Surging at full throttle?

[sprucegoose]

I have noticed that my 98 Riv has a slight surging just before 4,000 RPM when I am at full throttle. It doesn't seem to be there in 1st gear, but when it shifts to 2nd and reaches that RPM is where you feel it. If I am not on the pedal all the way it isn't there either. It almost feels like an ignition miss, or possibly a fuel problem. Any thoughts?

There are no trouble codes, and it runs perfect otherwise. I guess I could start by changing the fuel filter as I have no history on when that was done last...

[maxwedge]

Do it and see what happens, typical symptoms.

[HotZ28]

We seem to agree with changing the filter first. If the hesitation is still there after the filter change, be sure you purchase the best gas available (93 octane) and add some good injector cleaner, like Lucas. I recently had the same problem during the gas shortage when 93 octane was scarce. I had to put some 89 mixed with 87 octane in my PA Ultra. It ran fine until I went to full throttle. What happens under this condition is, the knock sensor detects detonation (ping or knock), and retards the timing immediately, hence a hesitation or delay under full power. You could have some bad gas and need to change where you purchase it. It is not uncommon for the tankers with regular 87 to have some left in the tanker and they will dump the rest in the premium storage tank, if the station owner agrees. Heck, the owners make more money and the poor unsuspecting customer thinks he is getting 93 octane! Everyone is happy, until they experience what we have.

When I first had the problem, I suspected what the cause was and went straight to Advanced to buy some octane boost and Heet! I drove less than five miles and the hesitation was gone.

One other thing, the fuel you buy in the winter is less than the advertised octane anyway! As we all know, a cooler engine is not as likely to detonate as a hot one! That is why you have the "winter fuel". (And yes, it's legal)

[sprucegoose]

Originally Posted by HotZ28

We seem to agree with changing the filter first. If the hesitation is still there after the filter change, be sure you purchase the best gas available (93 octane) and add some good injector cleaner, like Lucas. >>>>>>

One other thing, the fuel you buy in the winter is less than the advertised octane anyway! As we all know, a cooler engine is not as likely to detonate as a hot one! That is why you have the "winter fuel". (And yes, it's legal)

HotZ28: I think you hit the nail on the head. I didn't even think about lower octane fuel being the problem till you mentioned that. I have been putting 89 octane in since I bought it, at the previous owners advise. Not to mention the cost savings! It did make a difference thoughj. I just put in 15 gal. of 93 octane, and after 10 miles or so of driving it no longer has the hesitation or miss! I'm still gonna change the filter this weekend though.

Yes, good ol winter gas huh? That sucks doesn't it? Also, If possible I always tank up in areas where the do not have "reformulated" gas, because my cars run much better and get better mileage with non-reformulated fuel.

Apparently this SC V-6 is more sensitive to octane than my Cadillac Northstar, cause I use to run that all the time (unless I was headed to the strip!) and never had any problems. It wouldn't be as quick, but it never had a surge or miss like the Buick. Allthough I do know that was a pretty sofisticated DOHC V-8 in that car...

Off topic... I just got back from a 5 day trip to China, and I couldn't believe all the Buicks I saw over there! Mostly Regals, but there was this little boxy 4door hatchback I never saw before. I'll post a picture of one if I can find it...

[HotZ28]

Glad to here your back to normal!

Yea, be sure to change the filter to keep that "high dollar" juice flowing! The SC engine is very sensitive to low octane, due to the boost. I run the 2.2" pulley, which raises the boost up to 10-12 lb range, so that is why I have to use 93 + octane boost. The Nothstar also uses timing retard to lower the timing if it senses detonation, you just don't feel the retard, like you do with the "huffer"!

I would like to see some "China" cars and other pics if you have them. You can go to my profile & select the Email option, if you like.

[sprucegoose]

Originally Posted by HotZ28

I would like to see some "China" cars and other pics if you have them.

Thought I would post them here so others could see them. I finally got my user gallery to work. Was having trouble with that for a while...

Here is a couple of Regals. They are big in the chrome fender look over there!



Here is a typical plugged up freeway. What a zoo! There was people riding bikes and even walking out in traffic everywhere. Note the little Buick in front of us, and the taxi driver's swinging bell!

[sprucegoose]

Update: I was still ocaisionally getting this slight surging at WOT, even after switching to nothing but 93 octane premium. I knew I needed to replace that tired fuel filter, and finally did so today. It did look quite ancient, I'm sure it was long overdue.

I went to relieve the pressure like I normally do, by pulling the relay for the fuel pump and running it till it dies. It started for just a second or two, then stumbed and died. I figured the pressure must be gone, so I proceeded to pull the filter. I wrenched the nut back, and was just lightly brushing the threads to clean them off and WOOSH, out came a huge geyser of gas! Man, I'm glad that didn't spray my direction! It probably sprayed out close to a quart or so.

I was wondering, is there a better method of relieving the pressure? Isn't there a way you can do it off the fuel rail or something?

