Non-Opel Question Regarding Mass Air Flow Meters

[West Coast GT]

First place I came to was the OpelGT forum because of (1 expertise, and (2 you guys always help.
I’ll search the internet for a Miata forum, but I’m not expecting much from that avenue.

Here the SitRep.

I changed plugs & wires on my wife’s Miata. It started fine, ran smooth.

Then I changed the air filter. Removed the electronic connection to the Mass Air Flow (MAF) meter that sits on top of the filter housing. Retaining clip on the female connector was a little buggered, so I decided to fix it. Removed two screws that hold the male connection housing to the MAF meter body. As I eased the connector out of the body, what looks like metal ganglia began to emerge. Felt like I was pulling something that dragged (like it was spring loaded) and offered slight resistance. I immediately slid the whole thing back into the body, fixed the retaining clip, and plugged the electrical lead back in.

Car will crank. Fuel pump kicks in. Engine catches, fires momentarily, dies like it has no fuel or spark. Doesn’t even stumble.

Anyone know about that metal ganglia thing I pulled out of the MAF meter body? Did I screw up some sort of electronic sensing fingers (ganglia)? Am I screwed on this to the point I’ll need to purchase a whole new unit?

Extenuating circumstances: Original owner installed a high-priced security system. User manual discusses an engine disable device. I don’t know if this installation included that feature or not. One of the sensors (hood switch) was near where I was working and there’s a good chance I was leaning on it. I don’t know if this factors into the problem.

My 1st suspicion is the ganglia stuff I pulled out of the MAF.

Ideas? Comments? Direction?

Thanks in advance.

[baz]

have you tested for spark @ plug?
have you tested for real fuel pressure
map sensors should unplug ok without undoing screws so it could be that but test others first
try removing the battery ground to see if you can reset the alarm system
is it a key or phob alarm btw?
last of all we have to get you away from the sci-fi channel (ganglia)

[baz]

forgot to say the maf should unplug ok without removing the screws so you may have killed it (dont know for sure) but now its dead why not remove it fully and see if a ganglia [i love that word] has got crossed you may be able to put it straght

[West Coast GT]

Baz -
1. spark - Yes
2. Real fuel pressure - did not test, but it does fire initially (feels like it gets "cold-start" injection, but then dies.

I'll keep this question in mind and try to find a convenient spot to attach pressure gage.
Meanwhile;

3. I will go disconnect the battery.

4. Alarm system activates/disables via key fob only.

Thanks

[opelbits]

The Miata forums are helpful, but the biggest, like MiataNet, cost to join.

The easiest test is to find another MAF that is known to be good and swap them. If it runs right, yours is bad.

On the other hand, If you want to give up (or like to collect things), I have a friend selling a nice 94 Miata. It has a Simpson design Miami Roadster front clip and leather interior. Nifty Nardi steering wheel, too.
The Roadster kit was almost $4k, which not much less than what she wants for the car.

[Old Hippie]

WCGT, sounds like the:1) wire broke from the connector or 2) there's now a bent pin. Should be a easy fix. It ran good before you moved it so that's where the problem is.
Just my 2c's.

[West Coast GT]

Originally Posted by opelbits On the other hand, If you want to give up (or like to collect things), I have a friend selling a nice 94 Miata.

Opelbits - giving up and buying another car is not an option. This summer our minivan had leaking inaccessable freeze plugs. One must drop the engine, transaxle, and front sub-frame to reach them. Cannot be reached from below or above the engine. So I tore out the seats, carpet, and entire dash to create an alternate route to those freeze plugs. After cutting through the firewall I discovered I had also cut a structural beam, rear airconditioning lines, and rear brake lines. Then also discovered the "real" firewall was on the other side of the intersitial space and untouched. I had the van towed off and bought a Bonniville.

So, as you can see, I cannot fail here or I will never be allowed under the hood of a car again.

Thanks for the suggestion on swapping units though. If all other suggestions don't work, I'll try this one.

[West Coast GT]

Here's the meter with the connector, well, uh, unconnected. The two screws I removed are visable on either side of the male connector.

