Jump to content

Turbo Lag On A 460


Recommended Posts

My AC 460 the other day started not spooling up and it would not accelerate for about 2 to 3 seconds and then it would take off. Once it gets to working it will work right going down the road. It seems to work better with the cruise on. Pull up to a stop sign or get behind slow traffic it will idle down and sometimes it will try to die unless you can get back on the throttle and pump it a time or two and then it may keep running. If you can keep it on the interstate it seems to work better I had it at the dealer the other day and they repinned the connector to the VGT ? and I couldn't make it mess up so I thought it was fixed but it wasn't When you are coasting along and mash down on the throttle it won't work but if you pump the throttle a couple of times it will then respond. Could it need the pedal calibration deal from Mack the 12B fix ??????? Can somebody help me Mackpro68 where are you?

Link to comment
Share on other sites

I was first thinking maybe low fuel pressure but probably not. I would go ahead and get the lastest software and data files for both ECM's (step 12B) and make sure your turbo has a *****5176***** in the part#. If it has a ****5171**** series turbo(2004 year model mostly) dont change the software. When we changed turbos from a 5171 to a 5176 the dealer has to change the engine software and data files. Most of the 5171 turbo are all gone/blew up. We have run across some customers who changed their own turbo to the new style and didn't get the software changed or the VGT calibrated and this caused all kinds of weird problems. With that said I would get the software/datafiles up to date, have the fuel pressure checked (80 psi)(if the supply pump has never been changed it might need it), have them check the boost pressure relief valve on top of the intake manifold (spring wears through the end of the housing), have them check for fault codes for the VGT/turbo and calibrate the VGT (must have 150 degree water temp) lastly have them unplug the connectors for the engine ECM and check for antifreeze in the harness plug. Thats all I can think of for now.

Link to comment
Share on other sites

Thanks for getting back with me Mackpro. I'll check the turbo number. As a side note, I got the best mileage ever on this trip with the the thing running like crap, 5.89 MPG, and that was running down through the hills of north Arkansas. They just put a new EGR cooler on it the other day and last week was the first trip out with a load on. I don't know if that has anything to do with anti-freeze in the ECM connector.

Thanks for your help

Larry

Link to comment
Share on other sites

Just got off the phone with the tech at the dealer. They came and picked up my truck at the firehouse. He said he couldn't get it to act up on the way back to the shop. He put it on the dyno and finally got it to do it. The diagnostics said it was the mass flow tube, the truck only has 55 miles on the new tube they put on when they replaced the EGR cooler. The tech's computer says to try a known good tube and if it still does it, it could be the ECM. He told me if it was running fine when the cooler went out, and it was, it probably is the mass flow tube. He calibrated the pedal and he said it checked out fine. So now I'm just sitting here waiting for him to call me back and give me an update

Link to comment
Share on other sites

Just got off the phone with the tech at the dealer. They came and picked up my truck at the firehouse. He said he couldn't get it to act up on the way back to the shop. He put it on the dyno and finally got it to do it. The diagnostics said it was the mass flow tube, the truck only has 55 miles on the new tube they put on when they replaced the EGR cooler. The tech's computer says to try a known good tube and if it still does it, it could be the ECM. He told me if it was running fine when the cooler went out, and it was, it probably is the mass flow tube. He calibrated the pedal and he said it checked out fine. So now I'm just sitting here waiting for him to call me back and give me an update

Good to hear they could get it to act up. Keep us posted on how it turns out.

Link to comment
Share on other sites

Well the tech called about 11 last night. He said the new mass flow tube helped it. He couldn't make it do it again on the dyno. But, (and there's always a but), he's not really all that happy with the numbers on the computer. Like he said the mass flow was off 15 or 17 lbs with the old tube and now it is only off by about 2 to 3 lbs. He said there really isn't any sense to go any further with it till it throws some more codes, he said it was like chasing a ghost. I agree, what do you guys think. I mean it ran fine when I took it in there on the 5th, the only reason I took it in was because it was showing the code "45", I think that is what it was, for the EGR cooler being bad. They said they had to put a new mass flow tube on when they did the cooler. When I took it in last Thursday I asked them if it could be a bad tube because what it was doing was very similar to what it was doing last July on our way to Walcott, they put a new tube on it then and it ran great,(or at least I think it seemed to) all the way until this episode. I drove 50 miles back to the shop after the cooler was replaced, and it sat for a week and a half. I hooked it to the flatbed and went 7 more miles and then it started this little fit. So I hope that was it, I'm going to pick it up on Wednesday morning and see how it does.

There was a post a couple of weeks ago about good and bad dealerships. I've had extremely good luck with F & C Truck in St. Louis. They've really gone the extra mile (so to speak) to help me get this problem resolved.

