GEMS MAF keeps failing?

[nvail]

So it seems that my GEMS discovery keeps causing MAF's to fail.

Things I know: good fuel pressure, good spark, good compression, new plugs, new wires, no vacuum leaks (at least spraying brake cleaner all over the place won't cause the engine to stall), fuel temp sensor is good, crank position sensor is good, airbox and air filter are fine, cats seem to flow fine (no unusual overheating when looked at with an IR thermometer).

So, the reoccurring problem is that in any gear when the engine is above approximately 2500 rpm there is a huge power loss and it runs terrible (sputters like it's receiving unmetered air). This only occurs when the vehicle is under load, and the problem is not noticeable when you just rev the motor.

When I put in an MAF known to be working it'll run great, plenty of power (relative term for a land rover) all through the powerband. Then I turn it off, restart again and immediately it runs with the same issues!? I thought I was crazy, but this has been the case with 3 different MAF's (genuine and aftermarket).

Anyone seen this before or have an idea to diagnose/fix? Thanks.

 

[jymmiejamz]

So whenever you install a new mass air flow meter the problem is fine until you switch the ignition off and restart it?

Ignoring whatever is going on with your mass air flow meter, I would check the wiring to the crank position sensor. The insulation on the two wires falls apart near the sensor.

 

[robertf]

Ignoring whatever is going on with your mass air flow meter, I would check the wiring to the crank position sensor. The insulation on the two wires falls apart near the sensor.

yup. I think now that these things are 20 years old we finally have a new problem showing up. Mine were completely bare, but didn't cause a problem until I disturbed it with an engine swap.

 

[stu454]

Agreed on the wire insulation taking a dump. I cleaned mine up while doing a preemptive swap on the CkPS recently.

 

[ptschram]

ONE time I've had a problem with a GEMS MAF. They seem to be bulletproof.

CkPS wiring-that's another story.

 

[Jagfixer]

PT wise man, listen!

 

[4Runner]

I would maybe look at your coil pack or maybe the cam sensor after that,if it has one. I am sorry, I don't remember if it has one.

 

[discostew]

Does it store any faults when you start it the second time? I don't think I have seen a GEMS mas air flow sensor fail

 

[boxster]

Had same problem, thought it was maf, after a lot of parts testing and replacing was the fuel pump! Ran ok at start up but when put in drive and under load could not keep up fuel pressure needed 35psi. Installed new pump and problem went away��

 

[discostew]

ONE time I've had a problem with a GEMS MAF. They seem to be bulletproof.

CkPS wiring-that's another story.

I agree totally with this. The only one I ever saw fail was because I dropped it.

 

[discostew]

Your not running a K&N filter are you? Also keep in mind that a lot of stuff causes the MAF sensor to throw a fault. Anything that makes the engine pull less air will potentially throw a MAF fault.