ninjabalt

If anyone could help figure this out- id love it.

Mechanics are having a hard time up here in NY. Because my car throws no codes or misfire.



I've taken it to several mechanics that are familiar with gm/ ecotec. Maguire chevrolet had a chevy specialist look at it for 2 weeks. I've had this rpm surge/bucking problem for way too long its been going on since july 2013, and i bought it in june 2013 with 27k, it started having problems surging/bucking stalling 500 miles later. The first problem was the stalling it threw codes for camshaft solenoid(exhaust) so i replaced both exhaust and intake solenoids. which cured the stalling, but the jerking and rpm surges still existed. So i replaced the original oem sparkplugs with ngk iridium acdelco sparks to see if that would cure the problem. My stock intake needed to be replaced so i put in k&n intake and new filter. I replaced the fuel filter that was a negative too. Changed the oil, and seafoamed her. The problem still occurred. Every mechanic was set in saying it was my Throttle Body and Mass air flow. So i just replaced those this past week- it did not solve the problem. I just spoke with GM and they had chevy maguires look at it once again for a week they did a crankshaft variable relearn-for my PCM. The car was awesome for fifteen minutes and the rpms bogged really low and the car started jerking violently. Everytime I've reflash or do a relearn the car acts like its brand new no hesitation, no lag- then it goes right back to what it was doing.

I feel like this may be something to do with my ECU


Things I've replaced:
New Camshaft exhaust/intake solenoids
New NGK iridium spark plugs
New Fuel Filter
Sea foam cleaner
New Throttle Body
New K&N intake/Filter
New Mass Air Flow Sensor
TCM reset
Crankshaft variable relearn

ninjabalt

Heres a couple videos whats going on.

Spawne32

iTrader: (1)

I have a similar surging problem, mostly when the car is idling or under hard throttle it will do this. I got off the highway after a 25 minute drive the other night and when I was sitting at the traffic light right off the exit it started surging really bad and then it would just stop, and then start idling high. I'm currently looking into whether its the camshaft actuators (the gears themselves) as to whether or not they are fully parking all the way. Sometimes it can be violent enough to shake the entire car back and forth. I have datalogged some cam angle errors but nothing enough to apparently set a code for it. I'm t rying to catch it surging while having it recording but have had limited luck with it, since its so random that it occurs.

ninjabalt

I'm sooooooo glad you understand what i'm talking about . Yeah I just got it back last week from GM-Chevy Maguires. They did a crankshaft variation relearn on my car. When i received it felt like i had a brand new car again ie: I had no hesitation/power loss, bucking or rpm surges. Then 15 minutes later driving the rpms bogged really low and then they bounced from 1k to 2k it started violently shaking the entire car. When i stop at a red light it likes to lurch forward too.
The problems all started when it threw the code for camshaft actuators ( which i replaced) - fixed my stalling , but a new issue arose which was the rpm surges/bucking.

Spawne32

iTrader: (1)

Well the part that you actually fixed was the solenoids (top of the valve cover). They control the oil flow in and out of the actuators themselves. I had no idea about the CPS relearn procedure, thats something ill have to look into as Ive already changed my CPS once before.

Anywho, the part that im talking about potentially being an issue (havent diagnosed it fully yet) is the actual gear itself. GM cam actuators are a vane style oil pressure driven system, that apparently are finicky if they are dirty or dont have sufficient oil pressure (for whatever reason). Ive heard numerous complaints from solstice and HHR folks about issues with violent shaking at idle from the cams not parking fully so this is what leads me to think the surging issue is related. Have you noticed at all if your gas mileage has gone down? (what exactly are you seeing for mpg on your DIC) I'm getting about 19.5-20.5 driving very modestly between city and highway, which is IMO horrific for this car.

ninjabalt

OH! well when i take it back to GM chevy maguires this Tuesday i'll have them look at the cam (gear)

When i changed my cam solenoids - they were pretty bad - if that gives you any sign of how bad the car was not taken care of. im guessing the oil was rarely changed. Note- the car runs fine at idle, but under throttle it violently shakes, if i stop at a red light it will lurch forward even with my foot on brake.


Yeah my gas mileage is horrific...It goes through gas like ridiculous. a full tank used to be 288 miles . now its like 120 miles. Like i go through a half a tank in two days driving bw city and highway.