Incidently, the test run after the change was great! No hesitation or surging at all. 0-100 went pretty quick too! First run up to that with the Riv, and it couldn't have been much over a quarter mile!

[maxwedge]

Pull the fuel pump fuse and run the engine till it dies, no fuel pressure.

[sprucegoose]

Originally Posted by maxwedge

Pull the fuel pump fuse and run the engine till it dies, no fuel pressure.

I couldn't find any fuse in the box to the right of the steering wheeel. I pulled the fuel pump relay that was under the back seat. Is there another fuse box? I don't see why pulling this relay wouldn't acheive the same thing...

[sprucegoose]

Ughhhh! Fix one thing and another comes up! Now I have a constant Service Engine Soon light on. I pulled the battery connection just now to try and clear the code overnight. I am thinking it must have something to do with me disconnecting that fuel pump relay. But then again, it didn't light up till this morning when I was warming it up...

[classicradiorepair]

NOOO!!! Don't pull the battery!!! I've pulled the fuel pump fuse just for fun (?) and I've never seen an MIL as a result. I'm not saying that that couldn't be the reason for one to be set, although it seems unlikely.

I pulled the batt. on my Riv when the check engine light came on, and now I have worse performance than when I bought the thing this summer. It would seem that unless your engine is operating at maxium efficiency (new), the reprogramming cycle that follows a computer reset will never equal the engine specifications that are loaded onto it at the factory. I am tempted to have the car reprogrammed at the dealer but I would much rather spend that money on parts I will actually get a long term benefit from.

Let us know if the light goes out - or what the error code ends up being if it does not! I am having what I think is a similar surging problem on a rare basis and am curious to see if your MIL could be related.

Nicholas

[sprucegoose]

Originally Posted by classicradiorepair

NOOO!!! Don't pull the battery!!! I've pulled the fuel pump fuse just for fun (?) and I've never seen an MIL as a result. ..

I pulled the batt. on my Riv when the check engine light came on, and now I have worse performance than when I bought the thing this summer. It would seem that unless your engine is operating at maxium efficiency (new), the reprogramming cycle that follows a computer reset will never equal the engine specifications that are loaded onto it at the factory...

Let us know if the light goes out - or what the error code ends up being if it does not!
Nicholas

Well, too late! It did the trick though (so far), it has not come back on in two days. I have not really got on it hard, but I feel no adverse performance affects from disconnecting the battery in everyday driving. Gives me a good reason to give her some WOT tomorrow and test it out though!

I had heard that the computer does some recalculations when you disconnect the power source, but my car was running really well even before I disconected it. I think the surging problem came from both poor octane gas and old/tired fuel filter. That thing hads been on ther a looooooooooong time, I could tell from the looks of it. I should have disected it to check for blockage, but never thought about it.

[mtmaurer8ooo]

I might be wrong, but aren't you supposed to run premium fuel on the supercharged engines anyway???? I do and I have zero issues, I mean, it's only an extra 2 bucks or so a tankfull. The only issue I had that kicked a light on was a misfire code that ended up being a bad plug(cracked insulator - plugs and wires, fuel filter - fixed her right up). And if you do pull the battery..they make this nifty little device that you plug into the cig. lighter that uses a 9V battery to maintain all the stored data. You should check them out. And you all know by now that disconnecting the battery is NOT the correct way to turn off check engine lights, and it certainly doesn't fix anything. Late. M

[sprucegoose]

Originally Posted by mtmaurer8ooo

I might be wrong, but aren't you supposed to run premium fuel on the supercharged engines anyway???? I do and I have zero issues, I mean, it's only an extra 2 bucks or so a tankfull......

And you all know by now that disconnecting the battery is NOT the correct way to turn off check engine lights, and it certainly doesn't fix anything. Late. M

Yes, as I mentioned earlier in the thread it does call for Premium. I was putting in mid-grade as that is what the prev. owner said he always used, and it DOES add up for me. When you are commuting 600 mi. per week and putting kids thru college it all counts!

Disconnecting the battery cured my SES light, what would you suggest otherwise? I know it doesn't "FIX" anything, but it will clear a random code that will otherwise take like 3 dozen turns ofthe ignition switch to clear.

[cbass45]

I agree on the gas adding up. I fill mine up with mid grade as well. Even when I do that it is close to $47.00 and I too have to fill up once a week.

I did notice that If I just use mid grade I dont get the performance that I should, so I did some checking around and a guy at the dealership told me that a high school girl brought her 99 Grand prix GTP in fue to a check engine light. She was using regular, they informed here that any 3.8 SC engine should be using prim gas. She stated that she cant even afford filling up with regular gas. So the shop guy told here to get around this is to fill up with regular and then go to walmart and pick up some STP octain booster/cleaner $2.50 and add it every fill up.

I have been doing this with mid grade, and the performance is always there just like I filled up with preim.

Sorry I went on and on. But it does work, and it saves you a few bucks.