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Discussion Starter #1
We've taken our 2001 saab 9-5 SE 3.0T (lol) V6 on a seattle-to-LA road trip every year for a few years (2) perfectly fine. The third year, the car made it about 6-8 hours into oregon, started misfiring, and died shortly after. To make the story short, we rented a car to get to LA and I picked up another DIC to swap in and drive the car back home on the way back to Seattle. Swapped the DIC and everything seemed alright for the majority of the drive back home.

By the time we got home the car started surging, misfiring, and feeling low on power again. Enough to trip the CEL again, but this time for the other bank ofcylinders, so I replaced that DIC as well, and all-around new spark plugs (ngk oem, checked 1mm gap) but it was still driving like balls.

I cleaned the maf, throttle body, map sensor. I checked the fuel pressure (35 at idle, 40-45 when giving it throttle). I tried fuel injector cleaner. and a new fuel filter anyways. I sprayed starting fluid everywhere in the engine bay, around every gasket and hose, and couldn't find or hear any vacuum leaks. There IS a hissing coming from somewhere inside the throttle body...? Doused the area with starter fluid and no change in idle...

After all this, under 0-15% throttle the car feels great and eager to take off, but anything more, and sometimes the power comes then goes away quickly never to be seen again, or most of the time it just slowly accelerates. If I do a hard WOT pull, I can see the boost gauge just enter the red zone then DROP into 3/4 to 1/2 the middle orange zone. When Im sitting in park/neutral, if I quickly fully press the throttle, the engine hesitates for a good half second before revving up.

When I tested the throttle body position with a code reader, I saw some interesting results. Linked is a video of me starting at 0% throttle (which OBD reports is already at 17%) and as I slowly apply pressure there seem to be dead spots, and it never goes above ~80% when I'm at full throttle: OBD TPS Test Video clicky clicky

So folks, would my remaining troubles be caused by the bad throttle body? Are those readings bad? Or am I on the wrong path here.

Thank you
 

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Mine is a 4 cylinder but the throttle body is almost identical and works the same way. My first reaction to the vid is to wonder what the %ages would be with the engine running. I'm not sure why the reader thinks 17% is the start point, but the interaction between the ECU, the pedal/cable and the throttle plate is complex and there is no direct relationship, at least in the 4 cylinder engine (unless its in limp-home mode where the cable directly drives the throttle plate).

The ECU sees throttle plate movement in terms of 0 to 100%, but pedal/cable range from 0 to 130% for reasons I'm not aware of. The pedal/cable effectively sends a signal to the ECU via a potentiometer in one side of the throttle body. The ECU combines this demand with the road speed, engine speed, what gear its in, boost level and other variables, and sends a signal back to the 2nd potentiometer, which actually rotates the throttle plate.

With the engine stopped, this interaction won't be happening.

Generic code readers tend to specialise in the emissions related defects. I know a bad TB comes in that category - I once had one - but to get the complete picture it needs interrogating with a Tech 2.

Older TBs did have a habit of insulation breaking down within. The defect on mine (a relatively new one) was the two potentiometers going out of synch. I sympathise in that there won't be many V6 TBs around compared to 4 cylinders, but it might be wise to get it read before springing for a used spare!

Especially as the replacement of the DICs caused a temporary improvement.

Doug
 

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That doesn't look good, but it seems to be the usual failure mode for the throttle body. Heat and age cause the insulation to crack and fall off. You know there are higher quality types of insulation that would survive the heat just fine, and probably wouldn't have added more than a few dollars to the cost of the throttle body. My dad used to buy bulk wire from Boeing's old surplus store, and the insulation on that stuff would survive a world war.
 

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Discussion Starter #7
You guys make me paranoid that I need to take my TB apart and check those wires!
When I first cracked it open, it appeared like most of the insulation was still there. Once I started taking it apart to the point the wires moved, all the insulation fell apart!

It may be best ot have a spare on hand in case you end up causing more damage just LOOKING at it, yeesh!

There doesn't seem to be a way to take this apart any further in order to replace ALL the wiring, since there's a few that go under the potentiometer to the other side of the throttle body. Anyone had success taking this apart and reassembling?
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I took one apart a long time ago and it did not end well. The other side does come apart but you need some kind of specialized tool to get the throttle plate through the potentiometers on the side you can see so that you can pull the shaft out the other side. I ended up breaking the potentiometers but did get it apart.

And to properly replace the wires you do need to get to the other side.

BBA Reman in CT does a refurb on them. Last I looked it was about half the price of a new one with a life time guarantee.
 

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I am happy to report a successful repair! I ended up doing this while waiting for the $80 ebay gamble replacement to come in, only for my worry to grow as I realized the same thing will happen if not repaired in some fashion or I drop good money on a new one.

Here's how I approached this:

There are 8 wires total, four that are soldered right to the potentiometer visible when you take the black cover and the magnet off, and four that go under that potentiometer and back through to the other side of the throttle body

For the first four wires that were easy to get to, I de-soldered them from the potentiometer, put shrink tube on, and re-soldered them on. Easy.

For the second four wires, I did this process one wire at a time. I cut the wire near the connector, and at first tried to push a length of shrink tube over the wire going under the potentiometer, and hopefully as far down the other side of the throttle body as I could get. Unfortunately there is not enough clearance under the potentiometer to do this, ugh...

So instead, I pulled the wire out from the other side the potentiometer, so that I could slide a length of shrink tube as far down that cavity the wires run through as possible. As I was doing this, the last bit of insulation back there crumbled apart, so I made sure to stuff the shrink tube as far down as I could before closing it up.

For some reason I couldn't manage to slide any wire back under the potentiometer to reconnect to the connector side, so instead I lengthened them enough to run around the magnet assembly once put together. Yeesh.

I noticed the first time trying to reassemble the screws holding the magnet down were pinching my extended wires. Had to fenaggle quite a bit to get it all fit properly, but I managed to snap the black plastic case back on.

Reinstalled on the car, and WOW. In the 4+ years owning this car it's never felt so great and peppy. Life restored!

I do not know how far I actually got the shrink tube on those back four wires......I may sacrifice the ebay part when it comes in if there aren't any existing photos, I'm very curious.

Tell me if this is absolutely ghetto a.f. or I should be ashamed, but the car drives great and it only cost me an hour of my time.


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Very interesting. I keep reading about the insulation breakdown problem but have never dismantled one and seen it. Great write-up, and I'll now know what I'm doing if I ever have to do the same.
 
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