OK, so I just realized that the MAF sensor hadn't been plugged into the car that I just bought a couple of months ago. I plugged it in and the car wouldn't rev. What's going on? With the thing unplugged it runs fine, no problems at all.

Should I be worried here? I've done about 1400 miles in it with no problems.

Thanks for the help

Rob

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1987 IROC-Z Auto (LB9)
Black/grey interior with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods due in March:
K&Ns
RAM Air
Air foil
AFPR

Hoping to get a couple of tenths with that lot

 

The previous owner probably converted it over to SPEED DENSITY which doesn't require a MAF. Trust me, you wouldn't be able to drive the car at all if the car was running the MAF setup and the sensor itself was unplugged.

Steve
p.s. pull the MAF off and sell it. They're worth over $350 bucks I heard (CDN)

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89 GTA G92
305 TPI WC 5spd w/3.45
Accel Cap & 8mm Taylor's
Custom 4" Cold Air Induction
Jet Airfoil
K&N Airfilter
160 deg stat/fan switch TB Bypass - Steel Rad
Cat back 3" Exhaust w/Terminator Muff.
HiGh FlOw Dynomax Cat
Spohn LCA's - KYB GR-2's
Autometer Vac+Oil Temp

 

Not true. After taking my car to an electrical shop to figure out I needed a ECM, they left the MAF disconnected. It acutally ran great with it that way. I think the computer just uses open loop info. I did plug mine back in though, I didn't want to screw something else up.

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Rob
'86 TA 305 TPI
Gutted MAF
Ported Plenum
TB Bypass

 

Is your SES light on? If not, it could be burnt out or even removed. Without the MAF, you force the car into limp home mode.... Most completely stock cars run fine in this mode, the ECM is just reverting to a set of pre-programmed info to run your car. Not really dynamic.

The MAF is probably bad. What was the original problem you had that prompted you to take it to a mechanic? If it was a driveability issue...the MAF was probably to blame... if not, and they did not know what they were doing, they could have inadvertantly damage the MAF (I had a tuneup done once and the monkey sprayed carb cleaner in my MAF to clean it!)



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Mike Metzler (Desert86Roc)
Mike@SpeedworldMotorplex.com
[*] Webmaster: SpeedWorldMotorplex.com[*] Click Here For My Racing Page[*]86 IROC 305 TPI (406 build in progress)
ET's @ 1250 ft[*] 14.28 @ 95.461 mph (uncorrected, NOS, no headers)[*] 15.365 @ 86.785 mph (uncorrected, Headers, no NOS)

 

Actually on my '89 (assume other years too??) when the MAF is disconnected at startup, the ECM uses a preset airflow for calulations, when the MAF is disconnected while the engine is running, the ECM will use the last MAF reading for airflow calculations.

It still tries to adjust A/F ratio using the O2 sensor, I've seen this on my scanner, but tends to keep the mv's on the richer side, and the crosscounts drop to 2-3.

Base timing is adjusted vis TPS postion, based on the MAF parametes set (as stated above),so it's not really limp mode, more like "MAF mode"

The only danger is in this that I see, is you're running a bit richer than is optimal, which could lead to higher fuel consumption, and possibly cat clogging,

 

Sorry, I oversimplified...the MAF bypass mode is more correct than my statement. I have had to use this method many times to get me home.

 

So if your car runs better with the MAF disconnected, does that mean its bad? What's another method to double check, besides hitting it?

 

It does not necessarily mean the MAF is bad, more likely one of the MAF relays are fried. I'd guess the burnoff, but I've seen too many go either way without throwing a code.

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"Only in Britain could it be thought a defect to be “too clever by half.” The probability is that too many people are too stupid by three-quarters."

John Major

 

So do you think I should be worried about it? I havent checked for codes as I just found out that the bulb is missing!! I'll replace it and check for a code.

As I said though, it runs great. What would you do if it was your car?

I'm thinking about a cam change in the summer, could this pose as a problem if the MAF isn't working??

Thanks again

Rob

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1987 IROC-Z Auto (LB9)
Black/grey interior with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods due in March:
K&Ns
RAM Air
Air foil
AFPR

Hoping to get a couple of tenths with that lot

 

Fix it. Plug it in, the car will probably run really rough, or not at all. If so swap out the two relays. They are only like $5 ea.

 

Red Devil

Where are the two relays located? I presume I just take them to a GM dealer and they will know what to replace them with?

Thanks again

 

According to my (new, just got Thursday ) 1982-1992 F body parts and illustration book,
the part number for the MAF relays (burnoff and power are the same) is 10067925. This is for the L98/5.7-8 engines.

The LB9 engine lists a different part # for the burnoff relay: 10094701

On my 90, they are located on the drivers side firewall.

www.partszoneonline.com lists the 10067925 for $5.59 each, plus shipping. The Autozone site lists them for $13.99.
10094701 lists for $8.54 at partszone, and
Autozone has it at $9.99...

The part # for thye relay should be printed on top of the relay itself.

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89 Firebird Formula
WS6 package,ZZ4 Crate engine
SLP 58MM TB, Edelbrock TES Headers
Random Tech 3" cat, SLP 3" stainless exhaust
9 bolt rear, Hotchiss swing arms, Lakewood panhard rod
Corvette 2/4 servo, kevlar band, full poly rear.
Centerline 16x8 rims, B.F Goodrich drag radials