Engine Issues after deleting DOD/AFM on rebuilt engine

[NathanS]

I have an 07 Z71 Tahoe. I started on deleting all the DOD/AFM mechanical parts. Once I got down to the short block I decided to pull the engine and send it to the machine shop for a rebuild. New bearings, piston rings and had the cam ( Texas Speed stage 2 .600 lift) degreed while it was there. New valve seats and springs on the heads. Trunion upgrade kit on the rockers and hardened pushrods installed. New Cam, Crank, Knock, oil level sensors. New 1 3/4 longtube headers from speed engineering with their y-pipe. I have AFP engine mounts. I also installed a new Circle D converter.

I got everything back together and I'm having some issue. I have not pulled any codes.

The truck is only running on 4 cylinders(1,4,6,7 not firing), won't rev above 4K, dash says stabilitrak issues, traction control , etc.

I only have the front O2 sensors plugged in. I had planned on getting it dyno tuned and did not think I needed to delete AFM for it to run right.

Without pulling the codes what can I check to see what will fix this.

I did rotate the engine with the coil harness unplugged to get oil pressure before starting the engine.

 

[randeez]

Did you remove the DOD function out of the tune?

Sorry, Didnt read where you said you hadn't tuned it yet

 

[NathanS]

Haven't got it tuned yet.

 

[randeez]

Without the vlom plugged in it defaults to 4 cyl mode. You're going to need to get it tuned

 

[NathanS]

 

[LanceD]

Nice! Yep gotta get it tuned out.

 

[Wolfbraid]

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Its pretty... I wish mine looked like that. with all the goodies too.

 

[NathanS]

I worked pretty hard to get it finished. In all my research in deleting the DOD/AFM this never came up. I thought it would just throw a CEL until I got it tuned. I would have sent my computer off and took care of it during the rebuild. Lessons learned I guess. Once I get it tuned I’ll post up the results.

I plan on having Mad Tunes Racing dyno tune it.

 

[undy]

Hope you didn't go with the Comp trunnion upgrade. They're a POS. They wear prematurely while sending metal shavings coursing through your oil system.

 

[RST Dana]

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Block color reminds me of old school mouse and rat motors I used to build.

 

[buddyhotrod]

That motor really looks good.

 

[NathanS]

To get it running on all 8 until I get it tuned I plugged in the old valley plate and zip tied it to the firewall. Not sure if I should be worried but it backfires every now and then. Haven’t drove it much yet. Still need to break in the rings.

 

[iamdub]

Ehrmahgerd. lol

I must applaud your ingenuity, though!

I'd be concerned that the backfiring is from the four AFM cylinders flooding. Or would it be running lean? Hmmm...

Maybe try to drive it in such a manner that keeps AFM from activating to reduce the backfiring and chance of damage?

 

[NathanS]

The tuner suggested that I plug in the old plate. Can’t take credit for that one. Texas speed said its backfiring due to AFM and not being tuned yet. Should be getting it tuned next week. Hopefully.

 

[NathanS]

My schedule didn’t allow me to take it to the dyno. I got a tuner to do it locally. Works at Steve’s Automotive in Saucier MS. He used HPtuner. Deleted AFM, changed shift points and line pressure. Changed a bunch of stuff I don’t know about. Air. Timing. Idle. It idles and runs really good. Very nice guy.

These guys completed the exhaust after the speed engineering y-pipe.
performanceofgpt.com
Outstanding customer service. Look them up if you’re in the area.

 

[NathanS]

I went with a 3” single in/out 18” magnaflow muffler with 3” tubing. I’m liking it more and more. Has a deep growl at idle but opens up at WOT. No real noise cruising at 75. Maybe a little from the headers.

 

[Ls2jorge]

Any Update on your build bro? Any vids of the Tahoe

 

[NathanS]

No vids. It’s running good. I’ve put about 5k miles on it so far and I’ve towed three trailers. One weighing about 5500 lbs. The exhaust it a little loud but t sounds mean. Averaging around 12-13 mpg.