Rough Idle? Hesitation? Clean your MAF Sensor first!

[Shredicus]

So just a quick tip I want to put out there in case someone has this issue in the future; if you're having rough idle or hesitation issues before you start replacing coils and vacuum hoses clean your MAF sensor first. Out of nowhere my car started bogging down horrendously. It was between shifts so i didnt think it was my trasnny crapping out but it honestly felt like my LS was dragging an RV behind it or something, it was hesitating that severely; scary stuff. I had just replaced the valve cover gasket/all coils/all plugs and I my vacuum hoses were in good shape so it kinda freaked me out. Well one thing I noticed was that the intake sounded really strange like it was choking or constricted ( I have a K&N FIPK). I took the filter off and everything looked fine then I pulled the MAF sensor and sprayed it down with some MAF cleaner. Lo and behold a CHUNK of dirt fell out of it. Not a speck or a fleck, but a small clod of dirt. I'm not sure how it got past the filter, I may have put it on hastily the last time I removed it, but once the MAF sensor was cleaned the car ran perfectly.

So long story short, clean your MAF sensor with a can of MAF sensor cleaner if you're having rough idle/hesitation issues before you start with expensive fixes.

 

[RigsLS]

Possible you are oiling the K&N filet too much ?

reason I ask is I used to run a k&N cold intake on my old GMC Jimmy
and i used to have replace the MAF sensor in it every so often,
later I learned I was over coating the filter and it was sucking
thick oily air into the intake, thus fouling up the sensor.

Possible ?

 

[Shredicus]

Possible you are oiling the K&N filet too much ?

reason I ask is I used to run a k&N cold intake on my old GMC Jimmy
and i used to have replace the MAF sensor in it every so often,
later I learned I was over coating the filter and it was sucking
thick oily air into the intake, thus fouling up the sensor.

Possible ?

Well I read a lot about the problems with over oiling K&N intakes so I was very conservative when I oiled it. The issue turned out to be a small clump of dirt inside the actual MAF sensor but I'm not certain how it got in there...

 

[Tchez27]

First time poster, please help

I'm having the same issue. Rough idle, hesitation when I hit the gas and after it warms up trouble going up hill. The car sat for almost a year ( although I would turn it on periodically) after getting the trans replaced. I changed the coils, plugs, air filter, cleaned out the iac, cleaned the MAF and eventually changed it, sprayed around for a vacuum leak and checked the TPS for current and functionality. The car runs better when I disconnect the MAF but still idles rough and after warming up it starts to hesitate again. I have a system too lean p0171 code so I'm thinking it's fuel related and not a clogged cat. Any suggestions would be great. It's been a week of tuning up and I'm running out of ideas. Btw it's a first gen 2000 3.9l so no pcv. Thanks

 

[Shredicus]

I'm having the same issue. Rough idle, hesitation when I hit the gas and after it warms up trouble going up hill. The car sat for almost a year ( although I would turn it on periodically) after getting the trans replaced. I changed the coils, plugs, air filter, cleaned out the iac, cleaned the MAF and eventually changed it, sprayed around for a vacuum leak and checked the TPS for current and functionality. The car runs better when I disconnect the MAF but still idles rough and after warming up it starts to hesitate again. I have a system too lean p0171 code so I'm thinking it's fuel related and not a clogged cat. Any suggestions would be great. It's been a week of tuning up and I'm running out of ideas. Btw it's a first gen 2000 3.9l so no pcv. Thanks

well first of all if the car has been sitting drain the old gas and replace it with new for sure. If that doesnt do it replace the MAF sensor. If it runs better with it unplugged and you're throwing a p0171 that sounds a lot like the culprit. Shoot Max at fivestarford an email and see what sort of price he can get you on a new MAF; generally they do much better than the dealerships. Also might be an EGR valve problem?

Additionally search on here for some of the other topics referencing the DTC code you're getting. I found one here with some good avenues to pursue:

http://www.lincolnvscadillac.com/showthread.php?t=59129

 

[Tchez27]

Thanks shredicus, I thought it was the MAf too. But I cleaned the old one and then replaced it when it didn't change and still no luck. I'll try putting in a new fuel filter and checking the egr valve. Could a bad IAC cause these issues. I thought the IAC was mainly for idle times and dont think it will affect driving lack of power issues but I'm no master tech.

 

[Shredicus]

Thanks shredicus, I thought it was the MAf too. But I cleaned the old one and then replaced it when it didn't change and still no luck. I'll try putting in a new fuel filter and checking the egr valve. Could a bad IAC cause these issues. I thought the IAC was mainly for idle times and dont think it will affect driving lack of power issues but I'm no master tech.

Hmm truthfully I know very little about IAC valves as the gen 2 doesnt have one. Here's a list of general symptoms of IAC malfunction though, could be relevant:

http://www.ehow.com/list_7219549_signs-idle-air-control-valve.html

 

[Tchez27]

Alright gents I'm at my wits end with this car. Someone please tell me if I've left out a step or if any has any suggestions. Here's what is wrong and what I've done. The car engine shakes at idle, sounds like its sputtering out of the exhaust and occasionally has acceleration issues. I've changed all 8 coils and plugs, cleaned out the MAF and then replaced it, cleaned out the IAC, replaced the egr valve, checked all my vacuum lines for cracks, sprayed around with carb cleaner for idle change and changed the fuel filter. I asked my local repair guy and he said he worked on one the prior week and without so much as turned it on told me it was the crankshaft sensor and the tranny has to come out due to the "plate wobble" where the crank sensor is. He said he could diagnose it but would take a couple hours. I dont trust this guy since he didn't even have the decency to have me turn the car on or go for a ride (place was empty) and considering all I've done I've taken a lot of the guess work out. My CEL is now back on with a p0174 code and a pending p0102 code. Please help this car was really nice until recently.

 

[LS4me]

.........cleaned out the MAF and then replaced it, ....My CEL is now back on with a p0174 code and a pending p0102 code........

Those codes suggest you need a new MAF sensor. Cleaning it incorrectly can ruin it.

 

[Tchez27]

LS4me, I thought the same thing that's why I said I cleaned it and when it kept doing the same thing I replaced it. Still same issue.

 

[joegr]

LS4me, I thought the same thing that's why I said I cleaned it and when it kept doing the same thing I replaced it. Still same issue.

Best possibilities:

1. New MAF is defective.
2. MAF connector is faulty.
3. Wiring between MAF and PCM is bad.
4. PCM connector is bad.
5. PCM is bad.

 

[Tchez27]

Those codes suggest you need a new MAF sensor. Cleaning it incorrectly can ruin it.

What is the best way to test out the connection to the MAF and/or PCM? The info I have indicates a multimeter is needed but also says to connect the negative meter wire to the battery. As we all know it's in the trunk so I can't do that.