96 850 R turbo break up

Flametrap666 · Post by **Flametrap666** » 19 Feb 2022, 22:33

I just purchased a 96 850 R.. when I dump the throttle and it pulls boost it hits about 4k bogs down and back fires.. check engine flashes due to the car misfiring on more than one cylinder. Its running a tune but I don't recall the brand as the car is 2 days new to me. I find it hard to believe it's related to the tune and feel as if something a little more sinister is happening. I've owned a lot of Volvos over the years but have never owned something with a tune and high pressure turbo. Please help with any possibilities of why this could be happening. I'm only looking for experienced people to respond as we know unfortunately lots of "Parrots" exist on these sites. Thank you in advance.. (New guy with 96 850 R)

Khyren · Post by **Khyren** » 20 Feb 2022, 00:02

I had a Turbo Thunderbird years ago that would backfire at anything above 14psi. Turns out, it was a weak fuel pump that didn't have enough flow for the higher demands above that boost. I would check your fuel pressures, spark plugs, and maybe even ohm the coil if it is having the spark blow out.

Post by **abscate** » 20 Feb 2022, 02:28

Are all your ignition components stage 0?

These cars run open loop on boost so the tune has to be dialed in precisely to the turbo and induction by the tuner.

Post by **Chuck W** » 20 Feb 2022, 06:28

As mentioned above, what is the fitness of your ignition components?

Have you checked all of your hoses between the turbo and the intake?

Do you have a stock ECU to toss back in it?

Post by **erikv11** » 20 Feb 2022, 08:47

If it cuts out with RPMs check ignition, if it cuts out with PSI check the CBV diaphragm especially if it wasn't refreshed recently. Swapping the ECU is a great troubleshooting idea.

Post by **Clemens** » 23 Feb 2022, 15:00

+1 on all above.
These cars really prefer OE ignotion parts, especially the spark plugs and wires, distributor and rotor.

My 96 R did the same thing as yours on the stock tune when I bought it. After refreshing all ignition components it really came to life above 4000rpm.

Post by **matthew1** » 23 Feb 2022, 17:11

Chuck W wrote: ↑20 Feb 2022, 06:28 Do you have a stock ECU to toss back in it?

My first thought while read the lead post. Besides looking for the simple things like blown off vacuum lines and the condition of the spark plugs, I'd swap in a stock ECU. You don't even need to buy one if you know of or can find a friend with a HPT 850.

If it's not that, then what Abscate said... look at Stage 0 checklist.