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Discussion Starter · #1 ·
Ok, last time I'm going to inquire about this I promise. My 1991 CD turbo misfires when its given a lot of pedal. I'm very sure that it is leaning out because it never happens when I swap the upper two lines on the boost controller. So that it runs very low boost. Also that no smoke or anything visible comes out the exhaust pipe during the misfiring. It feels a lot like the power ramps off. I'm guessing losing optimal air:fuel mix, and then it just completely loses all power. For some reason it really doesn't feel like a single cylinder. I took it to a local Saab/V**** place to get it checked out just a few weeks ago. The mechanic basically took my car out and beat the [expletive deleted] out of it. And yes I paid for this service.
Anyway he pulled the engine codes after getting back and it came up 2 mixture problems and a fuel injector problem. He then told me not to listen to that, it was a problem with my APC box. I have trouble beliving that because the manual boost controller I have performs exactly like the electronic. As to what the boost guage is doing during all this : It rises right on up to the checkered area of the guage and then starts bouncing back as the misfiring begins, but it will misfire its way up to the end of the checkered part of the guage where it meets the red if its floored. Anyone seen symptoms like these before? Would the fuel pressure regulator or pump be able to produce this kind of problem? Thanks in advance for any help.
 

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Whilst I'm trying to think why swapping the hoses around will just leave you with base boost...

It sounds very clearly like a problem with misfire under high boost. Under high boost (before getting into pre-detonation) it is more difficult to ignite denser the air/fuel mix.

I think I'm right in saying that you have a DI cartridge on your MY, and this being the case, it is a very likely culprit. The accepted diagnosis is to try a known good one. Once the DI cartridge misfires/fails, then all bets are off on the rest of the diagnosis until it is replaced as it also is used to measure combustion.

If your spark plugs aren't NGK BCPR7ES11 (or are worn), then that is also a possible cause.

Fuelling is also a possibility, an injector cleaner is worth a try.
 

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Discussion Starter · #3 ·
I forgot to mention that I've changed out the DI, and the plugs with the correct NGK more times than I can remember. I've had this problem for a while. Cleaning the injectors sounds like a good idea. Any guides around on how to run power to the injector while its out of the car?
 
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