I have noticed from slightly before Maxus until now that the car has a very slight, but still noticeable surge in the 1000-2500 RPM range, and that the top end is quite a bit...flat. Now we all have seen my quite disgusting dyno (see below) so I got to wondering, what could it be? In the last few days, I have checked compression 4 times (165,160,155,165,160,160 each time), have tried the fuel injection cleaning (the professional one), changed out my plugs yet again, changed the air filter, cleaned the first part of the throttle body, checked all the hoses and fittings on both the intake and the exhaust, and checked the battery condition, and all were acceptable. As a last resort, I remembered Ant95SE stating that something similar happened to him and it was his knock sensor, so I tested the ECU, and got the famous 0304, reset it and keep getting 0304. I then tested the resistance of the sensor, and got 542, again within factory specs. I am now at wits end. What am I missing?

Car specs:
-Fed spec 1995 GLE produced 1/95 (OBD-I still I believe)
-93,200 miles
-OEM plugs (800 miles old)
-Air and fuel filter changed within last 500 miles
-Fuel pressure 36 PSI running, 45 PSI at startup
-always use 93 Texaco gasoline (if available)
-EGR and PCV valve not changed since 60,000 mile service

 

Perhaps a good internal engine steam cleaning would help? Check MaximaDriver.com for the instructions.

 

There aren't any steam cleaning directions on Cheston's site.

 

Hmmm, do a search for it here. Ive seen some posts about it. Perhaps your catalytyic convertor is getting to be clogged? 93k is a few miles...

 

Thanks, but would a clogged cat have that big of an effect across the entire powerband? And besides emmissions testing, is there a way to test the cat? I'm really stumped by this and am open to ANY suggestions. I'll attempt the steam clean tomorrow, and will investigate the exhaust further if it continues.

 

Ok, update, the steam cleaning didn't do anything, the surging is still there. I still have the stock exhaust, and the Y appears to be tight, along with the rest of the system (well there is a loose ring right in front of the flex system, but the section is still intact). I hesitate to pull the Y off until I put the new exhaust in, but would a leaky gasket cause this?

 

I don't know how this Internal Steam Cleaning idea got started. I discourage people from using it. It can cause more harm than good.

1) What makes you think the inside of your engine is dirty?

2) What makes you think your engine would run better if it were clean?

3) What makes you think Internal Steam Cleaning is the right way to clean an engine?

4) If this procedure was useful wouldn't the dealer and every Quicky-Jiffy-Iffy Lube in the country be offering the service?

 

This is true, but a very respected member of the board (MardiGrasMax) suggested it, so I tried it, with no new ill effects. I'm literally running out of available options. Do you have any suggestions as to what to do short of replacing the KS? I will replace it if I can not resolve this before monday.

 

Daniel,

There is such a service as the Bilstein Engine Flush, which does claim to "clean" the inside of your motor. It seemed effective on my 94 Maxima with 80k on it.

Have I proof? Not directly. I have found it interesting that with similar oil change habits on my 94 and 99 Maximas, my 94 is "cleaner" in terms of elements in the oil.

Would would be super sweet would be for medicsonic to take an oil sample, go have this flush done, and then take another sample. But I'm probably dreaming here.

I would do it myself, but my 99 doesn't have that many miles on it to justify a $100 service and I would prefer to wait on doing an engine flush for a while.

medic,

If you're this **** about this (I can tell because I'm just as **** if not more **** about these things) I would have these two services performed:

First, the fuel injectors:

http://www.penskeautocenters.com/ser...ev/pwrmstr.gif

Then, the engine oil flush:

http://www.motorlife.com/online/efs/index.htm

To see who has one in your area:

http://www.motorlife.com/online/locations/index.htm

Be warned, as this is going to cost you $150 to $200.

I would guess that the fuel treatment would be more effective, but it's hard to say.

 

I want the car in PERFECT condition before the SC, so I'll do it. I'll post the results also. Thanks everyone. Any other suggestions on why the knock senosr keeps faulting?

