Just bought a 94' Marquis LS

[Sancho61]

Hi guys I just got a 94' marquis 4.6 with about 117k on it. It has the same problem everyone else on this forum has it lacks power. I checked the Maf, TPS sensors and they are fine. I also checked vacuum lines and they are also fine. You cannot floor this car the engine spits and sputters after 3/4 throttle. I am getting code 172 HO2 sensor detects engine lean left bank, 176 Ho2 sensor detects engine lean right bank. What's next?

[79lincolnlover]

Welcome to GMN! 117K is not too much but a tune-up might be in order...New plugs, wires, PCV valve, etc. If you want the best parts, go with Motorcraft. If you want to save some cash, try an after-market brand.

If you experience any other issues, post away

[DriverSideImpact98]

Don't forget new fuel filter.
Maybe try a new O2 sensor too. Not a bad idea to replace it anyways...

[Sancho61]

replaced fuel fliter didnt help, also has a tough time warming up sounds like engine is skipping till it's compleatly warm. plugs were whiteish head gasket maybe? I wan't to find out soon because it pains me to drive this car with it having no balls, it's a sweet car.

[DriverSideImpact98]

White plugs doesn't necessarily mean anythings wrong...but they're probably worn.
That's definitely where I'd start. New plugs and wires.
But if its throwing lean codes... it may be the MAF or EGR valve. How did you check the MAF? I've heard you can clean them with an electric parts cleaner I think the CFC brand makes one called "Lectra-Motive." Take the MAF out and spray it a few off.

[Rizzo]

White plugs doesn't necessarily mean anythings wrong...but they're probably worn.
That's definitely where I'd start. New plugs and wires.
But if its throwing lean codes... it may be the MAF or EGR valve. How did you check the MAF? I've heard you can clean them with an electric parts cleaner I think the CFC brand makes one called "Lectra-Motive." Take the MAF out and spray it a few off.

I mean to back you up not prove you wrong.


CRC makes a MAF cleaner and a non residue electrical contact cleaner.

Pull the PCM fuse OR the battery ground.
Remove the airbox
Spray the MAF wires without touching them with the spray straw.
Let it air dry for 20 minutes.
Replace airbox
Replace the PCM fuse.



Ah..Crap.. OBD I ..

Does OBD I have a KAM code file ? Will his PCM keep treating his clean MAF like a dirty one like OBD II cars will ?

[Lincolnmania]

egr passages in the intake may be clogged up also

[Sancho61]

I checked the Maf sensor using the voltage test same with the TPS sensor. I don't think it's the plug wires.

[DriverSideImpact98]

I mean to back you up not prove you wrong.


CRC makes a MAF cleaner and a non residue electrical contact cleaner.

Pull the PCM fuse OR the battery ground.
Remove the airbox
Spray the MAF wires without touching them with the spray straw.
Let it air dry for 20 minutes.
Replace airbox
Replace the PCM fuse.



Ah..Crap.. OBD I ..

Does OBD I have a KAM code file ? Will his PCM keep treating his clean MAF like a dirty one like OBD II cars will ?

Can't you erase the KAM codes by disconnecting battery for 30 min?

[Rizzo]

Yea, That's in the first line.

But if you pull the PCM fuse instead, you can keep your radio presets

[88grandmarq]

you say its not getting up to operating temp or slow to... have you replaced the T/stat?

[ironstealth]

maybe the engine is just ready to be put out of its misery....


put a 4.10 gear in it~

[Sancho61]

lol don't say that bud i just bought the car, and im not driving around that pos chevy cavalier!

[hemi_fan]

Just curious if you solved this problem. My car is doing the exact same things (slow to warm up, bucks over 1/2 throttle, poor acceleration) but seems fine when warm. I replaced fuel filter, air filter, plugs, and PCV and there was no change. I also had very white looking plugs. I get different codes however, the main one being 332 (EGR did not open/respond during test or if memory code, did not open intermittantly - EVR or PFE). If you fixed it please let me know. My next steps are replace EGR valve and clean passages, but I'm waiting for some warmer weather lol

[Mercury93]

Definatley look at your MAF. I fought my car all summer with the bucking, no power when cold. I had the MAF replaced and it was like driving a brand new car.