Coughing/stalling at WOT

CMF_PhilR32

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Hey everyone, I have a 95 SLX CG13DE, it drives fine up to half throttle roughly, then when accelerating beyond half throttle the engine coughs and splutters and has no power. I sprayed some throttle body cleaner down the throttle yesterday afternoon which fixed the problem, until I went to drive to work this morning and the problem was back. I only bought it yesterday and it was sitting for months before that. It's perfect until you press the accelerator pedal more than about 50%. Should I just keep spraying cleaner for a while and eventually it will clean itself enough? Or is there another problem? Should I just buy a new throttle body?

Thanks in advance!
 

CMF_Bishop

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Sounds the like the typical dry solder joint issue on the throttle body internal plug connector, you can pop the cover and re-flow the dry joints to fix it.

As to the temp, mine did the same when I got it, ran like a 1/3 temp all the time, new thermostat fixed it, either the wrong one is in it (they often come in different ranges), or it's just worn and they tend to stay a little open all the time when worn out.
 

CMF_PhilR32

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Bishop WROTE:

"

Sounds the like the typical dry solder joint issue on the throttle body internal plug connector, you can pop the cover and re-flow the dry joints to fix it.

As to the temp, mine did the same when I got it, ran like a 1/3 temp all the time, new thermostat fixed it, either the wrong one is in it (they often come in different ranges), or it's just worn and they tend to stay a little open all the time when worn out.

Thanks bishop, figured it was probably thermostat. Is there a write-up diy thing explaining how to resolver the plug? (I know how to solder).
 

CMF_Bishop

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There is a write up somewhere on this site, I forget where.

But, short of it is, there is a plate cover on the side of the throttle body, it's sealed on with silicone, so you just dig out the silicone, carefully pry off the plate.

After seeing mine, I knew exactly why it does what it does, the plug for the air mass sensor goes in right to the side of this plate, and directly under this plate, you see where the plugs pins solder to wires that then go to the circuit board, which is the board for the mass sensor wire/wires buried deeper in the throttle body.

The point where the wires solder to the pins of the plug internally, are chronic for being dry soldered, and I suspect this point also sees some vibration, so when you look at them under slight magnification, you can see where the wires in the plug pins have fractured.

You have to know what your looking at to understand, that this then creates fluctuating resistance through those pins, which on a lot of things is not so much an issue...

But, a air mass sensor, calculates air density by the passing of air across a heated wire, how that wire cools is how the car knows how much air your engine is getting, fed back as very fine resistance measurements to the ecu, the very finely and minutely cracked solder joints will expand and contract with heat and more vibration, creating all sorts of random readings, making the car do all sorts of weird things that mimic other problems.

I'm in a rambling mood sorry, you can solder in place, that's how I did mine, but I'm a fair to above average solderer, I made sure I totally re-flowed my joints to a nice shiny wet joint that I knew fully penetrated the join, but I will admit it's a prick of a job to do in place, if your less lazy than me, it's likely easier to pull off the throttle body and do it on a bench, then you can also be sure you did a good repair on the dry joints.

Should really find and post the pics of mine, I took some close ups that show just how dry the joints were, with the fractured wires in the middle of the solder blob...
 

CMF_Bishop

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I should just follow up with, there is a place out of Taiwan who sells reman bodies on ebay, not that expensive considering, $200 ish I think, not a bad option if you don't feel like all the work.
 

CMF_PhilR32

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Thanks for the help. I found the write up. In the attached pic do I resolder all 6 or just one set of 3? The ones on the board which are in the middle of the photo or the ones where the plug connects on the right of the photo?
 

CMF_Bishop

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Its the three on the right that will be dry and/or cracked, the three going into the board on the left on mine were shiny and looked fine, but you can reflow them if you think they look dull, while you have the case open which is the pain the ass part.
 
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