Indigent

NICE! Another yakamanian with some tuning guts! Lets get together this weekend. This is definitely all VG30E stuff though. I imagine the timing and fuel maps would be drastically different between the I and the E. Should still be fun to play with though.

I eventually want to get to making my own maps. I will need to save up for somethings like a wideband O2 and the pocket romulator. I also need to get on a dyno. I also install a socket to make future edits easier. Like I said earlier, I just yanked one off of an old ethernet card I had in the closet. If there is anyone here in WA that has access to a dyno that would be willing to help, that would be awesome. I want to open this whole thing up so everyone can get access to this info if they really want to. I will work on putting together all of the info I have so far during this weekend. If anyone has any other Nissan tuning experience please chime in! indigent.

Turn it into something as useful to your car as a brick. It is a nerdy way of saying break it. indigent.

Kingman92010: I wouldn't charge you for it if you post your results and contribute to the whole thing(well maybe a brew or two, to you know, steady the hand while soldering...) Get your rig in tip top shape as far as engine tuning goes, and establish a good baseline of your mileage. Remember, I am making no claims as to mileage or HP increase. At this point I am just experimenting, and this *could* theoretically brick your ECU. You will have to provide the chip itself. I would buy one or two from here. Let me know. That offer goes for anyone within driving distance of me (Yakima, WA). indigent.

I actually de-soldered the ROM chip from the board. I then put the chip into a ROM reader. The hardest part is the de-soldering, but with some simple and cheap tools it only takes about 20 minutes to get it out. All you need is a solder sucker and a soldering iron. 300zx ECU Tuning info. Check that out for starters. It goes into details that don't pertain to our ECU's but most of it is relevant. He talks about the pocket romulator, but that is more advanced that what I need right now. I don't need real-time tracing until I get access to a dyno. I went on ebay and bought a willem pcb 5.0 eprom burner. It was like 40 bucks shipped from Hong Kong. Then I went to www.moates.net and bought a few of the sst27sf512 chips. They are EEPROMs, which means you can write to them thousands and thousands of times and don't need a UV eraser. I got the chip socket off of an old ethernet card I had laying around. This is great to get such quick interested responses from this. I will put up pics and whatnot of my ECU teardown. Maybe start a howto similar to the one in the link. indigent.

For starters, sorry for the long post... I am surprised to see that there isn't any real discussion (that i could find in the search) about chipping the ECU's in these things. There is a ton of info on the 300zx that I have been reading and using. I recently pulled the ROM off of the board in my 90's ECU and started poking around. The setup is very similar to the 300zx maps, so it is pretty easy to navigate. I have a buddy with a 1990 Maxima, who graciously let me dump his ROM as well. I was able to find the Fuel and Timing maps quickly. I basically took those maps and put them in place in the Pathy ROM and crossed my fingers. Considering that they have the same MAF (confirmed by looking at the VQ Map) I wasn't overly worried. The truck started right up, and it was definitely more responsive. I don't have access to a dyno, but considering the official Nissan specs for the Maxima were almost 10HP extra, I think most of that is in the ROM. I still have a bunch of Terrano buddies from when I lived in Japan, so I called my friend Takuya up. He was kind enough to go and get a JDM 1993 R3M VG30E ECU at a junkyard (for about $50) and dump the ROM. He emailed me the .bin file. Aside from the fuel and timing maps, everything is the same in the ROM. The fuel and timing are quite different though. I put that .bin into my ECU and fired up the truck. It seems to have a ton more power. I have a route setup to test my truck when I do any major maintenance (it has nice inclines long straight stretches). There is one incline where the truck *always* shifts down to maintain the speed limit, but it didn't have to this time. I haven't done any real testing yet as far as fuel mileage or as mentioned a dyno, so take this all with a grain of salt. Is there anyone on this board that has messed around with their Pathy's ECU? Is there anyone in the Central Washington area that would like to participate in some experiments with this? Indigent.

The 1990 Terrano TD27T I had in Japan had a manual throttle adjuster that came stock. It was super helpful. Did none of the State's models come with one? Check the pic: pic link It's right there next to the tranny mode switch. indigent.

We are saying the same thing. Yes it is responding to the electrical signal from various sensors, the MAF included. When the brake pedal is applied, the booster is using air from the intake manifold, which changes the air flow inside the intake. The MAF sees that change in flow as an increased engine load, and the ECU tells the IACV to open a bit more to compensate. hope this helps, indigent.

Check out page EF & EC-20. It explains everything that the IACV compensates for. hope this helps, Indigent.

As far as the speedo not working, the ones before 94 had the speedo cable. If someone who didn't know any better pulled that cluster out could have reinstalled it wrong. There is a little spring loaded adapter (like a mini transmission for lack of better word) that mates the cable with the back of the cluster. It can be a PITA to get back in right. The pathy I have now had the same problem. I just pulled the cable and the adapter thing from my junker and put it in. For your own sake, pull the cluster and see if the adapter is in there. If it isn't you could get it from a junkyard for probably around $10. I wish I had a picture of it, but you will know if it isn't there. It is about 2 inches long and is spring loaded. The end that sticks in the back of the speedo is square, and there is a metal shaft that has burrs on it that sticks into the actual cable. hope this helps, indigent.

When you press the brake pedal, the brake boost assist puts an extra load on the engine. The ecu senses the load and adjusts the idle air control valve to compensate the idle for the greater load. The IACV solenoid isn't just for the brake, it is for any circumstance that puts extra load on the engine. For example, when you turn on the AC, it puts extra load on the engine, and the IACV opens up more to adjust for that condition. The brake booster runs off intake manifold pressure, which affects the ammount of air that is moving through the intake plenum. The MAF interprets that airflow change as greater engine load, which gets compensated for by the IACV. hope this helps, indigent.

