1995 Regal Custom Transmission Shudder

Hello to all forum members!!

I have recently bought my regal and after about 4 months I noticed that my transmission would shudder between shift points (i.e. when rpm drops from 2500 - 3000 back to 1500 and I try to accelerate).

I had the transmission replaced with a re-built (t460e i think) and I have noticed the same thing happening even when I have it in cruise control.

Before taking the car back to the mechanic I thought I would get a few ideas from the members as to what may be causing this.

Respectfully,

Drake

Any decent transmission shop should have given you a 6 month or 1 years warranty. Take it back as soon as possible and complain. If you wait you will have to shell big bucks to cover poor work. Really complain demand they fix it if after politely asking them first doesn't work. A quality shop will want to fix it as they want to maintain a reputation.

rhandwor,

Thanks for your reply!! I have an update on the problem:

Since the problem seemed to be getting worse, I took the car back to the mechanic on Friday. After a thorough test drive, the mechanic seemed to think that the problem was not transmission related but engine related. The mechanic claimed I was suffering from "fuel starvation".

The mechanic basically said that once the car shifted into overdrive lowering the RPM and I tried to accelerate there was not enough fuel reaching the engine. The car would then proceed to misfire causing the car to shudder as I tried to accelerate. The mechanic claimed that stepping on the gas more aggressively would make the shudder stop.

Now the mechanic's theory seems viable but I was wondering what the forum members think of his diagnosis. Fuel filter vs. transmission.

Thanks in advance for your thoughts or comments.

Drake.

Is this the exact same issue as before it was rebuilt, if so they misdiagnosed the problem and need you need to discuss this with them. It is possible an engine misfire can cause this, bad plugs, wires, low fuel pressure and so on.

maxwedge, thanks for your quick response.

The original work I had performed on the transmission produced the same shudder as I have been experiencing but the shudder would happen at all the shift points (i.e. 45-60 km/h, 65-95 km/h).

Also, the mechanic at the time they were replacing the transmission showed me the metal filings that were in the transmission pan. I have asked the mechanic to check the transmission pan again an ensure no metal filings are present (just to make sure).

Thanks again, I will provide an update latter this week after I get the car back and test drive it.

Thanks to everyone for your help, its great to know we have such a great resource for Buick enthusiasts!!! I look forward to being a member here as I just love my Buick!!

Drake

A further update:

I picked up my car today and the mechanic replaced my fuel filter and checked the transmission pan for metal filings. The mechanic is 100% sure the problem I am experiencing is not transmission related (a good thing I guess). The mechanic claims that one of my cylinders is running "lean" and that I do not have much power after 3000 RPM.

The mechanic went on to say that this problem is very difficult to assess saying that it could be anything from carbon build-up or a problem with the push rods. Since my experience with vehicles in general is very poor I no longer know what to take from this. The mechanic advised me that I should run the car for a few days to see if the new fuel filter would help clean a possible carbon build-up.

I took the car on the highway and I accelerated to 90-95 km/h after which my RPM's lowered to 1500 from here I tried to accelerate and the shudder was still there and now I am at my wits end. I do not know if I should go back to the mechanic or give it a few more days.

I am hoping the forum members could provide some insight or suggest what I can do to try and resolve this issue. I love my Regal and would hate to have to get rid of it (only has 145K kms).

Looking forward to your thoughts.

Drake

I would check the fuel pressure regulator. Pull the vacuum hose and check for a fuel leak. If you don't have a pressure gauge pinch of the rubber part or the return hose and check if this helps your problem. If it does you need a new pressure regulator.You really need to check the pressure as a plugged strainer can cause problems.

Do you seem to be using any antifreeze? I wonder the lower intake gasket has failed and your sucking antifreeze which is causing the misfire. Can they prove its a misfire? and my last question is the torque converter clutch locking up too soon causing a chugging?

A further update:

I picked up my car today and the mechanic replaced my fuel filter and checked the transmission pan for metal filings. The mechanic is 100% sure the problem I am experiencing is not transmission related (a good thing I guess). The mechanic claims that one of my cylinders is running "lean" and that I do not have much power after 3000 RPM.

The mechanic went on to say that this problem is very difficult to assess saying that it could be anything from carbon build-up or a problem with the push rods. Since my experience with vehicles in general is very poor I no longer know what to take from this. The mechanic advised me that I should run the car for a few days to see if the new fuel filter would help clean a possible carbon build-up.

I took the car on the highway and I accelerated to 90-95 km/h after which my RPM's lowered to 1500 from here I tried to accelerate and the shudder was still there and now I am at my wits end. I do not know if I should go back to the mechanic or give it a few more days.

I am hoping the forum members could provide some insight or suggest what I can do to try and resolve this issue. I love my Regal and would hate to have to get rid of it (only has 145K kms).

Looking forward to your thoughts.

