[T3] Bad day at the (FI) office

[Jim Adney]

On 3 Apr 2016 at 18:47, Daniel Nohejl wrote:

> Naturally, I looked at the stupid AFR gauge but #´s were so rich that they seemed impossible: between 7 and 9 whereas by most accounts I could find online the car should have been undrivable, belching black smoke out the exhaust. This got me thinking that perhaps the AFR gauge is having an issue. We pulled the plugs yesterday and they were pretty clean but for #TMs 1 and 4, both f which were half fouled and half white for some reason. If the motor had been so rich, the plugs would no doubt have been fouled. We have plenty experience of that from when we first got the car and before we realized it had the wrong brain in it¦..the plugs would be jet black within minutes of idling. Anyway, here are the plugsafter we pulled them yesterday:
> 
> http://images.thesamba.com/vw/gallery/pix/1486226.jpg

I don't like seeing them so mis-matched. Some shrouding of the 
insulator can be blamed on whether the ground electrode ends up 
facing the intake valve or not, but the ground electrodes should all 
look about the same color. Yours are way too different. Injectors 1 & 
4 are fired by one circuit in the brain, while 2 & 3 are fired by 
another. Unless one pair is getting more air, which seems unlikely 
since they use the same cam lobes, they should get the same gas.

Check the brain connections for the injectors and the injector 
grounds. Give all the crimps a careful visual inspection. All should 
be tight. If they are, try a different brain.  

> In the end, we kept 2 and 3 and replaced 1 and 4. Of course something
> iffy happened when re-installing the plugs.....After installing #2, I
> couldn´t remove the socket because it kept fouling on the eyeglass tin
> so we had to back out the plug again and it came out with a bit of
> metal on the end!! 

If it fouled on the eyeglass tin, that tells you that you had been 
screwing it in cross threaded, so lack of lubrication was not the 
problem. NEVER use a U-joint on your socket while installing plugs; 
you need to be able to SEE that you're putting it in straight.

> So, regarding the alleged richness, I tried removing the TVS and full
> load switch plugs as well as the wire from FI harness to the starter
> but that had no effect on the AFR. I also went through all the tuneup
> stuff but the valves and everything was fine. 

Okay, so we know that the problem was not with any of those parts.

> We´re now driving with the MPS more or less back to its original
> position and no resistor on the CHTS. This has had only the slightest
> effect on AFR but now the gauge is clearly under suspicion. Weird
> thing was that in changing the MPS back, the idle AFR would lean out
> as expected and then after a few minutes of driving would go bac? to
> very rich. ITMm giving very strong consideration to removing the AFR
> gauge and using other indicators to evaluate how the motor is doing. 
> 
> Then, we finally got around to taking some videos of the rear end
> bounce....one from each side. The left side squeaks noticeably when
> pushed on. 
> 
> Right:
> 
> https://www.youtube.com/watch?v=JrW_Bkr3iHs
> 
> Left:
> 
> https://www.youtube.com/watch?v=X8i_9a_iZhI

Looks to me like the sideshift is worse when you bounce the left 
side. Undo one end of that shock and verify that it has resistance in 
both directions as you compress and extend it.

-- 
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************