RB20, chipped, Z32 - Running rich

[rcrdps]

As the title says, I have an 95 240 with an RB20 in it. I had to replace the MAF a while back and went with a Z32. That was when I chipped it to take care of the MAF. Since then I've tuned it, then re-tuned for water injection. It ran great for quite a few months in that trim. Over the last 2 or so months, I've been having problems with it. It runs so rich that it will miss. It bottoms out my wideband. Just shows 7.4:1 once boost comes on. That sounded like a boost leak to me, so I tested for that. I found a few really small leaks, but none where bigger than what a boost controller would let out. I went ahead and fixed them though. The only other thing that leaks slightly now is from the crankcase. It's not audible, but if I plug the crankcase vents with my finger for a few seconds and let off, then I can hear a puff. I'm assuming that is from normal leakage around the rings. I did a leakdown test yesterday, and according to the equipment, it was at the higher end of low leakage,... but still in the green. Since all cylinders where the same, I'm assuming they're fine. Seems if something was damaged there, I'd see it on one or two cylinders.

So any ideas? My only idea is the MAF. It appears to respond correctly when I watch it on the conzult. Does anyone have MAF readings at say idle and cruise for a z32 MAF? That way I can check mine and see if it is really off?

Thanks,

Gene

[craz4240]

Weird I have a Z32 Mafs as well,my car has the same issue but it also idles way lean....which come to find out was the lower isolators for the injectors.I am gonna ago with big boost or vacum leak my man.

[rcrdps]

So how much of a leak will be noticed? Boost controllers leak air to raise boost. Before I took it out, my diy manual boost controller was the loudest leak. So it seems if there was a huge leak, I'd be able to really hear it hissing. I'm currently only running 12psi( stock). I've boost tested to nearly 20 psi, at which point my pvc fitting for boost testing blew out of the intake. At maybe 15 psi the pcv valve does start audibly leaking, but it's not much. It is definitely operating as a one-way valve. I can blow and suck on it and hear it opening and closing. It only hisses a tad at overboost.

Seems to me, whatever is coming from the crankcase or pcv wouldn't really matter as far as mixture would be concerned since those both would only return to the intake after the MAF. So that air is still accounted for even if it is lost boost.

Thanks for your reply. Keep the ideas and comments coming. I'm pretty stumped. If anyone has anything for me to test, let me know and I'll try it.

Gene

[rcrdps]

Just wanted to update this for anyone searching. It occured to me the other day that if the fuel pressure regulator diaphram was leaking, then the fuel would go out the vacuum hose and into the intake. That would case a rich condition. Today I was going to to some testing, but the car was running fairly good. The problem comes and goes. But I tested anyways, and found why it "seemed" to be running good. The fuel pressure regulator is stuck. When I removed the vacuum hose, the pressure didn't change at all. So the richness may not be it leaking, but maybe it's getting stuck open

Either way, I've ordered a new Nismo regulator. The current one seems to have lasted 25k miles or so. If this new one goes out that quick, I'll look more into a more universal mount regulator.

I'll post results here when I get it installed.

Gene

[Shocker]

thanks for the update!, thats the first I've heard of a nismo reg just going bad?

[rcrdps]

Sigh,... that didn't fix it. And it was a pain to take off. It had these two very soft screws holding it on, and one was up under the manifold. I ended up loosening the fuel rail and slotting the screw with a dremel to get it out. I think when I noticed the pressure not moving before, it was just the gauge sticking. It still does the exact same stuff.

Gene

[rcrdps]

Another update. I just replaced the injector o-rings. All 3 of them. My reasoning: I'm smelling gas, and my engine is running rich. So I figured the o-ring between the injector and manifold must be leaking, thus causing a boost leak, and blowing fuel/air mixture into the engine compartment.

That does seem to have fixed the gas smell, though now the upper o-rings leak in two of the injectors. Not sure why. I've wiggled them to try to get them seated, and that seemed to help, but when I come back to the car after it's been sitting for a while, the fuel pressure has dropped. So there is still a small leak. I'd consider it negligible for now.

