strange bogging around 45 mph

I've had this problem for a while now and i can't figure it out. Every time i get to 45 miles per hour or around there i get a bog like effect. I can't tell if it is the engine or if the transmission is just hesitating to shift. My SES light comes on when this happens. any ideas?

First idea is to read the DTC code with a reader or scanner. Many local autoparts stores will do this free of charge. That may tell you exactly what the problem is!

i may be able to bring it into the school shop to scan it, does this problem sound familiar to anyone? any ideas of what it could be? I am assuming it is a sensor because it throws a code, but i don't know exactly how that stuff works

The '95 needs a special code reader for OBDI. Does the SES stay on for a while after it happens? If so, how many times do you need to start the car before it goes out? I wouldn't assume a sensor is bad. It could be the sensor is working correctly and reporting the problem.

good point. But yes the light stays on, but i have never noticed how many times i need to restart it to have the light go off. Does the light turn off after a certain amount of restarts for different problems?

Yes, the SES will illuminate based on the number of consecutive "trips" it senses the problem, and will turn off after a certain number of trips without the problem. A fluke or intermittent issue will allow the light to turn on and then off, but the DTC stays logged in memory. A more constant problem will cause the SES to stay on. Sometimes you can deduce the severity of the problem is by how many trips it takes to turn the SES on or off. 3 consecutive problem-free trips is common for the SES turning off.

thanks, its always nice to learn something new about the riv

Okay so i changed the boost control solenoid about a month ago and replaced just about all of my vacuum lines and my SES light has not come back. I have noticed that when the supercharger whines i actually get a lot more power, but my problem at 45 Mph has never gone away. At 45 with about 2000 rpms it gives me trouble. It feels like it is a transmission problem because it feels like it is trying to shift, but is stuck in between shifts. If i give it slightly more gas the rpms won't move and engine bogs. But if i give it even more gas the rpm will rapidly increase and the problems will be gone. It does this when i have the shifter in D as well as 3. I thought it was a problem shifting into over drive, but it still occurs in 3. Any help would be greatly appreciated. Thanks Guys!

If you changed the boost control solenoid and the light went out with a noticeable difference in boost power then I would say thats what the engine light was for. I had a similar problem with the same solution. If the same, then you were only making 3 of the stock 6-7 PSI of boost before.

Without a scan tool its hard to tell what might be causing your bog at 45, but there are a couple of free things that you can try.(after making sure your plugs/wires, maintenance items are done)

First thing I would check is your throttle position sensor. Grab a volt meter, set it to resistance, and play around with the connections going into the sensor. Once you find the leads that gives a change when you move the throttle plate, you want to look for a smooth change of the numbers. Sometimes the sensor gets a flat spot(or 0 spot), which might be whats happening to you at 45.

The next thing I would try is to loosen the two bolts that hold the boost bypass actuator in place and move it as "high" as you can with its arm still touching the lower stop. I realize this is contrary to the "boost bypass" mod that some people do, but the m62 reaches full boost much faster then the m90, and even in stock form you can start dipping into the boost when under high engine load(like in 3rd gear at 45MPH). What happens is the heavy load starts you into boost, but your throttle position isn't even close enough for the computer to enter PE(power enrichment) mode. Gives a bogging feeling and sometimes KR. I had a similar issue with my (very) modified blower. Not saying you are having the same thing, but its a free thing to rule out.

Anyway, without more info, thats about all I can suggest. You would ideally have a scan tool to know what your fuel trims etc.. are doing when the issue is present to narrow things down.

RidzRiv wrote:

Okay so i changed the boost control solenoid about a month ago and replaced just about all of my vacuum lines and my SES light has not come back. I have noticed that when the supercharger whines i actually get a lot more power, but my problem at 45 Mph has never gone away. At 45 with about 2000 rpms it gives me trouble. It feels like it is a transmission problem because it feels like it is trying to shift, but is stuck in between shifts. If i give it slightly more gas the rpms won't move and engine bogs. But if i give it even more gas the rpm will rapidly increase and the problems will be gone. It does this when i have the shifter in D as well as 3. I thought it was a problem shifting into over drive, but it still occurs in 3. Any help would be greatly appreciated. Thanks Guys!

This is not necessarily a transmission problem. You however are gonna have to learn enough to do much of the diagnosis yourself so here goes...

1) find out if you have any "stored codes" and what they are
2) use a scanner to check the voltage pulse levels from your O2 sensors - how effectively is the cat working? As it clogs it still works but not as well Post the figures.
3) are you burning premium? If not that can be an issue if you are trying to drive in a "spirited" way
4) when (if ever) have you changed transmission fluid and filter? for all we know your filter has a heaping helping of clutch mud...

