dgsav

After clearing the ECU, Codes 23 and 24 have not returned. I now suspect they may have been stored for many months from past episodes of fiddling with the connectors and setting minimum idle speed. The ECU memory evidently does not clear itself if a problem doesn't come back after several engine restarts. All the wiring is in excellent condition, as are all grounds. While Codes 23 and 24 have not come back, Code 34 has, along with the intermittent CEL. I've traced it to the EGR purge solenoid having excessive resistance (several K ohm) when it gets hot. I suspect the solenoid winding is going open circuit when the engine warms up. Since I have to meet biannual smog inspections, replacing the solenoid with a 33 ohm resistor is unfortunately not an option for me. I'll pursue replacing the solenoid. Thanks for all the ideas, everyone.

(Long time lurker, long time borrower of other members' knowledge, newbie poster of own problems) I have an '88 GL wagon 5 speed dual range 4WD with 260K miles that's been in my family since new (I actually drove it off the dealer lot with 10 miles on it). Car is essentially stock and has been mechanically well maintained. Replaced engine at 213K, probably unnecessarily, and it's been running well all along. Last week the Check Engine light started coming on intermittently. I checked the ECU LED and found stored codes 23, 24, 34. I diagnosed the MAF sensor (23), the IAC (24), and EGR solenoid (34) per the FSM and they all checked out fine. The FSM flow charts conclude that the ECU has failed. I don't think I believe that, unless the alternator voltage regulator failure (overvoltage) 18 months ago has just now become an issue. I cleared the codes (actually, I removed the ECU and visually inspected it; looked fine as I had expected). A short test drive brought back the intermittent CEL, mostly toward the end of the drive, and a stored Code 34. I gather from lurking that EGR solenoid failures are not uncommon, although mine electrically checks out. Also, I know EGR failure does not affect performance, so the car would run fine. My car starts and drives just like it has done for 23 years, but the CEL is new and annoying. Aside from fuel pump driver issues, has there been experience with these ECUs starting to fail as they age? I've always thought that if an electronic unit didn't fail right away, it pretty much wouldn't fail at all (assuming no electrical or environmental mishaps). I'll continue to test and monitor the car, but I welcome any thoughts.

Good thought; now I remember reading here that the ones in the heads are known to fail from time to time. There's no apparent leaks, the overflow reservoir loses coolant too, I seem to lose coolant only when driving, and now it's blowing white smoke from the exhaust whenever the engine's running.

Long-time lurker, first post: I have an '88 GL 5 speed D/R 4WD wagon that my family bought new. I have maintained it pretty much by the book since new and it has 213K mostly long distance highway miles. We did have some hot-running problems with it for several thousand miles despite a radiator recore some time back, but a new 2 row radiator fixed that last summer, thanks to USMB's suggestion. The car's been pretty trouble-free other than that up 'til recently. The first issue - I've been losing coolant lately without any noticeable leaks, and just this week the exhaust started puffing white smoke. So I suspect there's a head gasket or head problem, at least. The engine's running good, though, and a compression check shows 165-175 lbs in all cylinders. I'm a little baffled as to how the coolant is getting into the engine (or exhaust), unless it's a crack in the head between a coolant passage and an exhaust port. I've also had an intermittent problem in which the engine would run on 3 cylinders for several seconds after a cold start, and then run fine thereafter. And the #4 spark plug has a bunch of deposits that don't appear on the other 3 plugs. The second issue - last fall, I had a sudden drop in oil pressure after a high RPM run through the gears. The engine also developed the valve lash "tick of death" at the same time, which it had never done before. I replaced the oil pump O-rings per the advice here, and the valve lash tick mostly went away, but it still comes back once in a while. And the oil pressure is still low. It used to run at the 45 PSI mark at 3000 RPM fully warmed up, but now it sits around 30 PSI or so at the same speed. The engine's been using some oil the past several thousand miles - maybe a quart in 1000 miles when it never used any before. There're no oil leaks to speak of - some seepage here and there. The bottom end is quiet - no loose or spun bearings and I know what that sounds like! Now for the repair options - should I pull the heads, replacing/repairing parts as necessary? This would probably resolve the coolant problem, but what of the oil pressure problem? Even if I make sure to reseal the oil passages to the camshaft/lash adjuster galleries, is it likely that this will resolve the low oil pressure problem? Or since I'd pull the engine anyway to rework the heads, should I just replace it? I've a question in to CCR to see what a replacement would cost - that will probably help answer the question. And if I do replace the engine, it's probably not worth the hassle in going to an MPFI engine to gain just a few HP, right? I'm not interested in going to a turbo and I don't have any extra parts to convert from SPFI to MPFI. Unless someone out there wants to explain what it would take and has the stuff available for sale... I welcome any thoughts.