My new 347

[Dono]

Thanks 4pointslow.
James thinks everything looks great also. The truck feels good also, I'm in to the final tweaking of minor annoyances. These can be the most difficult I think.

I'm still struggling with a 'hanging' idle that stays high until I'm physically stopped.
This is where I get confused. Is it mechanical, or in the tune? This is where is would be awesome to understand more about what can be adjusted, and if it doesn't adjust in the tune to look for a mechanical item. Back to education and understanding.
I adjusted my idle screw on the throttle body a couple of months ago with the iac valve unplugged. Maybe I opened up the butterfly too much? I'll start with that.

Also, my truck is a hard starter when its warm. From dead cold it starts great. I wonder if the pcm will learn idle trims? Back to having no clue.

 

[Turdle]

Thanks 4pointslow.
James thinks everything looks great also. The truck feels good also, I'm in to the final tweaking of minor annoyances. These can be the most difficult I think.

I'm still struggling with a 'hanging' idle that stays high until I'm physically stopped.
This is where I get confused. Is it mechanical, or in the tune? This is where is would be awesome to understand more about what can be adjusted, and if it doesn't adjust in the tune to look for a mechanical item. Back to education and understanding.
I adjusted my idle screw on the throttle body a couple of months ago with the iac valve unplugged. Maybe I opened up the butterfly too much? I'll start with that.

Also, my truck is a hard starter when its warm. From dead cold it starts great. I wonder if the pcm will learn idle trims? Back to having no clue.

I also noticed the "hanging idle" when rolling, even when I shifted to neutral for the roll before stop

http://www.explorerforum.com/forums/showthread.php?t=191880

 

[Dono]

Thing is, I would have noticed this before. I didn't have this issue till my idle was bumped up.
I'm not ready to call this 'normal', call me stubborn.

 

[CDW6212R]

...

I'm still struggling with a 'hanging' idle that stays high until I'm physically stopped.
This is where I get confused. Is it mechanical, or in the tune? This is where is would be awesome to understand more about what can be adjusted, and if it doesn't adjust in the tune to look for a mechanical item. Back to education and understanding.
I adjusted my idle screw on the throttle body a couple of months ago with the iac valve unplugged. Maybe I opened up the butterfly too much? I'll start with that.

Also, my truck is a hard starter when its warm. From dead cold it starts great. I wonder if the pcm will learn idle trims? Back to having no clue.

The idle speed adjustment screw is a delicate item not to be messed with, it doesn't operate like the simple old method of a carb idle speed screw. It operates together with the IAC, and the computer. There is a procedure to set it properly, where it should be when stock, and when someone moves it.

I suggest finding that procedure and beginning with that. Then be sure the IAC is working great, which is really the only finicky part that gives fits sometimes.

 

[CDW6212R]

BTW, if you can, avoid Accel parts. They are on my black list for the one Accel coil pack that died on me a few years ago. It was only a year or so old with less than 5000 miles on it, and when hunting a miss I looked at everything else before going back to the coils. A new part like a coil pack should last a long long time in normal use.

I have had some Accel wires too, from about 1982 on a Cleveland. Those were cut to fit and crimp the ends on too. They worked okay, but I didn't have the car a whole lot longer after that.

If you can't find a reasonable wire set, I'd sell you my used ones, which are likely at about 60k miles.

 

[Dono]

There's a thread here on adjusting the idle set screw to just below commanded idle with the iac unplugged. That's what I did, and it did help at the time. I do need to check now, and make sure things haven't changed. I need to start somewhere.

I have heard about tons of bad experiences with aftermarket coil packs, so I think I'll stick with my factory ones.

 

[CDW6212R]

Yeah, the OEM coil packs do well, and it's the same part used on every 4.6 up to 1999 when they got the coil on plugs(COP) system. If I choose a new coil pack again, I think the DEI(Screamin Demon) are very good too. They have a great reputation for the V6 versions and I have one.

