FAQ: Mass Air Flow (MAF) Sensor Issues?

The "upper intake" gasket is the Supercharger gasket. Yes, you'll need one of those too. It does NOT come with the LIM set. You have to buy it separately.

KnottyEagle wrote:

Closer inspection around the injectors today and I can see some more sludge build-up around the front three injectors and also what looks like some orange sludgy stuff. Probably old Dexcool. I know the previous owner said "and I got rid of that orange crap in there". Or, you just never changed it.

Hmmm. "and I got rid of that orange crap" - if that means he drained the radiator and filled it with green, there's probably a brown sludge in there now. The system needs a really good flush and thorough drain before you do the LIM gasket. Whatever you fill it with afterwards (I like DexCool for GM products), be consistent. The two don't mix well at all.

Use a vacuum gauge to diagnose a clogged exhaust.  That will also show you if you have a vacuum leak.  A healthy 3800 will pull a full 20" of vacuum, at idle, in Park, fully warmed up.  If you raise the RPM above idle, again in Park, and run the engine at 1500 RPM, the vacuum should remain steady at 20" or more.  If the vacuum drops off, you are looking at a plugged exhaust.  I have an Autometer boost gauge installed.  It has a vacuum portion of the gauge.

Like the boost gauge, but don't have one.
I will have to look into buying/borrowing a vac gauge.
Maybe a trip to Harbor Freight for that thermometer too.
Thanks for the responses.
Jbird

jbird wrote:

Like the boost gauge, but don't have one.
I will have to look into buying/borrowing a vac gauge.
Maybe a trip to Harbor Freight for that thermometer too.
Thanks for the responses.
Jbird

Try AutoZone or something. They might have a MityVac you can rent or something. Mine has Vacuum and Pressure on it. It's great for diagnosing vacuum-related issues (and many, many other things).

measured my vacuum with my Mityvac, didn't realize I could use it for that, I've only used it for bleeding brakes/clutch on my bike.

it was a solid 20 at idle and rose with RPM's, seems good.
one more thing ruled out.

The new MAF did nothing.

ruling things out slowly but surely.
About time to put it away for winter & let my wallet heal.
Jbird

Hey guys! When I first got my Riv it had just a P0102 code for a MAF. I would clean the MAF with mass air flow sensor cleaner and it would run normal for awhile and the code would come right back. I did this for awhile. Now, I have a P0171 code. I've checked all the usual things like vacuum hoses and I believe my fuel injectors to be working properly. I've also replaced the fuel and air filter.

What I did when my original MAF went bad was I went to a local junkyard and got a MAF off of an Oldsmobile Intrique thinking this will cure my problem. I think it did, but I have no idea if a non-Riviera MAF will work properly with a Riviera. The Intrique MAF was a direct plug-n-play. Took the exact same screws and everything. What I'm trying to get at is, will a non-Riviera MAF work with a Riviera? There's an obvious difference between the Intrique and Riviera in that the Riv is S/C and the Intrique is not. I didn't know if that would mess with anything. I figured that all the MAF has to do is read the air flowing threw the intake, and as long as it does that, it'll work just fine. I could be wrong though and that's why I'm asking here.

As long as the part numbers are the same you should be fine. GM did switch up their MAFs after '99, but I don't know if they changed the part number or not so you might want to stick with a similar/same year.

Just checked the year for the Intrique MAF and It's a 1998. So, I guess I can rule out the MAF as the cause for my lean condition. I hate this! It's like a mix between a scavenger hunt and connect the dots. I think of one possibility, and then it gets ruled out by something else.

I thought I would provide the symptoms of my '96 when it had a bad MAF sensor:

1:  Idle rpm control issues.

2:  Transmission didn't know when to shift and sometimes shifted with a serious "bang". Would stay in 3rd when it normally would have shifted to Overdrive, and lingered longer in the lower gears as well.

3: SES engine light and periodic "Traction Control Off" messages.

4. Periodic engine hesitation/ "missing" (with P0102,  MAF sensor low signal voltage) code. Mostly occurred under medium-high load conditions.  Would occur each day on a particular point in my commute:  60/65 mph going slightly uphill.

If someone would like me to elaborate on this, please reply and I will.

There's a fairly involved back-story but replacing the MAF sensor (there was a P0102 code) did solve the problem.

Just finished the LIM gasket repair, installed rebuilt injectors before this problem.  1996 Riv, 214k miles.

(Edited for clarity/completeness)

Thanks for the report, Brutusk! This info should be helpful to the next guy with mystery MAF symptoms.

Please let us know if your Traction Control lamp returns.