4l80e issue
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4l80e issue I have a 99 Sierra with a 5.3. 228r cam and supporting Texas speed springs, ported heads, etc. 4.10 rear end. Also has a 4l80e with adapter harness, a shift kit and 3500 stall TCI converter. My issue:
First vehicle with a high stall converter
Runs and shifts fine from cold start. Sometimes it doesn't seem to hit OD or maybe 2200 rpm is normal for the rear end/trans combo.
When I turn the truck off and restart a few minutes later (warm start) I have to rev it to 3500+ to get it into a gear...also the gear selector switches back and forth while this is happening until the rev makes it "catch", then it drives fine and selector shows either D or R, whatever was selected.
I know this isn't normal, but what are my options to fix it? I've had numerous performance cars, but all had manual trans, so I'm a little lost with the automatic. Im reading and learning the concepts, but this issue doesn't seem like it's been addressed.
Any help is much appreciated,
Bryan
Marietta, Ga
First vehicle with a high stall converter
Runs and shifts fine from cold start. Sometimes it doesn't seem to hit OD or maybe 2200 rpm is normal for the rear end/trans combo.
When I turn the truck off and restart a few minutes later (warm start) I have to rev it to 3500+ to get it into a gear...also the gear selector switches back and forth while this is happening until the rev makes it "catch", then it drives fine and selector shows either D or R, whatever was selected.
I know this isn't normal, but what are my options to fix it? I've had numerous performance cars, but all had manual trans, so I'm a little lost with the automatic. Im reading and learning the concepts, but this issue doesn't seem like it's been addressed.
Any help is much appreciated,
Bryan
Marietta, Ga
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From: Ann Arbor, MI
Please confirm, that you have to rev to 3500+ before you can fully shift the trans from Park/Neutral into Reverse or Drive?
If I understand that correctly, your car is haunted. You might need a priest more than a mechanic.
If I understand that correctly, your car is haunted. You might need a priest more than a mechanic.
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From: Ann Arbor, MI
It seems that none of the 4L80E experts are chiming in here because they don't understand what you saying - As I read your post #1, you cannot move the gear selector into "R" or "D" until you rev the engine. Really?
Now, if that is NOT what you meant - you meant that the car doesn't move until you rev the engine, then we have an understandable problem. I would suggest connecting a trans pressure gauge to see what your cold and warm line pressure is.
If line pressure is much lower when warm, then I would suspect the pump, but a 4L80E expert needs to chime in here to confirm or correct me.
Also, have you confirmed the correct fluid level with the engine running?
Now, if that is NOT what you meant - you meant that the car doesn't move until you rev the engine, then we have an understandable problem. I would suggest connecting a trans pressure gauge to see what your cold and warm line pressure is.
If line pressure is much lower when warm, then I would suspect the pump, but a 4L80E expert needs to chime in here to confirm or correct me.
Also, have you confirmed the correct fluid level with the engine running?
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Correct,I can move the shifter, but the light will not illuminate on the selected gear until I rev it. This only happens on warm start, cold start is fine. Sometimes the light hunts back and forth between D and 2 until I rev and it catches and starts to go. Interestingly enough, when it's doing this and I'm slow rolling in reverse or 1st, it will cause the truck to stall at a stop. If I get up to speed, pulls to stop fine and shifts normally. I checked the fluid and it was a little low, added a bit to get to the top of the cross marks and it wouldn't go into gear at all. Turned it off and let it sit for 25 minutes and fired it up, drove home fine. Dropped the pan and cleaned everything up, new filter and fluid. It's still on jackstands but was running and shifting fine on stands, didn't run it enough to get it hot, so time will tell. I'm pulling the driveshaft to change u joints and then I'll test/drive/final fill the trans. I will update after. It originally seemed electrical to me, but I guess if it's having mechanical problems finding a gear, the electrical will just show the issue.
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From: Ann Arbor, MI
Thank you for more detailed explanation.
If you think its electrical, disconnect the connector to the trans. The 4L80E will then start and stay in 2nd gear with very high line pressure. You will also have Reverse. (The 4L60E is similar but starts and stays in 3rd gear.)
If you think its electrical, disconnect the connector to the trans. The 4L80E will then start and stay in 2nd gear with very high line pressure. You will also have Reverse. (The 4L60E is similar but starts and stays in 3rd gear.)
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No idea...I'll look up how to do that...looks like 2 wires were pinned to the blue side of the ecu, can't tell where they go, but somewhere back to the trans. Supposedly has a conversion harness since it was swapped in (before I bought the truck).
Attached is a link to a guick video of it idling making some clanking noise. Sounds like it in the converter area. It's cammed, so you mostly hear that. Wonder if a bold backed out or the flex plate cracked...I doubt that would cause the issue I'm having... possibly just a trashed converter?
Attached is a link to a guick video of it idling making some clanking noise. Sounds like it in the converter area. It's cammed, so you mostly hear that. Wonder if a bold backed out or the flex plate cracked...I doubt that would cause the issue I'm having... possibly just a trashed converter?
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Additional video of the noise...a bunch of that noise could be the headers contacting the frame
and a video of reverse and drive, went perfectly other than the small slip in first that happens. I'll try to get a video of it being stupid tomorrow if I can get out and run errands.
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First video is hot start, backing out of parking spot and then eventually drive...notice the 2 to D shift that it does when I touch the accelerator. I adjusted the shift linkage before going out today. Also changed the oil and got some oil psi back.
Second video is hot start and eventually move forward...all the time it was in any gear until I start driving...it was able to roll like in neutral.
Second video is hot start and eventually move forward...all the time it was in any gear until I start driving...it was able to roll like in neutral.
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Of the pump is gone, would it still drive and shift normally once engaged, because that's what it does... getting it into R or D is the issue...once it happens, it upshifts, downshifts, everything fine except a tiny slip taking off in 1st
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I'll see if I can get my hands on a gauge this week and try to get some line pressures....is there any possibility that it's an electrical problem? There is supposedly an adapter harness, this 4l80 is bolted to a 5.3. I found 2 wires that were pinned into the blue side of the ECU, but can't tell where they go on the trans...the truck is lowered, so even on ramps space is limited. I'm tempted to manual swap it... I didn't pay much attention to the automatic transmissions in my mechanical education and tend to shy away from them when working on cars.
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I can get a pump cheap, would it be worth pulling the pump and replacing or is the rest of the trans jacked? I changed the fluid and filter, was dark, but not black...pan was a little dirty, magnet had the usual thin layer on it...didn't appear to be just disgusting. Haven't done it in a long time, but I'm pretty sure I can pull the trans out without too much grief
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I won't have access to an advanced scanner for a while, but my Bluetooth ECU scanner and torque pro app only show a code for a knock sensor...which is likely from the passenger side header vibrating on the frame. Where do I connect the gauge? Supposed to be a plug on the driver's side of the trans?
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Found this video on YouTube...sounds like my exact noise...the fix for this was a pump.
I'm still going to try to get pressure reading, but I'm having trouble finding a gauge that has good reviews for accuracy, has a long enough hose, etc.