Decrease in mpg?
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Launching!
Joined: Oct 2015
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Decrease in mpg? So my tranny went out about a month ago, and the shop I went to couldn't get it right, took it back 3 times within two weeks, they fixed the issue and it's been right since about feb 21st, however I have a much lower mpg appearing from the dash, prior to my tranny going out I was getting approx 17 street maybe 24,25 high way from my est, no dod active.
So during the evens I blew up about 2 torque converters. No jerking or awkwardness about driving
I guess the question would be what could have cause the sudden decrease? I just revved my engine while in park looks like my motor mounts are bad, again...lol anyone else got any other ideas? From the looks look like my air mad connection is tilted downwards toward the throttle...
So during the evens I blew up about 2 torque converters. No jerking or awkwardness about driving
I guess the question would be what could have cause the sudden decrease? I just revved my engine while in park looks like my motor mounts are bad, again...lol anyone else got any other ideas? From the looks look like my air mad connection is tilted downwards toward the throttle...
Thread Starter
Launching!
Joined: Oct 2015
Posts: 200
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Hmm not really...seems like it does most def pull a lot harder than it did before like it could rip the tires with eaz..the mechanic did tell me they went with a bigger convertor the second time cause they thought the first one was too small and my tranny just ripped it apart, I know they did mod the clutches and put in a transgo kit.
Fluid wise I was using the valvolene dex 6, what they put in I'm not too sure, I know they added a product with platinum in the name but the only way I know that is because I heard them over talking about it.
Funny thing is the odd shifting thing from when I'm cruising on the highway at about 60 then I press on the gas, I don't have that weird jerk or rpm jump like I used to sin, I remember talking to you in a thread previously about that. It could also be my tune working well with the new tranny, but the mpg is crap
Edit; called them and they put in a regular convertor, might be a higher stall than the stock one
Fluid wise I was using the valvolene dex 6, what they put in I'm not too sure, I know they added a product with platinum in the name but the only way I know that is because I heard them over talking about it.
Funny thing is the odd shifting thing from when I'm cruising on the highway at about 60 then I press on the gas, I don't have that weird jerk or rpm jump like I used to sin, I remember talking to you in a thread previously about that. It could also be my tune working well with the new tranny, but the mpg is crap
Edit; called them and they put in a regular convertor, might be a higher stall than the stock one
Last edited by Koren; Apr 14, 2016 at 09:51 AM.
If they were using the smaller of the two 4t65e converters the first time around, that could explain it. The HD transmissions are supposed to use a 258mm converter stock, not the 245 counterpart that the V6's come with. The interesting thing about this is, a 245 would not bolt up to your 258mm flywheel unless it had dual bolt patterns or they drilled it out to match. Unless for some reason they thought performance would be better with the smaller converter the first time around, thats the only reason i could think of why they had to make any changes to the converter in terms of size.
On a side note, after alot of discussion with shops about why my oe replacement converter stalls about 400rpm higher then what its rated for. Turn's out it has alot to do with the fluid spec changes GM made with dex6. These transmissions were originally designed for Dexron 3, and all of the ratings for the converters are based on that spec. So my 2200 stall converter stalls at about 2600-2800 now because of how thin the fluid is. Ill be making the switch back to dex3 using redline D4 trans fluid along with a combination of type-f (redline racing atf) to help get that stall speed back down into spec, it should have the side effect of increasing the efficiency of the converter as well. It might be something you might want to consider.
On a side note, after alot of discussion with shops about why my oe replacement converter stalls about 400rpm higher then what its rated for. Turn's out it has alot to do with the fluid spec changes GM made with dex6. These transmissions were originally designed for Dexron 3, and all of the ratings for the converters are based on that spec. So my 2200 stall converter stalls at about 2600-2800 now because of how thin the fluid is. Ill be making the switch back to dex3 using redline D4 trans fluid along with a combination of type-f (redline racing atf) to help get that stall speed back down into spec, it should have the side effect of increasing the efficiency of the converter as well. It might be something you might want to consider.
Thread Starter
Launching!
