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Thread: Small, small surge on the low end mild throttle.

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2019-12-06 19:56:43
Small, small surge on the low end mild throttle.
I know I have some issues with the driveability with my Sr20 and besides it looks like TPS signal is like it hangs up too quick, (I close throttle, engine does boink) there is a slight issue I am worried about.

I decided to drive without MAF connected. While I am aware with a cold engine I can barely drive, so bad it is not responsible to cross a crossing because the engine might stall, I drove to a full warmp up and unhooked MAF connector.

Someone told me that if there are problems, disconnecting MAF and then test drive tells if MAF is good or not. While I can agree to this statement so I tried, actually the problems that I have became worse.

I wonder, if I have issues with the drivabillity in daily traffic and WOT is good, what conclusion I may connect having the finding that disconnecting MAF makes my issues more bad?
2020-01-04 15:22:20
I believe I can answer this one myself. After vacuum hose replacing and swapping my air filter for a stock one I learned my issues became smaller but one but that is in another topic. Because of having my problematic Nx and a rust-egg I decided to give it a go to swap that fat rubber between the MAF and throttle body. I learned three things.

a. Those two big Nissan clamps for that big rubber, especially the one at the throttle body, can not be tightened enough but literally. I tested by putting enough force on them up to the breaking down of the bolt point and test-driving my car showed issues almost instant. Using the two big clamps from rust-egg made most problems go away. It is a common rvs clamp, half an inch thick and not two metal wires with a bolt that look good though but just can not apply enough clamp force everywhere, especially at the tightening bolt itself. My surge is gone now.

b. While it is not vacuum, this hose and clamp was cut off a little short on my Nx compared with rust-egg and rust-egg's hose looks still so-so, but it made the bucking go away in a lot of places, not all of them though. I forgot what it supposed to do and some leak-spray or other way of leak finding would save me a lot of time I suppose, but I'm glad I've found the main ten-year old culprits for a lot of swappiness and try-outs on the air intake side, while that was very annoying it was educating me good. I always felt my MAF was suspicious and while it did break down in the end, that was only a cold start stall issue that went away after very minor warming like three stomps on the gas pedal. The major PITA buck I've been whining about on this forum, finally died. In all my trial and error testing I'm pretty sure another used MAF died on me within a thousand miles and if you can remember my open loop mode misery, this turned out to be the first MAF that died on me and I learned that my used MAF's tend to die mysteriously, out of the blue and somewhere right in the subject I'm trying to address which is a small window of time. I can believe that besides it happened twice to me within a thousand miles and in the rust-egg trial and error period which was a pain but a great way of learning Sr20, rust-egg couldn't tell my MAF was good or not because it is four wire and I have three wire. So here is a picture, you will want to have that hose tight just like the fpr vacuum hose is the main target to replace for known good (new), this will save you potential Sr20 headaches, I'm sure.

I do assume my other crank case ventilation hoses are good (I checked visually and assume here), but here you can see a visually and mechanically proper looking hose that just was cut a little short by factory and maybe never was real good but I still think it is worth checking tubing on your Sr20 and if it looks like this, I believe you may suspect it. What kept me from finding this earlier is that I'm after a clean engine bay, so I just didn't want to install a common clamp but it would save me a lot of annoyances. Driving a Sr20 is fun, if that is spoiled somewhere, some small bad lot like I'm giving expression to in this long post is the malefactor that have let you check all your sensors and question all the mechanical soundness like thermostat and neutral switch going into ecu flight data recorder salvaging journeys.

c. Cars without lambda don't complain as much and certainly don't dive the mileage as much with a leak. My bad crank case ventilation fire suppressor hose does not give an issue at all. I found out by trial and error, what doesn't get measured at the exhaust, ecu will not attempt to adjust.
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