Folks,
I'm hoping for some insight, I've been getting pretty frustrated with my inability to troubleshoot an ongoing issue. About 8-9 months ago I started having very intermittent power cuts. Note I say power CUTS, not losses. The best way to describe what happens is that it's like the accelerator pedal cable momentarily disconnects. I'll be driving along, and the engine instantly loses all power and RPMs start slowly dropping to idle. No dash lights, other noises, shuddering or anything to accompany; I’m just coasting. I’ve tried shifting into neutral or to lower gears, doesn’t make a difference. Then, usually after just a few seconds, the power surges a couple times and comes back. And then it might not happen again for a week, or it might happen a minute later. There a days when it runs fine all day (this is my daily driver).
A few things worth noting:
— During these power losses, the accelerator pedal is DEAD. If I press the pedal, no response at all.
— There’s not much rhyme or reason to when this happens. It happens early morning while coasting downhill at 35mph or while 85deg out and going uphill at freeway speeds. It seems to be a little more frequent when it’s very warm outside.
—The power loss never lasts more than 10-15 seconds. Sometimes it’s just a momentary blip like I lifted off the pedal for a second, other times longer but power always comes back.
— I’ve done all kinds of electrical testing in the ignition circuit (relays, connectors), and can’t find any voltage losses anywhere. The ignition coil is still getting power during these losses.
I’m starting to suspect my trans. is somehow slipping and/or failing. I don’t know if the TCU can cause the engine to stop responding to accelerator inputs. I’ve read a little about the A-clutch being the common failure, but here’s where I’m looking for input.
***A couple questions for the crowd***
Can the 4HP22EH fail in this manner, i.e. total power loss, then "come back to life"?
Can the TCU cause the engine to go to idle?
Here's what I've replaced in the past year (that could be suspect)-
Main/Fuel pump relays
Ignition wires, dizzy cap, rotor
Spark plugs
O2 sensor
Injectors (flow-balanced, new filters/seals, all resistance checked OK)
Bell housing speed and reference sensors
Vacuum hoses
TPS (it's the uncommon multi-switch one, and operates as advertised)
All engine grounds cleaned, new straps installed
Both fuel pumps confirmed working, wires checked
Thanks to everyone in advance. I’m banging my head against the wall here.
Pete
I'm hoping for some insight, I've been getting pretty frustrated with my inability to troubleshoot an ongoing issue. About 8-9 months ago I started having very intermittent power cuts. Note I say power CUTS, not losses. The best way to describe what happens is that it's like the accelerator pedal cable momentarily disconnects. I'll be driving along, and the engine instantly loses all power and RPMs start slowly dropping to idle. No dash lights, other noises, shuddering or anything to accompany; I’m just coasting. I’ve tried shifting into neutral or to lower gears, doesn’t make a difference. Then, usually after just a few seconds, the power surges a couple times and comes back. And then it might not happen again for a week, or it might happen a minute later. There a days when it runs fine all day (this is my daily driver).
A few things worth noting:
— During these power losses, the accelerator pedal is DEAD. If I press the pedal, no response at all.
— There’s not much rhyme or reason to when this happens. It happens early morning while coasting downhill at 35mph or while 85deg out and going uphill at freeway speeds. It seems to be a little more frequent when it’s very warm outside.
—The power loss never lasts more than 10-15 seconds. Sometimes it’s just a momentary blip like I lifted off the pedal for a second, other times longer but power always comes back.
— I’ve done all kinds of electrical testing in the ignition circuit (relays, connectors), and can’t find any voltage losses anywhere. The ignition coil is still getting power during these losses.
I’m starting to suspect my trans. is somehow slipping and/or failing. I don’t know if the TCU can cause the engine to stop responding to accelerator inputs. I’ve read a little about the A-clutch being the common failure, but here’s where I’m looking for input.
***A couple questions for the crowd***
Can the 4HP22EH fail in this manner, i.e. total power loss, then "come back to life"?
Can the TCU cause the engine to go to idle?
Here's what I've replaced in the past year (that could be suspect)-
Main/Fuel pump relays
Ignition wires, dizzy cap, rotor
Spark plugs
O2 sensor
Injectors (flow-balanced, new filters/seals, all resistance checked OK)
Bell housing speed and reference sensors
Vacuum hoses
TPS (it's the uncommon multi-switch one, and operates as advertised)
All engine grounds cleaned, new straps installed
Both fuel pumps confirmed working, wires checked
Thanks to everyone in advance. I’m banging my head against the wall here.
Pete
Is my 4HP22EH dying? Power loss accompanied by sanity loss--
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