Aloha,

I have a 1985 GSL-SE on the island of Kauai. It was rebuilt about 8k miles ago and has stock internals. SR motorsports flywheel, exedy clutch, racing beat header and exhaust. Emissions were deleted but I put the BAC valve back on. It starts great, idles at 800 rpm with A/C on or off. Runs fantastic.

Issues: it backfires extremely loud after decel at low rpms and then apply gas again. Gunshot backfires. With the A/C on, it backfires less. I was hoping the when I put the BAC valve back it would help, but it didn't. When it backfires, the tourists duck and cover their heads like a fire drill .....

Poor fuel mileage: I've been getting a consistent 13 MPG for city driving. (shift at 4k-5k rpm, cruise at 3k rpm, redline once every few days) New fuel filter, fresh tune up, timing set correctly. Running rotella T6 ... idemitsu premix 1/2 oz per gallon. Not sure if OMP is working correctlly.

Steering wheel slack: replaced idler arm and put poly bushing in. Still have lots of play in the steering wheel, almost a couple inches either side. Looks like the someone tried to tighten the box before. Anything else i can do?

I have drag raced it twice. I want to post in the drag racing section, but no can because i dont' have enough posts. I ran a 16.08 best time so far 1/4 mile. Wanting to improve.

Thanks for reading

Been a rotary nut for many years.

Cheers

 

Have you replaced plugs and leads.

 

Yes.... Plugs, wires, cap, rotor are new.

 

seems like you are running rich. If its an efi then check injectors. i assume they must be dripping rather than spraying.

 

When were your plugs replaced? If your OMP is working, you're mixing your fuel and you aren't redlining every time you get in the car then I wouldn't be surprised to find that the spark plugs are severely fouled. Too much oil will take out plugs really fast man. Take plugs out and hit them with a wire wheel and see if that clears up the issue. There aren't too many things that cause backfiring.

EDIT: I redline every time I get in my car and it never sees anything under 3k unless I'm sitting at a red. I also mix and my OMP if functioning properly. If I putt putt for let's say a whole oil change(5000miles) my plugs will be pretty nasty. Driving it hard keeps the plugs cleaner. Mind you my engine is running flawlessly and it's timed perfectly -zero backfiring.

 

Thanks for the reply rotary alkymist

The plugs were replaced 2500 miles ago, about 9 months ago. I'll have a look at them and do as you said.

I have a question about the O2 sensor. I thought replacing it might help with gas mileage. I have what looks to be a RB road race header. I can't seem to find the O2 sensor under the hood. Is it possible it is not installed because of the header? Where is the exact location of the sensor? Do I have to get underneath the car to see it?

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