Mushiki

Hi everyone... my car is a pretty special one... mix of different **** from different cars

You can read my complete build here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/my-13b-na-build-thread-945483/

In a nutshell, it's the following:

• 13B NA S4 Engine, Rebuilt 1400 miles ago
• Pineapple Racing 6PI Large Streetport
• Pineapple Racing EP2A Exhaust Port
• Exhaust Port Sleeves Removed
• Euro LIM (Valve-style AUX Ports)
• S3 Distributor + DLIDFIS
• BAC, Air Pump, AC, and some other stuff removed
• OMP Removed (Obviously, running Premix)

Now to the problem... the car was running great, had plenty of power... sometimes had a tad more, some other times a tad less... but overall pretty good.

About a week ago, my brake booster craps out. The brake master cylinder was leaking a bit into it, eventually destroying it. So I took it to a shop and they rebuilt it. Good.

Now... I installed the rebuilt brake booster... no issues. I start the engine... no issues. Now... I take it for a spin, and the car feels like it has about 50% de power it had before... idles just fine, but I get sluggish acceleration, pretty aggresive backfires, RPMs going up in an irregular manner, bucking, etc.

I immediately assumed this was some kind of ignition issue, so I checked timing with a timing light. Strangely, no issues there... car idles at about 1200rpm, and I get 5* L/20* T (stock). The car still runs like **** though.

So... what now? Since the only thing I did for the car to run like this was fixing the brake booster... I thought it may be some sort of vacuum-related issue. Maybe the vacuum advance or something was working semi-properly with the leaky/broken booster, and the fixed one messed everything up for some reason...

So I disconnected the 2 vacuum hoses at the distributor and... the car runs better. Not 100% better, but I would say... 85% better.

Now... why would this happen? What should I do?

Thanks a lot for taking the time to read, and I look forward to any feedback you might contribute with

Mushiki

First... to correct my previous post, Leading is set to 0º, and Trailing is at +20º

Engine's idleing at about 1100rpm, TPS is now set to 0.98k Ohm... was at about 0.8

So I was just checking timing again... and I noticed this...

With the distributor vacuum hoses disconnected, I was able to see the timing advancing progressively when pushing the throttle.

Now... with the vacuum hoses connected I tried the same thing... and I noticed that timing advanced VERY abruptly... I just feathered the throttle linkage and I could see timing going from 0º to about -12º instantly... in about just a 100rpm difference (yes, a hundred).

Any ideas?

markeddief

Did u ever figure out what the problem was?