Engine Chokes at 2000 RPM

ckruzer

ckruzer

Infidel
Joined
Jul 2, 2015
Location
asheville nc
5.3 is choking consistently at 2000 rpm.

Brand new walbro pump
Brand new wix filter
Brand new MAF and Spectre filter

Checked tps it had some oil in it? Gunna try and replace that I guess.

Gunna rent or buy a fuel pressure gauge to plug into the fuel rail.

Anyone ever heard or seen this issue? Any ideas?

Thanks

 
Yes o2 has a foot ish of pipe. That's it tho no pipe past the o2.

Pulled the TPS. Supposed to be oil in there?
 
Does it clear up after 2k RPM, or does it still fall on its face? Throttle position sensors can get a dead spot in their travel range as the contacts wear. The oil may or may not be a problem, it depends on how much it would electrically insulate the TPS wiper contacts. If it's a fuel system problem, it would be rare for it to happen under light or no load because the fuel flow is so low.

Is it throwing any codes, or anything else to suspect that it's rev limiting itself in limp-home mode with a major sensor fault?? I don't know what RPM would be for an LS.

Crank and cam position sensors are always a suspect when the behavior is at a very consistent RPM as well. Engine load doesn't matter for position sensors, only RPM as they're either properly triggering on encoder teeth or they're not.
 
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2000. Can't get past it no matter what. Load or not. Doesn't matte. Just like in the video. Chokes, drops, and then idles. Hasn't stalled.

Haven't checked for codes. Don't have one and can't drive it to autovance lol. Don't have the light hooked up for codes. I'm sure I could find a led laying around somewhere
 
If it's hard stop at exactly 2k, that's level 1 limp.
 
Been thinking limp too.

Also just noticed. The harness company forgot the ground wire for CPP Switch (blue32, park grd)
 
If the TPS is nasty, take the throttle body off and clean out all of those cavities too. Sounds like it's sucking oil up through the passenger's side valve cover vent tube.

If you would, post a picture from the front and looking at the top of the motor. I'd like to see the intake tubing and top of the intake and all that, if possible. If everything mechanical checks out, then it's obviously electrical or something in the tune itself. If I were closer, I'd pull the tune and look through it for you.
 
GubNi said:
Well that's debatable. From what I know GM said it is acceptable. Think of it as blow by. Get a catch can to eliminate it.
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It was less than "less than a thimble" lol. But enough Ithat I decided to clean it up. The throttle body isn't gaumed up from oil, so hopefully not too bad of a thing.

The oil was old, not the clean I have in it now. And the sensor and TB shaft were all clean as a whistle. As if the oil was just put there..
 
Croatan_Kid said:
If the TPS is nasty, take the throttle body off and clean out all of those cavities too. Sounds like it's sucking oil up through the passenger's side valve cover vent tube.

If you would, post a picture from the front and looking at the top of the motor. I'd like to see the intake tubing and top of the intake and all that, if possible. If everything mechanical checks out, then it's obviously electrical or something in the tune itself. If I were closer, I'd pull the tune and look through it for you.
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Sure thing man. Yeah it's def not nasty.

I'm thinking it's the lack of park ground. Computer doesn't know it's moving.
 
@Croatan_Kid

sorry havent got the picture yet. doing it now.

doing the blue32 park ground fixed the issue.

so been driving around and trying to diagnose a intermittent lack of power issue (found that the passenger side header to downpipe flange was way loose). Potential big exhaust leak could be the cause.

I have zero codes except the po650 for the check engine light not hooked up yet.

Scheduling exhaust appt first thing tomorrow AM. I never planned for this far. haha. so i have no muffler!!! lol i may amazon prime something like a glasspack or else just have the shop straightpipe it and i can bolt up a muffler anytime. we shall see. maybe the exhaust shop will have some on hand
 
ckruzer said:
@Croatan_Kid

sorry havent got the picture yet. doing it now.

doing the blue32 park ground fixed the issue.

so been driving around and trying to diagnose a intermittent lack of power issue (found that the passenger side header to downpipe flange was way loose). Potential big exhaust leak could be the cause.

I have zero codes except the po650 for the check engine light not hooked up yet.

Scheduling exhaust appt first thing tomorrow AM. I never planned for this far. haha. so i have no muffler!!! lol i may amazon prime something like a glasspack or else just have the shop straightpipe it and i can bolt up a muffler anytime. we shall see. maybe the exhaust shop will have some on hand
Click to expand...

It's an exhaust shop they got a muffler or two


Sent from my iPhone using Tapatalk
 
Loganwayne said:
It's an exhaust shop they got a muffler or two


Sent from my iPhone using Tapatalk
Click to expand...
if not, leave...

