Dirty Fuel Injectors Symptoms?

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Jesus A Rodriguez

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My 04 V8 is getting horrible fuel economy about 11.5 mpg. It also hesitates when accelerating. The rpms shoot up when hesitating. Could this be dirty fuel injectors? I changed the coils and spark plugs. I used techron to try cleaning but no help.
 
Jesus A Rodriguez said:
Smh. Meaning new transmission?
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Maybe, but a less drastic repair may be possible. It all depends on exactly what is happening. You have not provided nearly enough information to guess at it. You'll have to have it diagnosed. I can tell you that the more you drive it like this, the more likely that full replacement will be required.
 
Well I just took it the shop. They did a full diagnostic and they determined its the throttle body and it needs to be replaced. He said the the part itself is about $600 OEM and with labor comes up to to about $1200 without tax. He said they have to take out the intake. I just wanted to know has anybody done this before and does the price sound right. I found the OEM throttle body for $399. But he charges around extra $40/hr labor if you bring your own parts SMH.
 
Tascaparts.com / rockauto.com / fordpartsgiant.com.

You'll be able to find a OEM throttle body probably a couple hundred bucks less. I am not an expert at mecanics but your mec shouldnt need to remove your intake to change the throttle body. Also, if it's really the throttle body that need to be replaced it's a relatively easy DIY type of job if you have any skills in turning wrenches. But again like I said I am not an expert it is just my opinion.
 
Jesus A Rodriguez said:
Well I just took it the shop. They did a full diagnostic and they determined its the throttle body and it needs to be replaced. He said the the part itself is about $600 OEM and with labor comes up to to about $1200 without tax. He said they have to take out the intake. I just wanted to know has anybody done this before and does the price sound right. I found the OEM throttle body for $399. But he charges around extra $40/hr labor if you bring your own parts SMH.
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You do not have to remove the intake to change out the throttle body. I've done it. Even the service manual does not say to remove the intake. (Procedure linked below.) Where did you take it? Most of the time when "a shop" claims the throttle body is bad, they are incorrect. Usually, it is a bad COP causing the PCM to trigger a false code.
A throttle body issue would not cause the RPM to increase while losing forward power.

http://deneau.info/ls/s6x~us~en~file=s6x34004.htm~gen~ref.htm

BTW, do not discard the gasket. You may not be able to get another one!
 
I just picked it up from the shop and I spoke to the mechanic. He said the car is choking because of the carbon billed up. he said the throttle body is done so he wants to replace it and take out the intake manifold gaskets and replace them, clean the carbon build up, replace the erg and pvc valves. But I thought V8's don't have PCV valves. My fuel economy is at 11.5. He said the job takes about 3 1/2 hours.
I just want to take care of this issue it's been pissing me off for a while. The car is drinking gas like water and these stuttering during accelerations and misfires are annoying. I changed the coils and plugs in October.
 
There are PCV lines and hoses, but no PCV valve.
It's very hard to believe that the carbon can't be cleaned off of the throttle body. If he doesn't know the 3.9 LS, he may not know how normal it is for there to be a small pool of oil in the bottom on the intake manifold.

At the end of the day, if your first description is accurate ("It also hesitates when accelerating. The rpms shoot up when hesitating."), it's really hard to believe that is an engine problem. If it is still doing it, could you do a test for me. Let's eliminate the possibility that you are describing a down-shift with low engine power. Get up to whatever speed that it does this at. Then push the gearshift over to manual mode. That will keep it in whatever gear it is in. Now, hit the gas and see if you get the same hesitation. If you do, also note if the tachometer shoots up.
 
I guess I can try that. I'm going to try cleaning the throttle body and the erg valve and see what happens. Paying $1200 plus tax is crazy. I don't feel confidante in his diagnose.
 
First question would be how many miles on the vehicle? Second, is your check engine light on? If so,,, do you know what the diagnostic codes are? Is the 11.5mpg based on highway or city driving,,, or combined??? Follow Joe's recommendations,,, but my guess is your "friendly neighborhood mechanic is planning on replacing the Throttle Position Sensor... and billing you for much more.
 
Jesus A Rodriguez said:
I guess I can try that. I'm going to try cleaning the throttle body and the erg valve and see what happens. Paying $1200 plus tax is crazy. I don't feel confidante in his diagnose.
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04_Sport_LS said:
First question would be how many miles on the vehicle? Second, is your check engine light on? If so,,, do you know what the diagnostic codes are? Is the 11.5mpg based on highway or city driving,,, or combined??? Follow Joe's recommendations,,, but my guess is your "friendly neighborhood mechanic is planning on replacing the Throttle Position Sensor... and billing you for much more.
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It just hit 80,000 miles. I drive it city and highway. No check engine light. I think the the throttle body, erg valve and manifold need to be cleaned.
 
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