"Chugging"

New to the board, looks like some pretty knowledgeable Riv owners here.

'98 3800 SC. Chuggs at steady speeds with ever so slight acceleration, like a mild uphill grade. It comes and goes, mostly present though. When it's exhibiting the chugg thing, it seems to have a slight vibration at highway speeds. When not doing the chugg thing, the is no discernable vibration. It also sometimes "lurches" when stopped and in gear, like at traffic lights. And, when it does it, it does it pretty good too. You're glad your foot is on the brake! It's immediate, it lurches, you freak-out, and immediately it's purring away again like nothing ever happened.

Here's what I've done:
New crank sensor/magnet
New cam sensor
New computer (thanks to my GM buddy)
New inginition module (under the coils)
New coils
new plugs/wires/fuel filter/etc, several times
Ripped off the intake to check for coolant in-leakage. No evidnece of it.

Keeps showing a crank sensor code. But, having replaced it I'm not ready to go back there again, not yet.

I'm thinking maybe tranny related, like the converter is frigged up. My GM buddy tells me that's dumb, it's in the engine.

Any ideas?

Seems transmission-related to me. I noticed a type of surging with mine, it came and went. I think what was happening was it was slipping with slight throttle, so when it would grab and it seemed to jump forward. To remedy, I used the PowrTuner to increase trans fluid pressure at low load (idle). A band-aid fix, but seems to have worked. No more slip, no more grab.

My trans also lost the ability to lock up TCC at the same time. Not sure if these symptoms are related or not. I never have gotten it to lock up again. I just drive around in 4th gear.

Thanks, that's kinda what I'm thinking. Can't explain the crank code though.

Take a look at this link for plenty of relevant info:
http://www.bonnevilleclub.com/forum/viewtopic.php?t=18351

Search around that site for other threads on it as well. You've covered all the possible engine electrical issues.

See if your GM bud can get the car on a techII to see if there are any 'hidden' trans codes.

thirdbird, that's pretty much exactly what mine did to the letter. although mine also liked to die sometimes at stops or stop-to-go driving. I had a PO102 (maf low voltage,freq) and PO341 (cam sensor range/perf) codes showing up. I did most of the stuff you did first too. But as it turns out it was bad wiring for me. Use a multimeter and test the wires plug to plug from the cam sensor to ICM, from the ICM to pcm (this was my bad one), and test the wires at the MAF connector also. ones a ground, ones a 12v fused power, and ones the signal. My signal was bad. If the failure is intermittent, like mine, you may not actually read a problem at first. The way to deal with that is to basically bypass all the wiring. On the MAF sensor, you can jump the middle pin to a good chassis ground, jump the 12v + wire to the batt post (suggest use a fuse for safety), and for the yellow signal wire, I used wire strippers and pulled back some insulation on the wire so i could connect a jumper to it but you dont have to cut it.

If you don't have the info, i can tell you exactly which wire they are on the pcm connector because it was a little tricky to find.

That was MY problem but yours may be different. Bottom line, I've personally found the wiring in this car to be a weak link and sometimes hard to catch.

check the egr

racinfan wrote:

Take a look at this link for plenty of relevant info:
http://www.bonnevilleclub.com/forum/viewtopic.php?t=18351

Search around that site for other threads on it as well. You've covered all the possible engine electrical issues.

See if your GM bud can get the car on a techII to see if there are any 'hidden' trans codes.

Thanks for that link, lots of good reading there. Didn't get all the way through it yet but, suffice to say, I'm not alone in my woes.

Good site you guys have here, thanks!!

how many miles do u have on it now...i had a somewhat similar problem except it was more like a bogging.....i fried my CAT....which is very common due to the fact that general monkeys couldnt have possibly isolated all the heat into a smaller area.

Car has about 168k on it.

Just finished reading the entire related thread over in the Bonniville site. Lots of good troubleshooting went on there, it was like reading a progressing story. But, low and behold, it ended after 11 pages without firmly nailing down the culpret of the chugging. That thread covered two years of work be people chasing this problem. Thread ended in 2005.

I wish it would have continued. For those of you who don't want to read the entire thread, in a nutshell, the troubleshooting progressed from ignition systems to tranny systems seeming to end up at a non-positive conclusion that transmission heat (excessive heat) was causing the problem.

Guys who added extra tranny coolers got rid of the chugging. Others didn't buy into that entirely and that's where is ended. Tranny solenoids were another very probable cause but, they were thought to go bad due to heat.

