Yup, and it's a good comprehensive thread for someone else who runs into the issue. What a b**ch it was removing the transmission and especially everything else before- the damn exhaust bolts were frozen. But it was a learning experience and something interesting to get into. This was my first major diagnosis and major repair. Before this the biggest thing I replaced was rotors, windows regulators, maybe a water pump. Now when I have to rebuild the tranny or replace head gaskets, it won't be so daunting.Glad to hear you got this resolved. Always nice when us 'shadetrees' figure out a problem, without having to use the 'parts shotgun' or reworking the solution a bunch of times
4l60e first gear issue after warm up
- Thread starter hollywood6964
- Start date
well hell. Like I said, didn't want to count all of the chickens. Seems there is still an issue. Here's the rundown.
So I pulled the transmission, and saw a worn pr valve. Worn to the bone and had little chips of aluminum in the bore. Rest of the pump looked fine. I did not remove the drums at all. However the teflon seals on the drum shaft looked good. I replaced every other seal from that part forward with original gm parts.
I had a lot of parts because I didn't want tog back in, so I replaced the pump cover completely, pump body w an alleged good used one, looked machined. The rotor, veins, guide, slide, pin and springs. Rebushed the pump body that was used I bought. I was a little suspect of the pump body, seemed like the rotor and veins didn't quite move freely. Maybe should've went with the devil I knew......
Anyway so back together and seemed to run well for a couple days. Now, the main issue where I'd have to tap the gas to engage 1st gear, and there would be a bump felt, that issue issue is gone. But, I still get a low rpm, when shifting into gear. It'll go from a normal 620ish in P or N, down to 420, then bounce up to 520, then down 450, then finally settle in at maybe 500, and really feel like it's bogging down. Condition almost seems worse than before, as far as the temp doesn't need to be completely warmed up anymore (although it was starting to happen at lower temps, like say 140, even before the repair, and was rapidly getting lower by the week). But when it's bogging, if I tap the gas, it'll run and is in gear, no bump felt. This doesn't happen nearly as pronounced in gear, and say at a stop light now, even warmed up, but I can make it happen easily by putting it in P or N for maybe 5 to 10 seconds, and then going into D again. Happens shifting in reverse too, really any gear. I suppose it seems more pronounced because before the PR valve was catching and so the rpms would stay low, and then I'd tap it and it would run freely with that little bump into gear. One thing to note is that before repair, when I had the issue, the line pressure would go all the way down to 46psi, bump gas and it'd grab and recover. Now, same bog issue, bump since the pr valve is replaced (entire pump cover), the psi stays right at 64 withe the issue or not, but I still have to tap the gas to feel like a normal idle.
Before repair idle- I had 70psi in D, P, N when no issue present. Not sure about R o r2, but they may be close to the after results, could be a bit different though.
After repair idle- 64psi in D, P, N. Reverse is like 83, 2nd is 70. All pressure stays the same weather issue is present or not.
after repair- I also pulled the trans fuse, and psi is at 195 to 200 w the a/c off in park.
So I lost 6psi....Maybe the pump body being shoddy and slightly leaking? Could be warped and eating the rotor veins, especially when first engaged in D? I'm going to drop the pan tomorrow and see if there is any shrapnel, if it is sheering itself in there.
Further, I cleaned the throttle body, maf, map and tps. No difference and no codes on that front. Doesn't mean there isn't anything to it, but since this has been a transmission issue, and at least was based on temp, I'm still leaning either TC or that pump body being compromised going in.
If anybody has anything they can suggest to try, I'm open to anything. Like the first time, I want to pull the transmission, if I'm sure about the part I'm to be replacing. Outside chance of an engine issue, I'm looking at that too.
So I pulled the transmission, and saw a worn pr valve. Worn to the bone and had little chips of aluminum in the bore. Rest of the pump looked fine. I did not remove the drums at all. However the teflon seals on the drum shaft looked good. I replaced every other seal from that part forward with original gm parts.
I had a lot of parts because I didn't want tog back in, so I replaced the pump cover completely, pump body w an alleged good used one, looked machined. The rotor, veins, guide, slide, pin and springs. Rebushed the pump body that was used I bought. I was a little suspect of the pump body, seemed like the rotor and veins didn't quite move freely. Maybe should've went with the devil I knew......
