msc171025

Hey everyone, I have a 3VZE that's been just recently having starting problems. I get in the truck, turn the key to start and the starter starts doing its thing but the engine will just not turn over unless i start pumping the gas pedal. After about 5-7 sec of cranking and pumping the truck fires up and runs like a charm, it idles bad at first but as long as i keep giving it gas for a few seconds it will stay idling by itself. I have no check engine light and it happened on Saturday morning just all of a sudden. (before it cranked and turned over no problem every time) Because it happened so suddenly i am guessing its an electrical problem and not a mechanical one since i haven't had any slow problems leading up to it. I looked at some other peoples threads with somewhat similar problems and wiring diagrams; I am thinking it might have to do with my Start Injection Time(SIT) switch, but I am just not sure. Any help or maybe some advice from someone who's had the same issue would be greatly appreciated.

Thanks Mike

ps When its a cold start it starts up without me having to pump the gas pedal. What the heck!!!!????? It just cranks and starts like normal.

pps I have already added some Heat with fuel injector cleaner in it to maybe see if its just bad fuel or my injectors are fouled up to eliminate those root causes from my problem list. (haven't made it through the tank yet)

msc171025

Alright update, so since that last post i have added sea foam to the oil, vacuum lines, and fuel and none of that has made a difference. I also took my air intake hose off and sprayed the crap out of the throttle body with 3/4 of a can of throttle body/air intake cleaner. Again no difference. The next thing i did was removed the cold start injector and cleaned that off also cleaned up the hole it sits in.

This surprisingly helped when i turned my car over it started right away and did so the rest of the day. In addition to cleaning the cold start injector I tried pushing on the cold start injection timing switch plug to see if it was not seated properly. I also sprayed it with some electrical cleaner.

Unfortunately after work the next day it went back to the way it was before i started messing with the cold start injection stuff; okay cold start, hard to start when warm (have to pump the gas pedal).

msc171025

It was my cold start injector! yep i finally gave up and took it to the stealership. So what was happening was that my cold start injector was constantly adding fuel into the air fuel mixture which was causing me to run rich. It also was causing the starting problem because my engine would be flooded with fuel. The problem had gotten much worse and because of the that the black crap was coming out of my tailpipe. (Result of bad air fuel mixture) Anyways the stealership wanted.... 500 dollars!?!?!?!?!?!? Heck no. They wanted to change my spark plugs out because they said that they were probably fouled up from running rich. I ended up still paying about 250 because of diagnosis and the cold start injector. I replaced the cold start injector myself. I am going to replace my plugs later when i change my oil. What makes no sense to me still, is how was it helping when i pumped my gas pedal to start the truck if the engine was already flooded with fuel .... :/? Well anyways problem solved.

Steve Weldon

Thanks. You're right, understand it, say it..

What I understand so far is that the o2 fault comes from either the sensor itself, the harness, or the circuit housed in the ECU?

If it is the ECU, are there any board layouts and schematics with component values?

Much appreciated.

Terrys87

iTrader: (1)

The ECU is very solid and nearly trouble free. I am not aware of any schematics of the ECU and sure there could be some where. I would suspect the AFM as I have seen several bad but never throw a code. Only time I ever got a code was when the harness was not plugged in. I would check and see if the flapper is moving freely. It sounds to me that it could be a little sticky and it is taking it a while for it to move which then engages the COR that then engages the fuel pump.