECU. On twinturbo.net someone did say that a tuner had found an issue with a 1995 dated JWT chip that was running super-lean. I am not sure what the date is on mine, short of pulling the carpet/plywood out of the passenger footwell, which I don't feel like dealing with right now. I will before my next phone call to JWT, because I may have to ask them about it. Thanks.

I got one of those (from a US based seller) and ended up returning it. On my 1993 TT it would not read the vehicle speed, it caused a HICAS error code, and put the car into "high speed steering mode" which reduces the power steering assist so you really needed 2 hands at low speeds. Did not matter if the computer was connected or not, and you had to cycle the ignition to put everything back to normal. Apart from all that, it worked just peachy. You will need to download drivers for the FTDI serial-USB chipset, all they put on the disc was the free Nissan Data Scan. You can get them here- http://www.ftdichip.com/Drivers/VCP.htm Your experience may vary...

You are kidding, right? :saddam: When I wanted to buy mine I was looking on Ebay (US) and Craigslist and figuring no matter what I was probably going to have to fly somewhere and drive it back to Montana. With my luck, it could have been in Florida (2,800 miles by road). But I ended up finding mine in Hamilton Montana, about 45 miles from where I am typing this post. 1993 TT, pristine leather interior, Cherry Red Pearl and immaculate body and paint. (I won't mention the deferred maintenance items that had to be dealt with...) Only bad thing (I thought) was it was an automatic. As other people have pointed out to me having an auto turbo is pretty nice for acceleration, you never lose boost for gear changes. The UK isn't that bad by comparison.

I am such a retard. You know how they say be careful when you are reconnecting the ECU connector to the ECU? Don't over-tighten the bold that holds it on? Well, don't UNDERTIGHTEN it either. Because if the connector isn't fully seated, then weird things happen- like pin 11 that feeds ignition signal for coil #4 to the PTU doesn't connect properly. Obviously I discovered this AFTER troubleshooting the PTU, the ECU-PTU harness and finding absolutely nothing wrong. Until I started reconnecting the ECU and realizing I was tightening it more than I had previously... OH ****ING HELL! On the plus side, all the PTU connectors are now clean and full of dielectric grease.

Today I checked the wiring between coilpack #4 and the PTU, good continuity. The connector between the harness and the PTU was green, used a bunch of electronics cleaner and a Dremel to clean up the contacts. Going to check the wiring between the PTU and the ECU tomorrow. Wondering if the ECU connector pin is not making contact. The first Google search I did for "300ZX code 21" came up with a thread on 300zxclub.com where the guy's problem was the female connector on the ECU harness connector backed out of the plug. I did have the ECU disconnected the day before the new CTS came in, when I was checking the wiring of my new CTS plug. After I make sure the wiring/connectors from the ECU to PTU is good, then I will test the PTU. See what I am doing? Check the inexpensive stuff first. A PTU here is $158, don't want to assume it is knackered until proven so.

If it isn't one thing, it's another. I replaced the CTS (checked the new one was within specs first) and started the car, it was running like crap. Dragged out the laptop, plugged it in, pulled codes. Code 21- No ignition signal. Tried a power balance test, #4 is not running. Only thing I can think of is that when I was manipulating the harness to replace the CTS plug I must have either broken a wire or dislodged one of the PTU connectors. Because if the PTU is actually bad I MUST be cursed. I did not have time beyond step one of the diagnostic procedure (EF & EC 119-121) to trouble-shoot. I work for myself, but I had to go take care of work stuff and so... tomorrow. Ever seen a grown man cry? I came close...

Got home too late to install the new CTS, let alone go for a test drive. It is supposed to be 85 F tomorrow (29.4 C) so a great day for seeing if the detonation comes back. What do I need to incorporate the Nistune stuff in my car?

Well that is a new one to me. Not only is the CTS bad, it is completely open. No resistance at all. Wiring checks out fine (total resistance was 0.2 Ohms). I wonder why that just happened. I know you in the UK complain about Nissan raping you on parts, but we get some of that here. MSRP on a CTS is $29.75. My local stealership has one in stock, they want $35.70 (Courtesy Nissan has them for $22.31). I want to get the car running today, so pay I must. Can't wait 3-5 days for Courtesy to send it to me. Oh, I called the place that has a dyno here in town. They specialize in diesel truck stuff. The tech basically told me unless I have my own knock monitoring equipment and software, there is nothing they can or will do for me. So that is a dead end.

Oh, and the aux. fan did not come on. Sorry, overlooked answering your question.

