Stumble at Startup

[earlrengland]

Needing some advise from the group. I have a 2019 GT350 and have done a few things to it since purchasing it in 2020. One of those things, was removing the IMRC garbage from the back of the engine and locking out the IMRC's because I "thought" they were the cause of my ticking sound between 1500 and 3000 when cold. I had read where some folks claimed they had gummed up on their cars and was causing the same sound I was experienceing. Well, now that I know the ticking is an actual "normal" sound that these engines make, and not the IMRC's, I'm noticing that now the car, when cold, will stumble and almost die when I first start it up, but recovers after about a second or two. Once warm however, there's no startup stumble whatsoever. I "thought" that PBD might of done something wonky with the tune when they deleted the IMRC's, but they claim that my logs look ok, even when the logs show the stumble at startup. Any ideas? I was going to remove my intake again, thinking that I may have missed something when I reinstalled it after locking out the IMRC's, but wanted to get the input from the forum before I waste my time doing it. Any help is greatly appreciated.

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[rolfe.oliver]

Needing some advise from the group. I have a 2019 GT350 and have done a few things to it since purchasing it in 2020. One of those things, was removing the IMRC garbage from the back of the engine and locking out the IMRC's because I "thought" they were the cause of my ticking sound between 1500 and 3000 when cold. I had read where some folks claimed they had gummed up on their cars and was causing the same sound I was experienceing. Well, now that I know the ticking is an actual "normal" sound that these engines make, and not the IMRC's, I'm noticing that now the car, when cold, will stumble and almost die when I first start it up, but recovers after about a second or two. Once warm however, there's no startup stumble whatsoever. I "thought" that PBD might of done something wonky with the tune when they deleted the IMRC's, but they claim that my logs look ok, even when the logs show the stumble at startup. Any ideas? I was going to remove my intake again, thinking that I may have missed something when I reinstalled it after locking out the IMRC's, but wanted to get the input from the forum before I waste my time doing it. Any help is greatly appreciated.

^there be your issue, I believe.

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[Crew4991]

Isn’t it cold up there in Indiana?
I’d almost die too if I woke up one morning in your cold ass temps. Sounds like normal operating engine behavior. Once warm no issues.

 

[JAJ]

Needing some advise from the group. I have a 2019 GT350 and have done a few things to it since purchasing it in 2020. One of those things, was removing the IMRC garbage from the back of the engine and locking out the IMRC's because I "thought" they were the cause of my ticking sound between 1500 and 3000 when cold. I had read where some folks claimed they had gummed up on their cars and was causing the same sound I was experiencing. Well, now that I know the ticking is an actual "normal" sound that these engines make, and not the IMRC's, I'm noticing that now the car, when cold, will stumble and almost die when I first start it up, but recovers after about a second or two. Once warm however, there's no startup stumble whatsoever. I "thought" that PBD might of done something wonky with the tune when they deleted the IMRC's, but they claim that my logs look ok, even when the logs show the stumble at startup. Any ideas? I was going to remove my intake again, thinking that I may have missed something when I reinstalled it after locking out the IMRC's, but wanted to get the input from the forum before I waste my time doing it. Any help is greatly appreciated.

Where did you get the idea that IMRC is "garbage"? It's there to improve torque at low rpm, a useful feature for the Voodoo. With the factory calibration, you'll never know it's there. As for "gumming up", after owning my GT350 for nearly 8 years now, and being on three forums daily, I've never heard of a Voodoo IMRC "gumming up".

And that's why I'm not seeing why you don't just re-enable IMRC and either go back to the stock calibration or get a revised PBD that doesn't try to compensate (unsuccessfully, it seems) for the IMRC delete.

 

[earlrengland]

Isn’t it cold up there in Indiana?
I’d almost die too if I woke up one morning in your cold ass temps. Sounds like normal operating engine behavior. Once warm no issues.

My car won't see the road until around the middle of April, and I never start it during the winter months. The issue with the stumble started happening after the IMRC lockouts that I did during early Summer of last year.

 

[earlrengland]

Where did you get the idea that IMRC is "garbage"? It's there to improve torque at low rpm, a useful feature for the Voodoo. With the factory calibration, you'll never know it's there. As for "gumming up", after owning my GT350 for nearly 8 years now, and being on three forums daily, I've never heard of a Voodoo IMRC "gumming up".

And that's why I'm not seeing why you don't just re-enable IMRC and either go back to the stock calibration or get a revised PBD that doesn't try to compensate (unsuccessfully, it seems) for the IMRC delete.

JAJ, by "garbage" I meant the unsightly nature that the IMRC's gave to the looks of the engine bay. Personal preference I'm sure, but that was my opinion of the visuals of it. Couple that with the probabilty that the IMRC's might of been the cause of the tick I was hearing, it didn't bother me to remove them. The other reason I removed them, was I had planned at some point to boost the car, which required them to be locked out anyway, so I figured it was one of those 2 birds, 1 stone scenarios. Fix the tick and get ready for boost. I've not done the boost yet, and the tick is still there, albeit I learned it to be a normal thing for these engines, and as for them "gumming up", I've read several stories about them gumming up with oil and sticking, and I can tell you, when I removed the intake manifold, I did see what appeared to be an oily substance on the runners.

 

[JAJ]

JAJ, by "garbage" I meant the unsightly nature that the IMRC's gave to the looks of the engine bay. Personal preference I'm sure, but that was my opinion of the visuals of it. Couple that with the probabilty that the IMRC's might of been the cause of the tick I was hearing, it didn't bother me to remove them. The other reason I removed them, was I had planned at some point to boost the car, which required them to be locked out anyway, so I figured it was one of those 2 birds, 1 stone scenarios. Fix the tick and get ready for boost. I've not done the boost yet, and the tick is still there, albeit I learned it to be a normal thing for these engines, and as for them "gumming up", I've read several stories about them gumming up with oil and sticking, and I can tell you, when I removed the intake manifold, I did see what appeared to be an oily substance on the runners.

Ok got it. So, the best "fix" is to get going on the boost project, right? Solves the appearance problem and the stumble in one shot.

The tick is probably "piston slap" and it's a common feature of engines built to operate at high power levels. Mine does it. These engines are built with a bit more clearance between the pistons and the bores to allow the pistons to expand as the engine heats up under high loads. Not all of them do it, but it's not a problem and it usually fades away once the pistons have had a chance to expand a bit as the engine warms up.

 

[tampasnake]

My car has had that stumble since new. It also on occasion has that same stumble when coming up to a stop light or at a light in traffic. It used to be worrisome, but I'm used to it now. Mine is stock with the stock tune.

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