But it didn't fix the rich problem. So now I'm just tuning it out. Been lowering the K value by 6 or so at a time. Got it up to about 9:1 now. Gonna keep going until it matches what the fuel map shows as the theoretical AFR.

Gene

[craz4240]

Hows the idle...I have my whole motor apart now waiting on some gaskets,if this doesn't fix my issue well I only have 2 other ideas.

Maybe you have a leaky injector or 2???I had mine out so I sent them to be flow tested and cleaned wile I had the mani off might as well.

[rcrdps]

I almost sent mine in too when I was changing the o-rings.

Maybe an injector. But then on the other hand, it seems to do closed loop well, so that seems more like whatever it is, is affecting the whole engine.

Tuning it out seems to be getting me closer, so it's probably a boost leak. I may try to rig up a better boost test. Last time my adapter would blow out somewhere between 10 and 15psi.

A guy down the road is interested in my car though, so tuning it out may be the extent of my troubleshooting for now. If I still have the car in a month, I'll get back on it.

Gene

[rcrdps]

Update Time! Yeah, so my car still doesn't run that well. It runs good enough that I drive it all of the time, but how it's going to pull is still hit and miss. I can tune out a little bit of the richness, but sometimes the problem gets less, so then it's really lean and backfires.

I sent my injectors to RC engineering to be cleaned. That didn't help.

I just boost tested it again to 15psi. The boost controller hisses, and there's a bit of air coming out of the crankcase, but that's it.

Gene

[240z4u]

Are you siphoning water out of your water reservoir? I had to add a check valve to my alky control system because of that.

[rcrdps]

I have solenoid valves on the water injection system. One switches it to the windshield, the other to the intake. But I also currently have the system turned off since the pump isn't working.

I might check more into the system though. Make sure something's not turning on and venting the boost. Maybe I'll put a clamp on the water tube to the intake.

Gene

[rcrdps]

Ok. I just went and made a run with that water line clamped. It didn't do any different.

Gene

[rcrdps]

Another update. Just ordered a new MAF. My current MAF responds fine, but maybe it's just getting a bit off. The MAF is near the exhuast side of the engine, so maybe the heat has weakened it. We'll see if this corrects the richness. I am really ready to figure this out.

Gene

[Kansei240sx]

Have you checked your Engine Coolant Temperature sensor?

[rcrdps]

Not with a meter, but I can see it on the ECU and it tells me the temps are around 81 degrees C once it warms up, which I'm pretty sure is where it's supposed to be.

[rcrdps]

Replaced the MAF and it's still running rich. So that's $110 wasted.

Here's what I know/ have replaced:

replaced MAFreplaced FPR ( both old and new are nismo)had RC Engineering clean and calibrate injectorsreplaced injector o-rings and "insulators"MAF, TPS, and ECT all appear to operate correctly when viewing on conzultcruises fine, bottoms out wideband when you floor it.did boosts tests quite a few times. Only a few small hisses from stuff like the throttlebody linkage. Nothing bigger than what a boost controller would put out.Leak-down test showed all cylinders equal, and in the green.I've looked at the plugs several times, and replaced them. They all appear to be running the same. I'll look at them again to see if any one cylinder is the culprit.

Just a reminder: This is not a new swap. I've had the car for quite a while, and it was running like a top and in "perfect" tune. So something must've gone bad or started leaking.

Gene

[rcrdps]

Checked the plugs. They all look the same to me. Doesn't appear to be any one bad cylinder. Looks a tad rich, but this isn't after a hard run. I'd assume they'd be sootier if I had just come off a hard run.



Gene

[rcrdps]

Here's a logged run at full throttle. Duty Cycle seems about 10% high to me. This seems so much like a boost leak, but I can't find one. I'm wondering if there is something that can turn on while you're running and cause a boost leak. Maybe the IAC? From what I can tell, everything loops back into the system, so shouldn't cause any extra air reading. I've removed my MBC and water injection circuits.

