Crazy Tach Help!

[cashen]

Car info: B18 obd1 in 88 crx. Chipped P28 ecu.

My tach has been going crazy, whenever I put my foot into it it goes crazy and just tach's out. Goes straight to 8k even though I know it's only at 5k. If I slowly accelerate it will get to about 4k then starts pausing and jumping. It'll go from 4 to 5.5 to 7 to 8 in jumps. Any ideas? I've checked all the fuses. Wires seem pretty secure too.

One other question I don't know if anyone knows it but thought I'd try anyway. On the ecu obd1 which two wires can I short to get the CEL light to start blinking? The plug on the driverside shock tower is not present on my car which is where it is for the original electrical system. So I thought I'd just go straight to the ecu and just short it out directly there. Looked at the pinout but doesn't say anything about what I'm looking for. Thanks.

 

[cashen]

Alright, I fixed the tach part. But i would still like to know how to get my check engine light to give me cell codes by shorting out wires directly at the ECU.

Solution to tach problem: checked spark plugs and the fourth cylinder wire connection to the plug had come lose enough to make it faulty, so I was running on like 3 1/2 cylinders for a week. Symptoms are the spuratic tach, bad gas mileage(went down by like 1/3) and little rougher idle than normal. Just in case it happeneds to someone else. Check your plugs and wires if the above is happening.

Anyone know the CEL part?

 

[posol]

https://hondaswap.com/reference-materials/88-ecu-error-codes-29109/
includes how to pull the codes.