4g61t.org

Im talking about my 90 colt 4g63t awd here. Last year it ran 11.8@123 mph before i melted a piston. This year i tossed in another stock older engine. it ran fine in the car it was in. I decided to detune the car back down to 12 second car. So it now has a 14b and stock injectors, stock ecu. Plus a gm maft combo. Everything else is the same stuff that made 400+ hp.

Problem is ever since i built it back up it has missed at high load. I cant even hit 10 psi without it breaking up. I tested for boost leaks it was fine then i installed a gm- maft combo.

First i did wideband cause i wanted to see what was happening. It has symptoms of weak fuel pump. It seems to lean out right when it starts to miss at mid-load. (10 psi at 1/4 throttle or 5 psi at full, an it all varies on rpm.) I also have replaced the pump, with another walbro i have a spare. replace the fuel pressure regulator (i have two full cars worth of spare parts) fuel filter, and checked the wiring at the pump. I really dont think its the pump, but it acts this way. I replaced the injectors, spark plugs, wires, coils.

I also installed the aem ems back in so i could log it and just see how it acts with it, It does the same thing. Misses at mid load.
The only thing i know i can do that will work for sure is to just take the turbo off. It runs fantastic anything under 150 hp.

When it misses its like its running on 2 cylinders Its either losing two or firing all four half the time.

There is no check engine light. I dont have a code reader anymore, but the cel does work for sure

Problem fixed- I replaced the wires with not old ones that were in my shop on another motor, but with NEW ones from a STORE. Miss is gone completely, and i installed a boost controller ans it boosts to 20 psi with no misfires. Man am i glad i bought new wires. I guess i have two sets that are exactly just as worn out- still work but not at high load.

The wires that ran the 11s last year must be on my van, i guess. Screw this im going COP haha.

Are you saying that you can go 12's on stock injectors, ecu and a 14b?

Not exactly. but yeah. It did 12.99 at 108 mph on a 14b. I cant remember for sure, it might have had a maft and 560s. Now it has alcohol injection, maft and stock injectors, but the stock injectors are leaned out a few clicks up top, because of alcohol, this setup should do more than that old setup ever did. I have bigger injectors but dont need them. I also have a vastly superior setup everywhere else than before.

My first pass i ever made on the car or any car for that matter was 13.1 at 106 thatwas on stock injectors maf, fuel pump, etc. So it definately would have ran mid 12's with slicks and stock everything.