 

[VR4]

Hanging idle is IAC control in the tune

Edit: didn't see the screw was messed with. Good luck. Very tough to get that right

 

[Dono]

Hanging idle is IAC control in the tune

Edit: didn't see the screw was messed with. Good luck. Very tough to get that right

The butterfly screw is set ok. I pull the iac valve connector and the idle drops significantly. No doubt in my mind its pcm controlled (Although, I'm wrong quite a bit).
I think I really need to learn this stuff.

 

[CDW6212R]

The butterfly screw is set ok. I pull the iac valve connector and the idle drops significantly. No doubt in my mind its pcm controlled (Although, I'm wrong quite a bit).
I think I really need to learn this stuff.

There is a proper way to set that TB screw, and I've seen it mentioned most often on the SBFtech forum. They bring it up whenever there is a chance someone adjusted it. It should never be adjusted, when it's known to be right(by procedure, not idle speed or driver opinion).

 

[Dono]

I understand that the iac is adjusted by the pcm to reach the commanded rpm. No issue there.
If the adjustment screw creates an out of range situation on either side, the pcm can try to reach the desired idle but the mechanical out of range condition will not allow it.

This drivers opinion is that he understands that the iac and adjustment screw works perfectly as it sits. There is no out of range condition happening.
Are you going to tell me that a bigger motor does not require more air to idle? I would think logic, math, whatever, suggests it does. Others have solved their Idle issue by adding holes to their flapper when his iac was out of range with their 347's. I chose to move my adjustment range by attempting to open the flapper slightly with the adjustment screw. I fail to see the voodoo here. The logic seems pretty straight forward.

If I pulled my iac connector and the idle did not drop, I would know I'm out of range. I am not. The pcm opens the iac until desired (commanded by the pcm) idle is reached. Works perfectly on my truck.

 

[4pointslow]

TPS voltage

TPS voltage is also important.
If the throttle stop is adjusted up too far the TPS voltage could be too high.

Can you get a voltage reading off the TPS with the engine idling? (not with X3)
Use a voltmeter or scan tool.

Also what is the RPM when the IAC is unplugged? It should just about idle with the IAC unplugged. If it Idles higher than normal, then when the IAC closes the RPM will still be too high.

If the RPM and TPS voltage are OK then there are things in the tune that can be adjusted. The PCM learns adjustment to the IAC and it is stored in memory until the PCM has its memory erased (battery disconnected/KAM reset)
Justin Starkey from VMP tuning had some instructions on tuning the IAC adjustments in the tune on his website years ago that I experimented with and had very favorable results with. Of course you would have to have James do yours and I am sure he could but you will need to check the TPS voltage and RPM before you have him do that.

There is also something called the dashpot effect where the IAC follows TPS movement when you open the throttle. It is there to prevent stalling on deceleration. When you open the throttle the IAC opens, when you let off the throttle real fast because you just saw the man with red and blue lights on his roof the IAC closes but it happens slower to prevent stalling. In cases where the vehicle has been seriously altered the RPM can hang too long or not at all, so you could have a hanging RPM or stalling. A plunger attached to carburetors used to catch the throttle linkage and slow its closing to prevent stalling on decel. It was called a dashpot, thus the name dashpot effect.

Let me know what you find with the TPS voltage and RPM at Idle and I will try to help as best I can.

 

[Dono]

Thanks 4pointslow.
I'll take measurements tonight.

Lastnight, I listened to the rpm's when I unplugged the iac and the idle dropped way down, but the truck was not in danger of stalling. I'll log the exact rpm.
I'll check and post TPS voltage tonight also.

This is appreciated as its all but impossible for someone to tune when there is a mechanical issue.

James sent me an update today, and he has all but cured the hard starting when warm. I'll know for sure with a few more days of driving.
He also made some adjustments to rolling idle. It is better, but the truck still pulls much harder than it should with my foot off the gas and sounds like the motor is racing.

As a side note, I'd never be able to to take my foot off the gas at 65mph and idle below 40mph without braking or finding a hill. Hill's are hard to come by here, were super flat.

James is being very helpful and sticking with me on this. I'm sure it is extremely frustrating for him trying to make these adjustments without actually getting seat time in the truck.