And the second shot shows where I've unscrewed the screws pulled the male connector away from the Air Flow Meter body.

[RallyBob]

Looks like you may have pulled a wire out. Best way to check is to remove the silicone-sealed plastic cover (the one on top in your first photo) and check the connections there. It can always be re-sealed with more silicone after the fact.

Bob

[jeff denton]

I'm hardly a Miata expert but I do have to deal with electronic sensors on diesels a lot, along with some experience with the GM system on boats.
And I did once stay at a Holiday Inn...
Anyway generally when you screw up a sensor, or it dies voluntarily, or even unplug it, the computer signals an alarm, stores the code, and goes to a pre set value to let the engine run in limp mode.
My best advice is to get the Miata book to explain how it all works, and expecially how to get a code out of the computer. Lots of rigs, if you click the key on and off quickly five times it will blink out codes on the check engine light. Believe it or not! The computer knows right away if a sensor is bad or is out of spec.
Next advice, if I had a Miata I'd get that fiberglass body kit that makes it look like a 68 Mustang convertible. Have you seen that? It was in Hot Rod Mag a while back. It is really neat!!

[pvcar]

that looks almost indentical to a late 80's toyota i have its a very complicated little board inside the if u remove that sealed cover i had to remove the cover on my old maf sensor due to basiclly the conditions ur describing, basiclly jus one day i was driving and the car would not idle and would stall out unless i kept given it gas and sometimes even when id be going, well this happend to me in our bordring country of mexico so no where for parts so i poped the cover and took a cnady bar rapper and stuck it kind of as a stop in there to keep the sensor open more then it normaly would be allowed to be got me back to mexico not to mention i was pulling a late 80's chevy blazer with an old fire house type materail rope, what adventures. im pretty sure u may have bent that little mettalic sensor in there its very sensitive, it may be repairable but cross refrence the part maybe u can find one in a pic-u-part lot.

[West Coast GT]

Baz - I disconnected the battery for 30 minutes (some systems need 10 minutes or more). Hooked it back up and condition remains.

RallyBob - good advice. Nothing to lose now. So I'll give that a try next.

Jeff - I'll pick up a manual in the morning. I should have had one long ago, but nothing's even broken before.

pvcar - We've gots of salvage yards around here. I like the idea. I'll most likely pass on the candy bar wrapper. (But I'm not ruling it out)

Crazy thing just happened. I checked the fuel injection fuse (hey, what can it hurt?) The stinkin' fuse busted off in the fuse block! It's one of those square plastic housings with a clear window so you can look at the link. I've learned long ago to check the resistance even if the link looks intact. But I shattered it into lots of little pieces and I still can't pull it, even with needle nose pliers. I've never heard of such a thing.

Thank you guys for your ideas.

[OrangPeEL]

Is your Miata "adaptive" EFI? - condition dependent to maintain stoich'? (I assume yes per battery disconnect/memory flash). I'm w/Jeff Ds input that you'd still maintain a run on preset parameters (in limp)... 'specially since you're starting cold (an enriched warm-up preset idle mode) & computer likely isn't considering MAF just right then. If warm-up is MAF dependent, and GANGLIA is hurt & sending false info, maybe try starting eng w/MAF lead disconnected & force the preset run?

-I JUST attempted this on '03 F150. I also disconnected IAT (intkairtmp). Started/ran as expected... triggered MIL and stored pertaining fault codes.

Anyway, Baz mentioned fuel pressure... false start symptoms sure sound like fuel pressure... fuse crumbled... my money is on fuel pressure.

-Dan

[madhatterpdc]

Ganglia? Interstitial? Me thinks you have medicine in your background. Or at least a lot of biology studies.

I saw that you verified you have spark, Have you verified fuel yet. Engines need air, spark and fuel to run. If you don't have the equipment to test fuel pressure, try little spurts of starting to try and keep the motor running. You also need to rule out the alarm system. If not for this problem, then definitely for future problems, you need to know how the systems works, and can be reset or you are going to be running in circles. Remember, it may not be the problem here, but it is a piece of knowledge that simply has to be associated with owning an alarm.

