Hoping my fellow forum members may be able to provide some guidance...my 2001 C5 coupe stutters at high speed.

Here's the history of what's happened, and I'm hoping you can give me some suggestions before I take this to the dealer.

1) About a month ago, immediately after filling up ~ 1/2 tank (from fairly close to empty) and getting on the highway, my check engine light comes on. On the highway (I had to drive home) I can feel the car sort of stutter occassionally (especially at speeds > 100 km/h). I can tell because I'll keep my foot on the pedal at a constant depression, and it will feel like the wind is blowing the car (kind of feel resistance, then none, then resistance again). It's almost like the car speeds up a couple of klicks then down again, etc.
2) I get home, thinking it may have been bad fuel, I put a bottle of injector cleaner in the engine and fill up all the way with Sunoco 94. Interestingly, the check engine light goes off within 5 minutes. However, I can hear a slight buzzing sound from the car (sounds like from the engine compartment but I can't be 100% sure).
3) Checked the codes, and the following came up:

10-PCM P0101H (MAF sensor performance)

Based on feedback from the forum, it was thought it may have been caused by bad fuel, and the code was a history code so no need to worry.

4) Took it to the dealer and they concur there is a slight sound "from the fuel pump" but "no repair necessary at this time". I'm thinking problem solved.

5) Car still feels 'different' when I drive. Still seems to be a bit erratic at speed.
6) Today, check engine light came on again. Engine feels even more erratic (but again, primarily at speeds > 100 km/h). It's like rocking back and forth the way it's feeling.
7) Stopped at the fuel station, put another bottle of injector cleaner in and fueled up, light went off again within 30 seconds.
8) About 10 minutes later on the highway, the light comes back on. Seem to be using a heck of a lot of fuel on the way home.
9) Got home, checked the codes, and this time, it shows a current code:

10 PCM P0151C (H02S Circuit low voltage).

I'm guessing this is an oxygen sensor.

Does anyone have any ideas what this could be?
The car only has < 40,000 km on it (summer driven).
I'm hoping there hasn't been any permanent damage done to the engine by driving it home in this condition.

I'll take it to the dealer next week, but prior to that, any ideas or guidance would be really appreciated.

Cheers
Jason

 

The P0151 is is an O2 sensor code. Circuit Low Voltage Bank 2 Sensor 1.
That is the sensor on the manifold on the passengers side. If the engine is cold see if the wires have been rubbing against the hot manifold. They could have melted and are now either shorted together or rubbing on the manifold. If that's not it, the O2 sensor probably needs replacing.
Also, I don't think you did anything to the engine, you babied it when the problem showed up.

 

Most of the time, engine studder or miss is caused by a loose sparkplug wire, bad boot, bad plug or coil issue. The code that you will see should be a P0300 code. Funny thing about that code is, it will clear it self shortly after the cylinder miss fire quits.

I recommend that you tr to recreate the condition and cause the CHECK ENGINE light to illuminate and when it is happening, read the codes. If you get a P-0300 code, you will just have to figure out which cylinder it is and what is causing the condition.

If you get a P-0300 code let me know and I will help you get to the bottom of it.

As for the H2SO codes, that can be caused by a bad ground on the frame. Look directly below the Vacuum Brake booster and you will see a ground stud. Remove that stud and clean the eyelet and chassis. That ground goes over to the drivers side of the engine block below the head. Make sure that that connection is clean and tight.

Bill

 

Thanks for your advice folks. Do you think there's any chance it could indeed be a problem with a fuel pump (intermittent/bad electrical connection)?
Cheers
Jason

 

with a 2001 the oil leaking onto the mass air flow sensor is most likely the problem.

There is some sort of oil catch can set up that can be used to help rectfie this problem.

 

AU N EGL

The MAF oiling issue comes from using an oiled gause filter and over oiling it. The oil mist from the filter deposits on to the MAF sensing wires and causes it get false air flow readings. The excessive oil comsumption issue allows oil from past the rings under certain engine conditions and allows the engine to burn the oil. You can also get oil flow from the crank case to flow through the PCV system. The oil enters the engine through the intake manifold. I doubt that either of these conditions is causing his issue. The car runs great under part throttle. Under heavy or full throttle it acts up. I would say that you are running out of fuel. Most probable cause is a dirty fuel filter or a defective fuel system compoent. I would change the filter first.

On the electrical side of the house, that is a possibility but why would it do it onlt at increased power levels of engine output? The fuel pump ground is the weak link in the fuel system electrical circuit. It is in the drivers wheel well aft of the rear wheel. Here is a picture of it:



Clean the stud with a wire brush, soak it in WD-40, remove it carefully, clean the frame, the eyelet and nut. reinstall. If the stud breaks off, drill a hole into the frame and secure it to the frame with a self tapping screw.

Bill

 

I stand corrected. Thanks Bill

 

After cleaning the ground connections use some dielectric grease on the terminals, bolt, and frame. A coating over the top after it is tight doesn't hurt either. This will go a long way to preserve the clean connection. Look for it in the electrical department at the hardware store. Otherwise look up your freindly local electrican. Then use it on all of your electrical connections that are exposed to the elements. To bad GM didn't run a grounding curcuit throughout the car with couple interior terminal blocks to recieve the ground wires of the various cuicuits. This is done in fiberglass streetrods, it prevents grounding problems.

 

Hi folks,

Well, the dealer called with an update today - the problem was simpler than I had thought (and the good news is no repairs needed) - the Donaldson intake I had didn't quite sit perfectly, and as a result the two little mounting pegs above the rad housing didn't perfectly align - consequently, there was a minute gap in the rubber inlet tube going into the MAF. Not too much of a problem at lower speeds, but this explains why at high speeds the problem arose (and I suppose the computer tried to compensate with varying the fuel, causing the car to stutter a bit). Crossing my fingers this actually fixes the problem when I pick the car up tomorrow night.

However, you have all made some very good points that I'm going to utilize. I still think I likely over-oiled the filter, which may have caused some problems, and will also use the dielectric grease and reattach all the grounds for good measure.

Thank you all for your help!!!!
Cheers
Jason

 

I was just about to post to tell you to check that, my vararam popped off and I couldnt figure out why it idled high,kept studdering,and kept going dead on me at 90+ish mph....