RPM Throttle Air Flow Injector Duty Cycle3675 4.08 2.99 12.31 373700 4.08 3.02 12.62 383750 4.08 3.06 13.06 403738 4.08 3.08 13.43 413700 4.08 3.12 14.03 433700 4.08 3.14 14.44 443750 4.08 3.18 14.54 453788 4.08 3.2 14.78 463862 4.08 3.24 15.02 483888 4.08 3.27 15.38 493900 4.08 3.3 15.68 503912 4.08 3.34 16.16 523938 4.08 3.35 16.37 534000 4.08 3.37 16.36 544025 4.08 3.38 16.43 554012 4.08 3.38 16.58 554050 4.08 3.39 16.4 554100 4.08 3.38 16.18 554150 4.08 3.4 16.11 554175 4.08 3.4 16.11 564188 4.08 3.42 16.14 564238 4.08 3.42 16.12 564262 4.08 3.42 15.94 564388 4.08 3.47 16.19 594425 4.08 3.5 16.42 604450 4.08 3.5 16.41 604375 4.08 3.48 16.36 594425 4.08 3.48 16.13 594488 4.08 3.48 15.93 594500 4.08 3.51 16.34 614688 4.08 3.56 16.29 634662 4.08 3.58 16.86 654688 4.08 3.6 16.75 654600 4.08 3.58 16.97 654712 4.08 3.6 16.56 654762 4.08 3.6 16.6 654862 4.08 3.62 16.45 664862 4.08 3.64 16.6 674875 4.08 3.64 16.72 674938 4.08 3.66 16.63 684912 4.08 3.67 16.82 684875 4.08 3.67 16.95 684962 4.08 3.66 16.44 675012 4.08 3.68 16.54 695075 4.08 3.7 16.52 695088 4.08 3.7 16.64 705138 4.08 3.72 16.61 715100 4.08 3.72 16.76 715175 4.08 3.73 16.65 715200 4.08 3.74 16.67 725212 4.08 3.73 16.49 715262 4.08 3.74 16.43 725212 4.08 3.76 16.83 735312 4.08 3.76 16.53 735350 4.08 3.78 16.72 745400 4.08 3.77 16.49 745462 4.08 3.79 16.6 755475 4.08 3.8 16.85 765450 4.08 3.81 17.05 775525 4.08 3.82 17.01 785500 4.08 3.84 17.31 795575 4.08 3.84 17.3 805612 4.08 3.85 17.29 805625 4.08 3.84 17.21 805675 4.08 3.86 17.19 815738 4.08 3.87 17.19 825725 4.08 3.88 17.44 835738 4.08 3.88 17.5 835712 4.08 3.89 17.65 845838 4.08 3.9 17.35 845900 4.08 3.9 17.33 855850 4.08 3.92 17.7 865888 4.08 3.92 17.64 866000 4.08 3.93 17.45 876038 4.08 3.94 17.48 876000 4.08 3.94 17.61 886050 4.08 3.95 17.59 886012 4.08 3.94 17.6 886050 4.08 3.94 17.5 886125 4.08 3.95 17.4 886150 4.08 3.94 17.31 886175 4.08 3.94 17.12 886162 4.06 3.94 17.01 876275 4.08 3.95 16.94 886275 4.08 3.96 17.02 896288 4.08 3.96 17.04 896288 4.08 3.97 17.09 896312 4.08 3.97 17.06 896375 4.08 3.97 16.9 896425 4.08 3.98 16.86 906412 4.08 3.98 16.91 906450 4.08 3.98 16.79 906500 4.08 3.98 16.77 906538 4.08 3.98 16.68 906550 4.08 3.98 16.62 906525 4.08 3.98 16.69 906588 4.08 3.98 16.6 916600 4.08 3.98 16.58 916650 4.08 3.98 16.4 906662 4.08 3.98 16.41 916712 4.08 3.98 16.32 916712 4.08 3.98 16.33 916750 4.08 3.99 16.25 916762 4.08 3.99 16.23 916775 4.08 4 16.29 916775 4.08 3.98 16.25 916850 4.08 4 16.1 916850 4.08 4 16.15 926875 4.08 4 16.13 926912 4.08 4 16.07 926962 4.06 4.01 16.1 936938 4.06 4.01 16.11 936988 4.06 4.01 16.07 936975 4.06 4.01 16.09 937025 4.06 4.01 16.01 93

Gene

[Yellow4g63]

How much boot are you trying to run? What size is the injectors? maybe you need to adjust your injector latency and K value?