Anyway so back together and seemed to run well for a couple days. Now, the main issue where I'd have to tap the gas to engage 1st gear, and there would be a bump felt, that issue issue is gone. But, I still get a low rpm, when shifting into gear. It'll go from a normal 620ish in P or N, down to 420, then bounce up to 520, then down 450, then finally settle in at maybe 500, and really feel like it's bogging down. Condition almost seems worse than before, as far as the temp doesn't need to be completely warmed up anymore (although it was starting to happen at lower temps, like say 140, even before the repair, and was rapidly getting lower by the week). But when it's bogging, if I tap the gas, it'll run and is in gear, no bump felt. This doesn't happen nearly as pronounced in gear, and say at a stop light now, even warmed up, but I can make it happen easily by putting it in P or N for maybe 5 to 10 seconds, and then going into D again. Happens shifting in reverse too, really any gear. I suppose it seems more pronounced because before the PR valve was catching and so the rpms would stay low, and then I'd tap it and it would run freely with that little bump into gear. One thing to note is that before repair, when I had the issue, the line pressure would go all the way down to 46psi, bump gas and it'd grab and recover. Now, same bog issue, bump since the pr valve is replaced (entire pump cover), the psi stays right at 64 withe the issue or not, but I still have to tap the gas to feel like a normal idle.
Before repair idle- I had 70psi in D, P, N when no issue present. Not sure about R o r2, but they may be close to the after results, could be a bit different though.
After repair idle- 64psi in D, P, N. Reverse is like 83, 2nd is 70. All pressure stays the same weather issue is present or not.
after repair- I also pulled the trans fuse, and psi is at 195 to 200 w the a/c off in park.
So I lost 6psi....Maybe the pump body being shoddy and slightly leaking? Could be warped and eating the rotor veins, especially when first engaged in D? I'm going to drop the pan tomorrow and see if there is any shrapnel, if it is sheering itself in there.
Further, I cleaned the throttle body, maf, map and tps. No difference and no codes on that front. Doesn't mean there isn't anything to it, but since this has been a transmission issue, and at least was based on temp, I'm still leaning either TC or that pump body being compromised going in.
If anybody has anything they can suggest to try, I'm open to anything. Like the first time, I want to pull the transmission, if I'm sure about the part I'm to be replacing. Outside chance of an engine issue, I'm looking at that too.
- Jul 22, 2015
- 2,724
Sorry to hear you're still having issues.
However, after reading through your latest post... I think you're tackling *different* issues, IMHO -- engine related (fuel / air / timing).
It may be that the pressure relief valve was 'masking' the idle issue, if you will. But it was there all along, and now that you fixed the valve / pump, it shows itself easier.
You mentioned cleaning the throttle body (and that's a good plan; I'd check that, too). But -- did you remove it from the intake, and clean the rear side of it? I know it can be a pain, especially if the coolant runs through the bottom of it -- but it really needs to be cleaned from both sides.
WRT the pump / trans and your idle -- it really shouldn't affect it. The trans is 'acted upon' by the PCM / engine / load conditions -- whatever feedback it sends doesn't correlate into engine RPM. And if the pump were stuck, per se -- the torque of the engine / flywheel would overcome the resistance of the TC / pump. In short, it's not going to make your engine run slower, by itself.
If your engine controls are like mine, your stated RPM are a bit low, IMHO. You should be in the neighborhood of 750-850 rpm @ idle. I'll dig up my HPT tables and edit this post, showing the cold / hot idle that the PCM will command (mine is altered in some cells, but only by about 50 RPM, if that). Yes, I have the 6.0L, and a P59 PCM -- but yours should be similar, I would think.
With that said... how to fix? Other than writing the PCM to command those speeds (if different), you're going to be looking for what's making them slower. Bad throttle body? Out of sync with TPS? Blockage or missing vacuum hose? It'll be a puzzle, to be sure.
(Will edit this post with the table info I reference, above.)
On edit: Here's the table I was referring to. X-axis is the coolant temp.
This is from my 'stock' factory file read. You can see that we're talking 800-750rpm is the norm here. You don't start getting into the upper 500s until you're at 154F. Which brings up a question -- your coolant temp sensor (CTS). Could it be on the fritz, indicating a higher-than-actual temp?
One more table to look at:
This one, I won't comment on at length, as I don't know all the nuances of it. From the 'tool tips' that show up in the HPT software, this references the speed (at or below) which 'stall saver' programming will kick in to keep the engine running. One thing of note -- the tables have the same values, whether in gear, or in Park / Neutral. Just something to consider, since we're talking about idle speed.
Finally, going back to the trans line pressure, and how reverse was showing higher line pressure -- that's normal. Pressure will be highest in reverse, and the pressure you're referencing looks just about spot on, IIRC.
My post isn't 'the fix'... but hopefully, it will give you some good info to move forward with.
BTW, there are a ton of other parms, etc., in HPT concerning AFR, etc. The above are just a couple of parameters I thought of, as I read through your post.
However, after reading through your latest post... I think you're tackling *different* issues, IMHO -- engine related (fuel / air / timing).
It may be that the pressure relief valve was 'masking' the idle issue, if you will. But it was there all along, and now that you fixed the valve / pump, it shows itself easier.
