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| Thread ID: 104897 | 2009-11-12 01:29:00 | Car trouble, please help! | biolyte (15417) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 829357 | 2009-11-12 01:29:00 | I just bought a old 1988 chevy cavalier z24, and when i picked it up the battery was dead but we boosted it and i drove it back to my house, then i tried boosting it again and it will fire up but wont stay idling. i have to keep my foot on the gas to keep it from stalling, im not very familiar with cars, is it just cuz i need a new battery or something else?.. :confused: | biolyte (15417) | ||
| 829358 | 2009-11-12 01:43:00 | No battery power left to create the spark, thats why you have to rev to create the charge to feed the spark, new battery required, check alternator too! | SolMiester (139) | ||
| 829359 | 2009-11-12 03:16:00 | If there's enough battery isn't the question but it IS the cause . The Z24 uses an ISC that has to be reset once the battery is disconnected . It requires a bi-directional scanner to do it right and someone who has done the calibration before to make it accurate . I suggest cleaning the whole TB too as it will affect the final settings . The ECM cannot find a baseline for the idle speed that's all . Many times the ISC gets stuck with gunk from years of non-service and poor quality fuels with methanol and waxy build-up from non-vegan lube oils . Drop a can of Chermtool (Berryman's B-12) or SeaFoam in the tank once in a while to keep the ISC and the throttle stop clean so you don't have troubles in the future - well, you will, but put it off as long as you can . Get a NEW battery as the one that went dead is NOT trustworthy any more and it will cause you a lot of grief in the days ahead . Use it for your lawnmower as they aren't computerized and can handle the voltage problems . Your Chevy cannot . This might be a quick fix if the ISC hasn't destroyed itself trying to close against a lot of garbage: Unplug the idle air control valve with the key ON and the engine not running . Shut off the ignition . Reconnect the ISC electrical connector and turn the key to run without hitting the starter position or trying to start the engine - LEAVE KEY ON and the ISC it will cycle a little as it closes all the way to find out where it is, and then re-opens . It also should be cleaned, and can be removed and hosed down with carb cleaner . The ISC usually screws into the front or side of the throttle body, and the port should be cleaned with a spiral brush soaked in the carb spray too . Try to NOT get too much cleaner to flow into the motor of the ISC unit - it is a stepper motor and doesn't like solvents of this composition on the motor windings . A little won't hurt - just don't drown it . Put it back together and go through the same process again of homing and resetting the ISC plunger . It might work - but a bi-directional scanner is the best way . |
SurferJoe46 (51) | ||
| 829360 | 2009-11-12 03:34:00 | Forgot about Model 500 TBI systems (ahem!) If you have that injection system, do it this way: # Turn the ignition switch to the ON position (engine off). # Turn the ignition OFF for ten seconds. # Start the engine and check for proper idle operation. This of course requires that you have a good, fresh and working/charged battery onboard! Unfortunately there were very few of these built and you may not have it this simple. I'm getting old so don't yell. :D PS - under NO circumstances try to move the pintle in or out on a used ISC motor. A NEW one can be moved but after a while if you glom onto it and try to move a used one it will strip the gears. |
SurferJoe46 (51) | ||
| 829361 | 2009-11-12 04:08:00 | The CEL has to be on - so if/when you get some decent idle going, check for CEL codes and let me know . There are some common problems in this engine with the ECM-TPS-ISC and (either) the MAF or MAP/BMAP . Different Chevrolet manufacturing plants used different FI systems and components . It's kinda tricky! :eek: DO NOT clear the codes if you can help it! They will be of great importance later on for diagnosis . :crying ECMs on this model were rife with bad circuit boards and they would act strange especially if they had been teased with a bad battery and an incorrect reference voltage from the diode trio in the alternator . If you can - try to give the ECM (under the dash,, above the glovebox insert, hanging down) a few gently whacks . If the idle changes or the engine dies you need a new (well, rebuilt or used really) ECM . Some particularly nasty codes to diagnose and repair::annoyed: 33 - MAP Sensor 34 - Vacuum Sensor circuit . 35 - Idle speed Control switch circuit shorted . 44 - Lean oxygen sensor indication . MAFs are another trouble spot if you have a dirty air filter or a K&N olied rag filter . DO NOT USE K&N filters on engines with a MAF! It would be better to run NO filter in an active rock quarry than use a K&N under normal driving conditions . |
SurferJoe46 (51) | ||
| 829362 | 2009-11-12 04:17:00 | Aren't you glad you bought this car? :thumbs: | Richard (739) | ||
| 829363 | 2009-11-12 04:21:00 | I'd have one in a heartbeat - they're good-looking, GM quality and the engine is bullet proof as is the transmission. I don't fear any ECM problems and have been working on these for years. Real oil Real gas Real service intervals and these go forever. |
SurferJoe46 (51) | ||
| 829364 | 2009-11-12 07:03:00 | I wonder if you can check for error codes manually (i.e. decipher the ignition or ECU light flash sequences) for that Chevy? I recently found how to do mine for the SR20 engine from Nissan/SR20 internet forums - by bridging two adjacent contacts, with ignition on, where the data scanner/reader is connected (Wish I knew earlier) Thus 55 (5 slow flashes - 2s gap - 5 fast flashes) means/indicates that all sensors are OK (within limits I guess). 12 = ignition circuit, 10 fast flashes/10 sec at 2000 revs for O2 sensor, 21 - AFM, etc. But codes self clear after 50 starter motor turns (as I was told), if error shows no more than once (I think)... |
kahawai chaser (3545) | ||
| 829365 | 2009-11-12 07:50:00 | I suspect, SJ, that in 1988 the New Zealand version may not have had all that anti-pollution stuff. | decibel (11645) | ||
| 829366 | 2009-11-12 16:21:00 | If there's enough battery isn't the question but it IS the cause . The Z24 uses an ISC that has to be reset once the battery is disconnected . It requires a bi-directional scanner to do it right and someone who has done the calibration before to make it accurate . I suggest cleaning the whole TB too as it will affect the final settings . The ECM cannot find a baseline for the idle speed that's all . Many times the ISC gets stuck with gunk from years of non-service and poor quality fuels with methanol and waxy build-up from non-vegan lube oils . Drop a can of Chermtool (Berryman's B-12) or SeaFoam in the tank once in a while to keep the ISC and the throttle stop clean so you don't have troubles in the future - well, you will, but put it off as long as you can . Get a NEW battery as the one that went dead is NOT trustworthy any more and it will cause you a lot of grief in the days ahead . Use it for your lawnmower as they aren't computerized and can handle the voltage problems . Your Chevy cannot . This might be a quick fix if the ISC hasn't destroyed itself trying to close against a lot of garbage: Unplug the idle air control valve with the key ON and the engine not running . Shut off the ignition . Reconnect the ISC electrical connector and turn the key to run without hitting the starter position or trying to start the engine - LEAVE KEY ON and the ISC it will cycle a little as it closes all the way to find out where it is, and then re-opens . It also should be cleaned, and can be removed and hosed down with carb cleaner . The ISC usually screws into the front or side of the throttle body, and the port should be cleaned with a spiral brush soaked in the carb spray too . Try to NOT get too much cleaner to flow into the motor of the ISC unit - it is a stepper motor and doesn't like solvents of this composition on the motor windings . A little won't hurt - just don't drown it . Put it back together and go through the same process again of homing and resetting the ISC plunger . It might work - but a bi-directional scanner is the best way . Umm i really appreciate you helping me but i didnt get what you are saying, i boosted the car lastnight and it idles fine now, but it doesnt die sometimes, im getting a new battery on friday any other suggestions |
biolyte (15417) | ||
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