[WhatsADSM]

That log is confusing as hell. There are 5 values yet 4 headers?!

The first value is definately RPM and the last 2 look like MAF Flow and IDC. Not sure what the others are.

I guess the first thing, is why aren't your TPS numbers right? I assume that is supposed to be the second number.

Also, as mentioned before check the coolant temp sensor, or at least make sure the coolant temps per the computer look good.

[rcrdps]

Not sure how it's displaying for you, but I show 5 and 5. The tps are the 4.06 and 4.08.

The injectors are stock. Boost is currently stock at 10psi. The problem is the mixture isn't consistent. I can adjust the K value, and it may work for that run, but then it may go back to normal, which means it is now lean and backfires. It used to work perfectly on this map. This is just a stock map adjusted for a z32 MAF using LiveEdit. LiveEdit adjusts the VQ map and K value automatically. I would love to just tune this problem out with the ECU, but it just isn't consistent enough.

As I mentioned before, the ECU shows coolant temp at right around 80 degrees celsius. It can go up to 84 or so.

Gene

[WhatsADSM]

Not sure how it's displaying for you, but I show 5 and 5. The tps are the 4.06 and 4.08.

The injectors are stock. Boost is currently stock at 10psi. The problem is the mixture isn't consistent. I can adjust the K value, and it may work for that run, but then it may go back to normal, which means it is now lean and backfires. It used to work perfectly on this map. This is just a stock map adjusted for a z32 MAF using LiveEdit. LiveEdit adjusts the VQ map and K value automatically. I would love to just tune this problem out with the ECU, but it just isn't consistent enough.

As I mentioned before, the ECU shows coolant temp at right around 80 degrees celsius. It can go up to 84 or so.

Gene

Ahh I see. So the TPS is in volts, and presumably it is "Air" and "Flow" and not "Air Flow". With "Air" being MAF in volts.

One idea I had was to collect a few logs when the car is working right, and then logs when the car is acting up. You may be able to cycle through the various parameters and find one that looks incorrect when the car is acting up.

Otherwise it sounds like you have done a BUNCH of stuff... Like you initially thought the boost leak was the first thing that came to mind. I have a few other ideas but they are getting to be more shots in the dark.

The first is to verify that your O2 sensor is working correctly. Some ECUs will actually use the known fuel trims at WOT (although not many) and so even if you were to adjust something it will work correctly for a while but then default back as the fuel trims get corrected. You should be able to verify it is working if your wideband reads correctly when you are cruising and idle (i.e. around 14.7:1). Again this is more of a shot in the dark.

Also, I know you mentioned that you already replaced the ECU. But I assume you moved the chip/emulator over as well. Have you tried getting a bone stock ECU and a bone stock RB20 MAF and hooking them up to see if the problem goes away? That would help just start to narrow it down a little to see if it is something in the MAF and/or tune.

[rcrdps]

I didn't replace the ECU. Only the maps. I'm on a stock map right now with exception for the z32 mod. To eliminate tuning errors, I have gone back to old maps that I know were working fine. I keep nearly every map I've ever made. It could still be the actual ECU. Or it could be the chip extender, or chip switcher. I might try taking those off, but I'm pretty sure I had the issue before I put those on. It's been over a year since all this started.

As far as it running at 14.7, it does dance around there a bit like it's supposed to( I actually have it tuned for 16.1, not 14.7), though it has some major spikes lean. And if I'm not mistaken, spikes are a sign of a vacuum leak. My throttle body does leak ever so slightly, so maybe that's it. It's very small though, and I would think a boost controller would be more. But if it's inconsistent, then maybe that's it.

