Chevy Impala 3.4 jerking when shifting

2003 Impala 3.4. Car jerks 4-6 small times when shifting from 1st to 2nd after warmed up. It only does the jerking when given just a little acceleration. When giving plenty of gas it shifts perfectly. It shifts fine at any speed when cold. Only when warm does it act up. I have new plugs and wires, front wheel bearings, cleaned MAF sensor, changed fuel filter and air filter. Any ideas?

Transmission fluid condition and level? Mileage? Last transmission service?

Is the Check Engine Light ‘on’? If so have you scanned the PCM for codes?

Transmission shop checked fluid and said it was clear and level was fine. 156,000 with no problems until now. Trans fluid changed 40,000 miles ago. Surprising they said it was clear and did not need to be changed. It it pinkish red. Possible trans filter?

No check engine lights on at all. Oil changed every 3,000. 156k miles on car with no problems until now.

Sorry, I missed the above post.

Every 30k is the recommendation for transmission fluid replacement by most people on this board. If your car is equipped, they normally recommend dropping the pan and changing the filter on the trans. (I have never owned a car equipped this way-mine always have had drain ports)

I hope that helps.

If you’ve gotten to 156K on one of those disastrous 4T65E transmissions I say its remarkable. They are built like a carton of egg shells and once things start to go no one seems to know what to do with them, including GM. (Ok, I might be a little annoyed with my own vehicle and overgeneralizing a little too much - but only a little).

Get it to a dedicated, local transmission shop and have it scanned for codes. There are plenty that will be stored without turning on the check engine light. Expect the worst.

You can post results here for comment if you wish.

As related to the original post I unplugged the connector on the EGR valve and it runs great and the jerking has stopped. Does this make any sense that the EGR valve could cause this?

As related to my original post I unplugged the connector on the EGR valve and it runs great and the jerking has stopped. Does this make any sense that the EGR valve could cause this?

It can sort of make sense. The EGR feeds exhaust gasses back into the intake. If the system (the valve itself is only one part of the system) isn’t working quite right it can basically cause something like a lean misfire (felt as jerking).

The only part that doesn’t make sense is that it really shouldn’t be connected only to a 1-2 shift. It would more likely be connected to an RPM range - so it should occur under similar throttle conditions at the 2-3 or 3-4 shifts - or really at any other time you’re under the same rpm/throttle conditions.

Its hard to argue with results though.

Did you ever get the thing scanned for codes?

It finally threw a PO336 Crankshaft Position sensor code and I had both the 24x and 3x replaced a few days ago with crank relearn (mine is the 3.4 liter). This did not fix it at all. Also had new trans filter and fluid replaced and this did not help either. I replaced TPS also to no avail. I simply unplugged the EGR valve connector today as a last ditch effort before looking at new transmission because I read about several people that had done it and it stopped the jerking. My mechanic says he has never seen anything like it and he is GM master mechanic. I figured it would wind up being a PO1811 (pressure control solenoid) which he has seen many times but it has never thrown that code and he said it is not behaving like the ones he has seen before. I am going to drive all day tomorrow with EGR valve unplugged to make sure that is it. It always starts jerking when the temp gauge gets to about 1/4. It did start jerking in different ranges from 10-15 mph and 25-30 then it started jerking a little when set on cruise above 65-70mph until I unplugged the EGR and never jerked once today. I appreciate your all your previous responses. Before today it would basically keep jerking until I let off the gas or gave it more. If it does ok tomorrow I would say new EGR valve or can you think of anything else that could be related? Thanks


Curious if new EGR valve solved your jerking problem. I’ve been experiencing similar jerking in my 1985 Toyota 22R, which is pre-computer and pre-diagnostic codes. Disconnecting EGR system eliminates my jerking too …

Since it seems clear that the EGR system has something to do with your jerking when shifting, then you want to learn about how your whole EGR system works and then figure out which part of the system may be causing the trouble. It might turn out to be the EGR valve itself. But maybe not.


That’s sort of where I am now. I am hoping that jassar is still monitoring this website and can tell me his results. I am new to this whole forum thing, and Caddyman has given me some good suggestions, but would love to hear more opinions. The post which I started is titled 1985 Toyota 22R with hesitation ONLY when hot, in which you can learn more about my symptoms and things tried so far. Thanks in advance for any thoughts you can share.

First time I have checked post for a long while. Thought the impala was fixed after the new MAF but I was wrong. I am in sales and I just rolled over 170,000 and it is still doing the hesitation/jerking. At around 156,000 I thought it was fixed when I put new MAF on and disconnected battery for awhile to reset. It started again a day later. It has been 16,000 miles since the issue started and it is no better or worse. I have put new front O2 sensor in since and tried a another Delco TPS to no avail. So in all I changed plugs and wires, EGR valve, front wheel bearings, MAF sensor, fuel filter, air filter, CAT, TPS, crankshaft position sensors, O2, transmission fluid drain and fill with new filter. Fluid was not dark or burnt.

It almost has to be the transmission dying slowly but it did not throw the famous 1811 or any other transmission codes at the transmission shop when I had it checked. The things left that I have not done that I wonder about are the coils, MAP sensor maybe sending some skewed info to computer about shifts, fuel pump, fuel pressure regulator or camshaft position sensor. It is just funny that it starts the issue at exactly the same spot ( one mark past 1/4) on the temp gauge everyday like clockwork. Still gives me some hope that it is a sensor that is off enough not to throw a code when they go into loop.

Current symptoms are the same as before but only 2-3 jerks at 20 mph and the shaking/pulsing at cruise when at around 75mph when on interstate only when going downhill. It only does this intermittently as it will pulse/jerk all the way down a certain hill but not on the next. This is not the normal cruise catch up or slow down but a pulsing/slight steady jerk downhill.

As far as one of the previous responses about the EGR system as a whole. The EGR line is in good condition and is clear. I am no mechanic but what other part of the EGR system is there. The only codes it has thrown since 154k to 170k where it is now is evap emission loose or faulty gas cap. I put new cap on, gasket was dry rotted and it fixed issue.

I have not tried anything new as far as EGR. I will unplug it tomorrow and drive it to the temp where the problem starts and see if it still helps the problem.

How about the egr relay?

I have a 2000 grand am and I had that same issue. Surging at 2100-2400 rpms unless under load. It was my harmonic balancer. When I bought the car it had been sitting for a year and the harmonic balancer had hardened and a chunk broke off making the belt squeal. I checked it out and I had the mechanic put in a new tensioner pulley and the balancer. It was only after that work that I noticed the surge. For over a year I researched, questioned, etc. Finally the ses lit up with a crankshaft sensor code. I had just replaced the one on the back of the motor but not the one by the crankshaft which was the one I had suspected to be the culprit. Didn’t matter because not long after that the harmonic balancer split in half and shot out. The mechanic apparently didn’t know what he was doing when the initial work was done and damaged the part on install. New balancer, no surge.