code 53 84 cutlass

[Richard S]

I have a 1984 cutlass 3.8 litre. I have checked my voltage to the egr solenoid (A and B terminal) not sure what c and d go to, wiring diagram does not show these two have also checked for vacuum leaks. Voltage is correct according to my manual and vacuum is holding according to manual. I have replaced the solenoid and I keep getting same code. I am curious about the computer now. With the switch on ( motor not running) the TPS is always clicking and the ISC motor keeps extending and retracting. It is only a small movement but I don't remember it doing this before. Car seems to run fine.

[maxwedge]

The MC solenoid is ticking not the tps, normal. Does the egr work with direct vacuum?

[Richard S]

yes, I can hook vacuum from motor or handheld vacuum pump and it works both ways.

Is it normal for the isc motor to try to extend and retract? It seems to be pushing gas in the carb.

I cleared the code out of curiosity and it isn't there now but I have a map sensor code and O2 sensor lean code. Idle is very low now only 400 rpm out of drive. put it in drive and it goes to 550 rpm.

[maxwedge]

If the engine is lean or has a vacuum leak the idle will be erratic, and the isc will be trying to maintain the idle speed. Check engine vacuum, if the mc solenoid is bad or carb mis adjusted or the o2 sensor is skewed, these can cause codes.

[Richard S]

I checked vacuum it was low. Thought I better check timing, it was off. I don't understand this though. According to label under hood I am to disconnect the 4 prong connector going to dist. and set at 15 degree BTDC.
I did this and killed the car to re tighten dist. Checked timing again it dropped to 12 degree but wait about 1 minute sometimes less and engine speeds up and timing goes back to 15 degrees BTDC. Vacuum is at 17 1/2 when it is there and steady.

replug the 4 prong connector check the timing it is at 12 degree. vacuum at just less than 15. I thought the computer would speed the motor and act like vacuum advance. Speeding the timing marks where I could not see. Maybe I am wrong.

The thing with the ISC motor still confuses me. Engine isn't running the switch is just in the on position.
I could see it extending and retracting trying to keep idle steady if engine was running.

Thanks for any advice and the advice you have given this far.

[maxwedge]

Don't worry about the isc for now. The timing when controlled by the ecu can vary significantly, vacuum is a little low but not bad for an old engine as long as the needle is steady. Again ,fuel mixture has a great effect on all these issues.

[Richard S]

88111 original miles. Vacuum guage needle constant jumping about 2 inch above and below. I rechecked timing at first of start up it is around 12 let it idle for a few minutes and it jumps to 15 you can hear the difference in the sound of the engine. I turned the idle down to 650 in drive and it tries to keep running when you kill switch like it is out of time. Had new timing chain and gears put in not to long ago. Ran good and basically still does just keep getting egr solenoid malfunction code. I rived the engine up and had my fingers under egr to see if it was moving, it did. I'm not sure exactly what the % on my scanner means, but it goes up to 80% and sometimes more on the EGR going down the road.

[Richard S]

Changed the EGR valve and all codes are gone. The old one seemed to be working correctly but apparently it wasn't, must have been leaking or not sealing somewhere. We still have other small issues but they should be easy to fix unless we get into something unexpected which is always possible. Thanks for the help.

[Richard S]

apparently I didn't get it fixed. code is back. It has a slight stumble on acceleration. Temp is about 230 most of time when it is normal operation.
Took line off at EGR valve and tested vacuum. 0 at idle and I revved engine up and vacuum went up. I didn't pay attention as to how much or rpm just wanted to know if I was getting vacuum. Vacuum is now stable at 17.5 no movement of needle on manifold. Has good idle. Engine does detonate when I try to kill it. Timing may be some of issue but I think it is caused by EGR. I think I have it set at 15 BTDC like label says with 4 prong connector disconnected but it did drop back to 12 BTDC after a while. Distributor was tight and idle did increase, but I did not notice that today. Drove around quite a while after installing new EGR valve with no problem then code came back.