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Old 06-10-2021, 11:25 AM   #1
Teeth
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Default b230ft Hesitates at WOT, low rpm

1989 745T, 13c turbo:

Running really well otherwise, but if I really stomp on it from a stop it behaves as if it is either getting too much or too little gas--or too weak a spark to ignite? Happens too early in rpm range to be far into the boost, If I feather throttle slightly, engine comes back and pulls pretty hard. Not a big issue unless I'm drag racing, but, you know, I'd hate to lose the drag race

I did replace the nylon fuel lines with rubber high-pressure lines--which I had a wideband installed to see if was running rich or lean.

Eventually I'll start by pulling the plugs, but posting here to see if there is an obvious answer for this behavior before I start digging.
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Old 06-10-2021, 02:49 PM   #2
John242Ti
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Look at the rubber hose between the turbo and the intercooler. Specifically on the bottom. Is it split? That will cause exactly what you describe. Accelerate hard to get onto the interstate, car bogs down, starts making a wuffling sound, then you let off, and it rockets forward. Had this on an '87 744Ti. Temporarily, duct taped the split section of the hose, and problem went away. Picked up a good condition replacement, never had the problem again.
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Old 06-11-2021, 06:36 PM   #3
dl242gt
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Also the hose from the mass air sensor to the intake of the turbo can get sucked shut causing the the issue you describe. The hoses on the hot side near the turbo get very oily and decay as John pointed out.
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1993 245 Classic, 435k miles, enem V15. IPD bars and chassis braces. Simons sport exhaust from Scandix. sbabbs ezk chip. Been a good road warrior. Genuine Volvo rebuilt leaky M47.
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Old 07-23-2021, 08:36 PM   #4
Teeth
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Fount it.

Good advice, though I replaced the MAF hose with silicone a while back just to prevent the issue. This time it was just old plugs, bad wires. Gap had eroded out to .040, New plugs, Bougicords and no more issue.
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Old 07-23-2021, 08:50 PM   #5
dl242gt
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Good work! Nice when it's the simple stuff.
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