Anyone look into this any further?

Jason wrote:

check the egr

One of the many items replaced early in the process. Thanks.

I really don't buy the trans cooler solution, either. There are those trans cooler die-hards out there who think adding a cooler will fix everything. I've run into these guys on forums before. According to them, if I don't run a cooler, my trans wont last 10k miles. My feeling is, if you keep the fluid changed at 40k mile intervals, heat won't kill your trans. Mine lasted 145k before the first sign of a problem. It still works 90% like new.

Having said that, I'm not as against trans coolers as I used to be. I think there are good reasons to run one, but it's not going to fix a problem like yours unless you notice it only happening when extremely hot.

There are so many parts inside an automatic transaxle, I find it amazing they work for as long as they do. How we manage to drive these cars for nearly a decade with no issues is beyond my comprehension. I figured mine would've gone out 50k miles ago.

My first post was in regard to your lurching symptom. As for the vibration at speed, this is a common problem when the TCC engages overdrive. I have some info in the shop manual that I will share when I can. Personally, I never liked Buick's programming for when to engage the TCC. Always seemed like I was being jipped out of using 4th gear. When I obtained the PowrTuner, one of the first things I did was allow the TCC to disengage at a very low throttle % instead of trying to hold on, which is when you'll get your shudder/vibration. This programming replaced the old "tap-on-the-brake trick". Are you able to avoid the vibration by tapping the brake before accelerating?

i dont buy the tranny cooling theory either, i have one, im not against them, but its not a solution to a mechanical problem. With 168K miles, i hope you dont still have the stock Catalytic converter

the pressure solenoid in my buddy's trans went out but he was getting more of a hard and delayed shift problem and trouble getting in and out of gears than chugging.

Well, just for chits and giggles, I pulled the MAF sensor after reading some threads over on the Bonnie site that said it helped the chugging problem. I was pretty sceptical about those claims and as it turns out, with good reason. It's the cleanest part on the frickin' car!! Cleaned it anyway, no difference in anything whatsoever.

Just posted this in case any of you guys had read those threads.

This chugging issue really pisses me off. There has to be a fix to it. I need to know what that fix is or I'm going to go broke replacing good parts!!!!!!!

ThirdBird

This Chuggle Could be a Trans related problem or an Engine
Drivability concern. I would first check the tcc slip speed with a scan
tool if possible this will tell you if the torque converter is slipping and chattering. If the slip speed is over approx 50 rpms with moderate throttle then the tcc is not holding. this could be caused by a valve worn in the valve body. If slip speed is ok then look into possible injector problems which could cause a chuggle.

JayDee wrote:

ThirdBird

This Chuggle Could be a Trans related problem or an Engine
Drivability concern. I would first check the tcc slip speed with a scan
tool if possible this will tell you if the torque converter is slipping and chattering. If the slip speed is over approx 50 rpms with moderate throttle then the tcc is not holding. this could be caused by a valve worn in the valve body. If slip speed is ok then look into possible injector problems which could cause a chuggle.

Thanks JayDee,
We did check the injectors (electircally) and they were fine. Plus, the chuggle is intermittent, if it were injectors or worn parts, it would seem the condition would be constant. Don't get me wrong here,,,, I appreciate all thoughts and ideas. I am just not thinking worn anything. After all I've read, nobody has dialed this common problem in. Since it's intermittent, I'm still thinking ignition system.

Like Turtleman said earlier, check the wiring harness, pin by pin, in the crank and cam sensor circuit. I have the same symptoms but it is the P0341 code (cam sensor). My wiring nightmare starts this weekend.

I'm having a very similar issue on my 97. (154K miles- supercharged)

I get a chugging at idle only- and only intermittently- some days she runs perfect. Here's my list of parts thrown at it:

Coil Packs
Plugs
Plug Wires
*Done by PO*
MAFS
CO2 Sensor (definitely needed to be done)
*done by me*

It randomly threw a Cam Sensor code once- But it always throws a Bank too Lean (Bank 1) code. Most recently it threw the Mass Air Flow Sensor code- but I just replaced that? They are giving me a new MAFS under warranty today.

One thing I noticed though- I have an open vacuum port on the back side of my motor- on top of the valve cover is a small electronic piece with 3 ports- one goes back with the fuel lines, one goes to the front side of the motor and one points to the back. The one to the back is open- no line, no nothing. I think this may be part of my problem. Can anybody tell me what should be there and where it goes?

