2002 GTI running out of things to try--PLEASE HELP

[rcgop]

Moving beyond frustrated. I have a 2002 GTI that I bought last fall and been having the same issue even with everything I have tried. Here is what I have done:

Compression check at 150 on both cylinders. Small block was replaced right before I bought it.
Replaced spark plugs several times
Replaced fuel filter, entire assembly so gasket and housing included
Rebuilt carb with OEM kit
Performed successful pressure check on fuel system following shop manual procedure
Replaced inlet and outlet air valves after pressure check
Replaced entire carb with new Mikuni from OSD

The only thing I haven't done is replace the fuel selector. I am about to bypass it and go out tomorrow to give it another try.

The issue is consistently the same. It starts up and takes off great, runs full speed, really smooth. When I take off the second time, it runs about half speed with WOT, then will take off at full speed a few seconds later. It progressively gets longer and longer before full speed at WOT until it will not reach full speed, but runs about half speed. I wants to stall when I give it no throttle after it has warmed up. I have noticed the speed issue is worse depending on the number of kids I am hauling at the time (worse under increased load).

Any help or direction would be appreciated. I haven't heard good things about my local dealer in Kansas City so I am trying to resolve it myself. I'm a step away from going to the dealer but the man I bought it from spent a lot there because of the same issue and they failed to resolve it for him. Thank you for your time and help!

 

[jdanthony]

Is the engine revving high when it's not making full speed?

 

[rcgop]

No. It acts like half throttle.

 

[Coastiejoe]

Bypass the selector if for no other reason your own satisfaction.

Unplug the rectifier and see if the issue goes away..

 

[rcgop]

Can you help me understand what the rectifer does?

 

[Mekanix]

Takes power generated by the engine and converts it into something that will charge the battery.
Also it regulates so that the voltage only goes so high.
If it fails, that can allow it to put out too much voltage which the computer doesn't like and that makes it act erratically.
But that's more applicable to the 787 engines.

If you find nothing fuel related.
Focus on ignition.
Those 717's are known for the flywheel coming a little loose and sheering in the keyway which causes the ignition to be retarded.
Even if it's slightly off and not completely sheared that would cause the behaviors you are describing.

And it will work great when cold but eventually slow untill half power or less when warm or loades. But it will Rev fine out of the water.


A retarded ignition behaves the same as a lean fuel bogg. More fuel just doesn't help though in this case.

You need to remove the flywheel to check this.

 

[Coastiejoe]

Above info is correct. But when they fail, or begin to fail, they output some A/C voltage which the MPEM hates. So it affect how it performs.

The ski will run fine while it is unplugged, it just won't charge.

 

[Mickirig1]

You cut a little off the spark plug wires? Pull off the front Mag cover. Should have 4-5 threads in front of nut holding fly wheel on. Should be a short 30mm socket to tighten or remove it. Pull cover off the E-Box that has spark plug wires coming out. Make sure it is not full of water and fused line is good. Clean and dielectric tune up grease all the connections. Use caution putting grease in the plugs. You can use a little. A lot and they will not fully seat. Test charging with it in the water if you have a carbon seal in the drive train. You can leave it strapped to the trailer backed into the water to do testing.
You do have the low speed and high speed screws set to factory spec? Use low speed to get good smooth idle then idle screw to get the right idle speed. Since you have a new OSD carb I doubt that is the issue. Might even be the coil. If not at least you would have a new one. With a spare.

 

[rcgop]

Thank you guys for all of the fresh ideas! I bypassed the fuel selector valve and unplugged the rectifier. I removed the flywheel cover to check if the flywheel is loose. According to the manual, it takes a special tool that threads into the flywheel to hold it still while you tighten the 30mm bolt. I rigged something up to hold the flywheel as still as I could while I tried to tighten. It didn't budge. There were not 4 or 5 threads showing, but a solid 2. For some reason I can't figure out how to upload a picture or I would show you. About a 1/4" of shaft stuck out beyond the flywheel. I couldn't shake it or find it was loose in any way.

I then put the cover back on and went out to the lake. SAME bad behavior. I had two of my boys on with me, so probably 350 pound of load. Started right up, full speed across the lake for 5 minutes. Let off, then WOT, and it went about half speed and half revs back to the doc.

Before going to the lake, I opened the rear electrical box which I had never done. It was extremely clean and dry. I checked the specs on the coil. According to the shop manual, it should read between .34 and .62 ohms at 68 degrees F. My garage was about 85 degrees and the reading was .8 ohms. Does that seem high to anyone or normal in my warm climate? Based upon the above suggestion, I went ahead and ordered a new coil.

I continue to appreciate any thoughts you have to share!!

 

[rcgop]

By the way, what is a carbon seal and how would I know if I have one? Is this an aftermarket or stock thing?

 

[Coastiejoe]

This is a CS.

 

[rcgop]

I replaced the coil and fuel selector switch and no change. I'm now questioning my original compression check when I bought it. It was a rented gauge and it was 150 plus. I rented a gauge this weekend that was virtually new and I got 130 front/127 rear. I ran it hard for 5 minutes, then did a compression check as fast as I could pull the plugs. I got 120 on both. Does anyone have advice on what this means? A friend suggested removing the head cover and taking it to a machine show to have it resurfaced, but I am sick of trying things with failure. I'm debating about ordered a rebuilt 717 from SBT. I would love and appreciate advice or suggestions before I drop that much. Thanks!

 

[Mickirig1]

I think at 120 the engine needs rebuilt. Check for air leak in fuel system. procedure is in repair manual. You did confirm the correct pop off pressure? Pop off tester can be used for pressure testing fuel system.

 

[Coastiejoe]

At 120, if everything else was in great condition, it will run. But 120 is the normal number where you will be opening the engine up and doing at least a top end. If there is 300 ish hours on the crank, then the entire engine needs rebuilt..