Guest Posted June 9, 2003 Share Posted June 9, 2003 I just got a 1988 with some 179K miles. Engine starts . . then dies about 15 minutes later. Will not restart immediately, but will restart after a few minutes. My first guess is that the fuel filter needs replacement. I don't have a shop manual yet and will appreciate a tip on the first place to look for the filter. <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" /> Link to comment Share on other sites More sharing options...
harry yarnell Posted June 9, 2003 Share Posted June 9, 2003 On an '88, it's on the framerail under the drivers feet. Link to comment Share on other sites More sharing options...
Guest Motu 56 Posted June 9, 2003 Share Posted June 9, 2003 check your codes. It sounds like an electrical problem. I would change the filter first because it couldn't hurt. Link to comment Share on other sites More sharing options...
Guest Posted July 26, 2003 Share Posted July 26, 2003 I just went through an incredibly long and convoluted maintenance process which ended with the replacement of the ECM. I had (among other problems) the EXACT symptoms you've described. I replaced the ECM because it was cheaper than trying the MAF (which I most suspected). Keep in mind that when you swap out the ECM you should keep your original PROM if at all possible. I had to replace that, too, and the car survived, but it's best to keep the original PROM... You're looking at about $150 for the ECM and $60 for the PROM. Don't pay for more than one hour of labor ($60-$85)Just FYI: Most any Jiffy Lube carries the fuel filter and will replace it fairly cheaply. It's easier than digging it out yourself - it's tucked away behind and below the MAF and a pain to work with. Link to comment Share on other sites More sharing options...
padgett Posted July 26, 2003 Share Posted July 26, 2003 I disagree. For the '88 you want the replacement 16123488 "ANCX" ECM PROM - there were a number of problems with the original that were cured with the update. Link to comment Share on other sites More sharing options...
Guest Posted September 1, 2003 Share Posted September 1, 2003 I've done some more expermentation before I lept in with the wallet and wrench because I wanted to understand what might be going on in the engine and controls. So I've done some more reading about how these systems are supposed to work, but I'm technically challenged. The problem is not yet solved but I have this to report.The engine starts easily when cold.The engine (usually - see below) dies when hot (after achieving what I think is closed loop operation.)The engine will not restart until cold again, unless I override the IAC from about 70 to 30 (Or maybe it is the other direction - I'll have to start keeping notes), then will restart and run (roughly) for a short duration before stalling again at idle. I'm guessing that this opens up the air (throddle plate) bypass which the ECM then proceeds to close. Right? Wrong?Once, several days ago, (after the battery had gone below cranking power and I jump started) I started and ran the engine at some 2500 rpm for over 15 minutes without it stalling and then let it idle for about 5 minutes before I shut it off (it did not stall). Both the loop and comp indicators were "lit". Idle rpm had dropped to 725 from the 850 experienced in my earlier trials. The BLM reported on the CRT was 117 . It had been about 128.I thought this was running (a richer program block) but other reading of postings on the Forum and elsewhere seems to indicate it was running leaner.Alas, it would not start again until it cooled(?) down.The sucessful experiment was unsuccessful when repeated.Any insights here on what all this logically means. (Other than I need to go ahead and spring for a new ECM?)Couple of other points on which I'd appreciate some clarification:As I understand it, spark advance is the point at which the plugs fire, usually expressed as, say, 20 degrees before Top Dead Center on cylinder no. 1. Right? Wrong?What is spark retard? If "knock" is deteched by OLDPA3, is the spark advance changed from say 20 degress BTDC to say 15 degrees BTDC? Or is spark retard something different.Is there a "normal" range for the OLDPA3. Would the OLDPA3 probably show high counts, say in the thousands range, if there was excessive engine vibration from either bad motor mounts or a damaged engine?Thanks for your observations and insights.Sincerely,Technically retarded. Link to comment Share on other sites More sharing options...
padgett Posted September 1, 2003 Share Posted September 1, 2003 Have seen knock counts peg almost instantly on starting. Ignore unless you are seeing a lot while just driving.What you are seeing is almost always a gummed up IAC. Usually all it needs is removal and cleaning (I use carb cleaner). Don't forget to clean out the hole the IAC came out of, if the pintle is black there is a good chance there is evem more gunk in the manifold. Link to comment Share on other sites More sharing options...
2seater Posted September 2, 2003 Share Posted September 2, 2003 I am not sure how low battery power has to go before the ECM resets, but if your BLM changed after this episode, it sounds like it may have acted like the battery was disconnected. When this happens the ECM learned memory is cleared and the engines starts in a (safe)default setting stored in the ECM. As the engine is operated, it will relearn the proper settings. It will generally be rich and will gradually lean itself out. If the BLM is at 117, is the integrator around 128? If so, it is operating normally, but I would check fuel pressure. If the fuel pressure regulator has failed, the pressure usually goes high, causing greater than normal fuel delivery, which the ECM will try to compensate for by reducing the injector "on" time.You understand spark timing correctly, although the advance is for every cylinder, but is measured in reference to #1 on a conventional ignition system. The retard is as you surmise, it is reduced from the normal programmed setting, not actually retarded to fire ATDC. I believe ED17 is the knock counts and ED16 is the actual retard (doing this from memory). Timing should show about 20 degrees in a warm engine idling in park/neutral, and should jump up 2-4 degrees when idling in Drive. If it is substantially below this, it is operating in the "limp home" mode. It takes quite a few knock counts to actually retard the timing. You can test the system by giving an engine bracket (something good and solid) a rap with a hammer. The knock counter should register several counts and you can sometimes make the engine stumble if it is idling when you do this. If the counter is constantly advancing when you know there is no knock, you could have false knock from something hitting or possibly an internal engine knock (unlikely). If the knock sensor was removed and reinstalled, it is critical the sensor be installed at the proper torque or it will be overly sensitive. One more thing, if the timing chain has never been replaced, it could be rattling around in there, retarding valve timing, among other things. Link to comment Share on other sites More sharing options...
grm Posted September 2, 2003 Share Posted September 2, 2003 padgett! you mentioned a newer updated prom, where do you get the update one or how can mine be updated. thanks grm Link to comment Share on other sites More sharing options...
padgett Posted September 2, 2003 Share Posted September 2, 2003 The factory update for the 1988 model year only is code ANCX pn 16123488 (whoever issued that part number had a sense of humor). A new one is about $50 with shipping from www.gmpartsdirect.com Link to comment Share on other sites More sharing options...
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