2002 GTX 4 TEC Surging 4500-5000 RPMs

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Flybouy6

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I need help diagnosing a strange problem with my 2002 GTX NA 4 TEC, 200 hours. The engine runs fine but surges when the RPM range reaches 4500-5000 RPMs. There are no codes present and the dealer is stumped. They contacted BRP and received little specific advice of known problems.

I just have a gut feeling it is the TPS, but...

Here is what the dealer did:

- Checked BUDS for codes...none present other than a few mis-communications.
- tested TPS for movement in BUDS Engine Monitoring....I watched...seemed smooth and linear.
- reset TPS.
- tested MAP. Read local barometric pressure pretty accurately.

Here is what I have done:

- replaced spark plugs
- drained fuel tank and cleaned. Replaced fuel filters in fuel pump.
- had injectors rebuilt. (BRP suggestion to dealer)
- replaced coils. (BRP suggestion to dealer)

I have not replaced the TPS yet.

I still have the freaking surge. The idle is a little rough too.

Anyone with these symptoms in the past or ideas of what it might be??? The 'doo is old but "usually" runs great.
 
How about an exhaust hose that has delaminated internally and is blocking the exhaust causing too much back pressure? Of course I'm assuming your motor won't rev to normal RPM and you didn't say it wont.

Confirm fuel pressure is correct
Make sure the ignition coils are in good condition, I hear sometimes they corrode.
 
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"- tested TPS for movement in BUDS Engine Monitoring....I watched...seemed smooth and linear."

You can also back probe the sensor connector center wiper (signal wire) using diaper pin and use an ANALOG meter instead of an DVM, I've found bad TPS's this way that others missed b/c it's easy to see see the analog needle jiggle at the noisy spots.
 
Great idea. Gunna have to blow the dust off my analog meter. Thx..

No exhaust obstructions. Motor pulls strong all the way to rev limiter. Just stumbles and surges between 4500-5000. Gotta be corrosion in the TPS.
 
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The thin film resistive trace is known to develop cracks and fall off the substrate it was deposited onto, so it's quite possible. I'm not sure if on that one you need the BUDS to set to zero voltage but the others (2-srokes) do supposedly require using the BUDS.

You might be tempted to measure the idle-position voltage before removing the original (esp since they have already confirmed it's correct) and duplicate that when installing a fresh TPS, this would probably work fine in my estimation.

Keep in mind, the air:fuel mixture is highly dependent on both the TPS and the MAP sensor b/c there's no O2 sensor on these.
 
So I cracked open the SEADOO manual, CHAP 7, Engine Management and started to test the TPS. The voltage tests were all correct. 0V at Ground…pin 1, 5V at ECU Input..pin 2, .60V-4.2 V and a steady increase/decrease on the signal..pin 3. I then tested the resistance at the ECU connection as described in the manual. All values within spec…or darn close to it. 1000 Ohms WOT, 2750 Ohms Closed across pins 24 (signal) and 39 (5v ref). So the wiring to/from the ECU is good.

I double checked for any obstructions in the exhaust…none.

I also ran another compression check… 180, 178, 178.

I may rig up a fuel pressure tester that I can run on the water tests with next. But, I reach 7000 RPMs and that should not happen with insufficient fuel pressure.

I am stumped. The ski is in tidewater VA now and I have lost confidence in the dealership at the beach. Not that they did not try, but other than a tour of BUDS, no real in depth troubleshooting. If anyone knows any Seadoo wizards in the area, please let me know.
 
Funny, I had similar results when my '02 GTX was giving me trouble. I had two of the same skis, so I started swapping parts from the good ski to the bad one. No matter what part I swapped over, I still had the same problem with the bad ski. I looked at the TPS, did compression checks, swapped over injectors and ignition coils, and even swapped over the jet pumps. It wasn't until I seafoamed the engine that I found the exhaust leak. I changed the leaky J-pipe, and I could tell the moment I started it that I had solved the mystery.
 
Heck. At this point I will try anything. mkov608, can you tell me exactly how you seafoamed the engine. Mix ratio, separate tank, etc? I would only want to use the minimum required. I am guessing that when you started her up and blew smoke from the seafoam you found the leak in the exhaust while the ski was in the driveway. Which end of the J pipe? or was it cracked somewhere? I have not messed with the exhaust, so it is original.
 
Go to your nearest auto parts store and get a can of SeaFoam Spray, not the stuff for your fuel tank, the spray.

Follow the instructions on the can.

If you see any smoke coming from inside the hull, you have an exhaust leak. My leak was huge! J-Pipe was leaking at the 6 O'clock position right behind the flange where it connects to the exhaust manifold.
 
I seafoamed the engine. There are no exhaust leaks anywhere. I do however have the cleanest intake around. The next step is to test fuel pressure underway while it surges. After that, I am out of ideas.

I did take a video underway, but do not know how to attach it here.
 
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Even though you just replaced your plugs, they could be bad. A dropped plug will fail.
We just had a thread on proper torque on the spark plugs. This solved the issue of unstable RPMs.
 
You ever resolve this? I have the same issue on my 04 GTX 185SC. How does an exhaust leak cause this?
 
Internal combustion engines need oxygen to run (among other things), and exhaust gases are devoid of oxygen since it was burned in the combustion process. The intake system pulls air from and through the engine compartment, so if you intake is pulling (or blowing in in the case of super charged engines), in exhaust gases, the isn't enough oxygen to support the combustion process. I have replace the J-pipe twice on one of my '02 GTXs.
 
I had too much oil in mine after an oil change....OOPs.....fixed the level and new plugs everything was fine afterwards. 2007 gti le 155hp
 
sanpan25 said:
I had too much oil in mine after an oil change....OOPs.....fixed the level and new plugs everything was fine afterwards. 2007 gti le 155hp
Click to expand...
I wish mine were that simple. I've checked and rechecked the oil level. I don't think it's that, but seems like you can never quite tell the oil level with a 4tec. In any case, it revs to 7600rpm, so that really overrules any notion that it's overfilled. I have been suspecting an exhaust leak for a while, and am 99% sure I've got one. I wonder if running with the hatch open if it would make it run smooth? Something tells me that I'd still have the surge.
 
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