I guess as a last resort, I might try another ECU, but unless I happen to find someone close that has one I could just try, I doubt that will happen. It would require re-wiring my MAF too.

Gene

[rcrdps]

One more thing to add to the list: I took off the throttle body and replaced the seal on the linkage side. I reassembled it with petroleum jelly. I also dabbed petroleum jelly on the tps side, and put an o-ring on the outside. It is crimped in, so I couldn't get it fully apart. Not sure if that really sealed anything there. But now the engine is quiet as far as boost leaks go. But it is still running rich.

While working on the throttle body, I broke the tps. I ordered another one. In the mean time, I expoxied it back together, and it works fine. I'll still replace it when I get the new one in though.

Gene

[rcrdps]

I'm going back to an old hypothesis that it's an injector. I sent them to RC Engineering a while back, and they supposedly came back good to go. But they tested at 36psi I think. When you have 10psi of boost, the fuel pressure jumps 10 psi. So I think that when it gets to 50 or so psi, an injector is leaking and causing that cylinder to run rich. To test, I turn on the ignition and verify that the fuel pressure jumps to 36-40psi. It does, and stays there for a very long time. The fuel pump turns off after a few seconds since the engine isn't running. That is a safety feature. So then I connect my boost leak checker, and give it 10psi. Then turn on the ignition and verify it goes to 50psi. It does, but when the fuel pump kicks back off, it drops down to like 45psi immediately. So where's that fuel pressure going? The boost is still there, so the Nismo FPR should be clamping the fuel pressure still. I checked all of the injectors to make sure no gas was leaking out of the O-rings and onto the manifold. The manifold was dry. So my assumption is that one of the injectors is getting blown open when the fuel pressure goes high and releasing the fuel pressure. If it does that when running, then that cyclinder will go rich. Of course, you'd think you'd see that in the spark plug, but I haven't done a hard run with fresh spark plugs and immediately shut off the engine. So normal running is erasing any evidence of the rich WOT run.

That's my hypothesis anyway. And I'm not currently in a position to afford replacing all 6 injectors. Wish I had OBDII so I could tell which cylinder is misfiring.

Gene

[rcrdps]

I pulled the injectors today. They seem fine to me. I fashioned a little tester for them. It was just a hose connected to a blow-gun and hose-clamped to the injector. I turned the air-compressor's regulator to 60psi, and held the injector close to my ear. I also connected some test leads to the injector and fired it with a 12v battery. No leaks, and they fired consistently. There was enough fuel left in them( or water in my air), that I could see when they fired.

So I guess it's still a boost leak, though I have no clue where. I think I've eliminated all electrical/sensor issues.

Gene

[rcrdps]

Good news!!!! I think it's fixed. It still misses a tad, but I think I just need to replace the plugs since it was running so rich before. The wideband shows it up there near where it's supposed to be.

I played with the throttle body some more today. I took a large socket, and put it over the caps that hold the seals in. Then wacked it a bit with a hammer to seat the caps and seals a little better. That appears to have fixed the problem. Unfortunately, it has also made the throttle a little more sticky, and so it doesn't fully close at idle. So it idles about 1000rpm. But if memory serves me, it has never idled as low as it's supposed to, so maybe it's always had that sticky area. Might be buildup in the intake area.

So I should probably replace it before too long, and I don't want to repalce it with another used throttlebody. Anyone have any suggestions for new throttlebodies?

Gene

[Kansei240sx]

Judging from the pictures of your spark plugs ground strap it looks like your timing a bit too retarded. Do you have an EGT set up for your motor? If so where is it?

[rcrdps]

I don't have an EGT. The timing has never been less than stock. But all of the rich running was probably keeping it cold in there, so it would look like retarded timing. But still, the heat mark is back on the bend of the strap. Seems like that would be pretty close to stock heat.

Gene