 

Dont need to be "****", but The First Link is just a link to a gif, its not pointing towards a direct link. Just thought I'd help

 

I am not disparaging a legitimate fuel system cleaner. I do question the benefit of this so-called Internal Steam Cleaning. It involves introduction of water, and then solvent, into the intake tract of your engine by means of a vacuum hose. There is no means to precisely control the rate of water input. There is no assurance that each of the six cylinders receives an equal amount of water. There is no evidence that water is an effective cleaner. Water or solvent introduced to the intake manifold completely bypasses the fuel injectors so it cannot dissolve deposits inside the injectors. Forgive this rant, but this Internal Steam Cleaning idea reeks of voodoo, not science.

 

Here are some Cat test ideas, along with the source of each.


From http://www.misterfixit.com/cat.htm

You can do a vacuum check at idle and then at 1500 RPM. If the vacuum is say 21 inches at idle and like 15 inches at 1500 then the cat is likely clogged.


From http://www.ghg.net/fastlaw/vacuum.html

Blipping engine speed ... Quick drop to zero then return to
normal reading indicates that the Muffler is clear.
Blipping engine speed ... Slow drop of pointer then slow return
to normal reading indicates that the Muffler is choked or blocked.


From http://www.turbotektoys.com/_TipsDisc/00000007.htm

Connect vacuum gauge, run car at 2500 RPM. If the converter is plugged, the vacuum will slowly drop. A one minute test is plenty of time.


From http://www.2carpros.com/topics/catcon.htm

To test for a plugged converter, drill a small hole in the exhaust pipe right before the catalytic converter. Install a temporary hose fitting and attach a long rubber hose and a 0 to 10 pound pressure gauge. With the gauge inside the car, drive up a hill or accelerate and read the pressure. Normal is 2 to 3 pounds, restricted 4 pounds or higher. The drawback to this method is the small hole will need to be welded shut after the test; a minor job if you have a welder.

 

The resistance measurement is a useful but not conclusive test. If your Knock Sensor fails the resistance test it is surely bad. The converse is not true; it could pass the test and still be bad. The dealer, with his sophisticated CONSULT tester, can do a better test than the we driveway mechanics can do with an ohmmeter.

Don't be too quick to condemn the KS. Diagnostic Trouble Code 0304 points to a bad KS or its associated connector and harness. Don't overlook the wiring.

 

True, I was just posting about a more legitimate service, which attaches to your oil filter on one side to a "super duper" small micron filter on the Bilstein machine and the other side in the oil drain plug, where it pumps a flushing agent in one side and sucks it out on the other. Then a regular oil change is performed......

I would tend to think the fuel injection service would be more effective.

 

instead of spending all this money on all these different try this and try that things. get a new knock sensor. I THOUGHT i heard it was around 200 bucks and easy to install. don't quote me by any means.

 

Here's something you can do which is easy, can't do any harm, and might do some good.

Note the two ground wires fastened to the intake manifold between fuel injectors #2 and #4. These are in plain sight and easy to reach. With the engine off, remove both, clean the contact surfaces, and install both. In other words, make sure those engine grounds are good.

 

Steve, I appreciate the concept, but I wanted to TEST the car before blindly changing something. While it may solve the problem, if I replace it and it continues, then that is a $164.08 part that didn't need to be fixed. Unfortunately, I do not possess a vacuum gauge (only a compression tester, digital multimeter and assorted home mechanic tools), and the two closest auto shops do not have this. I am really starting to believe that it may be cheaper if I just go to the dealer and get a 'Consult ride'. I will attempt to get a vacuum guage before then, but if the dealer is open on monday, the ride may be the quickest route.

Actually, D.B. Martin, while replying to the thread, I noticed that you responded to the thread with the ground idea. I will attempt it now and report the results. THANK YOU EVERYONE for your time.

 

ya but a 164 dollar part might fix it, how much have you spent so far on all these trial and error fixes.

 

Okay, I took EVERYTHING off again and put them all back on. The only out of spec/broken piece that I found is that the vacuum hose for the PCV valve has a hairline fracture on it that I temporarily sealed again with some tape. When I started the car, I noticed that it is a little noisier than it was before, but the hesitation seems to have disappeared in the 1000-2000 range, but there is now one at about 2500 RPMs. I didn't check the error codes yet, I'll do that tomorrow.

 

just curious... how do you go about getting a dyno test and how much does it cost?

 

Call up local performance shops, they usually know the location. Cost? 75-100 dollars.