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Discussion Starter · #1 ·
Funny peculiar, not funny ha ha.

Had a bunch of running around to do so I took the 84 for its first (with me) longish trip. Highway driving...cruises great; City driving...drives like a 29 year old car :) But at one point I buried the pedal to get on the highway and as the boost climbed (slowly) into yellow it started to buck like crazy when it got mid-yellow. I figured it was sensing knock and shutting the fuel flow off. But then immediately following that, I couldn't hold revs and eventually it shut down...as in stalled out shut down. I started it right up again and drove on as if nothing happened :confused:

So...what happened


I do notice that it takes a LOT of skinny pedal to get it to boost into yellow...normal acceleration doesn't really do it.
 

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Also check that all your spark plug leads are on at both ends.
 

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You may have a problem as well but the 8v throttle response feels very different to electronic control
 

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Discussion Starter · #5 ·
Don't think it's a vac problem...could be a split in a boot that opens up under hard boost and then seals itself back to Dr Jeckyll after turning into Mr Hyde I suppose. I'll have to check that. I'm going to have to check time on it too...it may be too far advanced. I know too that the radiator cooling fan is not coming on and that might be contributing to an "over" knock situation. Been way hot here so hard to judge it!
 

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dont rule out fuel pump pickup problem, the 8v ones are rubber they often rot and fall into the tank, fill car up and check to see if it doesn't do it anymore, if it doesn't it's probably a rotten pickup.
 

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Fuel pumps can do that. Does it do it with a full tank?
If the "bucking like crazy" was directly related to boost, check the Pressure Transducer and the Overboost Switch. Look at the ignition pickup to make sure the wires aren't shorting.
 

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Have you got a wideband afr gauge. I would certainly recommend buying one if not . It helped greatly in sorting the problem with my car and could save blowing a motor up.
 

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Discussion Starter · #9 ·
Fuel pumps can do that. Does it do it with a full tank?
If the "bucking like crazy" was directly related to boost, check the Pressure Transducer and the Overboost Switch. Look at the ignition pickup to make sure the wires aren't shorting.
Mr Mesthene, you are absolutely right! I cannot say with 100% certainty that it was directly related to boost. I can say that it was directly related to hard acceleration and boost just comes along with that. There are fuel demands and spark timing that are also part of hard acceleration so they could be just as likely (may be even more likely) to be the cause of the bucking.

I'll putter around with it over the weekend. First I will check spark plugs and wires as well as timing. Can't say for certain about the full tank but this was all happening with 3/4 of full. As this is the winter Saab I have plenty of tinkering time in between buttoning up the little odds and ends on the vert.
 
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