K&N = Engine Check Light?

[JAFO]

Be careful using compressed air on the K&N -the high pressure will tear the cotton gauze and you'll end up with a hole.

Your symptoms sound a lot like those experienced with torn intake manifold gaskets -after you've run through the standard MAF sensor cleaning, give those a look.

mbeach, Where is the intake manifold gaskets?

I have completely removed the intake tube, with the MAF. I couldnt figure out how to get the MAF out of the tube though. It was still stuck even after removing the clamp. I didn't pry the tube because I didn't want to damage it.

I heavily sprayed the inside of the mesh screen with electronics cleaner that they sold me at AutoZone. I have the original air filter back in and I disconnected the battery twice. But it is still surging on startup then the engine check light comes on and the RPMs level out.

Also when I drove the truck home, approximately 3 miles, it died twice.

I looked and as best I can tell the little wires on the MAF behind the mesh look ok.

Also what is the little sensor on the oposite side end of the tube next to the intake? O2 sensor?

[mbeach]

I'm not going outside to check right now (it's about -40), but there's no O2 sensor on the intake, I can't picture what you're talking about. I'll look it up later.

The intake manifold is under the plastic cover on the top of the engine. Where the manifold meets the heads (on both sides) there is a gasket that you may or may not see.
Start the truck and spray some carb cleaner along this area -just a dusting, not soaking it down. If the engine surges, then you have a leak -the engine's vacuum is drawing the carb cleaner into the cylinders through the torn gasket.

The purpose of the MAF is to determine how much air is entering the engine. If there is a leak post-MAF, then the air measured is not what is actually entering the cylinders. This will lean out your air/fuel ratio and throw off your O2 sensors. The only component that the OBD can reference is the MAF -so it throws a MAF code even though the problem might be elsewhere.

[Raque Thomas]

Are you certain that the MAF sensor wiring harness is hooked up? Mine did this same thing when I unplugged the connection to get more slack in the tube when installing a new filter. Could the plug be what you think is an O2 sensor?

I also ran an oiled K&N with no CEL, and now a Hot Shot tube with an oiled cone filter w/o a CEL. I'm betting your connection is the problem. If the harness is connected to the side of the MAF, disconnect it and check the condition of the connectors, then try plugging it back in.

[psychos2]

if it is gettting a code for the maf then that is the problem. not the intake gaskets.either a wire is pulled out or a bent prong or it is dirty or covered in oil.the other sensor is more than likely an air temp sensor. shawn

[mbeach]

if it is gettting a code for the maf then that is the problem. not the intake gaskets.

Not necessarily.
The engine only has one way of determining the correct a/f ratio before the burn -that's the MAF. After the burn you have 2/4 O2 sensors.

If there's a leak (air) between these sensors, the ECU can pick the most likely item. It finds the fault at the O2 sensorS (all of them). Since it is unlikely that both banks would simultaneously go lean, the ECU has the sense to choose the component which measures the incoming air to begin with.

Disconnect the intake tube from the throttle body and I'll bet that you throw a MAF code.

[JAFO]

Ok, I have found what happened. While I was installing the headlights, before I put in the K&N, I had the cover off the air box but not disconnected from the MAF or tube. I had pushed the air box cover towards the dash and hooked it over the top of the fuid bottle next to the air box to get it out of my way while installing the headlights. I think this is the power steering bottle, I don't recall. Any ways when I did this I was not as carefull as I should have been and it put too much tension on the cable going to the MAF. Upon close examination of the MAF plug I noticed that one of the wires was loose. It actually broke the wire where the pin was crimped on.

Unfortunetly nobody in town as either the right 3-pin replacement plug or wire terminals small enough to fit. So I am going to have to wait until Monday to order a new plug or pin.

[mbeach]

I'm glad that you found the problem.

[psychos2]

Not necessarily.
The engine only has one way of determining the correct a/f ratio before the burn -that's the MAF. After the burn you have 2/4 O2 sensors.

If there's a leak (air) between these sensors, the ECU can pick the most likely item. It finds the fault at the O2 sensorS (all of them). Since it is unlikely that both banks would simultaneously go lean, the ECU has the sense to choose the component which measures the incoming air to begin with.

Disconnect the intake tube from the throttle body and I'll bet that you throw a MAF code.

sorry, but that is not how it works.the computer has parameters and when it is outside the parameters it throws a code for that sensor.and the maf is not the only sensor it uses to determine a/f ratio. it also uses the air temp sensor . i agree you would get a check engine light if you disconnect the intake tube but it would not be because it picks the most likely sensor. it would be because it knows there is oxygen coming in (engine cannot run without it) but it is not getting a reading from the maf saying there is air coming in. and you would more than likely get other codes due to the maf not showing air coming in. besides when something is functioning properly before you install something and is not working properly after there is a very big chance (probably 99.9%) that you screwed something up. like pulling the wire to hard. when diagnosing problems you start with the simplest things first. shawn

[mbeach]

If you read my first post, you'll notice that I said to give the intake manifold gaskets a look AFTER you're done with the MAF.

IAT sensor just helps the ECU determine air density (based on temp.). Unmetered air entering the engine (and being detected post-burn) will always point to the MAF. The intake gasket leaks are usually intermittent enough that they won't throw a code before driveability suffers. In fact, both of my trucks sprung leaks at the intake gaskets without a code at all.

If you rely solely on CELs to diagnose problems you're in for some long nights. Check the obvious, like you said, then check the likely.
If he had ruled out the MAF (could've just checked for continuity at the engine side of the sensor), where should he go next?

Having spent a number of years behind the wheel of a tuned scooby, I learned that CELs are only a guide, and not the be-all-end-all of engine diagnostics. Your statement "...if getting a code for the MAF then that is the problem..." smacks of finality, and will lead to headaches if you start replacing sensors unnecessarily.

[whtzmbi]

I just installed a K&N filter with no problem...the CEL has not come on at all (yet) I hope it doesn't either

[JAFO]

I just installed a K&N filter with no problem...the CEL has not come on at all (yet) I hope it doesn't either

You should be good. My problem was I wasn't carefull with the MAF wire under the intake tube and pulled the wire loose.

Now that the K&N is in I have been contemplating exhaust change. But I can't till my RX-7 is back from getting turboed.