Link to comment
Share on other sites

Well, that wasn't it. It did exactly the same thing, turbo wouldn't spool up and it died at intersections. I ran that load to AR and then went to dealer in St. Louis thursday evening. I took the tech and his laptop for a ride and when the EGR valve was supposed to be closed it was still showing 4 or 5 pounds. So after a talk with the engineer in Allentown they decided to put a new EGR valve on. I ran another load to AR on Friday and it didn't so much as even burp one time. So I guess we are good to go till the next issue comes up. As a side note, I'm hoping that my mileage stays up. The last load to AR when it was screwed up I got 6 MPG. I haven't fueled up since I ran the load with it fixed.

Link to comment
Share on other sites

Well, that wasn't it. It did exactly the same thing, turbo wouldn't spool up and it died at intersections. I ran that load to AR and then went to dealer in St. Louis thursday evening. I took the tech and his laptop for a ride and when the EGR valve was supposed to be closed it was still showing 4 or 5 pounds. So after a talk with the engineer in Allentown they decided to put a new EGR valve on. I ran another load to AR on Friday and it didn't so much as even burp one time. So I guess we are good to go till the next issue comes up. As a side note, I'm hoping that my mileage stays up. The last load to AR when it was screwed up I got 6 MPG. I haven't fueled up since I ran the load with it fixed.

glad to hear all is fine, how many miles on your truck.

the added mpg could be from water injection, from the leaking egr cooler, (just a brain fart)

how many miles since your last egr cooler.

how low do you let rpm's go, before downshifting.

my 04,would ussually have problems in the 55mph states, jerryb has a lot less trouble since they raised speed limit in ill. maybe just a fluke,

maybe have to run egr motors above 1,300 rpm's

we have to try to share as much info as posible on these egr motors, because we are a bad dream they want to forget, so any new idea's have to come from mechanic's(not tech's)who care and dumass truckdrivers, scarry thought.

mine is out of warrenty now, one deal like that once a year, i would be trucking for repairs........

Link to comment
Share on other sites

Hey Bigen

I have a 183,000 miles on it now. A couple of months ago I started kicking the RPM's up and it seems to do better on fuel. I went up 12% by keeping it above 1500; from 4.7 pulling the tank to 5.1 or 2 and 5.0 up to 5.6 pulling the flatbed. According to the paperwork I have on it it says the sweet spot on it is 1600 plus or minus 50. It might have also helped that when they did the EGR cooler, I had them run the overhead and that was the first time I believe that was done. As far as I know that is the first replacement cooler but it's the 3rd mass flow tube, one last summer in July, second one when they changed the cooler, and the third one when they had it last week. I think this is the first replacement EGR valve for it.

Link to comment
Share on other sites

Hey Bigen

I have a 183,000 miles on it now. A couple of months ago I started kicking the RPM's up and it seems to do better on fuel. I went up 12% by keeping it above 1500; from 4.7 pulling the tank to 5.1 or 2 and 5.0 up to 5.6 pulling the flatbed. According to the paperwork I have on it it says the sweet spot on it is 1600 plus or minus 50. It might have also helped that when they did the EGR cooler, I had them run the overhead and that was the first time I believe that was done. As far as I know that is the first replacement cooler but it's the 3rd mass flow tube, one last summer in July, second one when they changed the cooler, and the third one when they had it last week. I think this is the first replacement EGR valve for it.

i would be curios as to what mackpro say's about that many mass flow tubes.

not nitpicking , did they install new style bolts when they run overhead.

Link to comment
Share on other sites

Hey Bigen

As far as the overhead was concerned, they didn't say anything about changing out any parts, but I will go back and look at my paperwork and if it says anything.

The first tube was because it had a ceramic insulator broken on one of the probes. The second one was changed because they said they had to put a new one on when they changed the cooler. The third one was changed because they thought the second one could have been bad from the start, but apparently it wasn't.

Link to comment
Share on other sites

glad to hear all is fine, how many miles on your truck.

the added mpg could be from water injection, from the leaking egr cooler, (just a brain fart)

how many miles since your last egr cooler.

how low do you let rpm's go, before downshifting.

my 04,would ussually have problems in the 55mph states, jerryb has a lot less trouble since they raised speed limit in ill. maybe just a fluke,maybe have to run egr motors above 1,300 rpm's

we have to try to share as much info as posible on these egr motors, because we are a bad dream they want to forget, so any new idea's have to come from mechanic's(not tech's)who care and dumass truckdrivers, scarry thought.

mine is out of warrenty now, one deal like that once a year, i would be trucking for repairs........

That's right bigen since the speed limit went up I don't have as much truck trouble plus I get better fuel mileage.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...