HiCustomer welcome to justanswer. My name is IKE.
Is your check engine light on?
Okay, the service manual troubleshooting guide leads me to replacing the ECU, just as it always does, but this is seldom the problem. If you can, clear the code (pull the clock/back-up in the passengers dash fuse box fuse for 10 seconds with the ignition off) unplug the 4 pin connector on the back of the alternator and test drive the car again. If the DTC sets again, the distributor housing is bad. If it does not set again, have the alternator checked. A bad diode in the alternator can cause interference with the CYP sensor.
Here is a copy of a service news article that you can look at to check your VTEC code.
I know you probably can't hook it up to a tester, but you can connect pos and neg to the 2 pin connector momentarily to see if the VTEC solenoid is engaging. Listen for a light click noise from the solenoid.
On '98 Accord L4s with VTEC, DTC P1259 (VTEC
system malfunction) can set at idle or above 4,000 rpm:
switch circuit (switch, connectors, or wiring).
the VTEC system.
To find and correct the cause of the DTC, do this:
1. Use the PGM Tester to check the vehicle's freeze data
or snapshot data to see when the DTC was set.
2. Disconnect the 2P VTEC pressure switch connector,
and jump its two wires.
3. With the ignition switch ON (II), the PGM Tester
should show that the VTEC pressure switch is ON.
connectors are OK, so the switch must be bad.
Replace the switch, clear the DTC, and return the
vehicle to the customer.
between the switch and the ECM/PCM or between
the switch and ground. After you repair the open
circuit, recheck the switch, then clear the DTC, and
return the vehicle to the customer.
4. Remove the valve cover, and check for a loose center
head bolt on the intake manifold side. A loose bolt can
cause a drop in pressure in the VTEC system.
turn it another 1/4 turn, and then turn it another 1/4
turn. If the bolt won't tighten, its threads are
5. Remove the VTEC rocker arms, and inspect them for
sticking or missing synchronizer pistons or other valve
train problems that could cause an oil leak.
replace the faulty parts. Then clear the DTC, and
P1259 troubleshooting procedure on pages 6-7 thru
6-9 of the '98-99 Accord S/M.
Get back to me with what you find and I'll help as much as possible.