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Installed my F&B 70mm throttle body Saturday; replaced my plugs while I was at it (autolite 5224's). Got the standard high idle hovering around 1250 then slowly dropping to normal idle speeds. Been driving it for two days now and the butt dyno says everything is GOOD, pulling real nice, more torque; lights up the tires at will etc; all around running really nice. By today (Monday) the idle has settled in to normal and life is good. Anyway about 10pm I run out for a pack of smokes taking it easy (saving gas, you know how it is) when all of a sudden engine losses power and dies; check engine light comes on and won't start back up. After about 5 minutes it decides to start and I get it home before it dies again. Put the SuperChips on it and it pulls a P0068 code; display reads (Correlation MAP sensor signal does not correlate to throttle position sensor signal. Possible vacuum leak.). A vaccum leak though possable isn't likely; anybody have any ideas / experience with this?
 

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oO_Rogue_Oo said:
Installed my F&B 70mm throttle body Saturday; replaced my plugs while I was at it (autolite 5224's). Got the standard high idle hovering around 1250 then slowly dropping to normal idle speeds. Been driving it for two days now and the butt dyno says everything is GOOD, pulling real nice, more torque; lights up the tires at will etc; all around running really nice. By today (Monday) the idle has settled in to normal and life is good. Anyway about 10pm I run out for a pack of smokes taking it easy (saving gas, you know how it is) when all of a sudden engine losses power and dies; check engine light comes on and won't start back up. After about 5 minutes it decides to start and I get it home before it dies again. Put the SuperChips on it and it pulls a P0068 code; display reads (Correlation MAP sensor signal does not correlate to throttle position sensor signal. Possible vacuum leak.). A vaccum leak though possable isn't likely; anybody have any ideas / experience with this?
oooook....

MAP sensor.... or Manifold Absolute Pressure. I'll explain in short, cause I gotta hit the sack soon....

Basically your motor is getting air INTO the motor AROUND your throttle blade. The throttle blade is made of a plastic material... it tends to give a bit. Basically your "throttle position sensor" signal is COMPLETELY closed, yet your "MAP sensor" is reading that you are gaining air pressure in the motor.... hense the jumping idle at first..... your computer was adjusting for it by increasing your rpm to compensate for the extra air,... but then your computer is like wtf... no bitch.... you're gunna idle at 600 rpms... not 1200... go back down you hoe... so it pushes it back down... well then your MAP sensor senses pressure so it's just one big circle of hell. The only way to get this all fixed is get a new throttle plate that fits better so no air can seep around it.

Paul
 

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Discussion Starter #3
YAAAABUDDY03 said:
oooook....

MAP sensor.... or Manifold Absolute Pressure. I'll explain in short, cause I gotta hit the sack soon....

Basically your motor is getting air INTO the motor AROUND your throttle blade. The throttle blade is made of a plastic material... it tends to give a bit. Basically your "throttle position sensor" signal is COMPLETELY closed, yet your "MAP sensor" is reading that you are gaining air pressure in the motor.... hense the jumping idle at first..... your computer was adjusting for it by increasing your rpm to compensate for the extra air,... but then your computer is like wtf... no bitch.... you're gunna idle at 600 rpms... not 1200... go back down you hoe... so it pushes it back down... well then your MAP sensor senses pressure so it's just one big circle of hell. The only way to get this all fixed is get a new throttle plate that fits better so no air can seep around it.

Paul
Sounds logical but I have some more details that might shed some more light on the subject. This has happened 3 times since Monday; all three times I was at part throttle (2k to 3k rpms). The engine will not start once it dies till I turn the key to the off possistion; it will then start and run normally. Since its happening at part open throttle I feel like it probably isn't a flexing throttle plate issue; though your explanation did give me something to think about (a new line of thought that I hadn't considered). Something else, the idle has settled in nicely, with no wandering at a very normal 600 to 700 rpm, and idles down from speed normally; not hanging at upper levels before finally settling down as it did the first day.

Food for thought here; I did NOT reset the PCM when I installed the throttle body; now I'm wondering if this might be due to some old learned behavior that conflicts with the larger Throttle body.

Thanks for the responce, best one I've gotten so far (have this posted on 3 sites) and I welcome more thoughts.
 

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oO_Rogue_Oo said:
Sounds logical but I have some more details that might shed some more light on the subject. This has happened 3 times since Monday; all three times I was at part throttle (2k to 3k rpms). The engine will not start once it dies till I turn the key to the off possistion; it will then start and run normally. Since its happening at part open throttle I feel like it probably isn't a flexing throttle plate issue; though your explanation did give me something to think about (a new line of thought that I hadn't considered). Something else, the idle has settled in nicely, with no wandering at a very normal 600 to 700 rpm, and idles down from speed normally; not hanging at upper levels before finally settling down as it did the first day.

Food for thought here; I did NOT reset the PCM when I installed the throttle body; now I'm wondering if this might be due to some old learned behavior that conflicts with the larger Throttle body.

Thanks for the responce, best one I've gotten so far (have this posted on 3 sites) and I welcome more thoughts.
The way I view it... your Throttle position sensor is sticking or isn't sending the correct throttle position. Here's why I say that. Your throttle position sensor might be telling the computer that it is 1/4 open... but in fact your blade is 1/2 open (this is all relatively speaking... out of the box speaking). So basically your computer thinks the throttle plate is open 1/4 so it sends a 1/4 of the gas it needs for a 100% correct mixture but... your motor is actually getting twice the air,... and your engine realizes it so it dies... that may be what it's doing.

Paul
 

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Throttle Body Problems

Hi,
Actually this may have helped me with a problem im having as well, i just installed a JET throttle body spacer on my 4.7L dakota and im getting this hissing noise when i give it about 1/4 throttle, the vehicle seems to be driving fine but after about 20km from when i installed it the check engine light came on, could this be because the throttle body spacer didnt seal up properly with the intake and throttle body? Thanks.
 

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silverdakota81 said:
Hi,
Actually this may have helped me with a problem im having as well, i just installed a JET throttle body spacer on my 4.7L dakota and im getting this hissing noise when i give it about 1/4 throttle, the vehicle seems to be driving fine but after about 20km from when i installed it the check engine light came on, could this be because the throttle body spacer didnt seal up properly with the intake and throttle body? Thanks.
OK, yours is an easy fix. Take off the TB spacer and use it for all that it is good for, a paperweight.
 

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He's right,... the throttle body spacer that you have is completely worthless for your motor. They were used to spin air and fuel together so there would be a better mixture on carburated engines, there is no use on a fuel injected motor.

The hissing sound you speak of is the TB spacer doing it's job. The hissing is from the air swirling when it hits the spacer.

Paul
 

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TB Spacer

Seriously? Wow that sucks... okay well im going to try a couple of things in the morning to see if i can get it to co-operate with my sensors and if i cant get the check engine light to go out then im just going to remove it. I also put a KNN Cold Air Intake on the truck today at the same time. I thought the throttle body spacers helped with fuel economy and a tid bit of power though? Anyways thanks for the advice.
 
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