You mentioned cleaning the throttle body (and that's a good plan; I'd check that, too). But -- did you remove it from the intake, and clean the rear side of it? I know it can be a pain, especially if the coolant runs through the bottom of it -- but it really needs to be cleaned from both sides.
WRT the pump / trans and your idle -- it really shouldn't affect it. The trans is 'acted upon' by the PCM / engine / load conditions -- whatever feedback it sends doesn't correlate into engine RPM. And if the pump were stuck, per se -- the torque of the engine / flywheel would overcome the resistance of the TC / pump. In short, it's not going to make your engine run slower, by itself.
If your engine controls are like mine, your stated RPM are a bit low, IMHO. You should be in the neighborhood of 750-850 rpm @ idle. I'll dig up my HPT tables and edit this post, showing the cold / hot idle that the PCM will command (mine is altered in some cells, but only by about 50 RPM, if that). Yes, I have the 6.0L, and a P59 PCM -- but yours should be similar, I would think.
With that said... how to fix? Other than writing the PCM to command those speeds (if different), you're going to be looking for what's making them slower. Bad throttle body? Out of sync with TPS? Blockage or missing vacuum hose? It'll be a puzzle, to be sure.
(Will edit this post with the table info I reference, above.)
On edit: Here's the table I was referring to. X-axis is the coolant temp.
This is from my 'stock' factory file read. You can see that we're talking 800-750rpm is the norm here. You don't start getting into the upper 500s until you're at 154F. Which brings up a question -- your coolant temp sensor (CTS). Could it be on the fritz, indicating a higher-than-actual temp?
One more table to look at:
This one, I won't comment on at length, as I don't know all the nuances of it. From the 'tool tips' that show up in the HPT software, this references the speed (at or below) which 'stall saver' programming will kick in to keep the engine running. One thing of note -- the tables have the same values, whether in gear, or in Park / Neutral. Just something to consider, since we're talking about idle speed.
Finally, going back to the trans line pressure, and how reverse was showing higher line pressure -- that's normal. Pressure will be highest in reverse, and the pressure you're referencing looks just about spot on, IIRC.
My post isn't 'the fix'... but hopefully, it will give you some good info to move forward with.
BTW, there are a ton of other parms, etc., in HPT concerning AFR, etc. The above are just a couple of parameters I thought of, as I read through your post.
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Busy all week. I'll try and bullet point point what I've got. I appreciate your response and trying to figure this out with me. This is a tough one from the start. Kinda got a lemon here.
1- I know it was there, and getting worse by the week.
2- didn't remove, but cleaned the entire body extensively. There was nothing left. Gears, sensor, everything.
3- Torque converter failing will lower and rpms and even stall. When the PR valve was worn n jammed, it would stick the rpms at 500, and would take a nudge to move it up, when normal coasting should've lifted it a hundred or so rpms. Also wasn't thinking about the tolerance of the machined pump body, moving the TC back, n maybe, possibly not close enough to the flywheel. Not out of the woods on that whole situation.
4- put it on a scanner w a mechanic and the rpm stock is 520 in D. 620 in P. Sure it gets down to 520, but overshoots the runway by 120. If I turn the wheel right after shifting to D, hits about 385. I'm sure it would hit lower if the a/c was dragging at that moment. All sensors looked ok and fuel trims, etc. But of course, even though the scanner was worth more than my heap, they don't catch everything. Oil pressure was 36 hot idle in D, 38 in P.
5- with that said, I found a hose that kept popping off after. pcv valve tube- 12607406. I didn't know before that, kind of a hidden one. Put it back on, made sure it was snug- no change. You would've thought it would changed something, but it didn't. Values on the scanner didn't show a clear vac leak.
6- early on, changed the valve cover gaskets, and it wasn't gummed up inside. But, I had a bad blow by issue. So bad, coming out of the dipstick tube when you'd pull it. Used ATS oil treatment, and it worked. No more blow by since. Now, could changing the gaskets gave no more room for burning oil to escape? And after the blow by settled in, it's causing the issue being gummed up on the injectors, valves, etc? Possibly, I guess. It's not blowing by now, but it was for a bit til around 7 weeks ago.
7-temp reader should be good. every scanner reads the same, and me watching it seems to be working, comparing.
8- the maf, map, tps, body motor, etc could one or all be causing an issue, I just don't think so, however I could be wrong of course. If I had to put money, it'd be the TC of some sort. Maybe a vacuum leak.
9- checking for leaks w brake cleaner spray, checking the pan as well tomorrow if that doesn't produce anything. After that, might check line pressure again, see if there's any degradation over the last 2 weeks.
10- If you have any suggestions from there let me know. Looking to check anything right now before replacing the TC.