ecm open loop question
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From: maui.HI
ecm open loop question
I'm probably going to get bashed by asking this question because it pertains to a ch@#Y but I've tried posting on 3 different forums of that type of truck and got absolutely no replies so here goes my question. I've got an 89 4.3 engine that I start and run on an engine cradle. It runs quite well except that it does not go into close loop, even after it reaches normal operating temp. I veiw this on an autoxray scanner connected to the aldl plug. I figured I'd try here because most OBDI run on the same principle and alot of you guys work on vehicles other than Fords. My question is what might cause the ecm to not go into close loop? Is it because the engine is not actually driven? All the sensors seem to be within specs e.g. TPS idle, TPS wot, CTS, MAP, and O2 fluctuating between .4 to .7v. sorry guys but thanks for any replies.
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From: Louisville,Ky.
Well, we'll let you slide on the brand X thing this time 
If it is reaching over 180* than it should go into closed loop I would think.
Are there any fault codes showing that may keep it from going closed?
Are there any sensors that are not hooked up such as transmission gear/ lock-up converter or clutch pedal switch? VSS perhaps?
What is the harness out of?
If it is reaching over 180* than it should go into closed loop I would think.
Are there any fault codes showing that may keep it from going closed?
Are there any sensors that are not hooked up such as transmission gear/ lock-up converter or clutch pedal switch? VSS perhaps?
What is the harness out of?
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From: maui.HI
Lxman I knew you'd catch this one but I bet your wrenches spend countless hours turning bolts other than Fords huh? LOL
The harness/ecm is the stock 4.3 tbi from the same truck. It seems my readings on the scanner shows no flat spots on the TPS. O2 seems to react when a vac. hose is removed, But I know that the ecm is ignoring while in open loop. MAP values also change and there are no existing codes. I've even disconnected the battery several times hoping it would close. CTS even goes up to 197 deg.
The only thing I can see is one cylinder is burning oil. Not really that bad. I'm wondering if the engine needs to be driven on the road and see trans lockup? I hate to drop this into my project and end up removing the efi system. Oh one more thing, the cats been removed by the previous owner.
Thanks
The harness/ecm is the stock 4.3 tbi from the same truck. It seems my readings on the scanner shows no flat spots on the TPS. O2 seems to react when a vac. hose is removed, But I know that the ecm is ignoring while in open loop. MAP values also change and there are no existing codes. I've even disconnected the battery several times hoping it would close. CTS even goes up to 197 deg.
The only thing I can see is one cylinder is burning oil. Not really that bad. I'm wondering if the engine needs to be driven on the road and see trans lockup? I hate to drop this into my project and end up removing the efi system. Oh one more thing, the cats been removed by the previous owner.
Thanks
Last edited by mauicruza; Feb 15, 2008 at 03:01 AM.
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