BTW Advance or O'Reilly will have mufflers on the shelf
 
Here is the pic

9a51d4b27934cea1ed43cc049f897206.jpg
 
Any chance you can get a 90 elbow on that intake and get the filter out from right behind the radiator? You will be constantly taking in HOT air (~180*) from the radiator into the engine. This can cause problems such as knock and/or low power. The pcm has tables that will progressively pull timing if the intake air is over ~113* or so. That can be tuned out, but then you risk actual knock because of the high intake air temps.
 
NC-V said:
Any chance you can get a 90 elbow on that intake and get the filter out from right behind the radiator? You will be constantly taking in HOT air (~180*) from the radiator into the engine. This can cause problems such as knock and/or low power. The pcm has tables that will progressively pull timing if the intake air is over ~113* or so. That can be tuned out, but then you risk actual knock because of the high intake air temps.
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That makes sense!!! I just need to find an elbow and length tube?
 
NC-V said:
Any chance you can get a 90 elbow on that intake and get the filter out from right behind the radiator? You will be constantly taking in HOT air (~180*) from the radiator into the engine. This can cause problems such as knock and/or low power. The pcm has tables that will progressively pull timing if the intake air is over ~113* or so. That can be tuned out, but then you risk actual knock because of the high intake air temps.
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That's really good to know I'll deathly fix that but as I was sitting here thinking I had the Hood off the entire time so I don't think it would have been sucking in super hot temps to do what you were saying it being close to the same thing
 
NC-V said:
Any chance you can get a 90 elbow on that intake and get the filter out from right behind the radiator? You will be constantly taking in HOT air (~180*) from the radiator into the engine. This can cause problems such as knock and/or low power. The pcm has tables that will progressively pull timing if the intake air is over ~113* or so. That can be tuned out, but then you risk actual knock because of the high intake air temps.
Click to expand...

Also could you help clarify this is just a little bit better so I can understand? Just thinking on it back when I've done all the research I've done we're trying to plan this build if I recall correctly most of the LS swap's I Saul or people using Shorty air filters just like you see in that pic. So is the hot air issue a mild symptoms that you will experience or something long-term effect? What I was experiencing was pretty drastic as far as this awesome power after the rev limiter issue was fixed. It seems that the big exhaust leak would make the most sense currently however my interest peaked a lot at the mention of timing retard due to the heat
 
I was just saying in general it will definitely affect performance and could possibly cause problems. I doubt it has anything to do with the issue you are experiencing right now. Plenty of people do use very short intakes directly behind the radiator, plenty of people also have relations with dirty prostitutes, but I wouldn't do it and I wouldn't recommend it. Stock tune files can pull upwards of 7* timing if they are seeing intake air temps up above 160*. Like I mentioned this can be tuned out, but you would need to datalog to make sure you aren't getting knock at those intake temps. Generally on street cars it isn't as big of a deal because once you start moving you will get some air circulation under the hood and even with the intake right behind the radiator, the air in the engine bay is being exchanged out with fresh air. Back to my old go to of sitting on a rock at 4k rpms you are not exchanging too much air in the engine bay, you may see intake temps approach coolant temp (not good.) The more open your engine bay is, the better off you will be and the farther from the radiator/exhaust you can keep the intake, the better.
 
NC-V said:
I was just saying in general it will definitely affect performance and could possibly cause problems. I doubt it has anything to do with the issue you are experiencing right now. Plenty of people do use very short intakes directly behind the radiator, plenty of people also have relations with dirty prostitutes, but I wouldn't do it and I wouldn't recommend it. Stock tune files can pull upwards of 7* timing if they are seeing intake air temps up above 160*. Like I mentioned this can be tuned out, but you would need to datalog to make sure you aren't getting knock at those intake temps. Generally on street cars it isn't as big of a deal because once you start moving you will get some air circulation under the hood and even with the intake right behind the radiator, the air in the engine bay is being exchanged out with fresh air. Back to my old go to of sitting on a rock at 4k rpms you are not exchanging too much air in the engine bay, you may see intake temps approach coolant temp (not good.) The more open your engine bay is, the better off you will be and the farther from the radiator/exhaust you can keep the intake, the better.
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Thanks so much!!! Understand your point. Ow and totally agree!!! My plan was temp for the shorty. I'm planning to 90 90 with pvc and run into the firewall. That won't happen if I ever plan to have a top again tho.

So you think it's an immediate concern or something I can postpone until I workout what I want to do intake wise for permanency?

Thanks again!
 
No, not an immediate concern. It should be fine, most tuners are smart enough not to mess with that table too bad without logging, yours is most likely unmodified so it will just pull timing as the IAT warms up. No big deal (just lose some power). Don't rush, design your intake how you want.
 
Glad you got it figured out! The exhaust leak is definitely causing a power loss, so that should be an easy fix.

Sorry for the slow response time...I'm in Okinawa, so I'm actually posting this in the future since it's 13hrs ahead of eastern time :D
 
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