Engine boggs @3500 after sparkplug replacement gapped at .045

[Alexb]

Hey guys,

I am hoping someone can give guidance here. I have a new 8.1l suburban 2001. I just added a throttle body spacer and replaced my plugs and wires. I gapped them at .045 with Ac delco 41-993 iridium plugs. I used taylor thundervolts 82225.

The engine runs great up to 3600 rpms. Then it is bogging. I have two guesses as to the problem.

1. The spark plugs are not firing properly at that rpm.
2. The air to fuel mixture is off due to the new throttle body spacer. Airaid PowerAid TBS Throttle Body Spacers 200-512-1.

I have removed all the plugs and wires to check for damage. They all look fine. I was under the impression gapping at .045 was supposed to make the 8.1s perform better at high rpms.

It also could be the throttle body spacer is making the air much more dense at high rpms.

More background info. I just cleaned the MAF. which is a Delphi and looked like it was replaced recently. I also scrubbed and cleaned the throttle body. I started the truck and it ran fine after cleaning the throttle body and before putting it on.

I am also In the process of getting a custom tune from diablo Lewis. I am hoping he will be able to help me with air/fuel mixtures and that will resolve the issue. Otherwise I will replace the plugs with standard .060 gapping to see if that fixes it.

Anybody experience this or know which direction I should head in?? Thanks and I will try to upload the video I took.

 

[Sasquatch]

I would start by removing the spacer and see if you can get a refund because they are proven to do absolutely nothing but drain your wallet.

 

[Alexb]

Yeah that is my plan for tomorrow. I need to figure out where the problem is coming from. I suspect it is a leak in between my MAF and the intake manifold.

And it was only 100. It was worth a try. Hopefully summit racing will let me return it.

Hey guys,

I am hoping someone can give guidance here. I have a new 8.1l suburban 2001. I just added a throttle body spacer and replaced my plugs and wires. I gapped them at .045 with Ac delco 41-993 iridium plugs. I used taylor thundervolts 82225.

The engine runs great up to 3600 rpms. Then it is bogging. I have two guesses as to the problem.

1. The spark plugs are not firing properly at that rpm.
2. The air to fuel mixture is off due to the new throttle body spacer. Airaid PowerAid TBS Throttle Body Spacers 200-512-1.

I have removed all the plugs and wires to check for damage. They all look fine. I was under the impression gapping at .045 was supposed to make the 8.1s perform better at high rpms.

It also could be the throttle body spacer is making the air much more dense at high rpms.

More background info. I just cleaned the MAF. which is a Delphi and looked like it was replaced recently. I also scrubbed and cleaned the throttle body. I started the truck and it ran fine after cleaning the throttle body and before putting it on.

I am also In the process of getting a custom tune from diablo Lewis. I am hoping he will be able to help me with air/fuel mixtures and that will resolve the issue. Otherwise I will replace the plugs with standard .060 gapping to see if that fixes it.

Anybody experience this or know which direction I should head in?? Thanks and I will try to upload the video I took.

I would start by removing the spacer and see if you can get a refund because they are proven to do absolutely nothing but drain your wallet.

 

[afpj]

I was under the impression that iridium plugs shouldn’t be regapped due to how delicate the tips are...they’re long lasting and withstand the rigors of the combustion chamber, but not designed to be bent. It’s the center electrode and insulator that breaks easily, and may be damaged internally. I cannot speak for the 8.1 L, but for my 5.3, the original spec was for 0.06 gap, but was later changed by the GM to 0.04 for the iridiums.

 

[Alexb]

Yeah that's what I heard too. But they are all in tact and look perfectly fine.

Once I remove the spacer hopefully I'll get closer to my answer. I have a second set of plugs. I may install those without touching them to see if that solves it. That is if it isn't and issue with the spacer . I may have a leak in my tubing

 

[drakon543]

ya you shouldn't regap the iridium plugs unless you have the special tool for it. the spacers really are a waste unless your after a little better mpg. literally all they do. however as it was just stated in this post twice that they really dont do anything your culprit is either a leak at your spacer unless you had this issue prior to this or a plug is now cracked.

 

[iamdub]

And it was only 100. It was worth a try. Hopefully summit racing will let me return it.

No, it wasn't. That $100 would've been better spent ANYWHERE else, even at a mystery-poop-in-a-box store. It physically can NOT make the air more dense or do anything other than make a whistling noise. Hopefully you can return it.

I need to figure out where the problem is coming from. I suspect it is a leak in between my MAF and the intake manifold.

So, you replaced the plugs, installed the spacer, cleaned the MAF and cleaned the throttle body all at the same time then realized the problem after doing all of that?

Perhaps you damaged a MAF wire or something with the TB, like the TPS? Maybe left a gap in the intake duct after the MAF? Rule out those easy items as best you can. Then, someone proficient with a scan tool that reads live data should be able to narrow down the possibilities if not pinpoint the cause.

 

[Alexb]

No, it wasn't. That $100 would've been better spent ANYWHERE else, even at a mystery-poop-in-a-box store. It physically can NOT make the air more dense or do anything other than make a whistling noise. Hopefully you can return it.



So, you replaced the plugs, installed the spacer, cleaned the MAF and cleaned the throttle body all at the same time then realized the problem after doing all of that?

Perhaps you damaged a MAF wire or something with the TB, like the TPS? Maybe left a gap in the intake duct after the MAF? Rule out those easy items as best you can. Then, someone proficient with a scan tool that reads live data should be able to narrow down the possibilities if not pinpoint the cause.

I cleaned the Maf and throttle body yesterday no problems. Did the plugs and spacer today. I will start by unplugging the maf. See what happens. Then remove the air intake tubing and run straight throttle body. Then take off the spacer all together. I'm hoping I'll have my answer by then

 

[iamdub]

I cleaned the Maf and throttle body yesterday no problems. Did the plugs and spacer today. I will start by unplugging the maf. See what happens. Then remove the air intake tubing and run straight throttle body. Then take off the spacer all together. I'm hoping I'll have my answer by then

Valid troubleshooting measures. Awaiting the results...

 

[SnowDrifter]

How's fuel pressure at the time of issue?

Cats?

What's your spark advance and knock retard at time of issue?