Drake
Drake, this is a shame in my opinion, both of his suggestions, if you understood them correctly are false. Neither " pushrods" or " carbon" can cause this . Get it to another mechanic, don't tell him the backround and let him drive it or check it out then give you a diagnosis. Again, was this trans overhauled for this conditon, if so you have an issue with that job, possibly.

The mechanic claimed I was suffering from "fuel starvation".

The mechanic basically said that once the car shifted into overdrive lowering the RPM and I tried to accelerate there was not enough fuel reaching the engine. The car would then proceed to misfire causing the car to shudder as I tried to accelerate. The mechanic claimed that stepping on the gas more aggressively would make the shudder stop.

Your mechanic's fuel supply idea makes no sense to me because less fuel is being consumed when it shudders than at times when it does not. Nothing you have written about what your mechanic said makes any sense. Your mechanic doesn't have a clue. Maxwedge offers good advice. Show the next mechanic what it does and let him diagnose the condition.

GM used a different type cam position sensor on some cars. I think yours may be one of them. It uses a back-up sensor that takes over when the primary sensor fails. When the primary part of the sensor is intermittent the signal bounces back and forth between the two sensors. There are a few degrees differance in timing between the two, the computer can adjust to either consistent signal. While the signal is alternating it causes a shudder. It will also set a miss-fire code.

You might believe it but I put a rebuilt long block in a 3.8L buick. I had the same type of problem and I used a gauge and checked fuel pressure. Checked for codes. Checked all the plug wires and checked for vacuum leaks. The machine shop put different push rods in the engine. I pulled and rolled them on glass and when checking the length they varied from 1/16 to 1/8 inch in length. I took all of them back and they gave me a new set. This solved all problems.
I haven't heard his engine but a worn valve guide will cause a misfire kind of hit or miss or sometimes bent a push rod.

Do you seem to be using any antifreeze? I wonder the lower intake gasket has failed and your sucking antifreeze which is causing the misfire. Can they prove its a misfire? and my last question is the torque converter clutch locking up too soon causing a chugging?


troy1, thanks for your reply my antifreez levels seem normal they are between the hot and cold levels on the resevoir.

I would check the fuel pressure regulator. Pull the vacuum hose and check for a fuel leak. If you don't have a pressure gauge pinch of the rubber part or the return hose and check if this helps your problem. If it does you need a new pressure regulator.You really need to check the pressure as a plugged strainer can cause problems.


rhandwor, thanks for the suggestion and please excuse my ignorance could you kindly tell me where the fuel regulator would be located and exactly what steps I need to take to diagnose the unit.

Thanking you in advance,

Drake

To all forum members,

I forgot to mention in my previous posts that my mechanic ran the problem codes from my computer and nothing came up. (if it were only that easy....lol)

It should be in the fuel rail. It is about 3/4 inch dia. and about 2 1/2 inch long.
A vacuum line is on the bottom first pull the vacuum line. If it has any gas in the unit replace. You have two fuel rails one side has the primary with a line to the otherside. This side is the return. The gas line with the filter is the supply the other line is the return. Use vise grips and pinch off the rubber hose. If the engine has a lot more power replace the regulator.
The only other thing you can do is use a gauge and check pressure before and after.
About 90% of the time the vacuum hose has gasoline if they are bad. Also check your air filter. It will shut down a car if dirty enough. Any cracks in the inlet hose will mess up a mass air flow sensor.

It should be in the fuel rail. It is about 3/4 inch dia. and about 2 1/2 inch long.
A vacuum line is on the bottom first pull the vacuum line. If it has any gas in the unit replace. You have two fuel rails one side has the primary with a line to the otherside. This side is the return. The gas line with the filter is the supply the other line is the return. Use vise grips and pinch off the rubber hose. If the engine has a lot more power replace the regulator.
The only other thing you can do is use a gauge and check pressure before and after.
About 90% of the time the vacuum hose has gasoline if they are bad. Also check your air filter. It will shut down a car if dirty enough. Any cracks in the inlet hose will mess up a mass air flow sensor.


rhandwor, thanks for the help. I went out today and purchased a Haynes manual to help me with some of the suggestions posted by the members. I replaced my air filter today with a K&N and test drove the car and still I have the same problem I inspected the inlest hose (I assume the large hose from the air filter housing to the engine) and found no cracks (one less thing to worry about....lol

I hope to check the regulator this weekend (I hope I can find it lol) and check the condition of the vacume hose for fuel.....do I need to disconect the battery or anything like that?

I will provide updates as I check various suggestions posted...Thanks everyone I hope that with all the help we can get this problem solved.

Drake

Just to pull the vacuum hose and check for leaks you don't need to disconnect the battery. If you replace I would disconnect the neg. terminal at the battery. Its possible you could bump something.

you also might want to check the quality of the plugs and wires. My friend had a 91 regal that did exactly the same thing, and the only way the shuddering stopped was really hitting the accelerator. It turned out, that one wire was finished, and the engine was really only firing properly on 4 cylinders.