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1995 Altima, old car, harnesses deteriorating particularly the connector having fuel injector leads and temperature sensor on passenger side aft of the head. Have that fixed as best I can. The knock sensor connector kept coming loose so I bought a new knock sensor and relocated it to an upper bolt on the oil filter pedestal to the block. I don't think that's good enough as I've been having acceleration curve difficulties. No codes but instead of a steady acceleration it will be doggy then get legs as the revs go up. And my fuel efficiency is poor so the ECM is probably giving it some programmed curve rather than reacting to sensors. Would a relocated knock sensor too far from the head cause this? I've read elsewhere it could be the temperature sensor but I've changed that and again there's that ratty connector. New exhaust manifold o2 sensor, new EGR, fairly new EGR solenoid, distributor not too old and not leaking any oil and its connector replaced. Compression fine on all cylinders. Valves shimmed well. If the acceleration issue is due to the knock sensor relocation, is there any work around to compensate?

billj
 

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I don't think there's any question they placed the knock sensor too inconveniently given they moved it some years later.
 

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Somewhere here I have an old knock sensor I replaced while the problem had been something else, perhaps back when I had a loose and noisy timing chain. If I can find it I'll use it to form a plug. The plug will go to existing knock sensor lead and have wires to the spare knock sensor. I'll search for alternative knock sensor mounting positions. I see others have mounted the knock sensor on intake manifold bolts but I'll look for other alternatives directly to the block. The extra lead length I'm adding will expand the possibilities.
 

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The knock sensor is a microphone situated on the block aft top center. Hottest cylinders I suppose and most likely to have pre-ignition for which it's listening. But that wouldn't be all it potentially registers. Mounting elsewhere, e.g. passenger side intake manifold bottom outside bolt might register as wrong due to the distant cylinder firing to be significantly less loud than #1. If besides listening for pings it looks for cylinder firing levels that suggest it isn't in the correct mounting position maybe it goes into higher fuel consumption mode to prompt attention by a mechanic but not actually throwing a code or setting the CEL?
 

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The knock sensor OEM position is CAREFULLY chosen to not only detect knock instantly but to not pick up spurious repeat vibrations that reverberate through a cast iron part, or maybe aluminum.

You need to put it right back where it was, there is nothing convenient about the location at all and not intended to be so.

Even the torque tightening it down can mess you up, I never torque anything ever but those I do and EXACTLY.
 

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I inspected the engine looking for a better spot to mount the knock sensor. Meanwhile I happened across a post on cargurus where a mechanic said he could always tell when a shade tree mechanic worked on a car as the IAC/AAC would be set wrong. Now I set mine with an inexpensive tach that gets its signal from a wire I leave permanently wrapped a sparkplug wire to the tach I keep velcro'd to the air filter housing. The mechanic said the proper setting for the IAC/ACC was 2.5 - 3.5 turns. I check mine and it was closer to one turn. How that could be when I set it with the tach? Who knows. Anyway I had the car out today without any other changes aside from setting the IAC/AAC to 3 turns. Acceleration was right, the transmission was much more likely to shift up and down in cruise control and just generally running better. I didn't do any kind of relearning procedure so it might take a bit to get right. A while ago here in central west Georgia a Georgia paper did a study of water in gas at stations in this area and showed a glass that had a third water and the rest gas and said many of the stations tested had watered gas. So, figuring a national gas chain not found here much but often up north or in Florida, which I expect get their tanks filled with trucks branded with the national brand and more likely not to have excessive amounts of water in their gas, I started filling from one of the few stations around but some distance away. Price is higher of course. Using the AC a lot I filled not long ago and was disappointed with the poor gas efficiency, hence why I though it might be the knock sensor. But, the car ran well today so when this tank is almost done I'll report back and relate any improvement in efficiency.
 
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