95 Maxima bad hesitation

Hi all. First of all, thank you to the participating experts in this group. You all really helped MadNeighbors with his stalling.

I have a problem that is very similar, but I want to avoid the expense he went through if at all possible :)

I run the car for a while and it works great, sometimes 20 minutes, sometimes 2 hours. I'll suddenly get a real bad hesitation on accelleration that lessens as I back off the gas or coast. It is about a 500 to 1000 RPM drop off, depending on how hard I press on the gas. The harder she comes, the harder she falls. This "drop off" oscillates about every second... on off on off etc...

It will stall at a light, running a little rough at 600 rpm (normal idle for this car is about 850 rpm) Pulling away is difficult, as the drop off in RPM's can stall the motor. If you apply steady gas, it will never actually quit, it will just ride like a hobby horse when accellerating.

This will continue until the car cools completly down, then it will be OK again, for an unpredictable amount of time.

The first thing I thought of was water in the gas. I ran it to just a gallon or so in the tank, poured in some ISO alchohol (Heet), and changed the fuel filter. I then added premium gas, and all was well for a few days, then it started again. Ran it down to empty again, added more alchohol, put more gas in.... still doing it.

I ran the Check Engine light and got codes for the MAF Sensor, Knock Sensor, and EGR Hi/Low flow.

Because the TPS is mentioned in the other post, I checked that first. Before the problem I had about 530 ohms, going up to over 4100 ohms in the open position. Durring the problem I had about 600 ohms at closed throttle and about 4200 at open throttle. This is a little high, the instructions say 500 ohms closed and 4000 open. I'm not sure if those readings I am getting are out of range or not.

I cannot find a link for testing proceedures for the MAF. The one I found said it had a five wire plug, and mine has only three wires (assuming I am looking at the right part:)

So, any usefull links, comments, or diagnosis would be greatly appreciated!

Thank you in advance Bill Roman snipped-for-privacy@ultravideo.com

Reply to
caterpillar
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Nirav?

Care to field this one ?

Reply to
NissTech

The drivability issues are most likely the MAF - as indicated by the CEL code. The knock sensor code may be a side effect - so I would recommend fixing the MAF issue (replacement of the MAF), reseting the CEL and if the light doesn't come back on, check for codes anyway and see if the knock sensor code returns.

As for the EGR hi/lo flow code, that is *most likely* due to clogged EGR passages. The EGR port on the rear of the plenum and the EGR guide tube that carries the exhaust fumes from the EGR valve back into the manifold have a tendency to clog up with carbon deposits over time. This is not the only cause of the 0302 code. You could also have a faulty EGR valve, faulty EGR temp/flow sensor, vacuum leak, etc. In my experience, I have found that the clogged ports are the most common cause.

As mentioned in the earlier stalling thread, a new MAF is not a cheap part. You can look on Ebay for working used MAFs.

Cheers, Nirav

96 Max GLE, 119k
Reply to
njmodi

Many Thanks Nirav, I saw som threads in maxima.org where folks are replacing the MAV just to revive or improve overall performance. Most seem to think it is worth the ($215.00) price. I'll let you know what happens. Bill Roman snipped-for-privacy@ultravideo.com

Reply to
caterpillar

Bill - a new MAF for the 4th Gens (95-99) is a lot more than $215. You can probably pick one up on Ebay for much less. Keep us posted.

Cheers, Nirav

Reply to
njmodi

That was the price quoted by autozone and advanced auto parts. They want a core trade in as well. Do you think they are quoting the wrong one?

Do you have a testing proceedure for the Gen4 MAF, so I can verify it is bad? The one I found in a maxima.org link had the wrong configuration. It said there was supposed to be a 6 wire connector with five wires, and to run the test on the second wire. The MAF I am seeing is just behind the air filter and only has a three wire connector.

Thanks, Bill

Reply to
caterpillar

I do not have a MAF testing procedure (or know of one). This is the first time I have heard of an aftermarket MAF being available for our cars, so I can't vouch for their quality or fitment.

Cheers, Nirav

Reply to
njmodi

Man, there sure is allot of talk in this NG about hesitation in the Gen4's! Here is what I found out so far.

The other day, I decided to disconnect the MAF sensor (as that was one of the codes I was getting), and see what happened. As expected, it ran terribly, and would not rev over 2.5K RPM, once again, as expected. What I didn't expect was when I reconnected the MAF, it ran great for two days! The next time it happened, I pulled the plug off the MAF, reved it up a little and reconnected it. It then worked (hesitation went away) for another hour or so of driving. At the next occurance, I decided to do a little test.

  1. Turned off the car and let it set by the side of the road for about
5 minutes. When I took off from a stop, the hesitation was still there.
  1. I pulled over again and wiggled the wire bundle goint to the MAF, that didn't work either.
  2. I removed the connector and just reinserted it (without revving the engine whilst disconnected), And it WORKED! The hesitation went away for about 7 minutes of driving, and then returned.
  3. Ok, so now I removed the connector and pushed it in and out several times, making sure I pushed it home real hard the last time. Worked again! This time for several hours of driving. I sprayed the contacts with contact cleaner, with no obvious effect. Ir ran well for about 10 minutes, and after pushing harder on the connector, has been running well ever since (about an hour of driving).

Now, thats gotta be a bad plug! If it is, then I really lucked out, considering the cost of a new MAF. The only thing I can think of elstwise is that somehow when the connector is unplugged it resets somthing in the sensor that makes it work for a while. But, the problem is definitely related to that sensor.

As soon as the Nissan parts dept. opens Monday, I will get a replacement plug and clean off the MAF contacts with a pencil erasor. Then, if the problem occures, i'll need to bite the bullet and replace the sensor.

Here's the deal though for you other Gen4 owners with Electrical / Hesitation problems: A few years ago, I had a dieing Battery problem that did not go away when I replaced the alternator. I came to find out that it was a bad connector plug at the alternator.

So, everyone, don't overlook the connectors. Last time I needed one , the dealer just gave it to me!

_Bill Roman

Reply to
caterpillar

I used to have an 88 Sentra. It had a problem with the MAF, would not rev above 2500 RPM. I replaced the MAF at great cost, only to later discover a series of articles listing an "MAF bad ground" problem with this car. Maybe that is where your problem lies.

Al Modie.

Reply to
Al Moodie

Thanx for the input. I'll need to look at that. Not revving above 2500 occures on my car when I disconnect the sensor completely. The same hesitation occures, but at higher RPMs when I am experienciong this problem too.

One thing I found out today is that Nissan DOES NOT SELL replacement plugs for this sensor!! How about that! They suggested I get one from a Junk Yard!

They did give me the plastic outside of the plug to see if that worked for me. I'll let you all know.

Reply to
caterpillar

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