Joined: Oct 2015
Posts: 200
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Well the reason the car burnt up the first two is cause the idiots didn't replace a valve stem I believe it is, basically the fluid wasn't flowing how it should have been due to them not replacing it so it over heated even with my trans cooler, it was so bad the last time I took it back, every stop light I drove to I had to put the car in park and turn it off and back on to keep rolling, I couldn't go past 45ish otherwise the rpms would sky rocket and the car gears would be gone. I did do a jerk test on the engine, and sad to say it does jump and it also looks like it's sinking a bit.
I read that when you change the tranny you should change the mounts, I think I only ever changed the front one but left the others alone...but I cleaned the throttle and maf...checked the cheap wheel hubs..
I do get this weird idle though, I thought it was because of the tune but not I'm not so sure..my tuner didn't see any misfires or vacuum leaks while scanning the car during our drive, so I'm not too sure on that either lol..
Edit; I'm gonna do a stall test to see what it's at.
I read that when you change the tranny you should change the mounts, I think I only ever changed the front one but left the others alone...but I cleaned the throttle and maf...checked the cheap wheel hubs..
I do get this weird idle though, I thought it was because of the tune but not I'm not so sure..my tuner didn't see any misfires or vacuum leaks while scanning the car during our drive, so I'm not too sure on that either lol..
Edit; I'm gonna do a stall test to see what it's at.
Well the reason the car burnt up the first two is cause the idiots didn't replace a valve stem I believe it is, basically the fluid wasn't flowing how it should have been due to them not replacing it so it over heated even with my trans cooler, it was so bad the last time I took it back, every stop light I drove to I had to put the car in park and turn it off and back on to keep rolling, I couldn't go past 45ish otherwise the rpms would sky rocket and the car gears would be gone. I did do a jerk test on the engine, and sad to say it does jump and it also looks like it's sinking a bit.
I read that when you change the tranny you should change the mounts, I think I only ever changed the front one but left the others alone...but I cleaned the throttle and maf...checked the cheap wheel hubs..
I do get this weird idle though, I thought it was because of the tune but not I'm not so sure..my tuner didn't see any misfires or vacuum leaks while scanning the car during our drive, so I'm not too sure on that either lol..
I read that when you change the tranny you should change the mounts, I think I only ever changed the front one but left the others alone...but I cleaned the throttle and maf...checked the cheap wheel hubs..
I do get this weird idle though, I thought it was because of the tune but not I'm not so sure..my tuner didn't see any misfires or vacuum leaks while scanning the car during our drive, so I'm not too sure on that either lol..
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Launching!
Joined: Oct 2015
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Yeah hptuned I went to a really good tuner here in Saint Louis for it. So I checked it it looks like it's about a 2500 stall? 2k-2500ish? It def rips but after the engine test I can feel when the engine moves cause I can notice it now after seeing it. I'll call my guy and have him email it to me and I'll have you look at it, I got it tuned at performance by joe
So my tranny went out about a month ago, and the shop I went to couldn't get it right, took it back 3 times within two weeks, they fixed the issue and it's been right since about feb 21st, however I have a much lower mpg appearing from the dash, prior to my tranny going out I was getting approx 17 street maybe 24,25 high way from my est, no dod active.
So during the evens I blew up about 2 torque converters. No jerking or awkwardness about driving
I guess the question would be what could have cause the sudden decrease? I just revved my engine while in park looks like my motor mounts are bad, again...lol anyone else got any other ideas? From the looks look like my air mad connection is tilted downwards toward the throttle...
So during the evens I blew up about 2 torque converters. No jerking or awkwardness about driving
I guess the question would be what could have cause the sudden decrease? I just revved my engine while in park looks like my motor mounts are bad, again...lol anyone else got any other ideas? From the looks look like my air mad connection is tilted downwards toward the throttle...
Thread Starter
Launching!
Joined: Oct 2015
Posts: 200
Likes: 0
Its still possible the ratio was changed, most do when they rebuild but that should be something you ask for and not assumed so hopefully that is not the case. Its worth the question. What model car do you have?
Thread Starter
Launching!
Joined: Oct 2015
Posts: 200
Likes: 0
2007 Monte ss, I'm assuming that would also show up via hptuner no?
