![]() I have wondered both about the MAF and throttle body. ![]() I have modified relays that I can force to stay on for testing such things but I'll check the fuel pump when cranking also. If none of that pans out check connectors for water.Ī hair dryer comes in handy to isolate cold issues. The throttle body has to be replaced if the TPS is bad. If grease from the throttle actuator gears gets to the TPS you can have a problem. If the TPS reading is out of whack the ECM can think it needs to go to clear flood and it disables the injectors. A loose connector is bad mojo.Ĭheck the TPS when cold. IAT and ECT also set the starting pulse width. It will throw a code, but if it fires at all suspect a bad MAF. Turn to run and give it 10-20 seconds to figure things out, then try to start. Pull the MAF plug and force the engine to run off of the MAP sensor. Bad MAF can set zero or extremely short injector pulses. The MAF is used during starting to determine the fueling required. If the pump is running you should have CKP pulses. After the 2 second pump run with the ignition in run the ECM looks for crank position pulses and energizes the fuel pump relay. Either measure for voltage at the relay socket or listen for the pump. To check the CKP see if the fuel pump is running during starting attempts. Intermittent crank sensors are a common problem on many EFI systems.Ĭold start brings all of the following sensor into play: Cranks sensors provide precise timing (clock) signals to the ecm to allow fuel pump operation, ignition system for spark, and injector pulses. If injector pulses (noid light) aren't generated, either the main injector fuse is blown or the ecm is faulty. Spraying starting fluid into throttle provides fuel if the ignition system for spark is working. An intermittent crank sensor will not allow the ecm to operate the EFI system. The ecm runs only if the crank sensor outputs timing signals as the engine rotates. Injector pulses and spark occurs only if the ecm runs. Cranking without the engine firing up boils down to active security (theft mode), no fuel and/or spark. If security isn't the problem, move on.Īir, fuel and spark are needed for engine running. Ensuring security is off during starting removes security from interfering with normal engine starting/running. Normal security has the indicator blinking once every few seconds. With EFI systems and Passlock factory theft program, Passlock security activates and disables injector operation when security flashes quickly. Anyone have any other advice? wiring diagrams? I'm pretty much out of places to look. Will a bad cam sensor cause it to go dead in the water? I figured the ecm would use the CKP/CPS if the cam sensor went out. So basically I've narrowed it down to no injector pulse. ( tomorrow I'll jump the relays that it needs to run) Swapped relays around to help eliminate a relay problem. Pulled the fuse/relay box from the engine compartment to check for corroded wiring/connectors and everything looks good. Pulled the ignition switch out and froze it and hooked harness back up and it checked out. Also checked resistance of ground and positive cables. Pulled the ecm checked wires and connectors let it warm up inside, reinstalled, and nothing.Ĭleaned all main and engine grounds, cleaned positive from the battery to fuse box. I pulled the bcm on a cold day that it wouldn't start, brought it inside and warmed it up, got nothing. Pulled the timing cover and timing is still dead on.ĬKP CPS whichever checks out 900ohms, I even froze it and put it back in on a warmer day to verify. Sprayed starting fluid into the throttle body and it fired up. But as soon as it warms up I can see the injectors hit. I hooked a noid light up and found I have no injector pulse on cold days. So again it gets colder, seems like anything below 30* and it wont fire up, cranks for days, battery is charged up etc. No antitheft light, no stumble, runs perfect. Couple days later it's upper 30s here and boom fires right up. Everything checked out fine, starts great, runs great, drives alright, then I went out on a cold day to move the car and nothing. Everything went pretty easy and did another compression and leak down test with fingers crossed. I replaced the gear along with the crank seal, cam seals, pulled intake replaced plugs and valve cover gaskets. I found out he misaligned a cam gear while bolting it back onto the cam and ruined the gear. I ordered a gasket kit, figuring if valve to piston contact did happen that I would all the gaskets to do everything. So after this i decided to pull the timing cover off and attempt to set the timing. Her friend didn't get the engine back in time. ![]() Hooked up a leak down tester to it and my suspicions were correct. Checked compression, numbers fell evenly across the front bank. He replaced cam seals and afterward she had running issues. Received this vue from a family member who had it worked on by a friend.
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