Twotone88

Looking for some help with my 88 Caprice Classic with a 305. The check engine light has always been giving me issues and I cannot figure out what is going on but I think water is somehow effecting it. For almost a year, the light has been steadily on which is typical. There was no change in performance so I decided to stop messing around with it since I could never get a code out of the OBD. I would jump the wires at the port, but nothing would happen at all. The other day, as I was driving, I noticed that the light would sometimes turn off, and there would be a change in the engine performance. The light would not be consistent and would sometimes flicker, be off for a few seconds, and so on, but each time you would feel the engine jump. Also, when the light is off, it would turn on when the brakes are pressed, but then turn off once you release them. Now that it has been doing this, I tried getting a code out of the OBD but when I jump the wires, it will do the "1-2" blink, as it should, but it never goes through a full cycle to give me a code, but just keeps restarting midway through the second "1-2" blink. It seems that water might be causing some of this as it has been very wet and rainy when this type of stuff has occurred, despite me going a year of driving through rain with no consistent change. It seems like there is just some kind of electronic component that is intermittently malfunctioning. I have changed out the ECM and PROM as few times but that doesn't seem to do anything. If anyone has any idea what it would be, I would greatly appreciate it. Just trying to keep this old bird on the road.

WyrTwister

I have a 91 Caprice with 5.0l . Have managed to read the codes , successfully , in years past . At that time , I read up on OBD , but have forgotten most of what I read .

The impression I got is OBD is not any where as capable as OBDII . Not even sure if OBD stores intermittent codes ?

If it was me , I would make a list of all the sensors that the " computer " uses & check the wiring and the connectors of each one . Un-plug the connector from the sensor . Visually inspect for broken & frayed wiring . Clean the connector & sensor contacts with electrical contact cleaner . Not sure , but it might be a good idea to apply dielectric grease to the contacts ?

Plug each one back together securely & go to the next one .

Visually and audibly check each vacuum hose and device . If in doubt about a hose , replace it . It is not expensive . Drive it & see what has changed or not . Change the fuel filter if it has never been replaced . Check the air filter . Check the ERG valve to see if it is sticking . Make sure the gas cap is tight & OK .

I do not know of an inexpensive OBD scanner .

Please repoty back .

Best of luck . :-)
God bless
Wyr

SBchevyfan

OBD does not support many sensors. Most common to go bad would be the O2 sensor. You should be able to read the computer by jumping the terminals of the obd port with a paper clip. Find yourself a copy of the Haynes manual on that model and it should explain the procedure. If you don't want to buy a manual, check your local library or look it up on line.

WyrTwister

https://www.google.com/search?q=1988...ntu&channel=fs

God bless
Wyr