Also- my cousin has a Monte Carlo with the Series II in it. He had almost the exact same symptoms, but I don't know what codes it sent out. His was resolved with a simple Fuel Pressure Regulator. He only has 55K miles on his though. Any thoughts on whether this could be the same issue on a Riv? I'm not keen on throwing out another $50 if it's not necessary.


Thanks

The little electronic piece you're talking of is the evap module and if you look closer the ''hole''is block off it's all normal it look like it.
But check if it work wit a scan(if it's obd2)i had trouble wit mine recently,the
valve stuck in and your engine tend to run lean.if it's a serie 1 try to unplog
it run the car 5 min and replog sometimes the pressure unstuck the valve but
it's a temporary solution if it works!

sounds like a cracked spark plug to me. Doesn't show up until the heaviest load, i.e. TCC locked and low-mid RPM. Check your plugs and wires

edit just read page two and the orignal post more carefully. Do double-check the plugs and gap, but it seems more like intermittent crank or cam sensor issues.

My Riv "Eleanor" has developed a "chuggle" at cruise under light load. I tried replacing the fuel injection pressure regulator - ended up installing a cheapie new one, which improved things but did not fix the problem. I have a Borg Warner FIPR on order which I will swap on tomorrow or Friday.

MAF was replaced a few months ago. CAT was replaced a couple years ago. IAC and EGR replaced last year (all maintenance).

I am thinking it may be time to replace the fuel pump again - I had replaced it once at 160,000 miles and it's now 100,000 miles later. It also may be time to replace the spark plug wires - I am running Magnecors which have been fine.

I am also thinking it may be "bad gas" as this all started after I topped off the tank (it was ~1/4 tank down) yesterday, with 91 octane at a local Sunoco. I have not tried adding fry gas or an ethanol stabilizer (or even Techron) yet.

If accelerating there is no chuggle or fishbite.

I also confess I've never serviced the injectors. I have a spare set that probably should be cleaned prior to install.

I am wondering if there is some maintenance I've missed.

I am also wondering if I should disconnect the battery so the transmission "forgets" - but it sounds like engine hesitation not transmission slipping. Thinking about it, it may be time for a maintenance fluid change in the transmission, I have to check my maintenance journal. (I do fluid change every 45K).

Please "weigh in" with your comments, thanks.

Albertj

If you haven't, check and clean all grounds!

Oh by the way I found this:

http://www.syty.org/old/d&e-surgechuggle.html

but is does not address that which is "typical" for a Riv...

I would certainly try installing the clean set of injectors, since you have them. At your mileage, if they've never been out, you're due.

Inspect plug gaps and electrodes. Sometimes there are clues.

Maybe coils? They can be tested, or buy a spare and swap it out with all three.

When you are "at cruise", do you mean it only happens when you are in cruise control?

AA wrote:

I would certainly try installing the clean set of injectors, since you have them. At your mileage, if they've never been out, you're due.

Inspect plug gaps and electrodes. Sometimes there are clues.

Maybe coils? They can be tested, or buy a spare and swap it out with all three.

When you are "at cruise", do you mean it only happens when you are in cruise control?

No, if I hold throttle steady (not hard to do) it will chuggle. I'll check out plugs/plug gaps too for clues. I'm running iridiums, these have been in 50,000+ miles.

I am thinking what I need is a Tech II, to command the fuel pump on and check pressure, and I also think I will fire up CarCode and take a data log, come back and look at it.

I also have this goofy anomaly where the turn signal relay will run by itself (sometimes) when parked and I step on the brake, or after it self-cancels after a turn. I was watching out for a chance to get a good turn signal switch instead of buying a new one at $300+. TS switch $300, FP $400, et cetera. Kinda looks like it's time for the annual maintenance spending jag...

...so I guess first thing is check those grounds. Like the one under the coil pack.

Thanks, and any more comments before I tear into this (Saturday) please shout out.

And thanks for all the help! I need it.

Albertj

Why do you need a Tech II to check pressure? Just use a fuel pressure gauge and turn on the key. You can even take a test drive with the gauge taped to the windshield.

I have a similar problem with my signal relay, though it happens randomly, and very rarely - not enough to be worried about. I am thinking the lighting control module might have something to do with it. Mine no longer turns on the headlamps at night (well, sometimes it does). When the relay clicks, it does not cause the exterior lamps to flash. I think it's actually the hazard relay, but can't be sure.

See more on this issue here:

https://rivperformance.editboard.com/t7499-relay-making-noise-after-releasing-brake-pedal