Hey R3V,
I've been having this cold start idle issue for at least a year or more. The engine will surge a bit before catching idle. The engine will almost die (sometimes it does) when you blip the throttle and it comes back down to idle off of deceleration. See my video here - https://www.youtube.com/watch?v=6IVx...nel=laidback93
I thought this was fuel related and recently tested the pressure with a gauge. At first the psi was around 43 or so and it kept pressure long after shutting the engine off. I tested it again a few days later and the highest the pressure would get was 30psi. Why, I don't know. Very strange. I might have done something wrong. The gauge wouldn't even move when I tapped the throttle.
Here's what has been done so far:
Smoke test - no vacuum leaks at all
CPS - New
CTS (both) - New
TPS - swapped used
AFM - swapped used
ICV - brand new Bosch - HOWEVER -it doesn't seem to be a free moving as my old one. Someone suggested I lube it up with lithium grease. THOUGHTS?
FPR - swapped with another used one I had in my garage. No change
Fuel Pump - I replaced this with a brand new unit. My old pump was extremely noisy and most likely on it's way out. NO CHANGE
Injectors - I'm running the M50 injectors that do not require a tune. All signs were pointing to one of them being leaky, but now I'm not sure because of this...
I tested a theory last week. Something had been in the back of mind and I proved it to be true. I realized that when I disconnect the battery and reset the DME (I assume) the problem goes away on the initial start up after reconnecting the battery. See this video - https://www.youtube.com/watch?v=7K4v...nel=laidback93
This leads me to believe it's sensor related. The DME must relearn the bad sensor readings and then the cold idle stumble comes back? That's my theory for now.
The only sensor I haven't replaced is the o2. I don't know how old it is. Might give it a shot.
I hope I'm getting close to finally figuring out this annoying issue.
FYI - the problem goes away after about 5 minutes of idling/driving. I'm assuming because it goes into closed loop.
I've been having this cold start idle issue for at least a year or more. The engine will surge a bit before catching idle. The engine will almost die (sometimes it does) when you blip the throttle and it comes back down to idle off of deceleration. See my video here - https://www.youtube.com/watch?v=6IVx...nel=laidback93
I thought this was fuel related and recently tested the pressure with a gauge. At first the psi was around 43 or so and it kept pressure long after shutting the engine off. I tested it again a few days later and the highest the pressure would get was 30psi. Why, I don't know. Very strange. I might have done something wrong. The gauge wouldn't even move when I tapped the throttle.
Here's what has been done so far:
Smoke test - no vacuum leaks at all
CPS - New
CTS (both) - New
TPS - swapped used
AFM - swapped used
ICV - brand new Bosch - HOWEVER -it doesn't seem to be a free moving as my old one. Someone suggested I lube it up with lithium grease. THOUGHTS?
FPR - swapped with another used one I had in my garage. No change
Fuel Pump - I replaced this with a brand new unit. My old pump was extremely noisy and most likely on it's way out. NO CHANGE
Injectors - I'm running the M50 injectors that do not require a tune. All signs were pointing to one of them being leaky, but now I'm not sure because of this...
I tested a theory last week. Something had been in the back of mind and I proved it to be true. I realized that when I disconnect the battery and reset the DME (I assume) the problem goes away on the initial start up after reconnecting the battery. See this video - https://www.youtube.com/watch?v=7K4v...nel=laidback93
This leads me to believe it's sensor related. The DME must relearn the bad sensor readings and then the cold idle stumble comes back? That's my theory for now.
The only sensor I haven't replaced is the o2. I don't know how old it is. Might give it a shot.
I hope I'm getting close to finally figuring out this annoying issue.
FYI - the problem goes away after about 5 minutes of idling/driving. I'm assuming because it goes into closed loop.
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