Could be the idle air control valve. Disconnect the plug to the iacv solenoid and see if it still happens. You can check the resistance of the solenoid with a multimeter too. It should read about 80 ohms IIRC. hope this helps, indigent.

I can verify 100% that there is NO top speed governer. I have dumped the ECU ROM and played with it. The cell for the speed limit is set to FF which is as high as an unsigned bit of that size gets. Rev limit is set at 6250rpm. I have played with that as well and bumped mine up to 7250. hope this helps, indigent.

If you know anyone else with a pathy you could put it in theirs, lol. I would clean it with MAF cleaner and test the wires first. I have never actually had a MAF go bad, but not to say they don't. I had a problem a few weeks ago where mine was giving me a 12 and not running very good. I just pulled it out and cleaned it up. Also, the way the wiring is routed, it is very prone to breaking. Especially if you don't remove the connector when changing the air filter. Get out the haynes, chilton, or fsm and check those wires. MAFs can be expensive. I would hate to see you buy a new one and have it not fix the problem. hope this helps, indigent.

Me too. I have never had to use a puller. It is probably because I bought one just for that a long time ago, lol. I have never pulled it off on this new (to me) pathy so we'll see tomorow night. indigent.

I laid down on the ground looking up at the balancer today. The whole crank pulley is wobbling pretty bad, at least enough to be noticed. I am starting to get the feeling that his is a pretty bad problem. If anything, that front crank bearing is not too happy with all of that shaking. I am going to take the balancer from my junk pathy this weekend and see if that affects anything. In a way I hope it is the distributor cap because I just bought it about a month ago, and it is still under warranty. I will update when done. indigent.

No change in idle when the timing jumps. When the timing jumps, I wiggled all of the plug wires and no change. I am going to take the whole distributor assembly from my other pathfinder and see if that helps. I know there is nothing wrong with the light. It flashes steadily without interruption. I was wondering if the O2 sensor affects timing at all. indigent

I recently picked up this pathy without a tranny in it, and since my other one's #6 piston gave out, I did a tranny swap. The thing is, I don't know how many miles are actually on this engine. (speedo cable had been disconnected for quite some time according to the prev owner). I decided to do some routine checks recently and timing was one of them. While I was checking the timing, I noticed that it was right on the money at 15BTDC, but it would sporadically jump away from there, to the point that can't see the timing marks any more. It isn't that the light stops working, because it still flashes perfectly. It is as if the timing is just jumping all over the place! My questions is this: What sensors affect the timing at idle, or what other factors could cause the timing to jump? There is no rhyme nor reason to it. It will go for 30 seconds without jumping, then bam. It always comes back, but this definitely doesn't seem right. Any thoughts? indigent

One more bit of advice: Replace those two little hoses with much longer ones (like 4-5"). Loop them around in a circle so they don't kink. Then the next time you have to get the plenum off, you will be able to lift it up and get to the hoses from an easier place, and maybe not have to remove them at all. Even if you only have to get it off one more time, it will make your life easier. Hope this helps. indigent.

I spent more time trying to figure out a way to get to that valve without removing the plenum than I would have if I had just taken that stupid thing off. I actually made more work for myself, because I attempted to just lift it up an not disconnect the coolant lines. Turns out that all of the wiggling I did cut one of the coolant lines pretty bad, and I had no idea. I was driving home from work and my engine started to overheat. I had lost all of my coolant through that line. Once you have taken that plenum off, it gets easier, I promise. Its only a couple bolts and those two little coolant lines. I have never had to use a new gasket either. I have been lucky that it stays intact, but YMMV. hope this helps. indigent.

I would check the idle air control valve solenoid. If you have a multimeter, it takes like 10 seconds to check. It is not a circuit that is monitored by the ecu so it wont spit a code. I had the same problem on my old pathy, but not saying that is your problem. There is a procedure in the FSM, but all you have to do is check the resistance of the connector that you take off to adjust your idle speed. If I remember right it should read about 70 ohms. (I don't have the fsm with me right now.) If it does read properly, it could still be bad mechanically or just stuck. They are pretty easy to disassemble and clean. I went through 2 timing belt changes, head teardown/valve replacement, fuel filter, and finally a new rig before I found out about that stupid solenoid. The only reason I found it was that I knew the intake from my old one (the one with the problem) was cleaner than the one on the newer pathy I bought, so I decided to swap it. The original problem swapped with it! Since there are only a few things to check on the plenum, I checked everything and found that solenoid bad. I swapped them out, and whala, idled like a champ. hope that helps. indigent.

I left the stock amps running the stock speakers in the rear. I ran a new remote wire for my sub amp. The head unit I have (pioneer) has seperate output just for subs. If you are going to use the stock speakers in the rear, you might as well just leave them on the stock amp. Personal preference I guess. Indigent.

I just put a pair of needle nosed vice grips over top of the nub on the outside to the base on the inside of the glass. I then had just barely enough room to get a 10mm open end wrench on the nut in there. indigent.

I ran into a similar problem with the one I had in Japan. I bought a cluster from a vg30 in the junkyard and it was different. What I ended up doing was disassembling the diesel tach from the cluster and putting it in the vg30 one. It wasn't all that hard. indigent.

There are no coolant channels that go throught the plenum and down to the manifold. All of the coolant that runs through the plenum comes from the two small hoses at the back of the engine. If you have coolant on that intake gasket, it is more than likely coming from somewhere up above. Do you have the ability to take a picture of this coolant leak? That would be incredibly helpful. indigent.