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What's wrong with this picture...

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MechRick
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Posts: 869
Joined: Wed Jan 04, 2012 7:43 pm
Location: Las Vegas, NV

What's wrong with this picture...

Post #1 by MechRick » Thu Apr 18, 2019 8:06 pm

I was diagnosing an emissions failure on a 4.9L F150 today. It was blowing 1300 ppm HC and 13% CO.

Thought I would share an image of the engine compartment. The owner has had a few different mechanics (using that term loosely) working on it.

See if you can spot what was wrong with it.

Image

Silver star goes to the one(s) that figure it out.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

Mdixon300f100
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Posts: 157
Joined: Wed May 02, 2018 6:43 am

Re: What's wrong with this picture...

Post #2 by Mdixon300f100 » Thu Apr 18, 2019 8:19 pm

You want a public reply?

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MechRick
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Posts: 869
Joined: Wed Jan 04, 2012 7:43 pm
Location: Las Vegas, NV

Re: What's wrong with this picture...

Post #3 by MechRick » Thu Apr 18, 2019 8:28 pm

To give others a chance, PM me or let it marinate for a while. :D
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

arse_sidewards
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Posts: 845
Joined: Mon Jan 21, 2013 7:18 am

Re: What's wrong with this picture...

Post #4 by arse_sidewards » Fri Apr 19, 2019 7:59 am

It'd say the fact that a vehicle that's pushing 30 is subject to emissions testing is what's wrong with it. The fact that someone replaced the alternator without just swapping in a 3G also seems pretty wrong too.
1994 F150 4x4 8ft, engine is basically stock.

66" leafs, extended radius arms, lockers in both ends, nothing special.

Backwoodswalker375
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Posts: 22
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Re: What's wrong with this picture...

Post #5 by Backwoodswalker375 » Fri Apr 19, 2019 8:11 am

Pm sent.

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MechRick
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Joined: Wed Jan 04, 2012 7:43 pm
Location: Las Vegas, NV

Re: What's wrong with this picture...

Post #6 by MechRick » Fri Apr 19, 2019 10:33 am

Ding! Ding! Ding!

We have two winners so far...

The coveted fordsix silver star goes to arse_sidewards and Backwoodswalker375 who both spotted the problem.

Bonus points to arse_sidewards for noticing the missing purge valve. Since it's speed density, that will make it idle fast.

I'll post an after picture tomorrow morning.

Anyone else?
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

arse_sidewards
Registered User
Posts: 845
Joined: Mon Jan 21, 2013 7:18 am

Re: What's wrong with this picture...

Post #7 by arse_sidewards » Fri Apr 19, 2019 11:13 am

MechRick wrote:Bonus points to arse_sidewards for noticing the missing purge valve. Since it's speed density, that will make it idle fast.


I wasn't sure I was going to mention that because I've seen so many trucks like that I figured it was configured like that from the factory sometimes. :lol:
Last edited by arse_sidewards on Sat Apr 20, 2019 10:04 am, edited 1 time in total.
1994 F150 4x4 8ft, engine is basically stock.

66" leafs, extended radius arms, lockers in both ends, nothing special.

Nebr Rex
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Posts: 3
Joined: Sun May 28, 2017 8:02 pm

Re: What's wrong with this picture...

Post #8 by Nebr Rex » Sat Apr 20, 2019 7:13 am

The injector in the picture looks to be a 19 lb. . The original is smaller is it not?


.

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MechRick
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Joined: Wed Jan 04, 2012 7:43 pm
Location: Las Vegas, NV

Re: What's wrong with this picture...

Post #9 by MechRick » Sat Apr 20, 2019 10:10 am

Yes, Nebr Rex. along with arse_sidewards and Backwoodswalker375, your sharp eyes noticed yellow top injectors rated at 19 lb/hr installed where gray tops are supposed to be (14 lbs/hr).

Image

Truck had a stuck open thermostat and fuel-contaminated engine oil (gee, I wonder why?). I went back for a second look, I knew that couldn't account for the HC and CO numbers.

With the correct injectors the truck is down to 14 ppm HC and less than 1% CO.

For further consideration, because we tend to modify our trucks...this is not the correct way to add fuel. The stock speed density computer isn't capable of dealing with larger injectors. The fueling range between idle and wide open throttle is fixed in firmware and won't change even if the fuel pressure is dropped to bring the idle air/fuel ratio into focus. A MAF computer running a larger than stock MAF housing calibrated to injector size works to some extent. An aftermarket tuneable ecu is the preferred method, but of course federally and in many jurisdictions that's illegal (what's that, a sick bird?). One of the problems with modding the big six (or any off the wall engine, for that matter) is the lack of EO-stickered parts.

Anyway, Bruce and crew are close to production heads that will flow significantly more air at wide open throttle. The stock speed density ecu isn't going to cut it, and adding larger injectors just makes things worse.

Thanks to all those that responded for playing along.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

sandboxer
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Posts: 234
Joined: Mon May 23, 2011 4:34 am

Re: What's wrong with this picture...

Post #10 by sandboxer » Sat Apr 20, 2019 1:09 pm

Very valuable information!
Thank you for sharing.

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