Question1986 Seville 169,000 mi. 4100 engine, A/C retrofitted with R134a
Hi,
This car has had several problems; however, I keep nursing it along. Today the A/C read low refrig. and I checked and it has unusually high pressure on the low side. I just had it charged at our Vocational School this spring, so I suspect the oriface tube is plugged up; however, I would appreciate any suggestions. By the way, I entered the BCM diagnostics and it had a high side temp. reading of 36 and a low side of 30.
Problem 2:
The transmision seems to want to almost slip into neutral as it upshifts into 3rd gear. If I manually shift it, it does much better. This transmission use to do the same thing in first and second and now they are strong. I suspect the seals are getting hard, and one of the transmission additives helped a great deal then. I realize this is about the milage for a transmission overhaul; however, the problems do not tend to get worse with time like s slipping transmission. I am wondering about the VCC and a potential connection to the next problem.
Problem 3,
The engine was running about the best it had in years last week, then it started running rough (i.e., like it was missing on a cylinder). No ECM or BCM codes displayed. I added some injector cleaner, checked the front side plugs and one wire was corroded along with its respective spark plug. All the plugs and wires have less than 3,000 mi. on them. I was surprised. I was even more surprised when a different wire did not solve the problem so I cleaned the plug and the wire. The cap and rotor are 3,000 mi. old and in good shape. I checked the ground. I have run additional ground wires to the engine as it has been a problem before. I have the original manual for this car so I checked EGR diagnostic proceedure. It indicated a short since the test light stays on brightly when pin A to the EGR solenoid is tested to ground; however, when I test across the two wires to the EGR solenoid, the bulb goes bright and dim as expected when the EGR goes through the diagnostic cycle. I also noticed the vacuum hose to the EGR was blowing rather than sucking with the key on, and the vacuum pump running, without starting it. When I started it, the same hose to the EGR has suction above 2000 or so RPM. I checked the proper connections to the Vacuum pump and everything is connected per the manual. I removed the vacuum pump fuse and it runs about the same with a little better transmission performance.
Other problems - the ISC motor is constantly making adjustments; not big ones which produce a code, but smaller ones. The RPM never has stayed uniform, even above idle. The IPC(i.e., Instrument Panel Cluster) occasionally works perfectly. Most of the time it is so dim it looks black and is unreadable during the day.
I know I gave you multiple problems. I am not expecting answer to all of them; given your background, some might be easily answered. I would appreciate any suggestions you have.
The A/C problem was the one that prompted me to write, since the manual does not addresss it. The car had a similar problem 4 years ago. Thanks for listening.
Rob
AnswerAs to your A/C sytem pressures what were your HIGH and LOW side pressures via the A/C manifold gages ?.
Are you POSITIVE that the vocational students used the R-134a refrigerant and NOT the R-12 ?. You DID inform them that you had CONVERTED it from the R-12 to the R-134a I HOPE.
If they installed the R-12 and or added to much freon or added to much refrigerant oil in the system this can also cause your problems.
Other problems would be:
1. Orfice tube.
2. Restricted A/C lines due to contamaination.
3. Evaporatoe retsriction.
4. AIR still in the system due to NOT properly using a
vacuum pump to evacuate the air BEFORE they charged the
system.
5. Reed valve problems within the compressor.
6. Insufficient flushing of the A/C system to remove any
foreign debris.
QUESION: Was the A/C repair due to an internal A/C compressor failure ?.
Problem 2 is having seal and or "O" ring problems within the clutch packs due to the additive that you put in it. All this additive does is swell the seals and seal and or "O" ring(s) failure is going to fail. I have taken apart many transmissions that had additives installed and when I removed the pistons from the clutches the "O" rings practically flew acroos the shop because they were swelled so much. Experience tells me that you are looking at a trans over haul in the near future. The VCC will not perform at proper efficiency due to the seal and "O" ring leaks.
As to the engine cylinder problem, Run a compression test on ALL cylinders as the 4100 engine is well known for having SOFT camshafts that were NOT hardened properly when they were manufactured and started to wear the lobes on the camshaft severly thus causing the intake and or exhaust valves NOT to open FULLY.
AS to the EGR. You will have FULL battery voltage on one terminal of the solenoid as this IS normal. the GROUND side of the EGR solenoid is controlled via the ECM thus the reason for the variations in illumination of your test light and this to IS NORMAL.
The ISC motors were always a source of problems due to the small plastic gears that tend to strip the teeth off over time. HOWEVER, your engine cylinder problem can and does effect the ISC to vary due to the weak cylinder.
On the dash display IF this IS a DIGITAL display this to has been a well known problem and in most cases was a fault within the cluster assembly illumination circuit which required sending it out to Ac DELCO for reapir or replacement.
This should keep you busy for quite awhile.
autohelp
