Regal chugging and hesitation during acceleration

[cckeeler]

I have a 1999 Buick Regal GS Super Charged. A couple days ago it started running completely lousy. The car starts up just fine and seems to idle fine. But when I am driving and I am accelerating or going up a hill the engine starts cutting out, hesitating, chugging, i'm not sure what to call it. It has no power and seems to jerk and hesitate. The check engine light did not come on at all.

I unplugged the MAF to see if that was the culprit but it ran exactly the same with it unplugged.

My next thought was to replace the plugs, wires, and fuel filter. Any other ideas what may be causing this?

I should also point out that at one point I received an error code related to the EGR valve but it went away a few weeks ago. Could this be related?

 

[xstickx]

This could be a variety of things:

The first thing I would look at is plugs and wires. If the shields are still on the plug ends, remove them. They cause shorts that resemble misfire.

The next thing I would check are the ignition coil packs.

Is there any loss of coolant? If so, you may have a fouled plug due to a leaking upper plenum. Antifreeze is leaking out of the plenum onto the lower intake and falling into a cylinder causing misfire.

Is there any odor associated with situation such as sulphur or the smell of rotten eggs? This could mean a bad catalytic converter.

Is there any slippage in the transmission? If so, your problem is a bad torque converter as the TCC is failing.

 

[xstickx]

I just read the part about the EGR. The upper plenum is probably your problem. The coolant leaking also falls into the exhaust port that goes to the EGR valve. It's actually the hot exhaust gas melting the plenum and causing the leak. There is a vacuum hose attached to the rear of the plenum that runs over to the brake booster. It's about 5/8" diameter. Squeeze the clip and pull it out of the plenum. Place your finger in the hole of the plenum and try to touch the top of the lower intake. If your finger comes out wet, bingo. It's the plenum. You'll have to buy an upper plenum which comes with the aftermarket fix to prevent the plenum from melting again.

 

[cckeeler]

Wow. This went from what I thought was going to be an easy fix to something a lot more complicated. This is where my ignorance is going to shine through. Is that the upper intake manifold? I will look around for that vacuum hose in the morning and give that a shot. At one point I was told that the engine's head gasket leaked, I wonder if it was actually the plenum.

Would that also create a burning smell? This car has always smelled like something is burning.

 

[xstickx]

If you don't have very thick white smoke that smells like antifreeze rolling out of your exhaust while you're chugging and hesitating, it is not the head gasket. Actually, the head gaskets on these motors are very dependable and will run forever unless your warp the heads by overheating the motor.

As for the burning smell, it could create it due to it being the exhaust gas that melts the plastic plenum. It depends on the type of burning smell. Transmission fluid, oil, power steering fluid, antifreeze, electrical all have distinct smells. You'd have to answer this one for yourself. Do you believe what you smell could be melting plastic?

Yes, the upper plenum is also referred to as the upper intake manifold. It is black and made out of plastic. It's not a real difficult job to do. It's just takes a little time (8 hours for the average do it yourselfer). It isn't expensive either, about $100, unless you decide to swap the lower intake manifold gaskets while you're doing this job. It isn't a bad idea if they have never been replaced and you have the cash. These are known to fail also because the factory gaskets were nylon and not steel reinforced. You'd be doing yourself a favor in the long run. Also, I'd pick up a Haynes manual #38010. It's based on a complete tear down and rebuild of your vehicle.

I should add that I would not drive this vehicle until I knew this was not the problem. If too much coolant leaks into the cylinder heads while it is running, it can and will hydro lock the motor and cause catastrophic engine failure. You don't want to be on an interstate when that happens. Don't test fate because fate will always win.

 

[cckeeler]

Alright, I went out this morning to start looking at this thing. After thinking about it, and I may be completely wrong, but isn't the upper intake manifold the supercharger?

Also, while I was out there I noticed one other thing that has me concerned, and may be part of the issue, but both of the hoses going in and out of the radiator are sunk in. What would cause that?

