Limp Mode 3800 II GTP HELP PLEASEEEE!!
09-23-2010, 10:22 AM
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Limp Mode 3800 II GTP HELP PLEASEEEE!! I am kicking my self in the *** every day since I was forced to sell my 01 LS1 and buy a more PRACTICAL (POS). The guys over at 3800pro don't seem to be much help so I default to my roots. Please advise!
I want to explain in detail what has happened so we are all on the same page.
About 7 months ago I lost overdrive in my 99 Pontiac GTP. As a result I pulled the engine/trans and started the rebuild process. This also gave me a reason to do a few motor upgrades (VS cam, ZZP 3.4 pulley, P/P housing, Exhaust). Now everyone over at 3800pro knows the 4t65e HD SUCKS! In stock form it is barely capable of holding 300whp.
After getting the car started up after the build I drive it like a baby for a few days and it seems to be shifting real low/early in the rpm band. Ok no problem it will learn as time goes on. And it did. Now realize I do have the reflashed ZZP PCM which changes shift points to 6200rpm.
So yesterday I decide I would give it a nice roll on pulling onto the highway and what happens next is very odd. The car is running great in 1st gear...it gets to 6xxx rpm and gets ready to shift when all of a sudden i hear POP POP (not a mechanical pop like something breaking but more like a backfire inside the engine/trans) almost like a transbrake coming off a launch. Then i let off the gas and it goes into 2nd. Still off the gas not knowing if i still have a trans left i very slowing start applying gas to see if the trans catches and it does just fine. In fact it seems to be shifting fine through all gears until i slow down and turn around. As i turn around it goes into 1st or 2nd all the way to 5k rpm under light gas and stays there. It wont shift. And to top it off my Stock boost gauge is frozen at 50% boost even with my foot off the pedal. A few minutes later the car can't find idle and bounces b/t 2 -2,500 rpm. Last night i unplugged the battery hoping to reset the PCM as I feel this is electrical since the SES was throwing one code (MAF). I replaced the MAF and the SES is out for good this morning. Upon start up it is not seeking idle anymore but it will just dye after running for 3-4mins with no warning. I took it for a ride a few minutes later and it is shifting great! even under light acceleration but...after 4-5mins of driving it goes NUTS!
The car is now stuck in one gear and won't let me go above 35ish MPH! I can give it all the gas I was but the transmission just slips until i go under 30mph then will grab again and slip at any and every rpm. And if i floor it and take it to 5,000rpm (with no engine power being transfered to the trans or wheels) the PCM will cut the throttle all the way down to 1k rpm even while the gas is to the floor! and then the rpms will come up again (almost like TCS). What the hell is going on? IS it stuck in LIMP MODE? finally I noticed that the boost gauge is not even reading boost even though i can hear it boosting.
I want to explain in detail what has happened so we are all on the same page.
About 7 months ago I lost overdrive in my 99 Pontiac GTP. As a result I pulled the engine/trans and started the rebuild process. This also gave me a reason to do a few motor upgrades (VS cam, ZZP 3.4 pulley, P/P housing, Exhaust). Now everyone over at 3800pro knows the 4t65e HD SUCKS! In stock form it is barely capable of holding 300whp.
After getting the car started up after the build I drive it like a baby for a few days and it seems to be shifting real low/early in the rpm band. Ok no problem it will learn as time goes on. And it did. Now realize I do have the reflashed ZZP PCM which changes shift points to 6200rpm.
So yesterday I decide I would give it a nice roll on pulling onto the highway and what happens next is very odd. The car is running great in 1st gear...it gets to 6xxx rpm and gets ready to shift when all of a sudden i hear POP POP (not a mechanical pop like something breaking but more like a backfire inside the engine/trans) almost like a transbrake coming off a launch. Then i let off the gas and it goes into 2nd. Still off the gas not knowing if i still have a trans left i very slowing start applying gas to see if the trans catches and it does just fine. In fact it seems to be shifting fine through all gears until i slow down and turn around. As i turn around it goes into 1st or 2nd all the way to 5k rpm under light gas and stays there. It wont shift. And to top it off my Stock boost gauge is frozen at 50% boost even with my foot off the pedal. A few minutes later the car can't find idle and bounces b/t 2 -2,500 rpm. Last night i unplugged the battery hoping to reset the PCM as I feel this is electrical since the SES was throwing one code (MAF). I replaced the MAF and the SES is out for good this morning. Upon start up it is not seeking idle anymore but it will just dye after running for 3-4mins with no warning. I took it for a ride a few minutes later and it is shifting great! even under light acceleration but...after 4-5mins of driving it goes NUTS!