I'll strip down the plug connections and make sure the splices are good. Actually even if they are, I have a new yellow connector w/pigtails in my parts box, I will just replace it. Then connect my multi-tester to ECU connector pins 28 and 30 and make sure I get good readings. Thinking out loud now- maybe this has been my problem all along? A bad connection or not-quite-good-enough connection that has been flaking out randomly, telling the ECU that the engine is too cold for boost? Maybe not, once the engine sees higher temps again, then it would allow boost. So, never mind. Plus I have not recorded any CTS codes before. I'll let you know what I find tomorrow. Mark

I am going to do that, tomorrow when I have 20 minutes to deal with it. But Noz, if you are still reading- something new happened today. After a normal start to my day I made my first stop, and when I returned to the car a few minutes later and started it, the idle jumped to 1500 rpm, then stepped down slowly over the next 5 or 6 minutes to normal idle (800 rpm). Thought that was a little weird, stopped at the next place I had to go, and the same thing when I got back in the car. After the 3rd time this happened, I plugged in my laptop to the Consult plug. Turned on the ignition and the coolant temp was showing it was 70 degrees (21 Celcius). This was after the car was sitting for only 20 minutes, and it was an 80 degree day. I started the engine, same wildly high rpms, and I sat in the parking lot until the temp on the computer showed it was 176 F (80 C), took about 5 minutes. Idle was where it should be after car is warmed up. Drove to my next stop, computer showing temp around 180 F, shut car down. Turned key to ON position, temp on the computer showed 75 F. Started the car, idle ran to 1500 rpm, then ran down to 0. Yes, for the first time since I purchased the car 4 years ago, the engine stalled. Transmission in Park. Started it again, and the car was in "cold start" mode again, with high idle, but it stayed running. Drove home, idle is a little high, 900 rpm, temp on laptop showing 178 F. Shut down when I got home, started the engine again, and once again it stalled. Stayed running the second time I started it. Checked codes, of course it is Code 13, CTS. But that doesn't explain the symptoms- I had a bad coolant sensor when I purchased the car and the auxiliary fan ran all the time. Idle was a little high, but not 1500 rpm. The CTS and the connector were replaced together, and I definitely soldered the new connector. I did a full temperature test of the CTS about 6 weeks ago, it passed with flying colors. Thoughts?

Last things on the checklist done- checked the injector resistances. What made the job easy was discovering I could do it from the ECU connector, pretty neat that I did not have to try to get all those connectors off (and remove the balance tube). #1- 12.1 Ohms #2- 12.3 #3- 12.1 #4- 12.1 #5- 12.1 #6- 12.0 That includes all the resistance in the wire to the injectors, theoretically 0, but what it tells me is the damn injectors are doing what they were designed to. After eliminating the unlikely, then that leaves only the impossible- my petrol sucks. Here in Montana all our gasoline comes from a refinery in Billings (about 300 miles from here) and they make 87, 89 and 91* (note below) AKI with 10% ethanol and 91 AKI ethanol free. It is intended for "Snowmobile and off-road use". * I was told that the refinery makes their Super 93 AKI, because it is also sold in Washington and in the Dakotas. More economical to just make one Super formulation, and sell it both here and at lower elevations. All the pumps here are marked 91 AKI, but because you are getting higher octane than you are paying for it isn't an issue. I am wondering if I should just give up buying the ethanol-free gas (who knows what they get away with putting into outboard engines and ATVs) and just buy the ethanol-gas blend. Then budget for a set of later-model injectors and the adapter kit when my current ones die from the ethanol. I have run out of ideas. I think I have checked everything. I will still take the car and have it run the dyno. We'll see if that finds anything, but I can't imagine what. Maybe I should just take it out behind the barn and shoot the damn thing.

Last things on the checklist done- checked the injector resistances. What made the job easy was discovering I could do it from the ECU connector, pretty neat that I did not have to try to get all those connectors off (and remove the balance tube). #1- 12.1 Ohms #2- 12.3 #3- 12.1 #4- 12.1 #5- 12.1 #6- 12.0 That includes all the resistance in the wire to the injectors, theoretically 0, but what it tells me is the damn injectors are doing what they were designed to. After eliminating the unlikely, then that leaves only the impossible- my petrol sucks. Here in Montana all our gasoline comes from a refinery in Billings (about 300 miles from here) and they make 87, 89 and 91* (note below) AKI with 10% ethanol and 91 AKI ethanol free. It is intended for "Snowmobile and off-road use". * I was told that the refinery makes their Super 93 AKI, because it is also sold in Washington and in the Dakotas. More economical to just make one Super formulation, and sell it both here and at lower elevations. All the pumps here are marked 91 AKI, but because you are getting higher octane than you are paying for it isn't an issue. I am wondering if I should just give up buying the ethanol-free gas (who knows what they get away with putting into outboard engines and ATVs) and just buy the ethanol-gas blend. Then budget for a set of later-model injectors and the adapter kit when my current ones die from the ethanol. I have run out of ideas. I think I have checked everything. I will still take the car and have it run the dyno. We'll see if that finds anything, but I can't imagine what. Maybe I should just take it out behind the barn and shoot the damn thing.