Kind of like your cytochrome P450's and serum levels.

[kwilford]

OK, I thought "what forum do I move a thread about Mazda Fuel Injection to?". Well, first of all, it KINDA looks like a Bosch L-Jetronic EFI, so now that I have said the word "Opel" (magic, n'est pas?), this is now an official Opel thread. And I moved it to the Fuel System forum.

[West Coast GT]

Keith - thanks for shoehorning this in as an Opel thread. I really needed the help.
If it helps, perhaps this same problem may appear to a fuel injected Opel????

[David McCollam]

Once you replace that fuel pump fuse, try this simple test on the MAF. The sensor should have a flap/door that moves in the airflow stream. When the flap moves from closed to open, the fuel pump should run when the key is on. Remove the air intake hose, access that MAF flap and try that with the key in the "ON" position. Typically, if the pump runs, then you can pretty much eliminate fuel pressure at startup/run as the problem. It will at least start and idle.

Your problem is that messing with the MAF wires at the connector, may have shorted the pump fuse. This would kill the pump operation.

Good luck.

[West Coast GT]

I removed the electrical connection. The car fired right up and idled. As soon as I gave it throttle it died.
I repeated this four times.
All results were the same.
Looks like the Air Flow Meter has a problem.

This morning I will open the top of the unit per RallyBob's suggestion and straighten the sensors. Concurrently, I will be tracking down a replacement unit just in case.

I've figured out how this relates as an Opel thread. The Miata is sitting next to my GT in the garage. ???? OK, its a stretch. But I really thank you guys for your help & suggestions.
Keith

[West Coast GT]

Dave - I accessed the swing gate (flap) as you suggested. It was open a crack, just like the butterflys on a carburetor, to allow enough air for idle.

But when I gently pushed on the gate, it had slight resistance as though something fragile (fra gee ly "must be Italian") were blocking it; something like a sensor.

I removed the screws discussed earlier and gently pulled the "ganglia" of sensors out 1/4 inch. The swing gate opens more, but not completely.

I fired the engine up. It idles poorly, but more importantly, the engine will reach and sustain 3,500 rpm. At that point it gets rough. I feel that the gate may be hindered from opening fully.

I checked availability & price for a new replacement; one week & $264. No way. That's like buying a Weber.

I'm checking junk yards now for availability since we are into the long Thanksgiving holiday and this may turn out to be the critical path.

Then I'm opening the top of my existing air flow meter as RallyBob suggested and attempting a mechanical repair/placement of the sensors.

(Although my wife is unhappy with me about breaking her sportscar, this sure beats a previous Thanksgiving when she discovered I was using her Turkey baster to remove excess brake fluid in my Opel.)

[David McCollam]

Keith,

Nice job on the turkey baster. I'll remember that the next time I over fill the brake res. On the MAF sensor, check the contacts on the circuit inside the cover. You'll see there are contact tracks inside with "fingers" or a set or two of contact points most likely. These are for the fuel pump and could possibily control a variable pressure regulator. If it idles roughly, but will climb in RPM slowly up to 3500, you have a fuel delivery problem.

You have a bad contact at the MAF due to the loose connection or a bent pin, I'd guess. This is probably one of the pins/connections that has voltage/resistance on it controlling the fuel pump circuit.

I danced all over this problem working on a '75 FI Manta. A fuel pressure gauge on the fuel rail will help diagnose the problem. Pressure somewhere in the 30-35 PSI range at idle and steadily increasing to 45-50 PSI at max throttle should be normal. This holds true for about 95% of most FI street cars.

Good luck,

[West Coast GT]

Guys -
Thanks for your help.
It's running great. Before sealing the cover back on, I took it for a test run, streets and freeway. I only took it to 5500 RMP on one shift. Engine rev'ed smooth through the entire range.

Idle is smooth.

I took it up to 80 on the freeway just to test fuel output - seems fine - no hesitation.

When I pulled the male connector out of the body, that long contact arm on the right that you can see is under tension (from top screw to lower screw) slipped out of position. I bent it after I slid the connector back in and tried to run the car.

Again, Thanks
Keith