 

[Turdle]

A 1/8" hole drilled into the throttle plate is how I got the idle to raise a bit without messing with the idle set screw. Setting that screw will mess with the TPS idle set point and might cause a need to "oval" the TPS mounting holes.

Without this hole the IAC was working overtime trying to hold idle.

 

[Dono]

Thanks Turdle. It is possible that my tps voltage is off, making tuning difficult.
I'll make sure the voltage is correct. I never did really adjust the screw a whole lot, but it is very likely enough to throw off the required voltage letting the pcm know the plate is closed.
I now understand the wisdom of a small hole in the throttle plate.

 

[CDW6212R]

A 1/8" hole drilled into the throttle plate is how I got the idle to raise a bit without messing with the idle set screw. Setting that screw will mess with the TPS idle set point and might cause a need to "oval" the TPS mounting holes.

Without this hole the IAC was working overtime trying to hold idle.

Ditto, adding the small hole to a throttle plate is the ideal way to adjust idle air and maintain the intended gap of the blade(s) at idle. For a carb, that is a critical issue because the idle and transition bleed holes/slots are right where the blade edge is.

I think the gap for the blade is not so critical, but the IAC's are made to adjust the idle air over a certain capacity of air flow, a range. The added 1/8" or so holes helps the IAC stay in it's best range.

 

[Dono]

tps voltage was about 1.1v.
My reading says this 'should' be within range, but I decided the best route to go is follow Turdles lead.
I dropped the tps voltage down to .0987 and made a bigger breather hole in the flapper. I brought the hole up to 15/64" and then re-flashed the pcm with the latest tune to clear any idle memory.

I haven't had any seat time, but this seems much better already. With the iac unplugged, I have an idle of around 500rpm, and with it plugged in I'm around 1k. In gear, the idle doesn't rise crazy high like it did before.

I'll get some driving time in, and then I'll know if I'm there. 1k is a bit high for me, as my cam has an lsa of 114 so it can definitely support a lower idle, but I think this is going to be acceptable.

Thanks for the tps voltage reminder guys, I had actually adjusted that set screw when I had my 302 in the truck, and there were no ill effects at all with that motor. I had all but forgotten I had done that.

 

[4pointslow]

347

How is the tuning going?
Do any WOT pulls yet? How does it feel?

 

[Dono]

Nope. I'm out of town till Friday.
James did ask that I elongate the tps holes slightly to get the tps voltage down to .97 to make sure its not going to be an issue.
A muffler was ordered for my truck. I was hoping to fit something after the turbo, but there just isn't room. So, next best solution is a 2-1 flo-pro that's the same as the magnaflow, just larger. I'm not completely happy with this solution, but I'm sure its a worthwhile tradeoff. Lets just say my neighbor is excited about me taming the beast as I wake him up every morning leaving for work. This happens on Friday.

I also need to see if I can get my iat's down. 164 degree's isn't doing me any favours. James would like to add a bit of timing, but I'm already hearing some detonation, so the way it sits it needs timing pulled.
Now that the motor is in, I need to keep going and get the radiator and pump mounted so I can get some coolant pumping in to the intercooler.

 

[Dono]

What was supposed to be an exciting thing for me has turned in to an absolute nightmare that just keeps re-occurring.
Went BOOM.
.....................again.

Shoot me.

Cam bolt sheared. Then the cam positioning dowel sheared. Then....Who knows what happens when pistons are moving at a different speed than the valves are moving.

So, See carnage pics showing the cause of the rest of the "yet to be determined determined" damage.
The picture showing the cam gear part way off with the (half) locating dowel still perfectly seated in the gear is kinda funny. I texted it to Tim last night, and he had one of those WTF moments as it just doesn't make sense. At least you can see my oil pump drive gear is still good. :shifty_ey


Tim's already all over this. He thinks we can have the motor out this weekend. Really, the faster I can get the motor apart and to the machine shop the better.

I do question if the cam bolt was an ARP bolt, but whatever. The damage is done. So...Can anyone guess what the next failure will be after this? I just shook my wallet while it was upside down and nothing came out.