Do tell, do tell.

Albertj

I agree with albert and Andrew in trying some self diagnostics first to eliminate possibilities. Having said that, I had the same problem and the dealer said it was my torque converter not locking up correctly. Not sure if the solenoid would fix that or not as I never got the job done since it was not going to be covered by warranty and was too expensive to pay out of pocket. Keep us updated as I am sure others can benefit from your progress.

Thanks guys! Yes i used a scan tool from my high school months ago to scan for my ses light. I got the code and brought it to you guys for help. It indicated a problem with either the evap purge solenoid or the boost control solenoid. I replaced both and my light went off with the boost control solenoid. Although my car now could use all of the boost like Karma was saying, i have still had the problem that i am now talking about. I have no light now. Thanks for your help guys! i will check out the voltage on my tps. I should also change my trans fluid and filter like Albertj said. I have never changed it so i'll have to take some dirty pictures of the filter when i get to it. Karma how what do i look for when i fiddle with the boost actuator? and BMD i will definitely keep you guys informed on any progress! Thanks again guys! I'm just starting college and i'm commuting so it's a good excuse to spend money on the riv!

Boost actuator is pretty simple. It sits right behind the control solenoid you changed. 2 10mm bolts, undo the bolts, let it "relax" up/right, the end of it goes to a lever that moves the dump gate in the SC, you want that to still be in closed position. Boost actuator goes as far up/right as possible without lifting the lever from the closed position.

Thanks, so do i adjust this during idle or with the engine off?

Engine off.

Alright thanks! I just made sure it was set up properly and will test drive tomorrow. This seems like a very likely cause of my situation.

Okay so today i test drove and the bogging still occurred. My father has a volt meter, so i will check out the TPS next time i'm at his house.

Well, I had a sort of similar problem but with no engine light. Was worse going uphill, I noticed. Anyway, new coils fixed it.

Hmm, mine doesn't have a light either. I'll have to check out my coils after i change plugs and wires

Okay so i read some advice that Derek gave another member in a recent thread and i tried it out myself. The advice was to tap the brake during throttle when it seems to be acting up. I did this today and the bogging went away and the rpm's went up like they should. So what does these mean for me now? Could my Torque converter be stuck? Thanks guys

I think you are noticing the normal behavior of the torque converter clutch. I didn't notice it on mine for several thousand miles, but after you get to know the car, and compare it to other (newer) cars, it tends to stick out. It's Buick's way of saving you gas, at the expense of throttle response.

On '96-newer cars, you can tune the PCM to stay out of TCC lock-up, but on '95 I don't know of a way to fix it. It's nothing to be worried about, but unfortunately it is the way it is. You can circumvent it with practice by applying the gas more firmly, and/or using the left foot to tap the brake.

Are you sure that its "normal" for the torque converter clutch to behave this way. Our cars didn't do that new, and not every GM FWD drive vehicle exhibits this behaviour. I am glad to hear you say that its nothing to worry about, and I have managed to block it out when it happens, but its still a result of the clutch not engaging properly. Would a TCC solenoid replacement fix that?

Not 100% sure. It might be something that isn't as noticeable when the car is brand new, but I think it's there. I also think not everyone perceives it as a problem.

I noticed it from shortly after the time I bought my car in 2003. It had less than 30k at that time. I considered it to be in "new" condition. It took me a few weeks to really pic up on it, but it was there.

Furthermore, when I had the transmission rebuilt at 151k miles, they replaced the torque convertor with a new one. They also replaced the valve body. The symptom was exactly the same. It felt the same as when new.

I've never driven a 3800-powered car that didn't annoy me with the TCC operation. In fact, many other automatic drivetrains do the same thing. However, tuning the lock-up and release points makes the problem disappear completely. If I change back to the "stock" program, it comes back instantly. It's like turning a switch on/off.

If your acceleration picks up when you unlock the TCC, that's normal. It should also unlock if you quickly stab the gas. If not, maybe you have an issue with your TPS? It triggers the unlock. If the unlock isn't happening you could perceive it as a "bog".

The 'brake pedal to unlock TCC' trick has worked on every TCC GM vehicle I've ever driven since the late 80s.

Thanks for the info guys, but i'm pretty sure there is a problem. Maybe the TPS or maybe something with the TCC clutch or something else. The lock up has always been apparent and slightly annoying, but now it is at the point where when i give it more gas to trigger the unlock i have to give it even more gas, and sometimes it seems like it's hard on the transmission, like it slams into gear. Mostly it seems like it is in the lock up for too long.

Also my girlfriend has a supercharged 95 riviera and it doesn't appear to do this even with 245000 miles.