 

[HotZ28]

Since the OP's car is a Regal GS (Supercharged) the UIM problem (which is common to the Base L36 Plastic UIM) is not the issue here. The misfire under load sounds like secondary ignition misfire, and as mentioned, you should check coils, wires & plugs. In addition, if you have a sticking (gummed-up) EGR, it may eventually require replacement. The "burning smell" may be leaking valve cover gaskets, which is quite common.

 

[cckeeler]

Would a clogged fuel filter cause hesitation or chugging like this? Wondering if I should check for that as well.

 

[HotZ28]

A fuel pressure test would tell the story, but normally low fuel pressure would affect the engine performance over a wide range of conditions, not just under load. Fuel filters are cheap insurance against low fuel pressure and early retirement of the fuel pump. I change my fuel & air filter (less than $20.00) every spring when the weather is more suitable for routine maintenance.

 

[xstickx]

That's my fault. The fact it was supercharged slipped right by me. I'm going with fouled plugs/bad wires, or a faulty coil pack. My money is on the plugs and wires.

What do you mean the hoses are "sunk in"? Do you mean collapsed? If so, it could be weather/temperature related and would have nothing to do with a hesitating engine either way.

 

[cckeeler]

Alright, well an update. I change the plugs and wires... No change. But a couple of observations while I was testing it. I have one of those cheap bluetooth OBD scanners that connects to my phone. I was watching the load dial and it seems to start chugging once I get up to speed but still giving it gas. I watched the load decrease and immediately followed by the chugging.

 

[HotZ28]

The next thing I would check are the ignition coil packs.

As previously mentioned, coils can fail and cause the same symptoms. If your "cheap bluetooth OBD scanners" can read misfire, you should be able to identify which cylinder(s) are misfiring. If not, you should take someplace where they have a scanner that can read misfire!

 

[cckeeler]

I'll look into whether or not it can read misfire. I still have yet to get a single code since it started doing this.

 

[HotZ28]

Normally, misfire can only bee seen with a scanner capable of viewing "misfire" info. A basic code reader will not work!

 

[cckeeler]

Looks like it may log misfires. I'll give it a shot in the morning.

 

[cckeeler]

Alright, well I loaded the custom PID's for GM vehicles into that scanner and watched the misfire data. Didn't show any misfires.

I think I have narrowed it down to exactly when it happens, but it worries me. It seems to happen when it drops into overdrive. I'll be in 3rd and once I reach a speed and maintain it the RPM's drop to about 2000 and it starts chugging.

 

[cckeeler]

Since I'm not seeing any misfires from the scanner, how would I go about testing the coil packs? I've had one go out on a gmc envoy before but it actually set a code that helped diagnose the thing. I am getting a code now but it's for the egr valve again which I think is unrelated.

 

[cckeeler]

Alright, so I was reading about this in other sites and saw one that mentioned this problem being caused by a camshaft position sensor. Could this be a possibility in this situation? Also, where is it located at? I may try unplugging it and giving it a shot if I can track it down.

 

[HotZ28]

Since I'm not seeing any misfires from the scanner, how would I go about testing the coil packs? I've had one go out on a gmc envoy before but it actually set a code that helped diagnose the thing. I am getting a code now but it's for the egr valve again which I think is unrelated.

I usually use a spark tester connected to the spark plug end of the ignition wire & grounded. While cranking the engine, observe the spark. If you see a crisp blue spark, the ignition coil is working properly. If you only see a pale yellow spark, more than likely, you have a weak coil.

When testing the coils primary resistance, use a paper clip to insert into the primary side terminals. (Female - Bottom side of coil) and place the two leads of your DMM on these to check resistance. On the secondary side, simply place the leads across the two coil output terminals and set your meter for reading K-ohm.

The specs for resistance are:
Primary (ohms) = 0.5-0.9 (ohms) Secondary = (k-ohm) 5.0-8.0

 

[HotZ28]

Alright, so I was reading about this in other sites and saw one that mentioned this problem being caused by a camshaft position sensor. Could this be a possibility in this situation? Also, where is it located at? I may try unplugging it and giving it a shot if I can track it down.

If the CPS were the problem, more than likely it would set a code. In addition, the CPS would cause problems through a wide range of acceleration, not just as you described this particular problem. Do you have a vacuum gauge? If not, get one and let's do some test to see if you have a broken/plugged cat.