The car is now stuck in one gear and won't let me go above 35ish MPH! I can give it all the gas I was but the transmission just slips until i go under 30mph then will grab again and slip at any and every rpm. And if i floor it and take it to 5,000rpm (with no engine power being transfered to the trans or wheels) the PCM will cut the throttle all the way down to 1k rpm even while the gas is to the floor! and then the rpms will come up again (almost like TCS). What the hell is going on? IS it stuck in LIMP MODE? finally I noticed that the boost gauge is not even reading boost even though i can hear it boosting.
09-24-2010, 10:30 AM
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Well, there is a couple things...
If you have put a cam in and not have the ecu tuned for it, you could have a timing problem.
The other issue is that you mention the car will shut off after 3-4 minutes. What is happening, the PCM is going into closed loop and reading more sensors. I would check those as well.
There may be a vacuum problem as the Boost by pass valve may be open not allowing boost even tho the s/c is turning. Thus no boost on your gauge.
I would suggest disposing of 3800no and going somewhere else. They do not have a great reputation and their worship of a particular vendor = ick.
The very first thing I would suggest is pulling the plugs (specifically #4) and check 'em for silver specks, white coloration or damage. I suspect that the ECU hasn't been properly calibrated for your setup and caused engine damage.
2nd...who rebuilt your tranny? A local tranny shop? Chances are, it wasn't rebuilt correctly. As a previous heavily modded GTX owner (SLP GTP) i know there are only a handful (or less) tranny shops in the US that have more then a general grasp on how to properly rebuild or "build" a HD transmission. There is a reason that some tranny shops charge $1k and some are closer to $2.5k or more.
3rd...I would suggest finding a blank (stock) PCM to swap out to try. If you don't have access to one, PM me. I have an unmolseted 1998-2002 PCM here if you are interested. If you swap it out, and drive respectably, and everything checks out (with the appropriate codes thrown), you may have a fried PCM. However, this is unlikely, but it does happen.
The poping sound you hear may be #4 and #5 piston ringlands breaking off. Check your plugs. I'd be interested to hear what you find.
If you have put a cam in and not have the ecu tuned for it, you could have a timing problem.
The other issue is that you mention the car will shut off after 3-4 minutes. What is happening, the PCM is going into closed loop and reading more sensors. I would check those as well.
There may be a vacuum problem as the Boost by pass valve may be open not allowing boost even tho the s/c is turning. Thus no boost on your gauge.
I would suggest disposing of 3800no and going somewhere else. They do not have a great reputation and their worship of a particular vendor = ick.
The very first thing I would suggest is pulling the plugs (specifically #4) and check 'em for silver specks, white coloration or damage. I suspect that the ECU hasn't been properly calibrated for your setup and caused engine damage.
2nd...who rebuilt your tranny? A local tranny shop? Chances are, it wasn't rebuilt correctly. As a previous heavily modded GTX owner (SLP GTP) i know there are only a handful (or less) tranny shops in the US that have more then a general grasp on how to properly rebuild or "build" a HD transmission. There is a reason that some tranny shops charge $1k and some are closer to $2.5k or more.
3rd...I would suggest finding a blank (stock) PCM to swap out to try. If you don't have access to one, PM me. I have an unmolseted 1998-2002 PCM here if you are interested. If you swap it out, and drive respectably, and everything checks out (with the appropriate codes thrown), you may have a fried PCM. However, this is unlikely, but it does happen.
The poping sound you hear may be #4 and #5 piston ringlands breaking off. Check your plugs. I'd be interested to hear what you find.
