The engine was running rough, idling high and low, so I changed the CKP Sensor. Also replaced the battery because it was cranking low. After starting up, engine was still running rough, so I took out the IAC valve and noticed it was not working. I cleaned it with electrical cleaner and then tested it again and it worked. While I was at it, I also cleaned the MAF sensor. Now, the engine will crank but will not turn over. Tested all the leads into the ignition control module - voltage and resistance tested fine, so I replaced the ignition control module. Still the engine will not turn over. I sprayed starting fluid in to see iof it might be a fuel pump, but still nothing. Stuck. Help? Where do I go next?
Can position sensor, maybe, or it might be called a pick-up coil. This sensor is needed along with crank position sensor for computer to determine spark timing.
When you get it started, and if you still have the up and down idle, check for an intake manifold leak.
SOURCE: buick lesabre nightmare
Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.
SOURCE: stalls at low idle
start right back up? if it does , then pull the vacuum hose off the fuel pressure regulator and and a stall . if gas comes out of the regulator/and hose. Thats the problem , bad diaphram in fuel pressure regulator!! $45.00 @ auto parts store , snapring pliers is only tool you'll need!! ($5.00 tool) Chep and easy!! :) Hope this helps!! Richie
SOURCE: 1990 buick lasabre with a
1. Monitor the 5v reference, Gray wire to the Throttle Position Sensor
(TPS) with a Digital Volt Ohm Meter (DVOM) set to the MIN/MAX setting.
2. Monitor the TPS signal circuit, Blue wire with a DVOM. Voltage
should range smoothly from approximately 0.44 to 5.0 volts as the
throttle is opened.
3. Tap test the Electronic Control Module (ECM) and see if the codes come back or if the engine reacts.
possible causes wiring or Powertrain Control Module (PCM)
162 views
Usually answered in minutes!
Finally figured it out - throttle position sensor. However, now that it turns over it stalls unless I keep the throttle open. When I do that, the engine revs high and low. I've replaces the IAC valve, the throttle position sensor, the camshaft position sensor, the CKP sensor. Will a scan tell me this? I have a lot of good leads to follow that you all gave me and will be checking all these, but just want to make sure it isn't another sensor.
There might be more codes. Good to check. If none are present, put a vacuum gauge on a vacuum line and see what your manifold vacuum has. If it is low suspect an intake manifold gasket, or a vacuum leak somewhere.
×