Need help with MAF questions

[goaliegod]

I've got a '99 GP3800 SE, and I get a Service Engine Soon light under hard acceleration (over 4K RPM). From the reading I've done here the Mass Airflow Sensor seems to be a common reason for this to occur. My air filter was FILTHY when I got this car, so my first question is whether it's posible to clean the MAF. My second question (which I suppose should have been my first) is if anyone has a picture of the location of this sensor. My 3rd question would be how to dismantle the factory air intake so I can get at it.

Thanks in advance.
Bryan

[maxwedge]

First what is the code, sounds like you are getting ahead of yourself here?

[phaelax]

Lots of things could cause that light to come on. And as someone who's just replace my own maf sensor, trust me you don't want to buy a new one unless you really have to. ($120)

The sensor is at the end of the intake hose leading from the airbox to the engine. It's a small, black box-like thing about 2x3 inches i'd say. 2 tamper-resistant screws hold it in place. No need to dismantle anything to get to it. Unless you have the plastic supercharger cover over the engine, the sensor is sitting right on top. You cannot clean it as that's probably not the reason it'd stop working.

Usually, some place like Advanced Auto will scan the car with their computer to tell you what code is triggering the service light. Highly recommend you do that before you go replacing expensive parts.


I found a picture of what your maf sensor probably looks like.
http://www.resnet.trinity.edu/jmccool/MAF.JPG

[goaliegod]

Thanks for the quick responses guys. I had the code scanned about a month ago and have just reset the computer the last 2 times the SES light came on. I don't remember the code number, but the guy at AZ said it indicated a misfire (maybe on cylinder #3? I'm not 100% sure). He said it was nothing to worry about unless clearing the code didn't make the light go off. My only concern is that I don't get the snappy acceleration I remember from this type of car above 3500 rpm. Instead the car seems to hesitate or stutter (so a misfire makes sense).

[richtazz]

If the air filter (easy to change) was neglected, what do you think the chances are the plugs and wires were changed? The "guy" at A-Z's advice is not very credible. The PCM will not trip a cylinder specific mis-fire code for no reason. Try tuning it up (plugs, wires, pcv, fuel filter) and see what happens. Avoid whiz-bang Bosch multi-electrode plugs, as they are JUNK!

[goaliegod]

I know for a fact that plugs and wires were done, as that was part of the money I put into the car after purchase. The fuel filter is a good call. A tech at a quicky oil change place told me that it needed to be done, but I don't really trust those guys too much. I guess I'll have to look into it. Thanks guys.

BTW, is this something I could do myself? I'm fairly comfortable working on my cars, but have no formal training and little experiance.

[BNaylor]

See fuel filter replacement tech procedure at the link below.

Click here

[goaliegod]

Originally Posted by bnaylor

See fuel filter replacement tech procedure at the link below.

Click here

Bob, you're my hero. That looks simple enough for my kid sister to try. I'll let you know how I do with it. What I wonder is how the guy at Penzoil could tell me I needed a new filter. Looking at that one I don't see a bubble or any way for him to tell it was time to change it.

[BNaylor]

Originally Posted by goaliegod

Bob, you're my hero. That looks simple enough for my kid sister to try. I'll let you know how I do with it. What I wonder is how the guy at Penzoil could tell me I needed a new filter. Looking at that one I don't see a bubble or any way for him to tell it was time to change it.

I'm no hero just trying to be helpful but thanks. Very easy and only simple tools required.

If I were the service tech I'd ask you when was the last time it was changed out. If you did not know the answer then I'd respond by telling you to replace the fuel filter first. Your problem could be fuel related and the filter is the best starting point.

After that I'd check fuel pressure at the fuel injector rail fuel pressure regulator just to make sure it is in specs and to rule it out. Good luck and keep us posted.

[goaliegod]

Yeah, but you've got to remember that this was a guy at a while-you-wait oil change place. He never asked me anything, just brought it up as an add-on to the oil change I went in for. I'm glad I didn't pay them $70 bucks for something I can do myself for 10 (and be sure it acutally gets done).

[BNaylor]

Originally Posted by goaliegod

Yeah, but you've got to remember that this was a guy at a while-you-wait oil change place. He never asked me anything, just brought it up as an add-on to the oil change I went in for. I'm glad I didn't pay them $70 bucks for something I can do myself for 10 (and be sure it acutally gets done).

Yeah, very good point. I've done DIY so long now I've forgotten about those fast lube type places. Definitely a rip off. The guy quoted me $27 for a generic no name fuel filter and $30 labor. Total $57 plus sales tax. I told him him no way and left. It has been over 10 years since I've been to those type shops.

[goaliegod]

Ok, so I'm looking for the schrader valve, but not finding it. It should be under the hood, correct? The pic on the PFYC.com website is a little too dark for me to make out what's in the background to help with where to look. I've got the plastic shield off my engine. Where should I be looking?

NM, used photoshop to lighten the pic up, and found the referance points I needed to find it.

[BNaylor]

Originally Posted by goaliegod

Ok, so I'm looking for the schrader valve, but not finding it. It should be under the hood, correct? The pic on the PFYC.com website is a little too dark for me to make out what's in the background to help with where to look. I've got the plastic shield off my engine. Where should I be looking?

NM, used photoshop to lighten the pic up, and found the referance points I needed to find it.

Item circled in red if engine is a 3800.



Also you can pull the fuel pump fuse located in the engine compartment fuse box and let the engine relieve fuel pressure. Just let it stall out.

[goaliegod]

That sounds easier. I'll try that tomorrow. Thanks again.

[goaliegod]

Ok, got the fuel filter changed, and the car certainly runs better at high RPM's. It got above 4000 RPM before the SES light came on this time. I had the code tested, and it's just P0303 cylinder 3 misfire.

I checked my records and definately had wires and plugs done, but it doesn't mention a full tune-up. Would the PCV valve be the next place to look? If so, could you circle that for me too Bob?

Thanks again for all the help guys.

Bryan