Possible Spark Blowout?

Hey y’all, I have an 86 Turbocoupe engine in my Pinto, it’s mostly stock to the donor car, just have a bigger T3/T4 turbo, mild cam, and stiff valve springs. 

The skinny of it is I get this intense bucking at higher rpm’s WOT when running 15 psi of boost. When boost limiter is limited to 10 psi and I get a smooth range. I’m running the stock 87 top mount intercooler. Couldn’t find anything too similar on here but looking at other car forums I found that it sounds like spark blowout. 

My AFRs look decent enough, around 14.7 at idle and in WOT around 11, pretty confident all my sensors are in check but I can’t run a check engine light because I think it’ll prioritize the no EGR over anything else. I’m running 12 degrees of base timing, with 91 of course, and I have the correct Motorcraft copper plugs, gapped to .026 I believe, which I thought was already a tiny gap, but apparently some people will even go into the teens to avoid blowout on other boosted applications, anybody ever experience anything like this?

Spark blowout could be the issue. I run 24 psi boost and had to set the plug gap (NGK 2238 / TR5 plugs) to .023 to eliminate the same issue you are having.

Spark blowout could be the issue.  I run 24 psi boost and had to set the plug gap (NGK 2238 / TR5 plugs) to .023 to eliminate the same issue you are having.

Oh interesting, NGK plugs, I was yelled at for suggesting anything other than Motorcraft once by another Turbocoupe guy LOL. I think I’ll try gapping my current plugs down a bit more and see how she feels, either way I’ll have to try those NGKs for my next plug change, seeing as someone running that much boost has no problem with em, thanks Jeff! 

I’ll report back with my findings, might take a bit, decided to start bodywork and paint on the car this week so that’s stopping me for now.

Previously I had similar issues which ended up being corrected when I replaced the fuel injectors.

Previously I had similar issues which ended up being corrected when I replaced the fuel injectors.

Thought about that too at some point, they’re stock brown tops, been told they’re good enough and they were flow tested before I installed them but it was by an unreliable flow tester, he had just burned the guy who sold me them right beforehand. Worth a shot testing them if gapping down doesn’t help. Thanks!

I had something similar happen from a boost leak. It would close to 15 psi then start bucking. It was the coupling between the turbo and top mounted intercooler was shot but would hold pressure until the boost got to around 15.
I am at .028" gap on my plugs without any problems at 17 psi.

I had something similar happen from a boost leak.  It would close to 15 psi then start bucking.  It was the coupling between the turbo and top mounted intercooler was shot but would hold pressure until the boost got to around 15. 
I am at .028" gap on my plugs without any problems at 17 psi.

I'm curious as to how you figured this out because I think I'm experiencing a boost leak as well.  I thought about adapting a fitting and hooking it to my air compressor and regulating the pressure down to 15# to see what happens.  If there's an easier what I'd love to know.

I had something similar happen from a boost leak.  It would close to 15 psi then start bucking.  It was the coupling between the turbo and top mounted intercooler was shot but would hold pressure until the boost got to around 15. 
I am at .028" gap on my plugs without any problems at 17 psi.

I'm curious as to how you figured this out because I think I'm experiencing a boost leak as well.  I thought about adapting a fitting and hooking it to my air compressor and regulating the pressure down to 15# to see what happens.  If there's an easier what I'd love to know.

I was lucky to just look for the boost leak visually and by tugging at the couplings.  I pulled up on the IC and it moved so i knew immediately. 

There are ways to make a boost leak tester if you can't find it visually.  I would do a Google search or look on Youtube for ideas.

AloofMaalouf- "intense bucking at higher rpm’s" sounds more like a bad/wrong plug wire based upon experience with the same symptom. Given that you've swapped this engine into a Pinto, make sure you're using the right plug wires, they are in good shape, and they are fully seated on the plug ("click"). I had a small cut in a boot that I chased for months. When cylinder pressures are high (like 15psi of boost), spark wants to find a better way to ground. At normal cylinder pressures, spark is happy to follow the wire. BTW, I'm running Autolite 103 plugs gapped to 0.028 and 22psi of boost with no blow outs.

Welp, months later and a nice fresh Oxford White paint job completed, I finally got the fix, credit to Mikey97D  , you were totally right, it was a goddamned boost leak, several actually  I’m embarrassed but it is my first boosted car and it’s been a lot of dealing with boosted problems. The car’s way too crazy now, leans out a bit top end, think I could fix it by richening the FPR a bit more but I’m in deep enough with this ECU, I’m going PIMP and big injectors before the end of the year, I’m so excited! Thanks again everyone!