Spawne32

iTrader: (1)

If your not under warranty they are going to crucify you for that repair lol

ninjabalt

I'm not under power train warranty it ended when i bought it ...how much you think

Spawne32

iTrader: (1)

assuming they do diagnose it being the gears, figure at least 300 for the gears themselves, and then probably an additional 200-250 for labor.

ninjabalt

Have you taken yours to a dealer?? ( assuming your close to an answer at this point) it may be the cam gear itself??

Spawne32

iTrader: (1)

nah, never. my car wasnt under warranty from the day I bought it with 126,000 miles.

ninjabalt

Good news- found out what was wrong with car today. After 8 months of agony...and it getting worse.

I personally Drove the head GM mechanic for 15 minutes. He goes " OMG..." " that's the torque converter locking itself and unlocking- slipping itself in and out of gear---- And it gets worse as you drive it.

Bad News. Torque converter will eventual break...

Thus Transmission needs to be replaced.

So all this time - it was the transmission. Calling the original shop i bought it from- because i took it back to them several times I originally had thought it was the torque converter/transmission. They told me they'd replace it...Now i have official confirmation from maguire's.

Spawne32

iTrader: (1)

lol transmission doesnt need to be replaced, thats the torque converter lockup solenoid engaging and disengaging the lockup clutch in the converter. Interesting that he would say that, cus usually when that fails it causes the car to stall and it gets stuck locked up in a 1:1 ratio. I've had that happen multiple times on older 4t40e's. Not exactly an uncommon problem. However the lockup solenoid is on the valve body inside the trans, which means usually the trans comes out for repair unless they can access it through the pan.

On the older transmissions the solenoid used to be exposed to the outside of the case and we would just unplug them, but it was horrific for gas mileage and transmission wear, although ive had cavaliers that went 250,000 miles with the lockup disabled from 100k onward. lol My old 93 used to lockup above 40mph and wouldnt unlock and id come to a stop and it would stall completely and you would have to N bomb it to get it to move because it would be locked 1:1.

Spawne32

iTrader: (1)

It's also possible that there is an issue inside the converter itself as well, which is why i decided to head off any issues like that ahead of time for 52 dollars. Oddly enough this car has the cheapest torque converters ive ever purchased, dunno if its because of the over abundance of them being that they are also 4L60E and 4T60E/65E converters.

Spawne32

iTrader: (1)

I watched your video again and it's very likely its the TCC solenoid, seems like your only getting it when the car shifts into 4th.

Spawne32

iTrader: (1)

Sorry for the numerous posts but did a little research for you, heres the general breakdown of it.

GM's 4T45E Transmissions; The Good, Bad And The Ugly - ETE Reman - Troubleshooting for Automatic Trans

- Failure of the TCC PWM, which stands for Torque Converter Clutch Pulse Width Modulation solenoid. The TCC is located inside of the valve body and is part of the internal wire harness. It is highly recommended that the internal wire harness be replaced at the same time you replace the TCC. - See more at: GM's 4T45E Transmissions; The Good, Bad And The Ugly - ETE Reman - Troubleshooting for Automatic Trans

ninjabalt

Is there a way to test that solenoid without dropping the whole tranny tho and wouldnt it show a code. The mechanic said eventually my torque converter is going to break (its getting worse) and eventually throw a check engine light.

Spawne32

iTrader: (1)

Unfortunately rather then being on the bottom it looks as though the valve body is mounted on the side, so the trans would almost have to be removed to have access to it. From what I can see from the diagrams it does look like the side plate comes off and it is repairable, they would have to replace the solenoid and the wiring harness per the repair instructions. As far as the torque converter goes, while its out i would just replace that as well, they are so cheap its not even funny. Like i said mine was 52 bucks after core return, even performance converters for this car barely get over 300 dollars. The thing your mechanic is talking about going bad is the lockup clutch inside the converter (looks much like a clutch on a manual trans) the constant engaging and disengaging is causing premature wear which could potentially flood the trans with material and kill it completely.

Plex

Hey I doubt anyone is going to reply to this saying how old this thread is but I have been having the same problem with my car that you are having and I was wondering if you ever figured out what it was. I have a new fuel pump on the way that I am going to replace in my car because I check my pressure and I had around 40psi instead of 50 to 60. And my car has 130k miles on it and I doubt the owners before me ever replace the fuel filter on it. I hope that fixes it but idk so I figured I would ask to see if you figured it out. The owners before me also took really poor care of the car so that doesn't help. I have basically re done most of the controlling and suspension parts of the car as well as a lot of other things.