1988 Nissan Maxima Sputters When Warm

1988 NISSAN MAXIMA
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JASONSEVENTEEN
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  • 1 POST
1988 Nissan Maxima 175,000 miles, V6 engine.

Recently, have had severe engine sputtering and missing.
This situation does not occur until the engine heats up. It runs like a top until you have driven about 5 miles and then it starts sputtering. In idle you can watch the RPM's bounce around. It runs better when not applying much gas. Bad during middle of the pedal and better when giving a lot of gas but still
misses. I have replaced the plugs and fuel filter and given a couple of treatments of injector cleaner.
Jan 31, 2007 at 9:34 AM
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KASEKENNY
  • ✓Experienced Mechanic
  • 18,907 POSTS
The fact that this is missing after it warms up is most likely due to a sensor issue because when the engine is cold it runs on a predetermined set of parameters. Once it warms up, it starts making changes based on the sensor data specifically o2 sensors.

However, we need to limit down what sensor it could be. Is it smoking at all when it is miss firing? Is it black or or dark in color? This would indicate a rich fuel mixture.

A lean condition can also cause this and most likely there is no smoke when that is the case. Clearly this is a basic way to try and determine if it is lean or rich.

Next we need to start monitoring the sensors and see what they are telling us. The o2 sensors would be first. If they are indicating a rich or lean exhaust then we can react to that however, that should line up with if it is smoking. If they are not matching then we can suspect they are the cause. If you don't have a scan tool that can monitor data, just stop by a parts store and ask them to scan for codes because we need those as well.

Lastly the fact that you said it seems better when giving light throttle, indicates a vacuum leak.

I have attached guides for each of these items. We need to run through this and report back. Also, I attached testing that covers similar items. We need to start crossing these off the list and then we will be able to narrow down what the issue is.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
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Mar 26, 2020 at 8:01 AM

Suggested Repair

After warm-up, scan for codes and monitor the oxygen sensors, comparing readings with whether the exhaust is smoking (rich) or not (possible lean). Also check for a vacuum leak, since light throttle runs better, and work through the misfire and vacuum tests before replacing more parts.

Conversation Summary

A 1988 Nissan Maxima with a V6 and 175,000 miles sputters and misses only after warming up, with bouncing idle RPM. It is worse at mid-throttle and somewhat better with light or heavy throttle. Plugs, the fuel filter, and injector cleaner did not fix it. The expert says cold running uses preset parameters, so a warm misfire often points to sensor data, especially oxygen sensors, or a vacuum leak. They recommend checking for smoke to judge rich versus lean, scanning for codes, monitoring sensor data, and testing vacuum before narrowing the cause.

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